Overview: Sea Ice and Rising Ocean Temperatures in Alaska

tunicates on a brickFishing for blue king crab near Little Diomede Island. Deborah Mercy/Alaska Sea Grant

In the past few decades, average temperatures in Alaska have risen twice as fast as in other parts of the nation. Consequently, Alaska is feeling the effects of climate change sooner, and stronger, than the rest of the United States. Rising temperatures are causing glaciers to recede and sea ice to thin and disappear. Bare sea ice reflects 50-70% of the sunlight that strikes it. As sea ice melts, an increasing area of open ocean is exposed. Dark open ocean water absorbs more than 90% of the sunlight that strikes it, causing the water to become warmer. As ice melts, more sunlight is absorbed, causing the water to warm and even more ice to melt, creating a self-reinforcing cycle of warming (called the ice albedo feedback).

It is not only the ice albedo feedback that is responsible for observed sea ice reductions. Sea ice loss is driven by a complicated interaction of long term thinning due to warming, a thinner and more mobile ice cover, arctic scale ice dynamics, warm water inflow into the Arctic Ocean, and weather patterns. While arctic warming causes ice loss, in autumn and winter the ice loss also drives warming because of intense oceanic heat loss to the atmosphere from areas of open water and thin ice. Also, because the lower atmosphere in the Arctic is quite stable, heat tends to stay trapped at the surface. There is also evidence that some of the warming relates to changes in cloud cover and water vapor, and the import of ocean heat from the Atlantic.

While sea ice extent undergoes an annual cycle of retreat in summer and advancement in winter, there is an overall downward trend in the area and volume of sea ice in the arctic region. It is predicted that summers in the Arctic could be essentially ice-free as early as the middle of this century. Why is this so significant? Sea ice is extremely important to the arctic ecosystem. Rising ocean temperatures and less sea ice have far reaching consequences on the ocean and coastal environments, marine plants and animals, and humans in Alaska and beyond.

How Can We Help Slow Ocean Warming and Sea Ice Melt?

The oceans are warming largely due to the release of carbon dioxide (CO2) into the atmosphere. The amount of human-released CO2 has increased steadily since the industrial revolution, increasingly warming the earth and the oceans over time. One way to alter the future path of human-induced warming is to reduce the CO2 emissions. Below are some ways that you can help:

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