Environmental Audit Committee
Sub-Committee on Polar Research
Oral evidence: The UK and the Antarctic Environment, HC 381
Monday 4 December 2023
Ordered by the House of Commons to be published on 4 December 2023.
Members present: James Gray (Chair); Clive Lewis; Caroline Lucas; Jerome Mayhew.
Questions 1-69
Witnesses
I: Professor Anna Hogg, Associate Professor, School of Earth and Environment, University of Leeds; Dr Kaitlin Naughten, Ocean Modeller Amundsen Sea, British Antarctic Survey; Professor Martin Siegert FRSE, Deputy Vice Chancellor (Cornwall), and Professor of Geosciences, University of Exeter, and Chair, UK Arctic and Antarctic Partnerships Committee; and Professor Karen Heywood OBE FRS, Professor, School of Environmental Sciences, University of East Anglia.
II: Dr Tom Hart, Senior Lecturer, Oxford Brookes University; Dr Jasmine Lee, 1851 Research Fellow, Biodiversity, Evolution and Adaptation Team, British Antarctic Survey; Dr Kevin Hughes, Environmental Research and Monitoring Manager, British Antarctic Survey
Written evidence from witnesses:
Professor Karen Heywood et al.
Witnesses: Professor Anna Hogg, Dr Kaitlin Naughten, Professor Martin Siegert and Professor Karen Heywood.
Q1 Chair: I welcome you all to this session of the Environmental Audit Sub-Committee on the Arctic and the Antarctic. This is our first session of inquiry into Antarctica, having produced our report on the Arctic some time ago, in October. Our purpose in today’s session is to seek to assess what is happening or has happened in Antarctica—what it looks like, what the reality is down there and, indeed, what people are doing about it and whether we are making it better or worse. That is a broad summary.
We have two panels. On our first panel, I am delighted that we are hearing from Kaitlin Naughten in person; thank you for taking the trouble to come in from Cambridge. Thank you also for seeing us last week—was it last week? Something like that. Joining us on Zoom, we have Professor Anna Hogg from the University of Leeds, Professor Martin Siegert from Cornwall, Exeter and elsewhere, and Professor Karen Heywood from the University of East Anglia. Rather than asking you to introduce yourselves, which always takes up time needlessly, can I crack on by asking a question that aims to set the scene? How important is the weather and the ice in Antarctica to the rest of the globe? To what degree is Antarctica an influence on the rest of the globe? Kaitlin, since you are here, we will start with you.
Dr Naughten: Thank you for having me. I would like to start by talking about sea level rise. Antarctica locks up a huge amount of freshwater—over 50 metres equivalent of global sea level. One way that Antarctica impacts the rest of the planet is that any change in the size of that freshwater reservoir will raise or lower—in this case, likely raise—sea levels around the world, which impacts coastal communities all around the world. The UK is an island, and it has quite a lot of coast, so Antarctica will directly impact a lot of our communities.
I have some other points, but I imagine that the rest of the panel will want to come in as well.
Q2 Chair: We will come back to you in a moment. What about the rest of our panel?
Professor Hogg: Thank you for inviting me to speak. Kaitlin mentioned the impact from sea level rise, but Antarctica also impacts on weather by influencing atmospheric circulation and wind patterns—it is a very large, high-elevation ice mass, so that is inevitably important. The release of freshwater also impacts on ocean circulation through sea ice formation, salinity and other elements, and Antarctica is, of course, a very large, white ice mass; it impacts the albedo of the globe, as it reflects a lot of the sun’s light back out from the Earth. Those are a number of additional ways, on top of sea level rise, in which Antarctica is important.
If we projected the map of the globe differently, with Antarctica at the centre, we would see a really interesting picture whereby Antarctica connects all of our oceans—the Atlantic, Indian and Pacific—through the circulation between all of them, so we might see it really as the centre of the global system rather than being at the bottom, as we normally see it in maps.
Professor Siegert: I have an additional point to make on the oceans. I suspect that Karen will make the same point and, as she is an oceanographer, she is probably in a better position to answer than I am.
Professor Heywood: I know that you will hear from a second panel on the biological and chemical aspects, but I was just going to point out that the Antarctic is particularly important for absorbing carbon and is the basis of a lot of world fisheries that a lot of people depend on. I know that you will hear more about that later, but it is—
Q3 Chair: We will come on to that in a second. Right now, I want to focus, for a moment, on the importance of Antarctica to the rest of the globe. I will come back to Kaitlin. Are we talking about enormous chunks of ice breaking off, as has often been predicted, or are we talking about ice melting? What in Antarctica will affect the level of the oceans?
Dr Naughten: The main process that is currently causing sea level rise from Antarctica is the melting of the floating ice shelves. Those are the floating bits of the ice sheet, all around the edges. They are in direct contact with the ocean from below, so the ocean melts them from below. That does not directly cause sea level rise, because they are already floating, but, if that melting increases and gets out of equilibrium such that the ice shelves become thinner, then their ability to buttress or hold back that grounded ice—the ice that is flowing in the glaciers on the rock just behind the ice shelves—will be reduced, and those glaciers, in almost all cases, will speed up their flow towards the ocean. That is what directly causes sea level rise; the transfer of ice from where it is resting on the bedrock to either unpinning and becoming an ice shelf or breaking off into the ocean in calving events.
Q4 Chair: Surely glaciers hitting the ocean and melting, or breaking off, is a perfectly natural process? Calving is a perfectly natural process that has happened for centuries. Why is it any worse now than it would normally be? I understand the barrier effect you mentioned, but in a way that is artificial, isn’t it? Surely Antarctic glaciers hitting the ocean and melting is a perfectly natural, normal thing?
Dr Naughten: In a way, you are right. We will always have some amount of basal melting of the ice shelves, but that will be balanced in equilibrium by the flow of the glaciers upstream. You can think of it as a dynamic equilibrium. If you increase basal melting in the ocean such that it is no longer balanced by snowfall accumulation and ice sheet dynamics but by the flow of the glaciers, you can get into a situation where the ice shelves begin to thin or have a retreating ice front. That is what happens if calving—breaking off into icebergs—is out of equilibrium. That is exactly what we are seeing in observations right now.
Professor Siegert: Adding to that, I have a few things to mention about Antarctica and sea level. If you think about how much sea level has risen in the last 150 years, it is about 20 cm or so, but about half of that has happened in the last 30 years. We know from satellite records that the amount of mass being lost by the ice sheets, in Antarctica in particular, is about six times more now than just 30 years ago. So there is an increasing contribution of water from the ice sheets into the ocean, causing sea level rise.
Historically, half of that 20 cm is because the oceans have gotten warmer, and they just expand. The other half is largely because of small valley glaciers all around the world losing mass. Hardly any of it is from Greenland and Antarctica. But here is the thing: today, the contribution of Greenland and Antarctica to that sea level is greater than the glaciers combined, and the contribution of the glaciers and the ice sheets is greater than the thermal expansion. Today, right now, it is the ice sheets that are going to be causing more sea level rise, and into the future that is going to go up. Historically, that has not been so.
Q5 Chair: Briefly on that point, you say that today melt from the ice sheets, whether from Greenland or Antarctica, is greater than from the little glaciers around the world. How would you know that?
Professor Siegert: That is a very good question. We have inventory of the volumes of ice from satellite imagery. There have been a couple of updates to the inventory of total valley glacier ice volume around the world, so we can see how much ice is being lost there. We have all sorts of field-based studies as well, but in Antarctica and Greenland it is satellite records that are giving us a comprehensive understanding of how much ice has been lost in both continents.
Professor Hogg: To add to what Martin and Kaitlin said, it is natural for ice shelves to buttress the grounded ice sheet behind them, but what is different is that we are predominantly seeing these glaciers speed up, because the ice shelves are thinning and reducing in their area. In theory, it would be possible for that process to be reversed—if you had lots more snowfall and allowed the ice shelves to regrow—but the loss is outpacing any potential regrowth at the moment, for the last 40 years where we have records to directly observe it in a comprehensive way. We have seen that almost all the ice shelves in west Antarctica are thinning and reducing in area and losing ice mass. Therefore, the glaciers on the ice sheet behind it are speeding up and losing ice mass, as Kaitlin has explained.
Q6 Chair: Can I pick up on one detail from your previous answer? You mentioned the albedo effect. Does that not apply more to the Arctic than to Antarctica with regards to sea ice? Presumably the acreage of ice in Antarctica has not reduced by all that much, and the albedo effect is therefore less significant than in the Arctic, or am I being simplistic?
Professor Hogg: I was answering your question of why it is important. Obviously, its albedo is white. It is a large white area, so it affects the earth’s albedo. There is also a large growth of sea ice both in the winter and summertime in Antarctica as there is up in the Arctic, so any changes in the area of the sea ice also matter in Antarctica in the same way as they do in the Arctic. Previously, the sea ice in Antarctica was relatively stable in terms of its area in the wintertime. It seemed to not be impacted or to change as rapidly as up in the Arctic. But in the last two to three years, we have seen a dramatic decrease in the sea ice area in Antarctica, as well as in the Arctic. So that’s of concern.
