The Importance of Sea-Ice
Why Will the Loss of Arctic Ice Be so Devastating to Our Planet?
Sep 2, 2008
Arctic and Antarctic sea-ice melts in the summer and forms in the winter. Recent satellite images of the northern hemisphere have shown that the rate of melting is exceeding the rate of formation, causing an overall trend of sea-ice loss. Sea-ice loss has the potential to have a detrimental impact on our planet. Magnifying the threat is the cyclical nature of the problem.
Sea-Ice Loss and Radiation
The Earth’s climate relies on the presence of sea-ice in the northern hemisphere. Because ice is white, it acts as a giant mirror that reflects the sun's radiation into space.
The reflectivity of a surface is referred to as its “albedo”. The northern hemisphere has a high albedo due to the fact that it’s mostly covered with ice – as opposed to equatorial regions which are darker colored and therefore have a low albedo. A document titled "Arctic and anartctic sea ice, 1978-1987," released by NASA in 1992 and written by Gloerson et al. stated that, based on satellite measurements, sea-ice reflects as much as 50-95% of incoming solar radiation; whereas an open ocean reflects only about 10-15% of solar radiation.
Sea-ice reflects the sun’s energy, keeping atmospheric temperatures cooler. Moreover, it keeps the ocean in the northern hemisphere cooler, helping to maintain the planet’s ocean conveyor system. This conveyor system helps to maintain ocean currents – both on the surface and at depth – which transfer essential nutrients throughout the ocean for marine life.
Climate Change – The Ocean-Atmosphere Cycle
The cyclical nature in which the Earth’s oceans and atmosphere are connected makes sea-ice loss an even greater problem. As greenhouse gases and pollution are emitted into the atmosphere, either by humans or by nature, the atmosphere warms. As the atmosphere warms, so do the oceans. And as the oceans warm, they are more efficient at melting sea-ice in the northern and southern hemispheres. But, as sea-ice melts, exposing more open water, less solar radiation is reflected back into space.
With less solar radiation being reflected back into space, more radiation is absorbed into the atmosphere and oceans, increasing temperatures faster than sea-ice can cool them back down. An article written by Serreze et al. in 2000 titled “Observational Evidence of Recent Change in the Northern High-latitude Environment” in the journal Climate Change stated that these changes are occurring at a measurable rate and that the 20th century Arctic is the warmest of the past 400 years.
Potential Hazards from Sea-Ice Loss
With the hazard of warmer atmospheric and ocean temperatures due to the loss of sea-ice, humans are at risk from hazards associated with rising sea-levels. According to a 2004 article titled "Glaciers and Sea Ice Endangered by Rising Temperature," written by Janet Larsen for the Earth Policy Institute, if a large ice shelf, such as the one covering Greenland, were to melt because of a warmer climate, the resulting sea-level rise would measure about 7 meters (23 feet) worldwide. For the numerous coastal cities that are already fighting back rising sea-levels, a catastrophic event such as this could leave only one option – abandon these cities and move to higher ground. This could result in the displacement of millions of people, most of them from underdeveloped countries.
Sources:
U.S. Geological Survey Newsroom
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