NEW YORK — An important wind circulation pattern over the Pacific Ocean has begun to weaken because of global warming caused by human activity, something that could alter climate and the marine food chain in the region, new research suggests. It’s not clear what climate changes might arise in the area or possibly beyond, but the long-term effect might resemble some aspects of an El Nino event, a study author said. El Ninos boost rainfall in the southern United States and western South America and bring dry weather or even drought to Indonesia, Malaysia and elsewhere in the western Pacific. As for the Pacific food chain near the equator, the slowdown might reduce populations of tiny plants and animals up through the fish that eat them, because of reduced nutrition welling up from the deep, said the author, Gabriel Vecchi. Vecchi, a visiting scientist at a National Oceanic and Atmospheric Administration lab in Princeton, N.J., and colleagues present their results in Thursday’s issue of the journal Nature. The slowdown was detected in shipboard and land-based data going back to the mid-1800s. It matches an effect predicted by computer climate simulations that trace global warming to […]