Q7 Chair: What kind of acreage or percentage of the Antarctic sea ice are we talking about here? It is easy with regard to the Arctic, where it is happening four times faster than the rest of the world, so it’s easy to give acreage measurements, as it were. What is the equivalent in Antarctica? How much are we losing?
Professor Hogg: I am not sure whether other panel members might be able to answer in terms of a specific percentage or acreage, but the sea ice in Antarctica grows around the whole continent every winter and decreases—goes almost entirely—during the summertime. What we’re seeing now is affecting the growth of sea ice; in the Weddell sea, in particular, we’ve seen a large reduction in sea ice in the last few years, which we know impacts various different elements of the Antarctic system. Research from the British Antarctic Survey has shown that the decreases in sea ice have had a significant impact on emperor penguin breeding, for example, in recent years. That’s very unusual. We haven’t seen those impacts because the sea ice—
Q8 Chair: We’ll come back to that in a moment. I am just trying to establish exactly what is happening or what has happened. I’m concerned that Karen hasn’t had a word in edgeways yet. Karen.
Professor Heywood: That’s all right; I’m quite happy for the others to talk about the sea ice. I don’t have that particular number to hand that Anna was referring to either—the percentage. We could find it out for you, if you would like, and provide it.
Chair: Martin?
Professor Siegert: Arctic sea ice has been receding pretty much every year—sometimes more, sometimes less—since the 1970s, ever since we’ve been observing it. That’s why it has got such particular focus. Up until 2017, really, Antarctic sea ice has been quite variable; it was growing in 2017, but since then it’s been reducing. In the last year—this last year—it has been reducing by an unprecedented amount. It’s at record low levels. The amount is highly variable. With the Arctic, it’s easy, because there’s the Arctic ocean and it’s all there, whereas the Antarctic sea ice is wrapped around the whole continent. It’s mobile, too, so how do you how do you actually measure it? But the volume of sea ice that ordinarily should be there in the winter compared with where it was this year is staggering—in the order of two or three UK-wide areas worth of sea ice that should have been forming that just wasn’t there at all. When the sun comes back at the start of the springtime, that sunlight will be absorbed by a dark ocean surface rather than being reflected back by a white surface. It is quite significant.
Q9 Chair: What would be quite useful—I’m not sure which of our panel members are best placed to produce this—would be to have some scientific or precise definition of how much Antarctic sea ice has disappeared over the last x number of years. That would be helpful. For the Arctic, you see maps of maximums and minimums every year—that sort of thing. I mention this for one reason: one of the common climate change sceptic arguments—I am not advancing it, I hasten to add, it is merely something people say to me—is, “Oh, it is nothing to worry about. The ice in Antarctica is increasing.” I just want some scientific and precise statistics as to how much it has in fact decreased, which we all know it has done, in recent years. Has one of our panel members volunteered to produce that for the Committee?
Professor Siegert: Yes. Anna and I did a paper on it just last summer, if that would be of interest. I don’t have it specifically to hand, but I can dig it out.
Chair: If you could make sure we have that, that would be great.
Professor Siegert: I can absolutely pass that on, yes.
Professor Heywood: They are correct that it was increasing, but it is very variable, as the others have said. In some areas around Antarctica, the ice may increase for a few years, and in other areas it will decrease. But overall, in the last couple of years, it has really shot down, as Martin was saying. We can get you the number.
Professor Hogg: In answer to your question and the comment that ice in Antarctica is increasing, the sea ice increased and we now see it decreasing. But the land ice, on the ice sheet, which is what directly contributes to sea level rise, has been persistently decreasing in its ice mass since satellite measurements began. That is why we’re seeing the sea level rise contribution from Antarctica being so sustained and in fact, increasing.
Q10 Chair: We may well have had that in written evidence already— in which case we are duplicating it—but from my ignorant standpoint, it would be helpful to have a really clear definition of how much ice has disappeared, over how long, and so on. We have lots of that with regard to the Arctic.
A final question from me: the other argument often advanced by the ignorant is that this is all just part of a natural cycle. That it has all happened many times before over thousands of years. To what degree do you think the reduction in ice that you have described is directly attributable to human activity in the last 100 years, and to what degree might it be attributable to a natural cycle? Who wants to take that first?
Professor Siegert: I can have a go at that. It is a very good question, and something that is on the minds of many climate and polar scientists as well. Every single question that we answer here we have to temper with an appreciation that Antarctica is very much an unexplored territory. I am sure you will appreciate the challenges of quite sparse datasets to try to unravel these things. But it has been the case—as Karen was saying—that Antarctic sea ice had been highly variable until about 2017.
For many climate models, that was quite perplexing because they pretty much all had the Antarctic sea ice reducing in the same way that the Arctic sea ice was. We just did not know why that was the case. Now, it is fair to say that the Arctic oceanographic situation is a lot more simple than the Antarctic, for reasons that Karen will no doubt be able to explain. But what has happened since 2017 has alarmed us because the sea ice loss is now much more in line with those long-term climate models—that is, the sea ice being lost—and the fear is that the Antarctic is now starting to behave like the Arctic does. That means permanent reductions in sea ice, the replacement of a white flat surface with a dark absorbing surface, and additional warming.
We know the Arctic is warming at four times the rate of the rest of the planet, largely through the process of albedo replacement. In Antarctica, we suspect—although it is still early days, because 2017 was not so long ago—that it is starting to warm at about twice the speed as the rest of the planet. It is a real concern.
Q11 Chair: You did not quite answer my question. My question was to what degree—let’s presume it is happening, because I am certain it is—is that ice reduction a natural cycle, as might happen in Antarctica from time to time, and to what degree is it directly attributable to greenhouse gases?
Professor Siegert: It is too early to give a definitive answer on that. We have had Antarctic sea ice loss since 2017, and if you look at the long-term records, there is variability. What we can say this year is that it is at an all-time low—it has never been lower. In the summertime you get somewhere between 4 million and 2 million square kilometres of sea ice; it dwindles down to that level—I am just reading our paper by the way, Anna. Last year, it was less than 2 million square kilometres for the first time ever.
It always difficult to apply certainty to questions like that, but I would say what we have observed in Antarctica is alarming, because that is now more in line with those long-term climate predictions that have been made.
Q12 Chair: I didn’t mean to argue with you, and that is not my place—you know what you are talking about, and I don’t. None the less, what you said a moment ago was, first, you haven’t got the numbers. You can’t tell me precisely how much the ice has reduced; indeed, some people say it has actually increased. You said you can’t tell me whether it is a natural sequence, or directly attributable to greenhouse gases, but then you say it is very alarming. I would say your first two answers indicate it is not that alarming.
Professor Siegert: I don’t think those things are contradictory. There is a lot of variability in the Antarctic system, you have to understand that. I think scientifically to attribute it to a long-term global warming signal, you can look at the climate models and say it is in line with those things—so that is good—and where we are at the moment, which is at an all-time low. You asked my opinion as to whether I think that is to do with burning fossil fuels, and I would say yes, I do. But if you were to say, “Is there more information you would need to add to the certainty of that answer?”, I would say yes, we would probably need more information.
Chair: What do other panellists think? Anna?
Professor Hogg: I agree with everything Martin has said. In Antarctic science, although it is hard to say in a generalised sense whether all the change we see is attributable to anthropogenic climate change, where we are doing really well is in isolated events that take place. Having that range of datasets—lots of information on weather, long-term climate, the environmental setting, and maybe ocean data as well—we can piece all of that together to be more certain about whether those individual events were driven by human activity, such as burning fossil fuels and increasing greenhouse gas emissions. For example, there was a widespread surface melt event on the Antarctic peninsula in its 2019 to 2020 summer, and the evidence and papers suggest that that was directly attributable to fossil fuel burning. That is just one event in one year where scientific literature confirms that that was linked to human activity elsewhere on earth. However, because of the vast size and complexity of linking all of these atmospheric, ocean and ice systems together, generalising it does us a disservice in some ways; it is the detail that really matters in linking all of these processes together.
Q13 Jerome Mayhew: We have heard that the Arctic has been warming about four times as fast as the rest of the globe, and yet, Martin, you were saying a moment ago that your estimate is that Antarctica is warming about twice as fast as the rest of the globe. Can you unpack that for me? You may not be able to answer with certainty, but what is your working assumption as to why that is the case? Why is it different from both the rest of the globe and the Arctic?
Professor Siegert: The main reason why the Arctic is warming so much more is because of the loss of that reflective surface. That solar energy would ordinarily be bounced back out into space because it would be reflecting off snow and ice surfaces. Instead, that energy is being absorbed by either the ocean—if it was sea ice on water—or the land, if it is snow and ice cover that is receding. That has been going on for some time, and that is why there is an additional heat component in the Arctic causing that additional warming that we know about.
In the Antarctic, the changes have been less obvious although, since 2017, as I said earlier, it does now look like things are changing. The amount of opportunity for that process to occur in Antarctica has just been less than it had been in the Arctic, hence it is warming up at not such a great rate.
Q14 Jerome Mayhew: Have you got a theory as to why, up until and including 2017, the sea ice in the Antarctic was not following the same pattern as in the Arctic?
Professor Siegert: That is a great question, and we need to understand the complexity of the Southern ocean and the polar oceans, compared to the Antarctic versus the Arctic. Maybe Karen can give you a brief tutorial on that, but they are very different oceanographic settings, and I think that that is probably what we should look to to understand the differences.
