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NASA scientist Claire Parkinson says that, from 2014-2017, Antarctic sea ice rapidly fell to its lowest levels in 40 years, which could trigger a devastating rise in sea levels
DIMITRI LASCARIS This is Dimitri Lascaris reporting for The Real News Network in Montreal, Canada.
Within the past week, the world has twice received troubling news about the state of the ice in Antarctica. First, on July 1, a study was released by the Proceedings of America’s National Academy of Sciences, or PNAS, showing that from 2014 to 2017, the extent of Antarctic sea ice declined rapidly. According to that study, the rapid decreases reduced the Antarctic sea ice extents to their lowest values in 40 years. Then, on July 8, PNAS published a second study showing that the Thwaites Glacier, an enormous Antarctic glacier that is the size of Florida, may be on the brink of melting so quickly it could cause catastrophic global sea level rise.
Now here to discuss these developments with us is Claire Parkinson, the author of the study published by PNAS on July 1. Claire is a climate scientist at NASA’s Goddard Space Flight Center. Her research is focused on satellite-based measurements of Arctic and Antarctic sea ice and she joins us joins us today from the Goddard Space Flight Center in Maryland. Thank you very much for joining us, Claire.
CLAIRE PARKINSON Thank you, Dimitri.
DIMITRI LASCARIS I’d like to start with the study that you authored, Claire, and which PNAS published on July 1. What would you say are the main takeaways from this study?
CLAIRE PARKINSON The study shows the results of a 40 year record that we have from satellite data of the sea ice cover in the Antarctic. And that record shows that the Antarctic sea ice cover was increasing for much of the first 30 some years of that record and then reached its peak in the year 2014. Then, it plummeted way faster than the decreases that have occurred in either the Arctic or the Antarctic. So there was a three year period from 2014 to 2017 where it was a very rapid decline. So it took it from its highest values in terms of yearly average sea ice cover in 2014 down to its lowest values of the 40-year record that we have in 2017.
DIMITRI LASCARIS That period–2014-2017, I understand–includes at least two of the hottest years on record. I believe 2016 was the hottest and ’17 was the second hottest. To a layperson like myself, it would make sense in years that were so warm by historical standards that you’d see a decline in Antarctic sea ice. But it nonetheless seems counterintuitive that for decades, when there were rapid accumulations of greenhouse gases in the atmosphere and the planet was warming, that there would have been a gradual and quite noticeable increase in the extent of Antarctic sea ice. Why does the scientific community believe that that happened during those decades of warming?
CLAIRE PARKINSON Each of your points is really good and really well-stated. The scientific community was very puzzled by the increases in Antarctic sea ice from the late 1970s until 2014. And it was a huge contrast versus the Arctic case, where the Arctic, although having interannual variability just like the Antarctic has, the Arctic sea ice cover was overall decreasing decade after decade. And so, that was what scientists expected. And it fit a nice pattern for warming of the Arctic, sea ice decreases, land ice decreases, permafrost dying. Everything was kind of systematic and coherent in the Arctic and scientists basically understood what was going on.
In the Antarctic, it was not what the scientists had expected. And so, a lot of studies were done to try to explain it. No consensus view has come out of those studies. There are various explanations, like maybe it was related somehow to the El Nino cycle; maybe it was somehow related to the ozone hole; maybe it was somehow related to changes in atmospheric circulation; maybe it’s somehow related to melting of land ice bringing very cold water into the oceans and therefore leading to more sea ice. So it really wasn’t understood, still is not understood. There is still no consensus in terms of the scientific community as to why the Antarctic sea ice was increasing over that time period.
DIMITRI LASCARIS Your study focused on the 2014-2017 period. Do we have any sense about what has happened to Antarctic sea ice since 2017?
CLAIRE PARKINSON Yes. The study did go through a 40 year record, so it’s the period starting in 1979 and ending at the end of last year, 2018. 2018 had a little bit of a rebound from the decreases 2014-17. So it’s a little bit of a rebound, a little bit more sea ice cover than in 2017 in terms of yearly averages, but not as much as 2016. So there’s a little bit of a rebound. This year so far, that rebound is not continuing. So far this year it certainly suggests that the decreases from 2014-2017 are proceeding, and of course we won’t know until the end of the year what the yearly averages are. But certainly, so far this year it does not indicate that the rebound is continuing.
DIMITRI LASCARIS I’d like to talk to you briefly about the second study, particularly about the massive Thwaites Glacier. Could you explain to us, in sort of layperson’s terms, the dynamics which might lead to the rapid collapse of this gigantic ice sheet?
CLAIRE PARKINSON Well, first, in terms of a comparison between the sea ice and the glacier that you’re speaking of–keeping for your viewers–would be when land ice decreases, like glacier ice–the Thwaites Glacier or other land ice–when that decreases, that can contribute to sea level rise. Sea ice is already in the ocean, so when sea ice changes, it’s not changing sea level. It’s having a lot of other impacts, but not sea level. So the important thing about Thwaites Glacier or any other glacier that’s showing a possibility of a rapid decay is that it could bring with it a massive amount of ice into the ocean. So that’s the important part. As for the technical details of exactly how this happens, you really should turn to the authors of that study and they could give you all the technical details. But the important factor is that can increase sea level, whereas the sea ice changes don’t increase sea level.
DIMITRI LASCARIS It’s my understanding, Claire, that if that glacier, Thwaites Glacier, were to collapse and melt entirely, it could raise global sea levels by approximately half a meter on its own. Earlier this year, in May of this year, there was a report, a study also published by PNAS, showing that global oceans could rise by as much as two meters by 2100 or six feet, which was approximately double the previous estimates. Do you think that this newer study raising alarms about the possible collapse of the Thwaites Glacier will now force the scientific community to revise this most recent estimate of maximum global sea level rise by 2100? Is it now plausible that we will be seeing an excess of two meters of sea level rise by 2100?
CLAIRE PARKINSON That is possible, and I think the scientific community is indeed looking into all the various factors of what could increase sea level. And so, that is possible, but it’s certainly possible that sea level will rise less than anticipated rather than more. So there’s a lot of uncertainty there. People have been worried about the so-called West Antarctic. The Antarctic continent is divided into the East Antarctic and the West Antarctic by a mountain range called the Transantarctic Mountains.
Most of the West Antarctic is in the western hemisphere, that’s why it’s called the West Antarctic. And it has, for decades now, been a greater concern than the East Antarctic because the West Antarctic is grounded largely below sea level, meaning that if you go down to the bottom of the ice in much of the West Antarctic, the bottom of the ice where it hits land is actually below sea level. Whereas in the East Antarctic, you go down to the bottom and you’re still above sea level. So it’s felt that the Thwaites Glacier and Pine Island Glacier and other glaciers in the West Antarctic could be more unstable and bring a decay in the West Antarctic more readily than the glaciers in the East Antarctic.
DIMITRI LASCARIS Well, we’ve been speaking to Claire Parkinson about two new studies relating to Antarctic ice. Claire is from the NASA Goddard Space Flight Center in Maryland. Thank you very much for talking to us today, Claire.
CLAIRE PARKINSON Thank you very much. Thank you.
DIMITRI LASCARIS And this is Dimitri Lascaris for The Real News Network.