This is a story (for once) unrelated to emissions from the two major-party candidates for President: The Guardian is reporting that, for the second year in a row, levels of carbon dioxide (CO2) in the atmosphere have risen by over 2 parts per million. This is unusual for two reasons: first, there has been no precipitating natural or man-made disaster to cause the levels to rise so quickly; second, that it happened for the second year in a row indicates that the measurement is not entirely anomalous.
One of the most disturbing explanations for what has happened is that the Earth's carbon sinks have become at least partially saturated. These sinks, which include the oceans, forests and other vegetation, and organic material in the soil, are what prevent CO2 from building up to dangerously high concentrations in the atmosphere, by absorbing and storing most of it. They're an essential last line of defense against the greenhouse effect, and the suggestion that CO2 levels are rising more rapidly than normal with no obvious and immediate cause is extremely serious. Previously, it had been expected that they would only become saturated in several decades' time.
It should be noted that this is all just supposition. Though 2001-2002 was the first non-El Ni??o year to see an increase in CO2 levels above 2 ppm (El Ni??o is significant because it warms the oceans, and warm oceans emit rather than absorb CO2), and 2002-2003 was the second such year, representing the first time since measurements began that a greater-than-2 ppm increase was sustained for over a year, there could still be any number of explanations that don't involve carbon sinks becoming saturated. 2 years in this case is not enough time to come to a conclusive finding, one way or another, about CO2 levels.
But it is enough to cause worry, especially since it indicates that the "tipping point" may have been reached, at which we would expect to see more rapid increases of CO2 levels in the atmosphere in coming years. Once that tipping point is reached, the Earth may enter a feedback loop where, as is explained quite nicely in this Independent story,
global warming causes alterations to the earth's natural systems and then, in turn, causes the warming to increase even more rapidly than before.
Such a development would mean the worldwide droughts, agricultural failure, sea-level rise, increased weather turbulence and flooding all predicted as consequences of climate change would arrive on much shorter time-scales than present scenarios suggest, and the world would have much less time to co-ordinate its response.
Ultimately, this increase should serve as notice that the time when we could ignore such easy and effective solutions as improved fuel-efficiency standards has passed us by. And as this article in The New Republic by Gregg Easterbrook notes, the differences between George Bush and John Kerry on this issue are stark:
A 2001 National Academy of Sciences study says that overall mileage can be improved by about one-third, using existing technology, without sacrificing safety or comfort and without forcing people into tiny, crash-vulnerable cars. But, when the Academy released its findings, Bush shelved the subject, employing the time-honored dodge of requesting further study. Kerry, in contrast, offered legislation to implement the improvement.
The Kerry-McCain proposal, introduced in March 2002, raised the federal MPG standard for new vehicles by one-third and dropped the loopholes that allow SUVs and pickups to meet lower standards than regular cars or to avoid standards entirely.
If the saturated carbon sink-theory is true, though, we may need to do more than just raise mile-per-gallon standards in the years to come, if we want to keep the Earth habitable for future generations.