Dr Naughten: I am happy to jump in here. The sea ice loss since 2017 is still so recent that there has not been as much research done on it as we would like, but there is some emerging research suggesting that it could be influenced by the build-up and release of heat in the Southern ocean. While the sea ice was slowly growing, the heat in the Southern ocean was trapped beneath the surface, but there is a hypothesis that that is now being released to the surface and contributing to the melting of ice.
Jerome Mayhew: Does anyone else want to come in?
Professor Hogg: Just to add to that, we are talking a lot about the extent of sea ice, but it is important to consider the thickness of the sea ice as well. Up in the Arctic, the sea ice is much thinner than it is in the Antarctic. In the Antarctic, because some sea ice lasts for multiple winters, it can become much thicker. We have methods for measuring the thickness of the ice, but that is also an important factor to consider when you are looking at the area changes. If it is substantially thicker, it will take longer for it eventually to melt away, so we need to consider that.
That is complicated in Antarctica because we have much less certainty about the amount of snow that falls on to the sea ice. As you can imagine, that is really hard to measure because the sea ice moves around so, while we might be able to measure the weather at a certain point to say that we expect a certain amount of snowfall to take place in that area, we have to move that around on the surface of the ocean as well because the sea ice is moving.
On top of that, we have far fewer in-situ measurements of the actual snow depth on top of the sea ice in the Antarctic because the field logistics would just be vast. The area is much larger and is much more inaccessible than the Arctic, where we have many more measurements of both the thickness of the ice and the snow depth on the ice to help us solve some of those problems.
Jerome Mayhew: Karen, do you have anything to add before I move on?
Professor Heywood: The point I would make is that, in some ways, the Southern ocean is a bit like the Arctic in that, once the sea ice is gone, the winds have access to bring that warm water up towards the surface. One reason why we are concerned about the loss of sea ice is that, in turn, it can warm the surface ocean and therefore make the formation of more sea ice even less likely. Once these processes start, there is very complicated feedback between ocean sea ice and the atmosphere. That is why we are all interested to know and, as the other speakers have said, I do not think we know the answers just yet.
Q15 Jerome Mayhew: I understand that there is no scientific certainty about this, but if your working hypotheses are correct, what should we expect to see in the next five years with sea ice cover in Antarctica? What would make you say, “Okay. This is supporting this thesis”, and what would make you say, “Actually, no; we need to think again”? Martin, perhaps you could start.
Professor Siegert: That is a very good question. I think the next five years will be quite telling, because what we have observed since 2017 appears to be a trend—a signal—and the next five years will determine whether that goes on. If the record ice loss we have observed this year turns out to be a one-off and in two or three years’ time it actually starts to build again, we might be able to infer more variability on the time series, if you like. But if what we see is continuing ice loss at or near these record levels, then that will be a major concern because, as Karen and Anna were saying, that equates to more heat being retained and absorbed in the ocean. The hypothesis, as Karen alluded to, is that if the heat prevents sea ice from forming and growing, we will see that in the next few years for sure. That will then be a major concern at a local level and, as we said right from the beginning, at a planetary level as well.
Professor Hogg: One other thing that it is useful to consider is that the sea ice in Antarctica is between a metre and 10 metres thick in total—obviously, it can be thinner than that as it starts to form—whereas the thickness of ice on the ice sheet is up to 4 kilometres thick at its thickest. Ice shelves are where the ice from the ice sheet has flowed out over the ocean, and they are about 300 metres thick around the margins of Antarctica. If we have a return to the colder weather that enables the sea ice to reform, it will reform and the sea ice can start to regrow again. However, ice shelves have collapsed and reduced in area and the ice sheet has suffered persistent long-term thinning at rates of around 9 metres a year—the height of a three-storey building per year—so it is very much harder to quickly recover that volume of ice. The different scales of the sea ice, the ice shelves and the ice sheet are worth noting, as is their respective ice thicknesses and the difficulties they would have in recovering over time if weather changes.
Q16 Jerome Mayhew: I have overshot my timeframe, but would very quickly like to ask about the heat we experienced in 2020 and 2022. We had, relatively speaking, very high temperatures in Antarctica. Why did we have them and are we going to see more of them? Who feels comfortable answering? Martin, your hand went up straight away.
Professor Siegert: They were two very different events. The one in 2020 was largely located in the northern tip of the Antarctic peninsula—north of 66° south, we should say. It is not uncommon for those regions to experience some warmth. The Antarctic is largely climatically isolated from the rest of the planet by the polar vortex and the Southern ocean, which enwraps it. It was opened 36 million years ago by the Drake passage, which separated the Antarctic peninsula from South America. It plunged Antarctica into the deep freeze, if you like. It is isolated. In the Arctic, you get this longitudinal transfer of heat from the low latitudes to the high latitudes—storm tracks which go up. For example, it is not uncommon in Svalbard, which is nearly 80° north, to have temperatures in the summertime in the teens—15°C or 16°C or so. However, it is really unusual to get that sort of thing anywhere near that latitude in the Antarctic, but there are two events that spring to mind. One was in the northern part of the Antarctic peninsula around Seymour island and the other place is where I think the record temperature is about 18.6°C, which is the highest temperature ever recorded on the Antarctic mainland.
In March 2022, when a very strong jet or atmospheric flow penetrated through the polar vortex, largely from Australia, deep into east Antarctica at a totally unprecedented level, that raised temperatures there by about 38°C—not to 38°C, but by 38°C. That is the highest heatwave, in terms of variation from the normal, that has ever been recorded on the planet and it moved temperatures in the middle of east Antarctica, which should have been more like -50°C, to something more like -12°C. It was in the autumn time, but if it had been in the high summer it is possible that we might have had a melt event really high up on the east Antarctic ice sheet, at the summit. Frankly, it would be unprecedented to have anything like that, so it is deeply concerning.
I am trying to predict what your next question would be. Is it to do with fumes? The first incident has had an attribution study to it, so the highest temperature recorded on the continent of Antarctica has been attributed to the burning of fossil fuels, but the second one hasn’t been. The reason for that is that we simply do not have sufficient amounts of meteorological data to be able to do a compare and contrast in the scientific way that you would need to do in order to do a proper attribution study, but the suspicion is that it is caused by burning fossil fuels.
Q17 Caroline Lucas: Picking up where you have just left off, I wanted to ask what effect climate change is having on the Antarctic ice sheet and whether or not those effects are uniform or whether different parts of the continent are responding in different ways? I was going to come originally to Professor Hogg.
Chair: Kaitlin has volunteered to answer that.
Dr Naughten: I am happy to let Anna start, if she would like to.
Q18 Caroline Lucas: Let’s go to Anna and then come to Kaitlin.
Professor Hogg: There have been huge impacts of change happening in Antarctica. We have seen glaciers speeding up by over 50%; we have seen glaciers thinning as well—as everybody mentioned, nine meters per year over very large areas—the height of a three-storey building. This is dramatic and big.
We have seen widespread surface melt in parts of the continent, in particular on the Antarctic peninsula, but approaching towards west Antarctica. These melt events not only melt the surface of the ice but cause surface water ponding which, as we have seen, can cause ice-shaft collapse.
We can see that these are extreme weather events. Martin was just talking about an air temperature increase, but we have also seen that there can be large variability in the amount of snowfall on to the continent, which is really important, because when there is a snowfall drought—no snow falls—then the ice that is flowing out into the ocean is not being replenished, so we have a large amount of ice mass loss. Equally, on the reverse side of things, if we have very, very large amounts of snowfall dumped on the continent, it can actually modulate and mitigate the amount of mass loss that we have in general from some glaciers. We have seen examples of that in west Antarctica.
In general, the vast majority of the ice loss in Antarctica—and Antarctica overall is losing mass—is concentrated in west Antarctica—the Amundsen Sea embayment. The Pine Island glacier, Thwaites glacier and the Pope, Smith and Kohler catchments are changing dramatically within our lifetimes—within years, in fact. However, there is also a large amount of ice loss happening on the Antarctic peninsula.
If we look at the relative contribution to sea level rise, we know that overall Antarctica is contributing about 7.5 mm of ice to sea level rise since the 1990s, and on a per-year basis Antarctica at the Antarctic peninsula has lost about 20 gigatonnes of ice per year and west Antarctica has lost about 94 gigatonnes of ice per year. In east Antarctica, we have a huge amount of uncertainty as to what is going on in general. It is the most remote part of Antarctica research. We think that over the same 25-year period it has gained about 5 gigatonnes of ice per year, but that is very uncertain. The uncertainty is about 46 gigatonnes, plus or minus, so you can see that it is very hard for us to say whether that plus 5 gigatonnes is statistically significant. Hopefully that paints a picture of the dramatic changes and where they are primarily occurring.
Caroline Lucas: It does—that is very helpful.
Dr Naughten: Anna gave a great overview. I would like to add something on the processes behind these changes. As Anna said, the most substantial ice sheet loss is in west Antarctica, and we believe that that is driven by the ocean causing basal melting of ice shelves. As I claimed earlier, that causes the glaciers to speed up. The Antarctic peninsula is probably a combination of the atmosphere and the ocean driving the ice thaws. In east Antarctica, there is gain of ice. That could be due to increased snowfall in a warmer climate, because Antarctica is just so cold. The best temperature for snow is actually closer to the freezing point, so if it is extremely cold, as you warm it up you generally increase snowfall.
