‘Cold blob’ of Arctic meltwater may be causing European heat waves

Global warming disrupts weather in many ways, but Europe’s string of record-breaking hot and dry summers has defied an easy link to climate change. Climate models do show Europe warming faster than the rest of the planet , but the recent scorchers were triggered by peculiar weather conditions: masses of hot, dry air parked over the continent , blocking any incursions of cool or moist relief. A new study suggests global warming could be responsible after all. It proposes a chain of events that starts with an infusion of meltwater from shrinking Arctic ice, which ultimately alters massive ocean currents and regional air circulation patterns. The study, published late last month in Weather and Climate Dynamics , also suggests monitoring such patterns, which are apparent during winter months, could allow forecasters to predict extreme summer heat months to years in advance. “Physically what the authors write makes sense,” says Judah Cohen, a weather scientist at Atmospheric and Environmental Research. Arctic melting—from both floating sea ice and glaciers on Greenland and elsewhere—is adding roughly 6000 cubic kilometers of water or more to the ocean per decade, more than enough to fill the Grand Canyon. As that freshwater pours into the North Atlantic Ocean, it sits on top of heavier ocean saltwater and impedes mixing. With less heat being stirred in from below, the surface water gets colder than usual during the fall ...
Source: ScienceNOW - Category: Science Source Type: news