Global Warming. Again. Sigh.

Can we stop talking about the global warming “debate” yet? I continue to receive emails from people hearing about how scientists are “torn” on the issue. Let’s get something straight: the overwhelming majority of mainstream scientists (i.e., those working on environmental science projects within recognized universities and institutes) agree that this is a serious issue; detractors tend to be economists, statisticians, TV weathermen and employees of the energy industry. With that in mind, here’s the lowdown:

1. Global warming is a fact. Since the beginning of the 20th century, the mean surface temperature of the earth has increased by about 0.6 degrees Celcius. Over the last 40 years, which is the period with most reliable data, the temperature increased by about 0.2-0.3 degrees. Warming in the 20th century is greater than at any time during the past 400-600 years.

   Additionally, mountain glaciers the world over are receding; the Arctic ice pack has lost about 40% of its thickness over the past four decades; the global sea level is rising about three times faster over the past 100 years compared to the previous 3000 years; and there are a growing number of studies that show plants and animals changing their range and behavior in response to shifts in climate.

While the overwhelming body of evidence suggest a warming, there are but 2 studies that raise any doubts. The first is the satellite temperature measurements since 1979 which show a warming but only half the value of surface measurements over this time. The second is a 1991 statistical study suggesting changes in the cycle of seasons are responsible for the global temperature changes over the last 100 years. At present, neither study poses a threat to the ocean of other kinds of evidence.

2. That human activity is the cause of global warming is still a theory, but a compelling one. A 2002 report to the United Nations presented by scientists working for the US government concluded that “human activities such as oil refining, power generation and car emissions are significant causes of global warming.”

   Our planet is still emerging from a mini-Ice Age which ended about 12,000 years ago. That might be the real base cause of the warming; I surely don’t discount the possibility. Or maybe it’s a combination of factors. Heck, it might even be a cyclical affair, with temperatures dropping again in a century or two. This point –the true cause of the warming– is the only one that is legitimately open to debate.

3. But even if human activity is not the cause of global warming, the phenomenon might still be catastophic for human civilization, and thus requires our immediate attention. We can’t wait a century or two for temperature to maybe drop again. Imagine the Asian tsunami reproduced in every coastal city on the planet. Think our civilization can survive that?

Do you get it now, people? Even if the Kyoto Accords don’t end up affecting global temperatures significantly, they are surely worth the effort and pain. Heck, anything is worth the effort to slow down or eliminate this very real threat. Kyoto is only a start, and I admit it disproportionately punishes Western countries. But you gotta start somewhere.