Q19 Caroline Lucas: What do past changes to the Antarctic ice sheet tell us about how it will change in the future? You mentioned the ice shelves. Are they responding to warming in the same way? If not, why not?
Dr Naughten: I would like to bring up one paleoclimate event of the last interglacial, which was the time before the most recent ice age. This was about 120,000 years ago. The global average temperature was about 1° warmer than our pre-industrial, so that is very similar to today, but it was elevated for long enough that the ice sheet was able to respond more fully. The sea level globally was at least 6 metres higher than at present, and we cannot explain that without a substantial contribution from Antarctica. We think that Antarctica was very much smaller in the last interglacial, which is a worrying analogue to today, when temperatures are very similar. Today the rate of change of climate is substantially faster than the interglacial cycles. That is the paleoclimate event that I am most familiar with, but I imagine the rest of the panel could have some other examples.
Professor Hogg: You asked about ice shelves as well as the ice sheet. We know that over the last 25 years, 71 of the 162 ice shelves in Antarctica have reduced in their ice mass. We think that that has released about 67 trillion tonnes of ice into the ocean. Some 62 ice shelves have experienced no significant change, and 29 ice shelves have gained mass. Very few of these ice shelves are gaining mass in comparison with the amount of ice shelves losing mass. For ice shelves to regrow and recover when they have had a big iceberg calved off them or if they have thinned, we need the flow of ice behind them to push that ice out over the ocean to extend them further. That takes years—actually decades. There have been news reports of these extremely large iceberg calving events we have had in the last few years, but what is not appreciated is that we need decades for the ice to regrow without calving again for the area lost in the big calving events to recover. In terms of the significance and how that informs future evolution of the Antarctic ice sheet and its environment, that is important to note.
Ultimately, if we look at the overall sea level contribution from Antarctica and how what is happening now will impact what will happen in the future, we know that ice loss from Antarctica is tracking the high end of IPCC projections—not the mid or low-level projections, but the high-end projections. That is what the observations show us is currently happening. We might have thought that the mid-level projection was our median, average estimate of what the future sea level rise would be, but that would be wrong based on the observations, which show currently that the high-end projections are more likely, because that is what the observations are tracking today.
Q20 Caroline Lucas: That is pretty terrifying—thank you. Before I bring in both Karen and Martin, at the same time as reflecting on that question could you also answer how vulnerable you think the Thwaites glacier is? Could it collapse? If so, what are the implications for the west Antarctic ice sheet?
Professor Heywood: I agree with all the comments that have been made so far. I want to respond to your question about why different ice shelves are responding in very different ways, which is very much a research question. Partly it is that, as we have heard, the west Antarctic ice sheet is very close to the ocean. There is a relatively warm Antarctic circumpolar current going round Antarctica, and it is bringing that heat closer to those vulnerable ice shelves. What is slightly intriguing is that, as Anna was alluding to, you can have adjacent ice shelves that you might think are experiencing the same ocean forcing, and yet are not melting at the same rate. That is one of the big uncertainties, and it is very under-observed. It is very much a research question.
You asked about Thwaites. Yes, it is vulnerable and potentially it might collapse—the glaciologists on the panel will know much more than me about that. Most of us working on Thwaites are a little wary of the “doomsday glacier” name, because that is overselling it. One would not want to give the impression that it is about to crumble away next year, but I will let our glaciologists respond to that.
Professor Siegert: In terms of how the past can guide our future, Kaitlin explained nicely the last interglacial, and actually we can go a little further back in time than that. The last time the atmospheric greenhouse gas and carbon dioxide concentrations were similar to what they are now were in the Pliocene, which was about 5 million to 3.5 million years ago. The CO2 level was upwards of 400 parts per million, just like it is today, but the temperature equilibrated at a higher level than it is right now—ocean systems and other things are making the difference.
The temperature in the Pliocene at various times was somewhere between 3° and 4° warmer than it is today, and as a consequence of that warming the sea level globally was at times over 20 metres higher than it is today. With 6 metres of sea level rise, you can kind of implicate Antarctica as contributing to some of that, but when you are talking about 20 metres of sea level rise, you pretty much cannot get that without the complete deglaciation of west Antarctica and some bits of east Antarctica. That is why we are really concerned. If we do not keep temperatures to the 1.5° scenario, or another 0.3° of warming, and let things drift to 3° or 4° of warming, the whole of the Antarctic ice sheet will become vulnerable—as will the Greenland ice sheet, by the way—and we start to unlock metres of sea level rises in our near and distant future. That is why we are worried about it.
The issue with the Thwaites glacier is an interesting geometrical feature. The ice is resting on a bed, but that bed is way below sea level. At the grounding line, it is 500 metres or so below sea level, but as you go into the ice sheet centre, the grounding of the ice is, at one place, 2.5 km below sea level. As the ice starts to retreat from where it is at the moment, it goes into deeper and deeper territory, and that accelerates further ice and mass loss. That is why we are concerned about Thwaites glacier, unlike some other places that are losing mass but seem to have some topographic pinning points that might prevent the ice from moving further. Pine Island glacier is a good example, as it is contained within a topography that really wouldn’t amount to a significant amount of ice loss, but that is not true of Thwaites glacier. If it starts to retreat, the whole of the west Antarctic ice sheet is impacted.
Q21 Caroline Lucas: Terrifying. I have one last question: to what extent do we know whether there are specific thresholds that would lead to irreversible loss of all or part of Antarctic ice sheets, either in terms of CO2 levels or heat? Obviously, you are describing scenarios and we are looking back millions of years and trying to extrapolate. Beyond 1.5°, is there anything that we as policymakers should be focusing on as a key threshold not to pass?
Dr Naughten: I can add something here. There has been one study that suggests there is a tipping point of stability of the west Antarctic sheet somewhere between 1°C and 2°C above pre-industrial. That is one finding of evidence for the 1.5°C targets. There is one thing that we are concerned about. Martin explained why the bedrock of Thwaites glacier is so vulnerable to retreat. It is called the marine ice sheet instability. There will probably come a point where, even if the global climate returned to pre-industrial levels, the geometric feedbacks within the ice sheet would cause the retreat to continue. When glaciologists say “irreversible retreat”, this is usually what they are talking about. Even if you take all the climate forcing away and bring it back to where the climate started, the ice retreat keeps going.
The latest research suggests that we are not quite at that point, but it might be getting close. There is a lot of model disagreement, but that is one definition of what people mean when they say “tipping point.” Obviously it is quite concerning if we reach that point.
Chair: Before we move on, can I ask our witnesses to be brief because we have only a quarter of an hour left? Clive Lewis is next.
Clive Lewis: Thank you, Chair—
Chair: I should be saying that to myself, actually.
Q22 Clive Lewis: Dr Naughten, can I ask you first? Can we predict the Antarctic sea melt and sea level rises that might occur? How much of that is inescapable and will happen? How much can we adapt to it in the next couple of decades, or perhaps in the longer term, next century—if we are still here?
Dr Naughten: It is hard to give an exact number, but we know the number is greater than zero because we have already seen that the sea level rise is accelerating. In the language of the IPCC, “It is virtually certain” that the sea level rise will continue. Even if all climate change stops, the sea level rise will not stop in its tracks. The IPCC’s projections from the latest report are that by 2100 the range from about 30 cm to 1 metre in sea level rise is dependent on the emissions scenario. There is quite a lot of uncertainty wrapped up in that—uncertainty about what the ocean will do, about what snowfall will do and about ice sheet processes—but 2100 is very much the beginning of the story. Ice sheets respond. In millennial timescales it will take thousands of years for their response to today’s climate change to fully play out. By 2300, even in the best case emissions scenario, you could see as much as 3 metres of global sea level rise, but that of course is very uncertain. The farther in the future you go, the harder it is to constrain all these uncertainties.
Q23 Clive Lewis: Professor Heywood, Professor Siegert, can you extrapolate from those potential sea level rises and talk us through the various impacts that they could have on the UK, and on low-level islands in the Caribbean, for example? I am interested to hear from you what effect those sea level increases will have on the UK and on the low-level islands around the world that we have heard so much about.
Professor Heywood: Do you want to go first, Martin?
Professor Siegert: Yes, I will start. It is an interesting phenomenon. These ice masses in Greenland and Antarctica are so huge and have so much mass that they have a significant gravitational attraction. As the ice in either Greenland or Antarctica starts to melt away and the mass is lost, bizarrely, the reduced gravitational attraction causes the sea level close to those ice sheets to go down. It’s really weird. But the further away from the ice sheets you go, that effect is negated. Interestingly, if the Greenland ice sheet changes mass, in the UK we don’t see much sea level rise at all, but the further away from us you get, you do seem to see that. We are on the other side of the planet from Antarctica, so mass loss in Antarctica will be felt in sea level equivalent terms across the UK and other northern latitudes. The mid latitudes on the planet—the low-lying Pacific nations, for example—will unfortunately get hit from both sides. They will be hit by changes in the Arctic and Greenland ice sheet and the Antarctic. That is why we are particularly worried about them: they are low lying and they will be receiving sea level rise issues from both places.
