The shrinking extent of summer sea ice in the Arctic is probably the most well-known major change occurring in the region. However, simple cause-and-effect relationships are very difficult to postulate because there are a great many other components of the Arctic region which are undergoing rapid change. The interdependency of the Arctic and the rest of the planet further serves to complicate the picture.
Among others, the lower amount of solar radiation reflected by (dark) sea water relative to (light) ice is a major cause for concern. As the extent of summer sea ice decreases, less energy is reflected and more is absorbed into the ocean, further contributing to ice melt. This is further exacerbated by the fact that it takes far less energy to warm water that is already liquid than to melt ice.
The interplay between ocean and atmosphere is another crucial aspect of climate science. The presence of greenhouse gases and aerosols changes how radiation travels through the atmosphere, controlling regional climate. Permanently frozen soil, known as permafrost, stores large quantities of greenhouse gases such as methane which are released if it melts. The impact of this little-studied effect on Arctic climate and radiative effects could be considerable.
Finally, all these physical and chemical processes affect marine and terrestrial life and biodiversity which, in turn, plays an important role in the regional and global cycle of carbon and other greenhouse gases. Studying fossil records and palaeo-records to investigate how plant and animal communities responded to climatic changes in the past could help us understand how current events may change the Arctic.
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Image credit: NASA