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Global Warming and Arctic Sea Ice Melting

-xwEXoMr1qF3LJK5OghZLhXbX4aJ90ysuDZfXWu4opb0AQAATgEAAEpQ_260x196In recent years, when we are complaining about the hotter and hotter summer, the arctic sea ice content has reached the lowest point for the last 1,500 years by the end of 2012. Eric Post, professor in Department of Biology, and his co-workers from University of Pennsylvania have published an article on recent Science, pointing out that the reducing of sea ice is not only due to the global warming, but also results in further global warming.

In the past two decades, the speed of warming up in arctic area is twice that of other regions on earth.  Post and his team was devoting in explore the “domino effect “resulting from the reducing of sea ice. They have investigated the ecological relationship of arctic algae, plankton, walrus, arctic fox and other arctic creatures. The results show that the shrinkage of sea ice has exerted significant influence on the whole arctic ecosystem.

The first fallen dominoes is the sea ice itself. The speed of arctic sea ice melting is higher than the expectations of most climate models. The increased melting speed for sea ice might be relevant to the lowered albedo—as sea ice keeps melting, ice areas that are able to reflect sunlight become smaller, resulting in more solar radiation received, and hence accelerates the melting of sea ice in turn. If things go on like this, the high-albedo sea ice will be replaced with no-ice water, which has far lower albedo, and the global warming issue can become even severe.

In addition to reflect sunlight, arctic sea ice is also an important habitant for producers. Each year, 57% of the total production of arctic creatures comes from algae in the sea ice and planktons below the ice; the shrinkage of sea ice will directly affect the seasonal growth of these creatures. The decreasing of fat content in algae living in ice layers results in reduced nutrition for other creatures that are fed by algae, thus the food cycle in arctic area would be impacted.

Moreover, the shrinkage of sea ice will indirectly influence animal activities, population mixing, as well as pathogen transmission. For example, since there are less ice connecting islands, the chance for animals to travel across ice layers and islands is significantly decreased, therefore, the genetic isolation between arctic wolves and arctic foxes is escalated, while the gene exchange between polar bears and grizzlies is enhanced. Additionally, the habitant for walrus is transferred from sea ice to coastal area, which might facilitate the pathogen transmission.

Last but not the least, due to the shrinkage of sea ice, the thinning of ice layers, and extending of no ice season, the arctic route may be extended to regions that were unreachable in the past. The changes in shipping activities certainly will expedite the mineral exploitation and oil drilling in arctic region, which will impact on land and sea animals.

Researchers emphasized that we should understand that the shrinkage of sea ice is not merely a signal for global warming, but also a force to change the entire ecosystem.

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