Can We Trust Climate Models? Increasingly, the Answer is ‘Yes’

Forecasting what the Earth’s climate might look like a century from now has long presented a huge challenge to climate scientists. But better understanding of the climate system, improved observations of the current climate, and rapidly improving computing power are slowly leading to more reliable methods.
by michael d. lemonick

A chart appears on page 45 of the 2007 Synthesis Report of the Intergovernmental Panel on Climate Change (IPCC), laying out projections for what global temperature and sea level should look like by the end of this century. Both are projected to rise, which will come as no surprise to anyone who’s been paying even the slightest attention to the headlines over the past decade or so. In both cases, however, the projections span a wide range of possibilities. The temperature, for example, is likely to rise anywhere from 1.8 C to 6.4 C (3.2 F to 11.5 F), while sea level could increase by as little as 7 inches or by as much as 23 — or anywhere in between.

It all sounds appallingly vague, and the fact that it’s all based on computer models probably doesn’t reassure the general public all that much. For many people, “model” is just another way of saying “not the real world.” In fairness, the wide range of possibilities in part reflects uncertainty about human behavior: The chart lays out different possible scenarios based on how much CO2 and other greenhouse gases humans might emit over the coming century. Whether the world adopts strict emissions controls or decides to ignore the climate problem entirely will make a huge difference to how much warming is likely to happen. ..more