The melting of the polar ice caps has been capturing the attention of scientists and climatologists, in fact, people from all walks of life around the world the past few years due to the dramatic changes taking place within them. The phenomenon affecting both ends of the Earth is considered an unquestionable harbinger of the changing global climate in both scope and intensity.
Both ice caps are shrinking from year to year, yet their effects on global ecology will be considerably different. This is because one ice cap, the Arctic, is floating on top of the ocean and is already displacing sea water.
Thus, were the Arctic ice cap to totally melt, there would be very little effect on the sea level change. Yet, other changes such as loss of the ice cap’s reflective properties (of light and heat) back into space and the introduction of enormous amounts of fresh water (which is what the ice cap is composed of) will have dramatic effects on climate and ocean salinity.
At the opposite end of the planet is the Antarctic ice cap, far more vast in its thickness and coverage. It also mostly sits upon the fifth largest of the world’s seven continents, Antarctica, with an area of about 5.5 million square miles (14.2 million square kilometers). About 98% of the continent is covered by ice. Were even half of this ice mass to melt, the rise in sea level would have devastating effects worldwide, not to mention the dramatic effects on global ecology. In fact, over 70% of the Earth’s fresh water is contained in the Antarctic ice cover.
The Arctic Focus
Today, we are focusing on the Arctic ice cap because it is the one surely to totally melt away long before the Antarctic ice cap and it has begun its decline for the year. (The Antarctic is beginning to experience its winter now.)
The Arctic ice cap has begun to shrink from its winter maximum extent of 5.85 million square miles (15.16 million square kilometers), and is expected by many scientists to reach a record low this year when it reaches its minimum coverage area in September, according to scientists at the National Snow and Ice Data Center in Boulder, Colorado. This winter’s maximum extent of ice coverage was similar to that of recent years, but lower than the average coverage between 1979 and 2000. 1979 is the year measurements began to be taken of the Arctic ice cap.
Sea ice extent averaged over the month of March 2009 was 5.85 million square miles (15.16 million square kilometers). This was 282,000 square miles (730,000 square kilometers) above the record low of 2006, but 278,000 square miles (720,000 square kilometers) less than the average extent for 1979 to 2000.
The greatest shrinkage of the Arctic ice cap was measured on September 16, 2007, when its sea ice extent was 4.13 million square kilometers (1.59 million square miles). This surpassed the previous record by more than 461,000 square miles (1.2 million square kilometers) established in September 2005.
Cause and Effects
As indicated earlier, the melting of the Arctic ice cap will not have a significant effect of sea level rise. It will, however, greatly affect the albedo (reflectivity) of the Earth’s surface in the Arctic region. The lower albedo of open ocean will mean less solar energy reflected back into space. Instead, that energy will be absorbed by the ocean.
The warmer water will melt more sea ice, and eventually the warmer atmosphere above the warmer water will melt more of the ice sheets on Greenland. Since sea ice and sheet ice both consist of fresh water, the result will be a huge increase in the amount of fresh water in the Arctic Ocean. This could lead to a disruption in the primary North Atlantic circulation (the ocean conveyor belt) and drastic cooling of temperatures everywhere.
Overall, it was a fairly warm winter in the Arctic. Air temperatures over the Arctic Ocean were an average of 1 to 2 degrees Celsius (1.8 to 3.6 degrees Fahrenheit) above normal, with notable regional variations. The Barents Sea region was over 4 degrees Celsius (7.2 degrees Fahrenheit) warmer than average this winter. This warmth probably stemmed from unusually low sea ice extent in the region throughout much of the winter, which allowed the ocean to pump heat into the atmosphere.
The Bering Sea, in contrast, experienced a cool winter, with temperatures 1 to 2 degrees Celsius (1.8 to 3.6 degrees Fahrenheit) below average. The cooler conditions were consistent with the above-average sea ice extent in the Bering Sea through much of the winter.
The Summer Melt Season
As the melt season begins, the Arctic Ocean is covered mostly by first-year ice which formed this winter, and second-year ice which formed during the winter of 2007 to 2008. First-year ice in particular is thinner and more prone to melting away than thicker, older ice. This year, ice older than two years accounted for less than 10% of the ice cover at the end of February. From 1981 through 2000, such older ice made up an average of 30% of the total sea ice cover at this time of the year.
While ice older than two years reached record lows, the fraction of second-year sea ice increased compared to last winter. Some of this second-year ice will survive the summer melt season to replenish the Arctic’s store of older ice; however, in recent years less young ice has made it through the summer. To restore the amount of older ice to pre-2000 levels, large amounts of this young ice would need to endure through summer for several years in a row.
What It All Means
What is taking place in the Arctic and the Antarctic reflects definitive changes in and evolution of our global climate, both natural and arguably induced through human impact. Still, it is part of the continuing cycle of Earth’s changes.
Can you imagine a planet where the Arctic ice cap did not exist and Antarctica was covered with trees? In fact, most scientists agree that the Arctic ice cap first formed through a series of cycles as recently as three to five million years ago and as long as 15 million years ago. The Antarctic ice cap is widely believed by scientists to be 15 million years old, and eventually replaced the vegetation that once grew on the land mass beneath it.
The truth is, humans learn and adapt. Collectively, humans can have definitive and measurable impacts on global conditions, as we’ve seen with global warming. Ultimately, however, the Earth’s cycles are not to be denied and humans can and will adapt. Just as we will see a changing ecology, for better and for worse, with the melting of the Arctic ice cap, we will also witness Earth’s continued evolution.
While the Arctic ice cap is expected to totally disappear by the year 2050 (some scientists say it could be much sooner), we will see a changing climate and environment. The Arctic is far less stable than the Antarctic and we will thus see the impact of its changes within a shorter period of time, including the opening of the Northwest Passage shipping routes between the Atlantic and Pacific Oceans.
But with the Antarctic comes a far greater set of challenges if its massive ice pack melts. It’s more stable, but is also showing signs of rapid deterioration. That is another story.
