Climate models fail at short-term forecast

Climate-prediction models can accurately forecast long-term climate patterns but struggle when applied to patterns shorter than 3 decades, U.S. researchers say. And while good at global-scale predictions they do less well at future projections for smaller geographical regions, they said. That was the conclusion of a study intended to bridge the communities of climate scientists and weather forecasters who sometimes disagree with respect to climate change, said Xubin Zeng, a professor in the University of Arizona department of atmospheric sciences who leads a research group evaluating and developing climate models. The weather forecasting community has demonstrated skill and progress in predicting weather up to about two weeks into the future, whereas the climate science community tasked with identifying long-term trends for the global climate has had a less successful track record, Zeng said. "Without such a track record, how can the community trust the climate projections we make for the future?" Zen said. "Our results show that actually both sides' arguments are valid to a certain degree." "Climate scientists are correct because we do show that on the continental scale, and for time scales of three decades or more, climate models indeed show predictive skills. But when it comes to predicting the climate for a certain area over the next 10 or 20 years, our models can't do it." "That is because our models are only as good as our understanding of the natural processes, and there is a lot we don't understand," he said.