Wow! Where do I start? When considering terrestrial ice my mind goes directly to Antarctica. Ninety percent of the world’s ice is found on Antarctica and 70% of all the world’s fresh water is contained in that ice (http://www.coolantarctica.com/Antarctica%20fact%20file/antarctica%20fact%20file%20index.htm). It’s no wonder I think of Antarctica when I think of terrestrial ice!
Antarctica compared to the United States. (http://www.iceonparade.com/about.htm)
Although winter freezing of offshore ice in Antarctica and increased melting of the ice sheet itself influences climate and cultures worldwide, I will primarily focus on permafrost in this blog response. When contemplating terrestrial ice, permafrost never entered my mind before this module and that is why I’m blogging about how permafrost (as terrestrial ice), climate and Alaskan indigenous cultures are all connected.
Permafrost, or permanently frozen ground, is soil, sediment, or rock that remains at or below 0°C for at least two years. It occurs both on land and beneath offshore Arctic continental shelves, and its thickness ranges from less than 1 meter to greater than 1,000 meters (National Snow and Ice Data Center).
Decomposition of plant material in cold climates is a slow process. Plant material builds up over time and becomes a huge storehouse of frozen carbon and methane (greenhouse gases) within permafrost. With the recently accelerated melting of permafrost, more and more carbon and methane is released into the atmosphere contributing to a positive feedback loop similar to that of the Arctic.
So what does this mean for the indigenous cultures of Alaska? As permafrost melts, both man-made and natural features are jeopardized. As the ground warms, the ability to support large structures is decreased. Landslides and erosion are more prevalent and new species may drive out indigenous species as the ecosystem changes.
In fact, there are already numerous ecosystem changes observed due to permafrost thawing. They include: destruction of trees and loss of boreal forests; expansion of thaw lakes, grasslands, and wetlands; loss of habitat for caribou and terrestrial birds and mammals; additional habitat for aquatic birds and mammals; increased coastal and riverine (along the banks of rivers) erosion; blocking of streams important for salmon spawning; increased slope and soil instability, landslides, erosion; and development of talik (a year-round thawed layer of what was formerly permafrost), and increased water table depth (http://www.usgcrp.gov/usgcrp/nacc/education/alaska/ak-edu-3.htm).
When contenplating climate change and terrestrial ice, one must consider permafrost. As permafrost thaws, it not only releases greenhouse gasses that feed into a positive feedback loop which accelerates global warming, but changes the environment as well. Thawing permafrost damages houses, roads, pipelines, and airports and requires costly maintenance expenditures. Indigenous cultures are also jeopardized. Native plant and animal species risk disappearance. Thawing of permafrost is likely to continue to bring widespread changes in ecosystems, increased erosion, harm to subsistence livelihoods, and damage to buildings, roads, and other infrastructure.
