In Svalbard reindeer must withstand up to nine months of snow cover and limited food availability. In wintertime the reindeer carcasses make up an important part of the arctic foxes' diet. The climate of Svalbard is changing. Summers and winters have been wetter and warmer. Rain-on-snow is an extreme situation that locks the deep-frozen arctic tundra under a sheet of ice. The ice keeps reindeer from grazing on their winter pastures. The result is that populations crash in the winter and spring after the extreme weather. In this situation, almost no reindeer carcasses will be available for foxes to eat during the following winter, mainly because the reindeer that survived the previous winter are stronger, and less reindeer are competing for the food that is available. The result is a deep reduction in the arctic fox numbers one year after the grazers die off.