In 1999, the Alfred Wegener Institute launched an ambitious project: the HAUSGARTEN observatory in the Fram Strait between northeast Greenland and Svalbard. Spanning ice-covered waters and extending to depths of more than 5,500 metres, this unique research infrastructure has become a key site for monitoring the impact of climate change on polar marine ecosystems. A special issue of the journal Deep-Sea Research Part II : Topical Studies in Oceanography now brings together key findings from 25 years of research at HAUSGARTEN, underscoring the urgent need for global climate action.