Climate science is not completely dependent on climate models. There are many threads of supporting evidence. Still, it is clear that climate models are telling us something important that we cannot afford to ignore. 

Let’s assume that the Obama administration and Congress get their act together this year and make good on their pledge of enacting meaningful climate legislation by establishing the nation’s first cap-and-trade system.

Let’s further assume, for the sake of argument, that the administration, working with its international partners, succeeds in drafting a robust successor to the Kyoto Protocol at the climate talks in Copenhagen later this year.

If we accept that the U.S. climate bill, known as the American Clean Energy and Security Act (ACES), will accomplish its goal of bringing down emission levels 80 percent below 2005 levels by 2050—which is nothing to sneeze at when you consider that a substantial fraction of policymakers (including some Democrats) vehemently oppose the measure—then the question becomes: Will it be enough to prevent the worst of climate change?