Any good business executive knows that the world is full of risks, ignored at a company's peril. Interest rates could spike. China could change its currency policy. Chaos in Iraq could push up gasoline prices. Smart firms account for these possibilities as best they can, adjusting business plans so that they aren't caught flat-footed. The same can be said of wise societies.
In late June, a bipartisan group of economic leaders argued that the United States must take this approach when facing the risks of climate change. It's still not perfectly clear how sensitive the climate will be to a given increase in atmospheric greenhouse-gas emissions. Nor is it perfectly clear how ongoing temperature change will affect complicated Earth systems. But these are not excuses for doing nothing, or too little, to reduce carbon dioxide emissions.
To back up its claims, the group led by, among others, Hank Paulson and Bob Rubin, treasury secretaries for George W. Bush and Bill Clinton, respectively commissioned an analysis of the risks that climate change poses to the United States. They only attempted to quantify the impact of a few changes that scientists are confident will occur to some degree with unabated warming: sea-level rise, higher storm surges, heat extremes, higher demand for energy and changes in agricultural production. As with a climate assessment the Obama administration published this year, the results should but probably won't snap Congress into action.