Geografi A new study by a University of Copenhagen researcher finds that thawing permafrost in Alaska causes colder water in smaller rivers and streams. This surprising consequence of climate change could affect the survival of fish species in the Arctic’s offshore waters. The study’s researchers discovered that thawing permafrost causes groundwater to run deeper, where it becomes cooler than when it flows near the soil surface. Photo: Getty Rising global temperatures are causing frozen Arctic soil – permafrost – to thaw. In a new study, researchers have discovered something surprising: small rivers, creeks and streams that flow into larger lakes and coastal waters seem be to getting colder as permafrost melts. The phenomenon was previously documented in Russian rivers in the Arctic. But until now, no one had studied why the water was getting colder, even as air temperatures are warming and the permafrost is thawing.