Move over global warming

If you thought global warming and its consequences were frightening, wait till you hear the latest version of this old environmental story. Its called global dimming, and its consequences, in combination with global warming are frightening. All the air pollution spewing out of human consumption, has two components of concern. The first are the greenhouse gases that we have heard so much about, the second is something we often take for granted - particulates. But I'm getting ahead of myself, let me explain..

Agricultural scientists over the last 10-20 years were puzzled by an observation, the sunlight we were recieving on the earth seemed to be getting less, about 10-30% less. What was even more puzzling was that the reduction seemed to be happening globally, but no-one knew why this was happening. These results were either ignored or filed away by most of the community. However, when this was combined with the observation that the water evaporation rate was decreasing all over, it meant that the decrease in sunlight was very real and had a real physical effect - as the water evaporation rate is highly dependant on the level of sunlight.

When scientists finally took notice and examined this further, they discovered that world was seeing a new phenomenon - global dimming - the sunlight falling on earth was decreasing. It was being reflected by a clouds in combination with a 3km thick band of particulate pollution in our upper atmosphere. This, as it turns out isn't too good, as decreased sunlight means changed changes in evaporation rates and heating of the surface of the earth, and consequently cloud patterns all over the globe. But, this was not all, the double whammy came in the form of its effect on the global warming and temperature on earth. Decreased sunlight through global dimming seems to have been mitigating the effects of greenhouse gases on global warming, by cutting the amount of sunlight getting through.

So the increase of 1 to 1.5 degrees C that we have seen due to global warming would have been much worse had it not been for global dimming. But thanks to decreases in particulate emissions all over the world, especially in the west due to strict emission standards, this protection (if you can call it that) will soon be gone. We may be seeing increases of 2-4 degrees C in temperature all over the world, which would be accompanied by large increases in the sea-level, and unpredictable weather over the next 20-50 years. No-one knows how bad its going to get or how quickly the temperatures are going to rise.

What really frightened me about this story is that none of the scientists that took part in this PBS-Nova special could really predict what the point of no return was, and they were sure there was one. When would the increases in the temperature on earth be too much for us to reverse?

God help all of us, and to my sons T & A, I'm so sorry.....