Professor Heywood: To follow on from that, as a resident of East Anglia, I am, like you, concerned about the impact on the UK. I am certain that the sea level rise that we are experiencing at the moment will have an impact on the erosion of UK coastlines. It is not just the average sea level rise that matters, but the fact that you can get storm surges and extreme events. For example, we will have to lower the Thames barrier and use it much more often, which will have a real impact on the UK’s economy.
You talked about small island states. Yes, I think it is a huge concern for them. Around the world, many countries have a large number of people living within the area that would be affected by extreme events exacerbated by sea level rise.
Q24 Clive Lewis: I get the impression that if sea levels are going to continue to increase irrespective of what we do, we are looking at some quite severe impacts that are beyond our control.
Professor Siegert: Yes. We did a paper a few weeks ago called “The Zero Emissions Commitment”. It sounds a bit of a mouthful, but it is basically about what the world is committed to after net zero is achieved, say in 2050. Say that by 2050 we have reduced carbon emissions to net zero and the world is 1.5°C warmer than it should be. What happens 10, 20 or 30 years afterwards? Does the world continue to warm or does it not?
It is very interesting. There is a bit of variability and uncertainty, but by and large, the worlds stops warming and everything seems to equilibrate pretty quickly, with the exception of one item: sea level rise. That just keeps going because it is a dynamic process that we have unlocked. It will happen irrespective of what we do to the climate because of the marine ice sheet instability that Kaitlin referred to earlier. The question isn’t about whether sea level rises will stop going up, but how much they will go up. Are we going to get by with tens of centimetres in this century, or will it be a metre or even more? Of course, it doesn’t stop at 2100; it goes on afterwards and so on. So it is about how much sea level rise we have now locked into our future, and the rate of that sea level change over the coming decades. It is going to happen, unfortunately.
Q25 Clive Lewis: In many ways, the decisions that we take now will determine what happens as we go further along that timeline. The greater potential impact is on future generations, so the decisions we take now may not actually affect us, but they will affect people later on.
Professor Siegert: Yes, absolutely. If we hit zero emissions and the world equilibrates when the temperature is 2°C, that will have a much more significant consequence for sea levels and the rate of sea level change than if we equilibrate at 1.5°C.
To answer the previous question about a threshold, we have already reached the threshold. We have unlocked the sea level issue; it is starting to happen. We can see it happening at an accelerating rate and that will continue.
Q26 Caroline Lucas: It is a bit relentless. Sorry, I need to take a breath after that. It is really worrying.
I want to ask Karen some questions about the Southern ocean. What role does it play in global climate and the global carbon cycle, and will changes in the Southern ocean slow or accelerate the pace of climate change?
Professor Heywood: Those are very good questions. In some ways, they link with the questions that we have covered already. The Southern ocean determines decadal and long-term climate. It impacts on our weather because it is a huge source or store of heat, so it determines the longer-term decadal variability of our climate system.
I suppose Antarctica and the Southern ocean cool the deep ocean. It is where most of the heat is lost from the ocean to the atmosphere. The very deep ocean is cold because of the heat that is lost around Antarctica. The impact of that is felt through the sea ice that we talked about earlier and through atmospheric weather not just in the southern hemisphere, but globally. Many studies show that if you make changes in climate models around Antarctica, it has a global impact. It can affect rainfall and temperature in different places around the world. It is not isolated around Antarctica.
Turning to carbon, the Southern ocean is absolutely crucial for the carbon cycle. About 10% of the carbon dioxide that we emit is absorbed by the Southern ocean. The impact of that is that it is slowing down the climate change that we are experiencing. It is vital for soaking up—like a sponge—the carbon dioxide that we are emitting.
There is a lot of literature on what is happening to the Southern ocean carbon sink, as it is called. Some people think it is increasing and some think it is decreasing. To be honest, it is one of the big uncertainties. We do not have enough observations to know what is going to happen in future. Understanding what happens to that carbon sink in the next few decades is a huge research question that many people are trying to unravel. It involves all the different aspects that we have talked about. It also involves the wind fields—what happens to the winds over the Southern ocean.
Of course, carbon does not just affect climate; it also impacts on the creatures that live in the ocean, through ocean acidification. These are very big questions. I don’t know if that answers your question.
Caroline Lucas: It does, although my colleague Jerome wants to ask something.
Q27 Jerome Mayhew: I was just interested in why. How does the Southern ocean absorb 10% of carbon dioxide? What is the mechanism by which it achieves that?
Professor Heywood: The carbon dioxide gets into the water and is then taken up by the phytoplankton—essentially the grasses of the oceans. They will absorb the carbon and emit oxygen, and when they get eaten by other things, like krill, which eventually excrete the carbon, it is carried down into the deep ocean.
Q28 Caroline Lucas: Thank you. I am anxious about time, so, very quickly—Martin?
Professor Siegert: Just to add briefly to that, the Southern ocean is the most biologically productive ocean in the world. It is teeming with life. That life is full of carbon, and that carbon comes ultimately from the atmosphere. That is why it is critical.
Q29 Caroline Lucas: I have a question for Kaitlin. How will warming in the Southern ocean and atmosphere affect the Antarctic ice sheet, particularly the ice shelves and ice sheet margins?
Dr Naughten: Two different processes are happening here. The first is that the upper parts of the Southern ocean, to the north of the Southern ocean, are warming from the top down, essentially absorbing heat from the atmosphere, but that doesn’t actually reach the ice sheet, because we don’t see that surface warming farther south, into the sea ice zone.
There is an entirely different process, and for this we don’t have enough observations to confirm, but our understanding from models is that the transport of sub-surface warm water, which Karen was alluding to earlier—it is called circumpolar deep water. It is about 1°, which in terms of Antarctic oceanography is very warm indeed. It is in the deep ocean, a few hundred metres below the surface, and some of it is carried on to the continental shelf of Antarctica. This is where it causes rapid melting, in west Antarctica. What models suggest is happening is that the sub-surface ocean currents, which carry this warm water on to the continental shelf, are speeding up. We are still unpicking all the processes that cause it to speed up. It might not be a direct response to atmospheric warming; it might be instead a response to changes in the winds or changes in the sea ice. I mentioned that we cannot confirm this is happening with observations. That is because observations of this part of the ocean began only in 1994, in the Amundsen sea region, and that is just too soon to be able to detect a trend. It is possible that it is warming; it is just that we haven’t been looking at it for long enough to see that trend yet.
Q30 Caroline Lucas: Karen, you touched on this question, and I don’t know whether there is anything more to add. How are the reduced sea ice and freshwater from melting glaciers impacting the Southern ocean and, in particular, what potential does that have to affect ocean circulation?
Professor Heywood: That is a really good question, because there is a lot of freshwater coming off the glaciers, as we have heard, from the ice mass loss. That is like a lid on the ocean. It means that the interaction between the ocean and the atmosphere is stopped by this freshwater lid on the top. Counterintuitively, that can lead to more sea ice in some locations.
There are now a lot of studies showing that one of the impacts of that freshwater being added to the ocean is that it goes all the way round Antarctica—from the Antarctic peninsula right round into the Bellingshausen sea and the Amundsen sea, which we have been talking about. Those oceans—the shelf seas—are getting fresher, and that is impacting the deep ocean, the dense water that is forming. So there are a lot of impacts on ocean circulation, because if that dense water is changing, that is part of our global ocean circulation. We can now see those changes happening in the deep water, which we believe are probably due to the increased ice mass loss round Antarctica.
Q31 Caroline Lucas: I will bring Anna in, but I wonder whether I can throw you the last question at the same time, Anna, and you can roll the two into one, although it is a slightly different question. Antarctic sea ice was expanding until 2016. Do we know why it has started to contract now? Was that because we passed one of those thresholds? Do we have a sense of what happened around 2016 that made that difference?
Professor Hogg: I will start with the previous question. It is important to note that in Antarctica almost all the ice loss we see from the ice sheet is caused, we think, by the warming of the ocean and the warm ocean water getting in and melting the ice. As Kaitlin has said, when the circumpolar deep water gets in and on to the continental shelf, the depth of the thermocline really impacts, because the ice is 500 metres to 800 metres thick—it’s grounded below sea level, as Martin mentioned in answer to a previous question. That can really erode, and accelerate ice melt in west Antarctica.
We think that, on the Antarctic peninsula, the ice loss is more of a mix between warm ocean water getting in and surface melt from atmospheric processes causing ice loss. That can lead to an increase in the freshwater input into the ocean—because surface melt is freshwater—as well as ice mass loss. That then impacts in the little fjords, because there are hundreds of glaciers on the Antarctic peninsula.
Kaitlin, you gave quite a good answer earlier in this session about why the sea ice started in 2016, so maybe I could hand back to you to say that again.
Dr Naughten: For sure. That is bringing it back to the build-up and release of heat in the sub-surface ocean. We think that that heat did not actually reach the surface, where it could access the sea ice, until around 2016. This is very preliminary, so I want to caution that we do not fully understand why that sudden flip from slow expansion to sudden decline happened. It is something that we are very interested in and are studying as much as we can.
