It was the largest Arctic expedition ever. Starting in October 2019, the research icebreaker Polarstern drifted through the central Arctic for an entire year, firmly locked into the Arctic sea ice, using only the power of natural ice drift. Supported by six research vessels and ice breakers as well as aeroplanes and helicopters, Polarstern became the first modern research icebreaker reaching the North Pole area in winter. For this expedition to the epicentre of climate change, where climate warming rates are four times larger compared to the rest of the world, the scientists followed in the footsteps of Fridtjof Nansen's historic expedition with the wooden sailing boat Fram in 1893-1896. Despite extreme cold, Arctic storms, a constantly changing ice landscape and the unimagined challenges of the Corona pandemic, they explored the North Pole more closely than ever before and achieved groundbreaking observations of climate processes in the central Arctic. They will thus be able to better understand and predict the climate system. Project and expedition leader Markus Rex reports on the dramatic climate change in the Arctic and gives insights into this unique expedition.