The Arctic is the fastest-warming place on our overheated planet, but so far, its polar opposite has managed to stay pretty cool. Why is Antarctica warming so slowly compared with the Arctic? The answer is complicated, but a new study suggests we’re overlooking a basic reality of geometry.
Scientists stand on an Antarctic ridge (Image Credit: Tarun Luthra)
Parts of our round Earth are flat; others are rugged and mountainous. Antarctica is a diverse landscape of snow-covered mountains, gaping chasms, rivers, lakes and waterfalls, with the highest average elevation of any continent. Marc Salzmann, researcher at the Institute for Meteorology at the University of Leipzig, thinks that extra height helps explain why Antarctica is warming up slowly, while the Arctic sizzles away like an ice block in the summer sun.
“Originally, most people thought that the reason you have rapid ice melting in the Arctic is because the ice disappears and leaves a darker surface,” Salzmann told Gizmodo. “That leads to stronger amplification of warming. But in recent years, it has turned out there are other effects causing strong warming in the Arctic. I wanted to find out why those effects don’t play out so much in Antarctica.”
To test the hypothesis that elevation may be buffering Antarctica from the heat of seven billion gas guzzling humans, Salzmann ran computer models of the landscape in a world with double the atmospheric carbon dioxide of the present. In one scenario, Antarctica was given its normal topography, in another, it was flatted out the way Shaq would want it to be. All else equal, his model runs showed that if the land height is reduced, temperatures respond more strongly to rising greenhouse gases.
“Antarctica warmed a lot more quickly when flattened out,” Salzmann said, noting that the continent became “more comparable to the Arctic”, but that land elevation couldn’t completely explain the discrepancy between the two. Salzmann says that a flat Antarctica allows more advection of warm air from the tropics to sweep over the continent.
It’s important to note that this is just one model that doesn’t account for every factor, and plenty of other scientists have their own ideas for why Antarctica is responding slowly to global warming compared with the Arctic. Those ideas include deep ocean convection around Antarctica, the ratio of land to water, and perhaps, additional heat uptake in the Southern Ocean thanks to the ozone hole. (Nice job, humans.)
Ken Caldeira, a climate scientist at the Carnegie Institute for Science, told Gizmodo that Salzmann’s mechanism “seems plausible” and “is almost certainly operative”. His only question is how important it is.
“Another thing to note is that Antarctica being high means that more of the atmosphere is pushed to the rest of the planet,” Caldeira said. “Because Antarctica is high, everyplace else has a little more greenhouse gas over it and thus a little more warming influence.”
It’s also worth emphasising that Antarctica is heating up, will continue to heat up, and that we should be worried about the consequences. The West Antarctic ice sheet’s Amunden sea embayment, which contains enough frozen water to raise global sea levels by 1.2m, is already melting rapidly. Several years back, researchers at NASA’s Jet Propulsion Laboratory declared its eventual collapse “unstoppable”.
Sometimes, the little things you’d never think of, like the reality of living on a lumpy ball, can have a big impact. So, too, can a few whiffs of invisible gas in the air.[Earth System Dynamics]
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