The world's largest fjord in Greenland, enclosed by ice for eleven months of the year, is a research area as unique as it is difficult for scientists to access. In this Arctic region, which is warming four times faster than the rest of the world, researchers sailed to observe an entire ecosystem at risk. "You hear about global warming but here you see it," says Vincent Hilaire, head of the Greenlandia association, which is leading the expedition in August 2023. IMAGES AND SOUNDBITES ARRANGED IN SEQUENCES