One of the talking points for climate change deniers concerns warming in Antarctica. “Why,” they ask, “isn’t Antarctica warming if there is global warming?” Of course, the answer is that it is warming. It is somewhat sheltered by circum-antarctic air currents that trap the cold air over the continent, but even that hasn’t been enough. Now, models show that it is getting even worse.Some of the ice sheets previously thought to be stable are now seen to be vulnerable.
Ice sheets, great expanses of floating ice at the end of glaciers, are susceptible to global warming from above and below. The warmer air will heat them from above while warmer ocean currents will melt them from below. The Amundsen Sea, located at the southern end of the Pacific Ocean, has been know for a long time to be vulnerable in this way. But, it was thought the Weddell Sea, at the southern end of the Atlantic Ocean, was sheltered from warm ocean currents. Now, research is indicating that isn’t as much of a sure thing as previously thought. As the atmosphere warms, this will help drive warm currents into the Weddell Sea and accelerate melting of the ice sheets there.
Melting of the ice sheets won’t, by itself, cause sea levels to rise. That is because the ice is already in the water and melting ice doesn’t cause the sea level to rise. Put ice in a glass of water and mark where the water line is. Come back later after the ice has melted and compare the water line. You’ll find it is the same. But, the ice sheets are preventing the glaciers from running down into the ocean. Remove the ice sheets and the land-bound ice will slide into the ocean more rapidly. Moving the ice from land into the ocean will result in higher ocean levels. In fact, pretty significantly higher. By the end of this century, the model shows the ice sheets will lose 1,600 billion tons of ice per year. This is enough to lift the oceans by .17 inches per year. In comparison, the oceans today are rising at a rate of .05 inches per year.
So, the accelerated melting of the Weddell Sea will result in an ocean rising rate that is more than three times the current rising rate and do it by itself. Then, there are the other causes of rising oceans to factor in. By the end of the 21st century, coastal land will be disappearing, either by submersion or erosion.
But, the end of the 21st century is a long way away. If you are reading this blog today in 2012, you will probably not see the year 2100. So, why should you care?
It is simple. You could turn your back on the future and let the people that follow us take care of our problems. Or, you can chose to take responsibility for your actions and do something about it. Of course, remember that things will be getting worse between now and the year 2100, so we all will suffer the consequences of our actions and inactions.
But, that is your choice. Which way do you want to go?