Chair: We probably ought to move on, Caroline, if that is all right by you. May I thank our panellists? It has been a fascinating first session with—just for the record—Professor Anna Hogg, associate professor at the School of Earth and Environment, University of Leeds; Dr Kaitlin Naughten, who is ocean modeller of the Amundsen sea at BAS; Professor Martin Siegert, deputy vice chancellor in Cornwall and professor of geosciences at the University of Exeter, and chair of the UK Arctic and Antarctic Partnerships Committee; and Professor Karen Heywood, who is professor at the School of Environmental Sciences, University of East Anglia.
Thank you all very much for your time and your evidence. Your evidence will be a very important part of the beginning of our inquiries, which will stretch over the next few months. We hope that our final report will meet with your approval and that you will see your influence on it. Thank you very much indeed for your time.
Witnesses: Dr Tom Hart, Dr Jasmine Lee and Dr Kevin Hughes.
Q32 Chair: We come to our second panel of the afternoon, which will look at the consequences, particularly with regard to biodiversity, of the very alarming changes that we heard about in our first panel this afternoon. We are delighted to welcome Dr Kevin Hughes, environmental research and monitoring manager at BAS; Dr Jasmine Lee, 1851 research fellow—you will have to tell us why it is “1851”—in the biodiversity, evolution and adaptation team at BAS; and Dr Tom Hart, senior lecturer and penguinologist at Oxford Brookes University.
It is very easy to imagine huge biodiversity in many parts of the world, but how important is Antarctica for biodiversity?
Dr Lee: That is a great question, and it is something that we think a lot about. I think we should start by saying that Antarctic biodiversity is globally unique, and that is one of the reasons that it is so important. Antarctica itself is considered one of the last remaining wildernesses on the planet—one of these pristine places—and the ecosystems that rely on it have remained largely untouched until recently. Antarctica has a really high level of endemic species in both the marine and the terrestrial environments. This means that there is a large proportion of species that are found nowhere else on the planet, including things such as the Adélie and emperor penguins.
This high endemism is due to the isolation of both the continent and the continental shelf, which have remained isolated from the rest of the world for almost 30 million years. The marine realm is extremely diverse and, as we just heard from Martin, extremely productive. The high level of diversity in the marine realm, which in some near-shore environments is estimated to be more diverse than coral reefs, is thought to be largely due to the isolation, age and large number of habitats in a very small area. So this diversity also results in diversity in the species that live there.
In the terrestrial realm, there are a high number of endemic species. They survive almost exclusively in permanently ice-free areas—you can think of these small islands of rock that extrude up through the ice and snow. They are found primarily around the coastline. A lot of the terrestrial biodiversity is around the coast. As you go inwards, it becomes less diverse.
The unique thing about all of these species is that they are extremely well adapted to the extremes. Antarctica is the coldest, windiest continent on Earth. It is also the driest, and it has extreme seasonality: 100% daylight in summer, and none in winter. All of the species are extremely well adapted to those kinds of conditions. That is one of the reasons why they are so important.
Q33 Chair: I sail to Dr Hart, who wants to talk about penguins.
Dr Hart: Always! I think that is a very good summary. Those adaptations are also what makes them vulnerable to climate change, pollution and human interference. As Jasmine said, they are very well adapted to seasonality. The previous panel talked about magnitude of change and uncertainty. We do not need very much difference in the abiotic in snow and ice before we see a completely different habitat for things like penguins. One degree centigrade of difference in Antarctica makes the difference between whether you can walk on the sea or whether you are swimming—a complete difference to the adaptation for, say, an emperor penguin versus an Adélie.
Broadly speaking, that is a lot of the change we are seeing. We are seeing the Antarctic specialists declining where habitat is changing fast, and we are seeing more generalists come in and take over in that area. It is also relevant that Antarctica is not homogeneous. The liveable bit is the peninsula and the islands. That is where we get all the great diversity. The Antarctic peninsula, the South Shetlands, the South Orkneys, the South Sandwich Islands and South Georgia is where we get the real biomass.
Q34 Chair: Are we right in believing that the emperor penguin population is declining very sharply?
Dr Hart: It is exceptionally hard to tell. The previous panel mentioned breeding failure—these are very long-lived species, so we actually expect that within their lifetime. The fact that it is the first time we have ever seen it is a concern. We are seeing similar patterns across other species. The emperor penguin is iconic, but we are seeing changes in all of the penguins around Antarctica. While we are on penguins, the other thing is that they are not necessarily representative of everything. The good thing about penguins is that we can see them and count them. What we cannot see, count or monitor is the concern. That is the big knowledge gap.
Q35 Chair: Dr Hughes, you look as if you are keen to come in.
Dr Hughes: It is very easy to talk about the charismatic species such as penguins, whales and seals, but what people forget is that Antarctica is continent for microorganisms. As you go away from the coast, that is really all you get in terms of life. You might get the odd little bit of lichen, but really it is dominated by viruses, bacteria and fungi. You get some of the most diverse microbial communities of anywhere on the planet. That has potential for all sorts of discoveries in terms of biotechnology—just a little word for the microbes there.
Q36 Chair: Can I ask an ignorant question? When I think of biodiversity, I do not think of microbiology of the kind you describe. Am I just being ignorant there? I do think about animals and birds and all that—do you think we should include things we cannot see?
Dr Hughes: Absolutely. In some parts of the continent, the only life you will see is a microbial mat: a very complex set of microorganisms interacting very closely and in a very specialist way to be able to survive in the extreme conditions. I would absolutely include the microbes. The protocol itself mentions microorganisms as something to be looked after.
Q37 Chair: You have not mentioned much about krill. Is it right that the krill are moving south from South Georgia down towards Antarctica? Is that having an effect on the general biodiversity of Antarctica?
Dr Hart: Yes. If I can speak for krill, I think that in terms of biology, krill are all we should be concerned about. That is absolutely the main uncertainty and the main worry. There is pretty good evidence that it is, on average, moving south. It relies on sea ice to breed, so there is a mechanism, as well as some empirical evidence—
Q38 Chair: Sorry to interrupt. Is that correct that krill rely on sea ice to breed?
Dr Hart: Yes, one of their life stages is under sea ice.
Chair: I had never twigged that; I did not realise.
Dr Hart: In a savanna ecosystem, there is light hitting grass and bison grazing on grass and that kind of thing; if you flip that upside down, that is a sea-ice ecosystem. There are loads of phytoplankton, zooplankton and krill foraging under that, which get released every year when the sea ice melts.
One of the most important species is Antarctica is krill, which is relatively unknown. It is very hard to monitor change in krill populations, particularly any kind of sudden change.
Q39 Chair: This is perhaps an absurdly extreme argument, but if the sea ice were to disappear in the Antarctic, as seems likely to happen in the Arctic, you are saying that the krill would disappear. That would have a huge effect on all of the rest of the biodiversity of the Southern ocean and Antarctica, would it not?
Dr Hart: Yes, and that is extreme, but, to some degree, we would expect that magnitude of change.
Q40 Chair: That is very significant. Can I ask you, very briefly, about the environmental protocol? What protections does Antarctica have thanks to the environmental protocol? Is that enforceable and, indeed, is it enforced?
Dr Hughes: I am happy to take that. The protocol on environmental protection to the Antarctic treaty designated Antarctica a “natural reserve, devoted to peace and science.” Famously, it prohibited mineral resource activities in Antarctica; you cannot go down there and do any mining, but you can do research that involves taking samples for geology or whatever else. The treaty also created the Committee for Environmental Protection, which provides advice on environmental protection to the Antarctic Treaty consultative meetings.
At the end of the protocol, there are a series of annexes that set out various tools for the protection of the continent. Perhaps the most important is annexe 1, which covers environmental impact assessments. For every single activity that we undertake in Antarctica, an environmental impact assessment should be undertaken and steps laid out to reduce the impact as much as possible.
Annexe 2 covers the conservation of fauna and flora. It prohibits the introduction of non-native species without a permit. If you inadvertently introduce a non-native species, you are obliged to try to eradicate it. Annexe 2 also allows for the protection of specially protected species. The protocol is already pretty good for allowing the protection of species, but this is a higher level of protection, so we have that tool as well.
The annexes also have quite tight guidelines on the disposal of waste so that you cannot really dispose anything in Antarctica except for sewage waste and waste water. The final annexe that is in force is about protected areas. It allows us to designate a suite of different sorts of protected areas. The most important of those is probably the Antarctic Specially Protected Area—ASPA—which allows for the designation of an area that contains outstanding values. Those values could be scientific, environmental, historic or just intrinsic. That is one of the key tools that we have for area protection.
It is down to the national competent authority to enforce those regulations. In our case, that would be through the Antarctic Act 1994, overseen by the polar regions department of the FCDO. On top of that, we have to remember that, under the treaty, nations are allowed to inspect the activities of other nations in Antarctica, so we could have a visit from another party to see some of our activities down there and ask, “Is the UK doing a good job? Are they ticking the boxes and complying: yes or no?”. They would then produce a report back to the treaty parties to that effect.
Q41 Chair: I will just ask about one example to check up on the enforceability aspect. You mentioned that every single activity on the continent requires an environmental impact assessment. What percentage of them do you think actually achieve that?
Dr Hughes: For the UK, I would say that that is almost entirely true; I think that an environmental impact assessment is done for pretty much everything. The quality of environmental impact assessments does vary, but on the whole the UK does a very good job.
