An article in the May 4 issue of Science shows that observed warming in the 16 years since 1990 is greater than predicted by models.

Perhaps models are underestimating future climate change. That would be bad news.

“Recent Climate Observations Compared to Projections”

We present recent observed climate trends for carbon dioxide concentration, global mean air temperature, and global sea level, and we compare these trends to previous model projections as summarized in the 2001 assessment report of the Intergovernmental Panel on Climate Change (IPCC). The IPCC scenarios and projections start in the year 1990, which is also the base year of the Kyoto protocol, in which almost all industrialized nations accepted a binding commitment to reduce their greenhouse gas emissions. The data available for the period since 1990 raise concerns that the climate system, in particular sea level, may be responding more quickly to climate change than our current generation of models indicates.

Those who argue that great uncertainty exists in our knowledge of climate need to recognize that uncertainty cuts both ways — things could be worse than we think just as easily as they could be better.