One question that's perpetually worth revisiting is how the current recession affects future climate and emissions scenarios. Sure, it's true that a growing chorus of climate scientists are warning us that things are much bleaker than previously thought—that we may be on track for a devastating 5C to 7C temperature increase by 2100 if we stay on the current course, and that if we want to keep the global average temperature rise below 2C, we need to start cutting carbon emissions sharply in the next few years. But wait! What about this economic slump? Aren't emissions falling right now? Doesn't that buy us a bit of time?

Well... yes and no. Fatih Birol, the head economist of the International Energy Agency, lays out the paradox here:

The economic crisis may lower carbon emissions in the short term but will raise them over the long term by crimping investment in cleaner energy sources, the International Energy Agency's chief economist said on Thursday.

The impact of the financial crisis and the ensuing economic slump on energy investments had been "stronger than anyone expected" and significant enough to have an impact on climate change and the whole energy supply chain, warned Fatih Birol.

"To think that lower economic growth is good for the environment is completely wrong," Birol told Reuters. "Because there are many investments that are good for the environment, like efficiency, renewables and nuclear, that are being postponed or canceled. One or two years of lower carbon emissions won't count for much at the end of the day."

Too bad my graph-making skills are so Paleolithic, because one could draw some easy-to-grasp curves representing all this. In the near future, emissions will be lower than they would be if there had never been a financial meltdown, since factories are sitting idle and utilities are selling less power. But that demand will eventually come back with a vengeance, and, because the world won't have invested in renewables and efficiency improvements and nuclear during the recession, the future will actually be grimier, with more carbon belching up in the atmosphere, than if there'd never been this epic slump.

One way to avoid this fate would be if the various governments of the world started ponying up more right now on clean energy and conservation measures, to make up for the shortfall in private investment. The Obama administration is doing this (and Congress is set to do more later this year), but the picture's much bleaker in Europe. There, the decline in energy use has caused the market for carbon permits to plummet, which means less pollution now, but also less investment in alternatives to fossil fuels (if pollution permits are so cheap, it's not worth anyone's time to invest in carbon alternatives). That's fine for now, but could make it more difficult to meet emissions targets after the recession's passed.

(Flickr photo credit: PrismRed)

--Bradford Plumer