Hansen’s 1981 Climate Projections Ring True: A 30 Year Review

A few weeks ago, researchers Geert Jan van Oldenborgh and Rein Haarsma published an article on RealClimate.org reviewing some of James Hansen’s earlier work. Apparently the researchers had decided to take a break from the rigours of everyday research and have a look at how far climate science has come since the 1980’s.

Upon reviewing Hansen et al.’s original global warming paper in 1981, they found that the controversial climate scientist’s predictions have so far proven remarkably accurate. Hansen et al. received 10 pages in Science at the time, and were making climate temperature projections for the next century. They successfully predicted that global temperatures would rise as a result of increasing CO2 emissions.

A comparison between a graph of Hansen’s predictions and observed global temperature data revealed the two graphs were roughly the same. In fact, if anything, Hansen’s projections were more conservative than what actually occurred over the ensuing 30 years. Some of these conservative estimates can perhaps be attributed to recognized uncertainties such as the effect of aerosol forcings and ocean heat uptake.

When evaluating the future effects of climate change, Hansen et al stated: “creation of drought-prone regions in North America and central Asia as part of a shifting of climate zones, erosion of the West Antarctic ice sheet with a consequent worldwide rise in sea level, and opening of the fabled Northwest Passage.”

And of course, we are already beginning to observe many of these effects today. Already the Northwest Passage is beginning to open up, with a few new shipping lanes emerging and several countries fighting over Arctic Sovereignty.

Although Hansen certainly has established himself as a controversial figure in climate science, it would appear his science remains sound and his predictions have proven accurate.

On the other side of the coin, one would be hard pressed to find predictions from “deniers” that have even come close to achieving any level of accuracy.

Image courtesy of NASA Goddard Space Flight Center: Satellite data reveals how the 2001 minimum sea ice extent opened up Northwest Passage shipping lanes (in red).