The impact of climate change is most acute in the Earth's polar regions. The Arctic and Antarctica are warming rapidly, with dramatic consequences not only for local environments but also for the wider world. The Arctic region is warming four times faster than the rest of the globe. These changes have environmental, social and economic impacts at the local level and, given the Arctic's role in the global climate system, far beyond the region's borders.

Warming at the poles is leading to dramatic physical changesThese include:

• Retreat of sea ice and glaciers.
• Thinning of ice sheets.
• Thawing permafrost.
• Extreme weather events and changes in precipitation.

For example, if the Antarctic ice sheet, which contains 90% of the planet’s ice, were to melt, it would wipe out every coastal city in the world. Even a modest rise in sea levels is likely to have serious consequences for coastal regions. Sea level rise is almost certain, but the exact timing and speed of this transformation remain unclear, partly because of the challenges of modeling ice loss in the polar regions and partly because any rise depends on how effectively—or ineffectively—we reduce emissions.

In addition to changes in the cryosphere, Oceans face a "triple threat": warming, deoxygenation and acidification. These changes, caused by human activity, in particular the release of greenhouse gases, are happening quickly and suddenly. The ocean has absorbed more than 90 % of additional heat from global warming since 1970 and absorbs about 25 % of annual anthropogenic CO₂ emissions, but is increasing its acidity. These threats are already becoming a reality in all European seas, with acidification progressing 10 times faster and warming twice as fast in the Arctic Ocean than in the rest of the globe.

Climate change and its consequences have widespread impacts on biodiversity, ecosystems and human communities.. Changes in vegetation cover, shifts in biodiversity, and impacts on indigenous and local communities are the subject of research. For example, catastrophically high reindeer mortality due to more frequent and intense rain-on-snow events poses a serious challenge to the socio-ecological systems of the Nenets. New species of fish and whales are spreading into East Greenland from the south, while ice-associated mammals (such as walruses and narwhals) are migrating north. In addition to environmental impacts, socio-economic factors such as fishing and tourism affect the communities dependent on these resources. There are also concerns about equitable and sustainable development, as new economic sectors and the industrialization of traditional livelihoods create tensions and conflicts over land use. Many in the Arctic perceive globalization as beneficial to large corporations, while local communities face the consequences of industrial expansion.

Understanding these changes is essential. Research and innovation are key to better understanding, modelling and predicting vulnerable components of the Earth's climate system and biosphere. Research projects analyse past climate conditions from ice cores, develop advanced Earth System Climate Models (ESMs) and produce better predictions of ice loss and sea level rise. It is important to integrate local and indigenous knowledge, as well as to involve local communities and diverse stakeholders in research processes and discussions.

Action on climate change is urgently needed. Resources They emphasize that urgent implementation of drastic reductions in greenhouse gas emissions is the primary cause of global warming and ocean acidification, to prevent further destabilization of major Earth system tipping points and long-term changes in ocean properties. Reducing greenhouse gas emissions upfront is better, more cost-effective, and causes less environmental stress than solving problems through geoengineering at a later stage. Climate mitigation is not optional; it will give us more time and more options for adaptation. It is important that people in vulnerable regions have access to clear and actionable information, for example on how to cope with thawing permafrost or adapt to changing fishing patterns. A comprehensive systems approach is essential to address climate change and its consequences. Spring

Glossary of key terms

• Cryosphere: All parts of the Earth where water is in the form of solid ice, including sea ice, lake and river ice, snow cover, glaciers, ice caps, and permafrost.
• Ocean-climate-cryosphere nexus: An interconnected system of ocean, atmosphere, land and ice sheets, changes in which significantly affect global climate and ecosystems.
• Permafrost: Soil, rock, or sediment that remains frozen (at 0°C or below) for at least two consecutive years. Its thawing releases greenhouse gases and causes surface instability.
• Sea ice: Ice formed from seawater that floats on the ocean surface. Its extent and thickness are sensitive indicators of climate change and affect the exchange of energy between the ocean and the atmosphere.
• Ice shield: A large mass of glacial ice covering a large area of a continent or island (e.g. Antarctica and Greenland). Melting ice sheets are a major contributor to sea level rise.
• Tipping points: Critical thresholds in the Earth system, the crossing of which can lead to sudden, nonlinear, and often irreversible changes in the system.
• Earth System Models (ESM): Complex computer simulations that represent interactions between the atmosphere, ocean, land, ice, and biosphere in order to understand and predict climate change.
• Biodiversity: The diversity of life in all its forms and at all levels of organization, from genes to ecosystems.
• Ecosystem services: The benefits that people derive from ecosystems, such as providing food, clean water, climate regulation, and cultural values.
• Pelagic zone: Open ocean outside the coastal area.
• Biological carbon pump: A combination of biological processes that transport carbon from the ocean's surface to its deeper layers, where it is sequestered.
• Citizen science: Scientific research conducted partly or entirely by amateur or non-professional scientists, often in collaboration with professional scientists. In polar regions, it often involves the involvement of local communities in data collection.
• Sustainable development: Development that meets the needs of the present without compromising the ability of future generations to meet their own needs, taking into account environmental, social and economic aspects.
• Social Licence to Operate (SLO): The informal legitimacy that a project or industry gains from local communities and stakeholders based on their trust and acceptance.
• Polynya: An area of open water surrounded by sea ice. It can be an important site for heat and mass exchange between the ocean and the atmosphere.