Thawing Thursdays: Antarctica update

Antarctica has been getting a lot of attention recently, and for good reason. What happens there over the next couple decades may make the difference between a difficult and deadly adaptation process, and global chaos.  Here’s one relevant bit of science news I came across that’s worth knowing about:

This comes from the ongoing efforts to compare what’s happening to our climate now, to what has happened in the past. During the warming period at the end of the last glaciation, ice retreated and sea levels rose a huge amount over a period of a few thousand years. What’s interesting is that about 10,000 years ago, the retreat of the Antarctic ice sheets stopped, and then reversed, and Antarctica began re-freezing.

Since we became aware of the dangers presented by rapid global warming, climate scientists have put a lot of effort into trying to find any natural factors that might either explain the warming, or naturally stop the warming. Michael Mann’s famous hockey stick graph came out of his efforts to find evidence to support the existence of a natural cycle that would explain the observed warming that Hansen talked about 30 years ago. Part of that research involves figuring out what happened in past warming events, particularly the one that led to the climate “Goldilocks zone” that gave rise to modern civilization.

A research paper published in the journal Nature has offered us insight into why Antarctica’s ice melt stopped 10,000 years ago, and it’s a good illustration of the size and speed of the change we’re experiencing now.

[The ice] retreated inland by more than 1000 kilometers in a period of 1,000 years in large parts of this region — on geological time-scales, this is really high-speed. But now we detected that this process at some point got partially reversed. Instead of potential collapse, the ice sheet grew again by up to 400 kilometers. This is a limited, yet amazing self-induced stabilization. However, it took a whopping 10,000 years, up until now.

-Torsten Albrecht , Potsdam Institute for Climate Impact Research

Unfortunately, this doesn’t offer hope for us, because they also found the cause of that stabilization – isostatic rebound. The sheer mass of the ice on top of Antarctica (and Greenland) is enough that Earth’s crust underneath it is pushed down into the mantle. As the ice melts, that section of the crust floats up, relieved of the ice cap’s weight. The problem is that this rebound process is slow. Earth’s crust is thin, compared to the planet, but it’s stiff. In a natural warming event, this would be be a stabilizing factor, but we’re cranking up the thermostat so fast, that the uplift will lag far behind the rate of melt, and the rate of sea level rise.

That continent will keep rising after the ice melts, but it won’t be fast enough to stop the melt from happening, so once again it’s all on us. For more detail on this, check out Sciencedaily’s article.

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