In this week’s #SkepticalTuesday post, I take a look at something that’s going to seem like fodder for the climate-change deniers, and why it really isn’t.
Every now and then, something crosses my desk that seems like something a climate change denier would cite (that particular one, by the way, has been completely rebutted here). But today one came along that, unfortunately, comes from a pretty good source, which means it’s going to be misrepresented in all sorts of ways.
Here’s the basics: a new study of the total mass of Antarctic ice seems to show that, rather than lessening, it’s actually increasing. It looks for the moment as though it’s not due to increased precipitation, but rather that it’s part of a very long-term trend. Right now, according to the study, Antarctic ice isn’t raising the sea level, it’s reducing it (by a fraction of a millimeter a year).
The study is titled “Mass Gains of the Antarctic Ice Sheet Exceed Losses,” and is published in the perfectly reputable Journal of Glaciology. There’s also coverage over at NASA, because it’s their study.
Here’s what your crank/science-denying uncle/grandpa/Republican relative will tell you over the table at Thanksgiving: “yeah well I heard that Antarctic ice levels are going up, NASA said so!” (hashtag checkmate atheists, etc.)
Here’s the reality:
The researchers have identified what they’re calling a long-term trend in thickening of the Antarctic ice, especially in East Antarctica and the interior of West Antarctica. By long-term, they mean over the last 10,000 years. This is despite the increased losses in the ice of the Antarctic Peninsula and the coastal parts of West Antarctica. According to this study, Antarctic ice formation is exceeding melt, and lowering the global sea level by 0.23mm a year.
(1) The speed at which ice is being lost is speeding up relative to the speed at which it’s being generated, such that in the 20-30 year timeframe, this will reverse. As Jay Zwally, lead author of the study puts it: “If the losses of the Antarctic Peninsula and parts of West Antarctica continue to increase at the same rate they’ve been increasing for the last two decades, the losses will catch up with the long-term gain in East Antarctica in 20 or 30 years — I don’t think there will be enough snowfall increase to offset these losses.”
(2) This does not mean that the sea level is rising any less quickly. Sea level rise is established fact. It just means that now we aren’t totally sure where it’s coming from. Zwally again: “The good news is that Antarctica is not currently contributing to sea level rise, but is taking 0.23 millimeters per year away […] But this is also bad news. If the 0.27 millimeters per year of sea level rise attributed to Antarctica in the IPCC report is not really coming from Antarctica, there must be some other contribution to sea level rise that is not accounted for.”
This means that when Antarctic melt does start outpacing accumulation, it’ll be an even faster increase in sea level.
According to NASA, sea level rise is taking place at roughly 3.2mm/year or an inch every 8 years, which is slow, sure. Until you think about just how much water it takes to raise the sea level by that much. Plus, all signs indicate that the rate will increase as time goes by. The Intergovernmental Panel on Climate Change is projecting anywhere from one to three metres of sea-level rise by 2100 (roughly 3 to 9 feet), and that’s global average — it’ll almost certainly be higher in certain areas thanks to currents and topography.
And worse still: new research just published in the Proceedings of the National Academy of Sciences indicates that if the West Antarctic Amundsen Ice Shelf is destabilized — that is, if it starts to slip into the ocean as indeed it appears to be doing from earlier studies — “then the entire marine part of West Antarctica will be discharged into the ocean.” If it goes, there’s nothing to stop it. And that might just speed up the “melt” side of the equation, if we’re being honest with ourselves.
So what’s next? Well, this is just one study, which is why they’re eagerly awaiting the launch of NASA’s ICESat-2, which will be able to map the thickness of the ice sheets in Antarctica to an insane level (think plus-or-minus a centimeter). It’ll go up in 2018, and will help us to determine whether this study is right — and if so, at what point we’re likely to see Antarctica start contributing to sea level rise as well.
For now, well, let’s hope they all agree to something good in Paris, shall we?
Richard Ford Burley is a writer and doctoral candidate at Boston College, as well as an editor at Ledger, the first academic journal devoted to Bitcoin and other cryptocurrencies. In his spare time he writes about science, skepticism, feminism, and techno-futurism here at This Week In Tomorrow.
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