Q42 Chair: What about the Chinese?
Dr Hughes: I do not know, is the answer. The higher-level environmental impact assessments, such as for the construction of research stations, are made available to the international community for comment, so we can all provide our input and suggest what improvements we might like to see to bring things up to scratch. On the whole, parties do take those recommendations into consideration. For these higher-level activities, which are described as greater than minor or transitory, there is opportunity to see what others are doing. On the whole, it works reasonably well, I think.
Q43 Jerome Mayhew: The main drivers for ecosystem change—let’s get them on the table, as far as you are concerned. Dr Lee, why don’t you go first? What is causing the changes you are identifying?
Dr Lee: That is a great question. There are four main drivers of ecosystem changes in Antarctica. Primarily, there is climate change. We also have non-native species, which relates to climate and human activities. Then there are human activities itself, and potentially the recovery of marine megafauna. Do you want to add to that, Dr Hart?
Q44 Jerome Mayhew: Before you do, what do you mean by marine megafauna?
Dr Lee: Things like penguins, whales and seals.
Dr Hart: To extend that, whales and seals were severely depleted by whaling and sealing in the last century, so when we talk about change there are some good news stories. We are seeing recovery of whales and seals. However, that impacts on the krill fishery. We need to take account of and make more room for what is recovering and is now present that was not there at the start of CEP and—now—CCAMLR.
Q45 Jerome Mayhew: Let us stick with the marine environment to begin with. How are marine ecosystems dealing with rapid changes to the oceans? What is going on?
Dr Hart: For indicator species like penguins, we are seeing rapid changes—well, moderate changes in distribution, and rapid changes in the timing of breeding and potentially breeding success. Adélies and chinstraps now breed 10 days earlier than they did 10 years ago. That is an incredibly fast rate of change.
Q46 Jerome Mayhew: Is that a straight line of change?
Dr Hart: Yes, year on year. Gentoo penguins, who are the generalists, are actually breeding two weeks earlier than they were 10 years ago. What we see at higher latitudes in the north of the peninsula we can predict will happen in the south. We have already seen that pattern and where it goes. That is a concern. For the species that are harder to study, such as whales, it is very hard to measure change. It is much harder. It is also therefore harder to measure any step changes—anything that is non-linear and sudden. Krill and whales, which are really important to the marine ecosystem, are two of the hardest ones for measuring change.
Q47 Jerome Mayhew: I have learned a new phrase: gelatinous salps. Sounds horrible, doesn’t it? What eats a salp?
Dr Hart: Almost everything that would eat krill. Salps are less nutritious. They are somewhat replacing krill where it is warmer. Where krill have moved south, you tend to see an increase in salps.
Q48 Jerome Mayhew: You say they are less nutritious. We are trying to get a feel for how big a deal this is for the ecosystems. On the one hand you could say, “Krill’s off the menu, but don’t worry we’ve got salps”, so it is like for like. On the other hand, it is nowhere near a replacement and this is a catastrophic failure of the ecosystem. Where are we?
Dr Hart: It is nowhere near a replacement, but I don’t know exactly the difference, I am afraid.
Q49 Jerome Mayhew: Does anyone else know? Is anyone studying this?
Dr Hart: We can definitely provide you an answer.
Q50 Jerome Mayhew: I would be really grateful if you could. We have been offshore. Now let’s go onshore. What is happening to the onshore ecosystem?
Dr Lee: In terms of climate change, there are both direct and indirect effects on terrestrial ecosystems. Of course, “direct” means increasing temperatures and increasing precipitation. When it comes to precipitation, this could mean a transition from snow, which is what should be the primary precipitation in Antarctica, to liquid rain. That can really change the water availability of systems, and the terrestrial ecosystems are heavily reliant on water availability. Given the seasonality and everything, they often have a small growing window in the summer, so if you change the water, that can actually mean quite a lot of different things.
There are also a lot of indirect impacts of climate change. One of these is changes in habitat. We talked before about the ice-free areas that are so important for biodiversity. With climate change, we expect these to actually increase in size, so there will be more habitat available in some areas.
The other indirect impact is on non-native species, so it will be easier for non-native species to establish themselves. They are, of course, a concern because they can compete with native species for habitat and resources. There is not a huge amount of evidence of what exactly the impacts will be, but there are some studies. For example, we know there are two native plants in Antarctica and that some non-native species are likely to outcompete them under some circumstances. The impacts are complex and uncertain, but some species will definitely benefit from climate change and some will be negatively impacted.
The species likely to benefit include some of our native plants initially, which will probably have better growing conditions but might be outcompeted by non-native species if they were to establish themselves. The specialist gentoo penguin, which breeds in these ice-free areas, is likely to benefit. In fact, we are already starting to see it increase in some areas. The ones likely to lose out are the Antarctic specialists. That can be things like dry-soil nematodes and the Adélie penguin, which potentially is being pushed out of its habitat by gentoo penguins and emperor penguins, which we mentioned before.
Dr Hughes: What we are seeing with climate change is an increase in energy going into the system in the terrestrial environment. That will likely lead to this greening of the Antarctic, particularly the peninsula, where we already see a reasonable amount of life. It is all about that threshold between a freezing environment and an environment where you have liquid water. Once you have that liquid water available, life can just flourish and really take off. Now it is getting warmer and warmer, the area where that liquid water is available is increasing, so there is huge potential for this greening into the future.
Also, as we have a shift in some of the penguin species and seal species with climate change, that changes where they release their nutrients, in the form of poo basically, upon which the terrestrial system relies for its growth and increase in biomass. It is complicated, but climate change might actually be, overall, good for the green environment, but the devil is in the detail. Some species will really suffer; some will do really well, particularly the invasive species that Jasmine has just mentioned.
Q51 Jerome Mayhew: Do we have sufficient research in this area? Are we currently able to identify a rapid change and feel confident in the data you have? There is always only one answer to that kind of question, so I give you the opportunity to give it.
Dr Hughes: Clearly, we always need more research, but I will give an example of why and how much we need it. Antarctica is a huge continent and, if we look at the Antarctic peninsula, there are probably only three laboratories where we have really good long-term marine monitoring—only two or three places where we can actually dive throughout the winter. That is on the peninsula, which is 1,000 or more kilometres in length. We know practically nothing and have so little expertise to try to tell us what is going on. We have done a really good job up until now, but there is so much more we do not know.
We do very well with remote sensing—it is able to do penguin counts from space and look at vegetation growth—but what it does not allow us is to know what is really happening on the ground. That is where we need the taxonomists and the terrestrial biologists, who are experts and have a long-term vision and understanding of what is going on. When I first came to BAS, we had 25 to 30 terrestrial biologists. Now we have two—one is over retirement age and one is almost there.
Chair: There are only two terrestrial biologists at BAS.
Dr Hughes: Yes.
Q52 Chair: I find that absolutely astonishing. I would have thought that there would be dozens and dozens.
Dr Hughes: No, and it is an issue for me as an environmental manager who is trying to look at conservation issues. I am not going to have anyone to get expertise from in a year or two’s time. That is a real concern for me.
Caroline Lucas: I feel a recommendation coming on.
Chair: Definitely.
Dr Hughes: I will leave that up to you.
Q53 Caroline Lucas: You have mentioned non-native species quite a few times already in your evidence. I just wondered, Dr Hughes, if you think that an influx of invasive species is inevitable, considering the environmental changes taking place in the Antarctic? What invasive species represent the worst risk for Antarctic wildlife?
Dr Hughes: I think that it is important to understand that you can have non-native species coming from outside Antarctica into the continent, but Antarctica itself comprises a diverse range of different habitats. Species found in the peninsula, for example, are not found in other parts of the continent. Humans can mix up the species within the continent, and actually that is almost as bad in terms of making it very difficult to do the science, frankly. Also, we have a stewardship role to not do that.
I think human activity does tend to bring species with them. It is not inevitable that we will cause these incidents, and I think that, with the use of good and effective biosecurity, we can reduce the rate at which these introductions are occurring. We have about 15 species that we know have been introduced. The numbers are likely to go up. We see species being brought in on ship hulls, which is biofouling. We see species being brought in on people’s clothing, on their footwear, with cargo, and with fresh foods coming into resupply stations. There are many different routes by which these species can be brought in, and we just need to put in really good-quality biosecurity to try to minimise the species that are being introduced.
In terms of the ones that are bad news, I think some of the globally invasive grasses that we see are also starting to be found in Antarctica. Our Polish friends have found it very difficult to eradicate a grass near one of their research stations. It was introduced in the mid-80s, and they are still trying to get rid of it and it has proven very difficult. It is always better to try and stop things getting in in the first place than to try and eradicate them after the event. Often, that is just not possible.
Another example would be near our own station, Signy. Back in the late ’60s, we introduced a flightless midge from south Georgia. This midge lives as a larva for most of the year, and it turns out that the biomass of that larva in the soil is ten times greater than all the rest of the soil fauna put together. That dramatically changes the rate at which we get chemical recycling in the soil and it could have consequences for what that community will look like in the future. The big problem is that that midge lives in Signy, but it could also, if transported, survive all the way down the peninsula. It has a very broad tolerance to temperature and it could, if it is spread, dramatically change these ecosystems.
