Special Issue: Cryosphere

In this Special Issue of Science, 3 Reviews and a Policy Forum highlight research on Earth's frozen places – from the Arctic to the Antarctic – and how it's changing due to climate change and the geopolitical challenges this important work faces. In the first Review, Julienne Stroeve and colleagues provide a preview of what the Arctic region may look like in a warmer world. Without stronger climate action, global temperatures are set to rise +2.7°C above preindustrial levels, causing irreversible Arctic transformation. Under this future, Stroeve et al. show that nearly all days in the region would exceed past temperature extremes, summers would see an ice-free Arctic Ocean, Greenland's melt zones would quadruple, and permafrost would shrink by half. While these changes would severely disrupt ecosystems, and damage Arctic communities and infrastructure, the authors note that stronger climate action could significantly mitigate these consequences, preserving the Arctic's stability and resilience. In a second Review, Helen Fricker and colleagues focus on Antarctic ice, which plays a crucial role in regulating Earth's climate, global sea levels, ocean circulation, and planetary reflectivity. Fricker et al. highlight key knowledge gaps in these processes, which create uncertainties in the stability of the Antarctic ice sheet and the potential impacts of its continued loss. According to Fricker et al., progress in these areas depends on high-resolution satellite monitoring, targeted field studies, improved modeling, and strengthened interdisciplinary collaboration to reduce uncertainties and refine future projections. A third Review focuses on Antarctic biodiversity. According to Luis Pertierra and colleagues, Antarctica hosts myriad unique life forms, yet much of the region's biodiversity and ecological functioning remains poorly understood. Outside of a few well-known vertebrate species, much about the region's invertebrate, plant, and microbial life remains unknown. Here, Pertierra et al. highlight the shortfalls in Antarctic biodiversity research, explain how these gaps hinder ecological insight and conservation in the region, and offer a framework for addressing them. Lastly, in a Policy Forum, Jennifer Spence and colleagues discuss the geopolitical challenges facing Arctic research. The Arctic is at the forefront of critical global issues, including the uneven impacts of climate change, the challenge of balancing economic development with conservation, and the complexity of governance across multiple boundaries. These issues are complicated further by rising populism, geopolitical tensions, and distrust in governmental institutions. Spence et al. highlight three key issues, including understanding the regional and global effects of climate change, ensuring research benefits Arctic communities, and maintaining international cooperation in the face of growing geopolitical pressures. However, despite these challenges, the Arctic region has pioneered innovative governance models that prioritize Indigenous engagement, as well as fostering international cooperation through institutions like the Arctic Council to promote sustainable development and environmental protection.