The Arctic is warming faster than any other region on Earth and rapidly becoming a wetter, more variable environment. Over the past 50 years, the Arctic’s temperature has risen at a rate more than twice the global average. JANET PAWLAK says these changes affect the Arctic’s role as a regulator of global temperature and its influence on Northern Hemisphere weather; its contribution to sea-level rise; the lifestyles and livelihoods of those who live and work in the Arctic; Arctic marine and terrestrial ecosystems and the habitats of Arctic species.
THESE ARE some of the conclusions of the 2017 assessment of climate and the cryosphere in the Arctic by the Arctic Monitoring and Assessment Programme (AMAP) in Snow, Water, Ice and Permafrost in the Arctic (SWIPA) 2017, the fourth climate report by AMAP since 1998.
Key findings of the report show:
The Arctic’s climate is shifting to a new state
Rising concentrations of greenhouse gases are driving widespread changes in the Arctic’s sensitive climate, hydrological and ecological systems. Downward trends continue in the extent and thickness of sea ice, land ice volume, and spring snow cover extent and duration while near-surface permafrost continues to warm.
Climate change in the Arctic has continued at a rapid pace
Arctic air temperatures are rising faster than the global average. Sea temperatures are increasing. The frequency of extreme events is changing, with fewer days of extreme cold in both winter and summer and increases in extreme warm periods in some areas. Sea-ice thickness has decreased and older ice that has survived multiple summers is rapidly disappearing. The decline in sea-ice extent and thickness and the timing of ice melt are affecting marine ecosystems and biodiversity with an increase in the occurrence of algal blooms. These changes influence diet among marine mammals and alter predator-prey relationships and habitat uses. The occurrence of rain-on-snow events and winter thaw/refreezing affects grazing animals such as caribou, reindeer and muskox by creating an ice barrier over lichens and mosses.
Changes will continue through at least mid-century, due to warming already locked into the climate system
Warming trends will continue because increases are locked into the climate system by past emissions and ocean heat storage. These will still occur even if the world makes drastic cuts in emissions. Declines in snow and permafrost will continue. The Arctic Ocean could be largely free of sea ice in summer as early as the late 2030s. The melting of land ice, particularly from the Greenland ice sheet, will contribute significantly to sea-level rise. Many of the smallest glaciers in the Arctic will disappear by mid-century. The Arctic water cycle will intensify, with model-projected increases in cold season precipitation of 30-50% over the Arctic Ocean toward the end of this century; a greater proportion will fall as rain instead of snow.
There will be significant stresses on ecosystems. Changes in sea ice can be expected to affect populations of polar bears, ice-dependent species of seals and, in some areas, walrus which rely on sea ice for survival and reproduction. There will also be losses of ice-associated algae. An increasing frequency of wildfire and abrupt thawing of permafrost could accelerate ecological shifts, such as the expansion of tall shrubs and trees into tundra.
Substantial cuts in global greenhouse gas emissions now can stabilize impacts after mid-century
While the changes under way in the Arctic are expected to continue through to at least mid-century, substantial global reductions in net greenhouse gas emissions can begin to stabilize some trends, such as snow and permafrost loss, after that. Efforts to control greenhouse gas emissions would also reduce end-ofcentury sea-level rise. However, the Arctic of the near future will be a substantially different environment from that of today.
Adaptation policies can reduce vulnerabilities
There is an urgent need for local and regional adaptation strategies that can reduce vulnerabilities and build resilience, given the inevitability of accelerating impacts in the Arctic and globally.
Effective mitigation and adaptation policies require a solid understanding of Arctic climate change Better knowledge is needed to predict the course and effects of climate change in the Arctic and improve our ability to respond to current and future changes. Coordination across monitoring efforts, modeling studies and international assessments can facilitate information sharing and avoid duplication of effort.
Download the full scientific assessment report Snow, Water, Ice and Permafrost in the Arctic (SWIPA) 2017 and its Summary for policy-makers. Information relevant to the development of local and regional adaptation strategies is addressed in three Adaptation Actions for a Changing Arctic (AACA) regional reports, covering the Barents, Baffin Bay/Davis Strait, and Bering/Chukchi/Beaufort regions.
JANET PAWLAK is deputy executive secretary to the Arctic Monitoring and Assessment Programme (AMAP) Secretariat.