Local predictions of climate change are hazy. But cities need answers fast
By Paul Voosen, Science.
Excerpt: Like many cities around the world, Austin is now facing questions about how to build and adapt for a changing climate. A growing number of these cities—as well as insurance companies, home builders, and farmers—are turning to climate modelers for answers. But despite decades of effort, forecasting how global warming will play out on a local scale remains a stubborn challenge, riven with uncertainty. There is little agreement on how best to convert climate models, which simulate the entire world at coarse resolutions, into the detailed local forecasts of temperature and rainfall that planners crave. Different methods lead to drastically different projections, especially in terms of rainfall—even when using the same climate model. ...The problem has become more pronounced with the discovery that global climate models, good at the big picture, often miss local impacts that are already painfully evident. For example, despite nailing the overall pace and intensity of global warming, models did not predict the more frequent heat waves that are plaguing Europe. In order to make local forecasts, modelers must not only do the global-to-local conversion, but also adjust for these model biases....