Antarctica and Global Warming

Antarctica, the southernmost continent is literally the last place on earth. It occupies about 14 million square kilometers (5.4 million sq. miles.) For comparison, it is about twice the size of Australia and half the size of North America. Because of the tilt of earth’s axis and local elevation, it is obviously the coldest with an average wintertime temperature of – 60°Celsius, and summers averaging -28° C.

Interestingly Antarctica is also the driest, windiest and highest. Annual precipitation is 20 centimeters (8 inches) and most of that falls on coastal areas with the interior even drier. Ironically, although it is a desert based on precipitation, it contains 70% of the world’s fresh water as ice.

Wind speed averages 23 mph across the continent, but straight line winds of 200 mph have been recorded. Compare this with a category 5 hurricane whose winds are a puny 156 mph. Only an F5 tornado creates wind speeds equivalent to that encountered routinely on Antarctica.

One of the reasons for the cold weather in Antarctica, as noted earlier is its average elevation. The North Pole is at sea level, actual below it because the land mass at the North Pole is under the Arctic Ocean. The average elevation however for Antarctica is over 8,000 feet. The South Pole itself is over 9,000 feet and the highest point is 16,300 ft. Ice over much of Antarctica is a mile or more thick.

So what’s up (pun intended) with Antarctica? The temperatures? Well, it’s complicated as parts of the continent are warming while others aren’t. First the warming part. Both computer climate models and recorded data over decades show that while the planet is warming as a whole, the polar areas are warming even faster. This is a result of several different phenomena. Clouds, ice cover, water vapor and large scale weather patterns have all be implicated.

Ice is shiny stuff and reflects much sunlight. As ice over the sea melts the sun warms the less shiny water more. The term for light reflected divided by light absorbed is albedo. For very shiny snow or ice the albedo is about 0.9 (total reflection would result in a value of 1.0). Open oceans are much less reflective hence absorb more heat and have an albedo of less than 0.1.

The south pole has a confounding variable – the ozone hole. Essentially the reduced amount of ozone over the south pole reaches a maximum in the austral spring. The ozone hole is gradually decreasing due to international protocols which banned the use of chlorofluorocarbons. As the amount of ozone returns to normal the temperatures in the south pole are expected to rise as rapidly as in the north. As the Antarctic continent warms and sea ice melts, some of the land based, 1 to 3 mile thick layer of ice will begin to melt.

Were all this ice to melt sea levels would rise over 200 feet. This catastrophic sea level rise would inundate Manhattan Island, Miami, New Orleans, Houston and on and on. This won’t be happening soon, but without first recognition of human impact to global warming, it will happen.

One thought on “Antarctica and Global Warming

  1. Julie Muzzall

    “The earth is an incredible dynamic force always seeking equilibrium.”
    And, as someone once told me, “We’re like fleas on a dogs back. All we can do is grab hold and hang on.”

    Reply

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