According to BBC News, global carbon emissions will drop by 2 percent in 2009, which marks the most significant such annual reduction in 40 years. The International Energy Agency, which measured the drop, explains that a quarter of the reduction can be attributed to various governmental policies, while about three quarters of it are due to the global recession. So while the reduction is, indeed, impressive, we should temper our celebrations of this news: Our economies, we should remember, won't always be recessed, and we need to find ways to reduce emissions during times of robust economic activity. And seeing as we need to cut emissions to 40 percent below 1990 levels by 2020, we're going to need to see dramatically larger reductions in each of the next 11 years to get close to that target.Photo (cc) by Flickr user hAdamsky.