In 2004, a scientific study analyzing driftwood freed by Arctic melt determined that sea ice in the coldest regions of the Arctic was at the lowest level in 3,000 years. Since that time, Arctic sea ice has continued to rapidly decline. Then, in 2013, another study of ice cores released just this month found that global temperatures are now as hot as they were 3,000 years ago.
The results of these two studies begs the question: did Arctic sea ice respond almost immediately to human caused temperature change?
The answer to this question is an important one because much of the assertion that human caused climate change will be gradual rests on the assumption that things like vast ice sheets only slowly respond due to the inertia inherent in such large systems. Inertia, in this case, is predicted to keep a degree of human caused climate change in check, giving us more time to mitigate, respond, and adapt.
However, if human-caused temperature increase has resulted in an almost immediate response from the Arctic sea ice, then what does that mean for the land-based glaciers and floating ice shelves in Greenland and West Antarctica? Will the ongoing ocean/atmosphere temperature increase that appears to have driven such rapid change in the Arctic also result in rapid change there?
Given the extraordinary and ongoing loss of sea ice in the Arctic, it would seem that providing answers to these questions begs a degree of urgency. A collapse in Greenland and/or West Antarctica of any rough corollary to the nonlinear melt of Arctic sea ice could be a disaster without parallel in human history. And the sensitivity of Arctic sea ice to temperature change, at least, hints at much greater climate sensitivity in the world climate as a whole.
It may be that the Arctic sea ice is very sensitive for specific, identifiable reasons that do not make it a good model for overall climate change. But, if the opposite is true, we should at least be aware so that we can provide appropriate mitigation and adaptation policies. One would think, in such cases, that more resources would be provided to clarify and, as necessary, respond to these risks.
The graph below, produced by Climate Progress and based on a new study published in Science, shows how temperature is as warm now as it was 3,000 years ago. It also shows how the pace of increase is without corollary for any time during the last 11,300 years — the space in which human civilization developed.