Forecasting Climate Change: Lessons from the Arctic

The Arctic is a hotspot of climate change research, particularly because it is more affected by climate change than other parts of the world. For the past 2000 years or so, the Arctic was actually cooling, up until the industrial revolution started kicking all sorts of greenhouse gases into the atmosphere.

Average Arctic air temperature for the past 2000 years

I’ve been reading the special report on the Arctic in the Economist (I know, I’m a month behind), and there was some language in there that made a pretty big impression on me. The correspondant describes how the pace of sea-level rise predicted by climate change models has largely underestimated how rapid sea level rise actually is. In fact, they go so far as to state that “it is worth noting that even the more extreme predictions of Arctic warming have been outpaced by happened in reality”. Simply put, even our most extreme models have been wrong, and not in a good way. For example, models have dramatically underestimated the extent of sea-ice loss in the Arctic for the past 50 years or so.

Arctic sea-ice extent for the past 100 years.

I’m an experimental ecologist attempting to determine how climate change will affect communities and ecosystems. I rely on these models to provide realistic projections of future conditions so that I can conduct the most realistic possible experiment; I don’t want to have a warming level way above what is realistically possible. To date, the ‘industry’ standard for warming experiments is a conservative 2˚C increase in temperature. But what if our models are wrong? Then there is a huge body of literature underestimating the effects of climate change on natural systems.

I conducted a quick comparison of IPCC model projections for global atmospheric temperature vs. observed temperatures and found that IPCC models, thus far, underestimate the severity of warming.

Average global air temperature for the past 50 years.

Granted, this is a very quick comparison with no rigor to it at all. I’m also no atmospheric scientist, so I’m likely to be wrong about the extent to which models are under-representing actual changes.

But the issue still stands: scientists are a cautious bunch and have been underselling the severity climate change (believe it or not). Our accumulated body of knowledge deals with a cautious estimate of warming. Thus far, even small increases in temperature can have big effects on community structure and function. If warming is more severe than predicted by models, and therefore more severe than we have been experimenting with, we are in for a wild ride indeed.

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