Glaciers On Top, Permafrost Below: Terrestrial Ice, get in the know

Explain

Terrestrial ice in the Arctic is changing. The Earth absorbs about 70% of the solar radiation that reaches the surface. Since snow and ice are very reflective, they have a cooling effect on the planet by reflecting solar radiation like a mirror. If there is less ice, more heat is absorbed because bare ground, vegetation, and open water all absorb much more incoming heat than ice or snow. If more of Earth’s ice melts due to warmer temperatures, the effect of less ice will in turn be more warming. Ice covers 10% of the Earth’s land surfaces. The vast majority of the Earth’s fresh water in the form of ice is stored in Antarctica. The next largest amount is in Greenland, with the remaining amount throughout the other continents (except Australia, no ice there). Without ice, it is likely that the temperature of the Earth would increase.

Glaciers cover 5% of Alaska’s land surface (USGS). If they all melted, it would raise sea levels about 0.05 meters. In comparison, if all of Greenland’s glaciers melted, it would raise sea levels by 6 meters. As the glaciers melt off and there is not as much ice weighing down the land, some areas of Alaska are currently experiencing post-glacial rebound where the land rises as much as one inch per year. At the same time glaciers are melting above the ground, underneath the surface the permafrost is melting. Gases such as methane are released into the atmosphere as the organic material that was previously frozen begins the process of decay. Incidence of forest fires increases as weather patterns change because of less moisture held in surface soils and lakes. As permafrost melts, different types of foliage and forest trees move in and Native Alaskan hunting grounds and animal habitats are changed.

Explore

If you want to hear an out-of-the-ordinary science song and learn more about terrestrial ice, watch Tunnel Man 4 (aka University of Alaska Fairbanks scientist Kenji Yoshikawa). You can see some psychedelic solifluction, thermokarst, ice wedges, ice polygons, pingos, buried glaciers, palsa, ice blisters, ice lens and all things related to terrestrial ice.

In an NPR article about the work of UAF scientist Katie Walter, it talks about her work using satellite imagery and field observations to measure methane emissions from arctic lakes. When permafrost under a lake melts, the previously frozen organic materials are food for organisms in the lake. The resulting methane released in this process can be seen in arctic lakes as bubbles of methane gas trapped in ice in the winter, or bubbling “boiling” water on unfrozen lake surfaces.

“Today there is as much carbon in the permafrost as there is in the atmosphere. So if all the permafrost warms and thaws and all of that carbon is converted to greenhouse gases it would double the amount of carbon dioxide in the atmosphere. But, in fact, much of the permafrost thaws beneath lakes. We estimate that the amount of methane that can come out of lakes is ten times the amount of methane that’s right now in the atmosphere.” –Katie Walker, University of Alaska, Fairbanks

Evaluate

Native Alaskans have noticed changes relating to terrestrial ice continue to worsen in their lifetime. Thousands of lakes are found in the Arctic because ice and snow melt, but are trapped on the surface since the frozen ground below does not melt. Fish, migratory birds and other types of wildlife in Alaska depend on the many areas of surface water. Lakes are shrinking. River banks are eroding, affecting structures as well as fish habitats. When riverbanks erode, the rivers become shallower and it is harder for salmon to get upstream. Since many Native groups in Alaska depend on salmon for subsistence, many communities are built on or near the banks of rivers. When a village faces the need to relocate due to erosion attributed to permafrost melting, it also faces the potential that a move may erode their culture. Native stories and way of life are passed down from hundreds of years of subsisting in one area where the people are connected to the land. To help face the changes that are happening in the Arctic, the same strong survival skills and close sense of community that have been valued by Native Alaskans for centuries are just as necessary today as they were in times past.