Q54 Caroline Lucas: That was my next question really. Dramatically change them, can you give us a sense of in what way?
Dr Hughes: It depends on what it is. If you have a grass, that can crowd out native plants in the near-shore marine environment. We do not have mussels in Antarctica, but if we were to have mussels introduced, say from South America, such as the Chilean mussel, that creates mussel beds and that can swamp out the native species. Many of the species we have found in Antarctica are just not used to competition. They are selected because of the extreme environments, but they are not used to trying to fend off other species. These species that are coming in have the ability to potentially outcompete the native species, and that could lead to local extinctions and other things.
Q55 Caroline Lucas: Are we doing enough to stop invasive species moving to the continent? You spoke earlier about the protocol and so forth. Is it happening because people are not following protocols sufficiently, or because they do not know about them?
Dr Hughes: The issue of non-native species has been taken very seriously by the Committee for Environmental Protection, and we have produced various guidelines, the non-native species manual and all sorts of information to help parties to put in place good biosecurity. I think the UK does a really good job; we have got some way to go, but I think we’re doing our very, very best. However, we just don’t know what others are doing, and ultimately you are only as good as your weakest link. That is the real concern.
Q56 Caroline Lucas: You say we have got some way to go. Unpacking that, are there particular things that we should be doing that we’re not?
Dr Hughes: We want to put in good biosecurity across the whole of the supply chain, from Cambridge, where the BAS is based, all the way back down through our gateway ports into our research stations.
It might be that at the moment we just do not have the facilities in the Falkland Islands or in Punta Arenas to allow us to put in really strict biosecurity for some of our containerisation. That is something that we really need to do, and we’ve got some plans, but it takes time.
Q57 Caroline Lucas: Is it expensive to do that?
Dr Hughes: Yes, it is expensive. For our Antarctic infrastructure modernisation programme, I think we’ve been putting about 1% of that budget into biosecurity. For example, with the wharf that we put in at Rothera, I think we spent about £400,000 on biosecurity. It’s not cheap, but we need to do it.
Q58 Caroline Lucas: I am just trying to understand what the barriers are. You are talking about what needs to be done. You mentioned time. So, I am interested: is the barrier time, or money, or anything else?
Dr Hughes: We have had the Sir David Attenborough for a couple of years now. That has driven a lot of change in how the organisation does its operations. I think we are catching up in trying to put in place the infrastructure that we need to deliver the level of biosecurity that we expect.
However, there is also the point that we need to be continuously improving. We’re never going to be good enough at this; we’ll always need to be going and doing better and better.
Q59 Clive Lewis: A lot of the points in the questions that I was going to ask have been covered pretty well. However, there is one question: how effective is the conservation of the Antarctic marine living resources in protecting the Southern ocean, and what is being done to ensure the sustainable use of the Southern ocean, especially in the convention area? A bonus point if you all answer.
Dr Hart: If I start with the krill fishery, it’s doing quite a good job, but there are still concerns. The krill fishery is very spatially aggregated, so a lot of things are taken very close to penguin and seal colonies. Again, whales are recovering, so we are seeing conflict that we didn’t before. In 2022, we saw the first by-catch of humpback whales ever in the krill fishery; so, whales were killed by the krill fishery. There wasn’t that degree of overlap until recently. It is very aggregated, and that is becoming more of a problem. There is limited evidence as to how big a problem it is, but it is certainly a large and growing concern.
Q60 Clive Lewis: Is it likely to grow?
Dr Hart: It is hard to tell. Certainly, some members are pushing for growth, and it is something that CCAMLR needs to defend against, or that we need to guard against.
It is a relatively small proportion of what is there, if you look at it as a whole, but it is all taken from very small areas that are close to penguin breeding sites, where whales are returning to, and seals. So it is a concern. We do not have strong evidence of how much it is impacting yet.
Q61 Clive Lewis: So you have no idea of how much it is impacting on ecosystems, for example, in that area?
Dr Hart: Limited. There is an association, particularly with penguins. Where we see the most krill being taken by the fishery, that is where there are declines in krill predators, like chinstrap penguins and Adelie penguins. That is not good scientific evidence; it is an association. So I will put it as a big concern.
Q62 Clive Lewis: Talk us through, if you can, any of the political complications here. Are there certain countries that are driving the krill fishing? Are there those that are trying to block it? What is the kind of political make-up of what is happening here?
Dr Hart: Well, that is a hard one—so maybe I will pass over to Kevin! Yes, there are a few krill fishing nations. A worry is that, even during the cold war, CCAMLR was relatively unified, and now it is not. That is the concern; CCAMLR is more pulling in different directions than it has historically.
Q63 Caroline Lucas: I meant to ask you about avian flu; how much of a risk is that?
Dr Hart: Substantial. It is something we have been predicting for about a year and a half, and those predictions have largely been borne out. It is a great concern. When we look at it in the Arctic and the Palaearctic, we can find analogues. It has reached the Falklands and South Georgia; that has been detected clinically. It is in the seabirds that migrate in. We are seeing very similar patterns in elephant seals on South Georgia. So it has reached South Georgia, and we are probably going to find out whether it has reached the South Sandwich Islands next week, when we have a team there. It does not seem to have reached the Antarctic peninsula yet.
It is too early to say, but it has not quite spread in penguins as we were fearing it might. However, it is too early to say anything conclusive. There is an animal health team going down fairly soon to do swabs that will result in clinical diagnoses.
Q64 Chair: I want to ask two quick things. The first is on CCAMLR, with the political splits in it and the difficulties that have been seen. You may well not have a view on the following question, but I would quite like to ask it anyhow. Some people have proposed a complete no-catch zone around the South Sandwich Islands, which would involve, therefore, the South Sandwich Islands becoming part of CCAMLR as opposed to part of the Falklands’ territories. Do you have a view on that? There are two very clear views there.
Dr Hart: Well, I do quite a lot of research on the South Sandwich Islands and I am very concerned about that. I think that we are at great risk with that, because there is a quota currently tied up but not taken in the South Sandwich Islands. The take-home message of this should be that krill are really important, and yes, there is a profound risk that that quota would be taken—
Q65 Chair: In other words, what you are saying, just to clarify, is that something like 15% of the total krill catch is off the South Sandwich Islands—
Dr Hart: Yes, 93,000 tonnes.
Q66 Chair: But we do not catch it. So, if there was suddenly to be a no-catch zone around the South Sandwich Islands, then that 15% would then be added to the Antarctic quota and therefore more krill would be caught rather than less. Is that correct?
Dr Hart: I think that is a good summary, yes, and that is my concern. There is a nice ambiguity at the moment that prevents that krill quota from being reallocated, and we know there is a strong push for that. There is a strong push to increase the overall krill quota in CCAMLR, and it would be even easier to reallocate an existing quota if it was declared that it was not being taken. So yes, I am concerned.
Q67 Chair: So, given that we have caught nothing in the South Sandwich Islands for 30 years, there would be not much point in banning it, really.
Dr Hart: No. It has actually been one of the longer de facto APAs in the world. There is scientific sampling, but I believe the last krill fishing was in 1992.
Q68 Chair: A final series of questions on pollutants—particularly plastics. I know there have been quite a lot found in albatross in South Georgia, and elsewhere. To what degree is the Southern ocean of Antarctica suffering from plastic pollution in the way that the Arctic, for example, might be? Is it a big problem?
Dr Hughes: I think there are an awful lot of different sorts of pollution in Antarctica, of which plastic is one. There are hydrocarbon spills, sewage waste, persistent organic pollutants coming into the atmosphere, heavy metals and waste chemicals coming off legacy dumps from the ’50s and ’60s. All of these things present a really major threat to Antarctic biodiversity. Plastics is one threat, and one we perhaps don’t know enough about yet, although there is research that is ongoing. It is likely that it will become a bigger issue as we probably see increasing amounts of plastics going into the ocean in the future.
It is very difficult to say how serious a problem it is because I don’t think we have really got there yet with the research. We definitely do know that we are getting debris coming off fishing vessels and from other marine sources. These can have very bad impacts on, for example, seals; they get bits of banding around their necks which cut in—that is really unpleasant. As you said, we see albatross and other birds with a lot of plastic in their guts. That is certainly not a good thing.
The other thing we have started to get some research on is that krill can ingest plastic at high levels, when it is done in a laboratory. It has been shown that can reduce their reproductive success and affect their ability to release carbon into the deep ocean. But we have got a long way to go before we really know the scope of the problem.
Q69 Chair: In terms of the threats from the globe faced by Antarctica therefore, there is definitely a threat from pollution of various different kinds, but that is relatively insignificant by comparison with climate change.
Dr Hughes: I would agree. I think we have not necessarily bigger problems but a whole suite of problems, of which plastics is one. But there are certainly other things which I would say are just as significant, if not more so.
Chair: I thank you all very much indeed for taking time out of your afternoon. You are all very busy, and it is very kind of you to come and give evidence to us. We are right at the beginning of our inquiry, and I hope none of our questions have seemed too naive. Perhaps it is worth asking a naive question, as it makes the scientists answer correctly and explain things to foolish people like me. I thank you for your expert witness; I think you will find it is reflected well in the report when we produce it—perhaps sometime around spring next year.