Global Implications of Arctic Warming

Arctic warming has global consequences. It is possible that Arctic warming could trigger climatic thresholds that would cause abrupt climate change in a short time frame. Such thresholds may be crossed due to certain self-sustaining positive feedback mechanisms that, once triggered, would cause the acceleration of global warming, and would be hard to stop.

Sea Level Rise

NASA satellites show polar ice sheets are shrinking and losing mass at increasing rates. Scientists have observed firsthand Greenland's outlet glaciers shedding ice into the oceans twice as fast as a decade ago. The accelerated rate at which the Greenland and Antarctic ice sheets are losing ice to the oceans poses the risk of inundation of the US coastline by as much as a meter by 2100, with sea level continuing to rise thereafter. Read more science at CA-CP's sea level rise science page.

The Thawing Permafrost

A positive feedback mechanism with global consequences has to do with the thawing grounds of the Arctic. The carbon and methane currently stored in the permafrost (frozen ground) of the Arctic could be released into the atmosphere should this ground thaw deeper, due to warming, which would further warm the atmosphere and cause further release of carbon and methane. The thawing of the permafrost could also cause vegetation to expand northward.

The Slowing of Thermohaline Circulation

Another such feedback mechanism pertains to ocean circulation. As more freshwater enters the Arctic oceans, ocean salinity decreases, slowing thermohaline circulation, the ocean's "conveyor belt" which circulates warm and cold ocean water throughout the planet. Decreased salinity, warmer waters, and increased precipitation caused by Arctic warming are likely to slow or shut down parts of the thermohaline circulation pattern. The “conveyor belt” would then transport less warm water from the tropics to the poles, causing Western Europe's temperate climate to cool for decades. Also, less carbon dioxide would be transported into the deep oceans, further increasing carbon concentrations in the atmosphere, and thermal expansion would increase, further causing sea levels to rise.

Download the Arctic Climate Impact Assessment's Key Finding on Arctic warming’s global implications (PDF)

Sources: ACIA, 2004, UNEP.

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