Life in the Rear-view Mirror

Climate Change: Myth or Reality?

Global Warming or Climate Change? It's difficult to find anybody living on earth that hasn't heard about the impending disasters of global warming and climate change, unless one is a recent visitor from Mars. But, is it myth or reality?

Davis Guggenheim's documentary, An Inconvenient Truth, featuring former U.S. vice-president Al Gore, has done more than anything else to make these phrases household words. He started out with a passionate appeal to do something about global warming, before it's too late. But now people talk less about global warming and more about climate change - a more encompassing phrase, which dilutes the focus but expands the field enormously, at least from a public perspective.

While it's relatively easier to provide evidence of global warming by direct measurement, it's much more difficult to scientifically demonstrate climate change. For example, proving that the planet is getting warmer doesn't prove climate change because the Earth's climate has been changing for billions of years. But it's a catchy phrase and it can be used after every tornado, hurricane, typhoon, el niño, or drought as evidence of climate change, even though they are phenomena that have been occurring from time immemorial. This has caused much confusion in peoples' minds and generated fear that we are near the edge of a precipice.

Almost on a daily basis, one can find media references to climate change for any climatic phenomenon. For example, the recent drought in California is being blamed on climate change, forgetting that it has always been a desert, just like the entire coast of Peru, in South America. The dust bowl reference to the severe draught in the prairies, during the depression years, happened well before greenhouse gases reached elevated levels. What's happening in California now is what happened in the prairies eighty years ago! It has nothing to do with global warming!

The premise for global warming is that the concentration of greenhouse gases in the atmosphere has been steadily rising, and is above levels never before seen in the history of the world. The CO2 trend is pretty solid, as it's based on measurements of ice samples from polar icecaps that go back hundreds of thousands of years. The time of the samples was estimated from the ratio of Carbon-14 to Carbon-12, a standard method for dating things or events that happened in the past. Therefore, the fluctuations of CO2 levels in the atmosphere are generally accepted without disagreement.

However, linking CO2 fluctuations to temperature fluctuations requires a great leap of faith. We simply don't know what the correlation between CO2 concentration and temperature was in the past few thousand years because we have no direct temperature measurements. There are ways of inferring what those temperatures might have been, but there are no direct measurements. Unfortunately, we have temperature measurements only for the last 130 years: not a lot to make long-term predictions!

What are the mechanisms behind global warming? The primary parameter is the amount of sunshine hitting the earth, some of which is reflected by the earth's atmosphere into space. Of the remaining part, the atmosphere absorbs some, and earth's water and landmasses absorb the rest.

The amount of sunshine is a well-known quantity, but there are annual variations due to sunspot activity and solar flares, which are cyclic, with a period of about eleven years from peak to peak. The amount of sunlight absorbed by the atmosphere depends on the amount of water vapour, particulates, and so-called greenhouse gases.

The sun's energy captured by the atmosphere causes it to warm up and to radiate heat into space as well as to earth. The earth's surface (land and water) also radiates energy back to space, in the form of heat (infrared radiation). Again, the atmosphere captures some of this heat, causing it to get even warmer, and radiates some of it back to earth and the rest into space. This is the much talked about greenhouse effect. The atmosphere acts like a giant greenhouse, preventing all the infrared radiation from escaping into space. If it weren't for the greenhouse effect, life on earth, as we know it, wouldn't be possible. Daytime temperatures would be much higher, and nighttime temperatures much colder. So, what is all the commotion about?