There is much confusion about global climate change and rightly so because the earth’s hemispheres march to the beat of a different drum. The Northern Hemisphere is classically warmer than the Southern Hemisphere and now it’s more evident than ever. However, the NOAA just reported, “Combined Global Surface Temperature Was Sixth Warmest for October,” The report went on to list global temperature highlights that validate the difference between the two hemispheres:
· The combined global land and ocean surface temperature for October 2009 was the sixth warmest on record, at 1.03 degrees F above the 20th century average of 57.1 degrees F.
· The global land surface temperature for October 2009 was 1.48 degrees F above the 20th century average of 48.7 degrees F, and ranked as the sixth warmest October on record.
· The worldwide ocean temperature was the fifth warmest October on record, with an anomaly of 0.90 degree F above the 20th century average of 60.6 degrees F. Warmer-than-average temperatures dominated much of the world’s land areas. The greatest warm temperature variances during October 2009 were present across Alaska and northern and eastern Russia.
· Cooler-than-average conditions prevailed across Scandinavia, New Zealand, the contiguous U.S., and parts of northern Australia and southern South America.
Other highlights of this report continued to show the southern hemisphere is cooling, “New Zealand experienced uncharacteristically cool conditions, resulting in the coolest October since 1945. The national average was 51.1 degrees F, 2.5 degrees F below the long-term average.” And while “Arctic sea ice diminished 19.2 percent less than the 1979-2000 average and the second smallest October extent, behind 2007, since records began in 1979, Antarctic sea ice extent in October was 1.6 percent above the 1979-2000 average, the ninth largest October extent on record.”
Evidently, the cooling in the southern hemisphere didn’t bring down the average of the two hemispheres enough to negate an overall warming trend. But why is the Southern Hemisphere cooling?
Remember the ozone layer depletion (holes) we heard so much about in the 70’s? Well, they are still around. The holes that allow so much of the earth’s rays to hit us, also allow trapped heat that causes global warming to escape. NASA explains: “Because ozone in the upper atmosphere absorbs heat radiating from below, stratospheric ozone depletion actually allows additional heat to escape into space. While this occurs worldwide, the depth of the springtime ozone hole over Antarctica results in Antarctica cooling while the rest of the Earth warms.” The ozone hole over Antarctica this year was exceptional, the size of North America. http://www.guardian.co.uk/environment/2008/nov/04/poles-climatechange.
Why are ozone holes still around? We were warned back in the 70’s that it takes decades for an ozone hole to heal, and the proof of that is still around. But as the reoccurring Antarctic ozone hole heals, the southern hemisphere will indeed catch up to the warming trends of the north and when it does, it will contribute readily to sea level rise since so much of the ice in the Antarctic is on top of land.
We have to wonder if pollution causes ozone holes and much of the pollution is in the Northern Hemisphere why is the ozone hole over the Antarctic and not the Arctic regions? There is such a thing called “the chemical equator—a natural meteorological boundary in the tropics” where there is a lot of upward moving air and rain that washes out chemicals traveling from north to south making the atmosphere cleaner down under but temperature plays the biggest role in driving ozone holes to the southern pole and not the north. The stratosphere in the southern hemisphere is always about five degrees Celsius colder than in the northern hemisphere and much more ice exists. The icy environment of the southern hemisphere makes the chlorofluorocarbons (ozone depleting chemicals) more potent. As an ABC article explains: “The chemical reaction that frees chlorine from CFCs takes place on the surface of tiny particles of ice in the stratosphere… The more ice there is in the stratosphere, the more ozone-destroying chlorine is liberated from CFCs.
Deniers like to cling to the expansion of ice in Antarctica and even central parts of Greenland in the north as proof of global cooling or at very least a standstill in global temperature gain. Besides the ozone hole contributing to a cooler Antarctic region, a quick look at the extremely different topography of polar places warming and polar places cooling offers an even greater explanation for the disparity:
The South Polar Ice Sheet is two miles thick. That means that the ice is at an altitude of over ten thousand feet where the temperature is much colder than a mere six or so feet as at the North Pole. This makes it impossible for the slight rise in global mean temperature to have any affect at all in the south accept around the edges of the continent.
Also, it sits on a continent rather than on water that is above freezing – as in the north. The ice in the north is an average of 6 to 12 feet thick and is being warmed from beneath as well as above. This has a much larger impact on the North Polar Ice Cap.
After reading all this material, I realized that the chlorofluorocarbons that cause ozone depletion are still around but slowly moving to the upper stratosphere on their final exit. Scientists weren’t kidding that these chemicals would hang around for years. We were warned, but out of sight out of mind. It’s something we should consider when they say CO2, methane, and host of other manmade global warming gases will indeed hang around long after we’ve put a lid on them and likely cause a host of climatic events even though they are slow to manifest now. If the past is a window, it looks like we can indeed expect climate problems to escalate even if we act now.