Sea ice reflects the sun’s rays back into space, reflecting more heat than it absorbs, which helps keep the planet cool. As sea ice decreases, there is more open ocean that absorbs more heat from the sun, and as the ocean absorbs more heat, more ice melts. This causes some other impacts, as well:
- Erosion of the Arctic coastline is increasing due to the decline in sea ice that previously protected the coast from storms, and because warmer oceans increase the frequency and severity of storms. Many cultural artifacts are found along the coast and river banks. Erosion may expose those artifacts and make them susceptible to damage or loss.
- With the decline in sea ice, shipping has increased, which increases marine contaminants and the potential for oil spills.
- Many people in the Arctic depend on hunting on the ice. With the loss of sea ice, people may not have access to traditional hunting areas, or access is much more dangerous because the ice is less stable.
- Coastal erosion and sea level rise also endanger coastal communities. Some Alaskan communities are discussing how to relocate their whole villages before they are lost to the sea.
Permafrost, soil that remains frozen year round, is thawing as the earth warms. Permafrost stores a lot of carbon; as it thaws, it releases greenhouse gases (carbon dioxide and methane, principally) into the atmosphere, which then contributes to more warming. This also causes other impacts:
- Thawed permafrost causes landscape slumps that can damage infrastructure such as roads, airstrips, houses, and utility lines. It can also cause or contribute to the severity of landslides. Many people in the Arctic depend on frozen ground to travel to hunting areas or between villages; as the ground thaws, transportation and access to resources is impacted.
- As permafrost thaws, hydrologic dynamics also change. As ice in the soil melts, it forms standing water. Think of the ice layer as a plug in a bathtub. As long as the ice remains, water cannot drain. When the ice melts under that water, it causes the standing water to drain, just like pulling a plug in the bathtub. Both scenarios change the hydrologic dynamics of a region and impact plants and animals.
- Snow-covered ground reflects more heat than ground covered in vegetation. As temperatures rise, more trees and shrubs colonize Arctic ground, absorb more heat, and increase the effects of warming in the soils.
In addition to these major system feedbacks, there are a number of other climate change impacts we experience in Alaska, including:
- Glaciers are abundant in Alaska. We have over 27,100 glaciers with a surface area of about 86,700 km2 of ice. Half of Alaska's glacial cover is in parks. Alaska's glaciers are decreasing in area and volume and are losing 50 gigatons of ice per year, which causes 0.14 mm/yr sea level rise, contributing 5.5% of the total sea level rise. Five-and-a-half percent of total sea level rise doesn't sound like a whole lot, but it is impressive when you consider that Alaska's glaciers are about one half of one percent of all the glacier/icesheet cover on the planet, but are contributing about 9% of the total icemelt globally. In other words they are melting and contributing to sea level rise relatively faster than most other glaciers and ice sheets on the planet.
- Geohazards, such as landslides, are an increasing threat due to unstable and melting soils.
- Ocean acidification is exacerbated by cold waters in Alaska and inputs of freshwater from tidewater glaciers.
- Shifts in plant communities are occuring due to raising temperatures and changing conditions.
- As plant communities shift, so do wildlife communities.