A Few Things Ill Considered

A Tale of Two Predictions

Real Climate has done two posts recently that I thought would be served well by their juxtaposition. The first one highlights an early projection of global mean temperatures made by Jim Hansen in 1981.

The abstract for that paper contains this choice quote:

It is shown that the anthropogenic carbon dioxide warming should emerge from the noise level of natural climate variability by the end of the century, and there is a high probability of warming in the 1980′s.

These are both things that have in fact happened. I think it is safe to call this a very successful early prediction of anthropogenic climate change. Also in the abstract we have this:

Potential effects on climate in the 21st century include the creation of drought-prone regions in North America and central Asia as part of a shifting of climatic zones, erosion of the West Antarctic ice sheet with a consequent worldwide rise in sea level, and opening of the fabled Northwest Passage.

The drought in Texas certainly fits this description, as does the opening of the no longer fabled but now geopolitically contentious Northwest Passage.

The second post is about arctic sea ice. You can go have a read for RC’s usual interesting and informative exposition, but for my purpose the topic is summed up very well by this graph from the 2009 Copenhagen Climate Change summit:
i-540544250154b041d6e453246c58be9a-sea_ice_prediction_vs_observations-thumb-500x375-74084.jpg
(h/t SkS)

I think it is valuable to place that graph next to this RC modified graph from Hansen et al 1981:
i-f65155d0b74bee699a2a5e35121331d8-hansen_1981_perdiction_vs_observations-thumb-500x299-74087.jpg

So the next time some one arguing in blog comments somewhere about unverified or unfulfilled global warming predictions pops up, put these two graphs in front of them. The arctic sea ice image is also an excellent reminder that uncertainty about the future just is not anyone’s friend!