One of the big problems with convincing people (and governments) that global warming is a problem is that you can't point to any specific weather event and say, "that was caused by global warming." While we know that the climate is changing due to atmospheric pollution, you can't assign causation of any single event to global climate change. Four hurricanes in Florida in one year? Record heat wave in Europe? Severe drought in the Southwest? Climate is dynamic and variable, and these could just be random variation. So, we can't blame them on global warming. At least we couldn't until now...
Using models (see the article in Nature for more information; subscription required), the scientists found that the heatwave was twice as likely with current CO2 levels as it would have been before the industrial revolution. This doesn't mean that global warming caused the heatwave, but it did double the risk that it happened. As an accompanying commentary in Nature noted,
What does this mean? I think two things. First, this is great ammunition for those trying to convince the skeptics that global climate change is both real and a big problem. It's one thing to talk about potential future problems like rising sea levels. But being able to argue that we've doubled the risk of killer heatwaves right now is much more powerful. Hopefully, more research will let us make similar statements about other weather events (drought, hurricanes, etc.). Those still arguing that climate science is too uncertain to take any action are dangling from a very thin rope.
But there's an even bigger implication of this research. In a terrific essay, Allen and Lord argue that just knowing that global climate change increased the risk of heatwaves makes CO2 emissions actionable in courts! As they write:
And that matters because:
If, say, a relative of yours died in the French heatwave, you could concievably sue for damages because carbon emissions contributed to the death. But who would be responsible?
But there are problems:
Still, this seems to me a promising avenue to pursue. Already, lawsuits targetting CO2 emitters are underway in the U.S. and abroad.
Low-lying Pacific island states including Tuvalu, at risk of disappearing if sea levels rise, are considering suing the United States, the world's top source of greenhouse gases, to force it to do more to curb global warming. (link)
Odds are it will be years if not decades before anyone wins a court award for damages due to global warming. And if this strategy bears fruit, I wouldn't be surprised if Congress jumped in to stop future lawsuits related to climate change. But given that the world seems to be making little or no progress in stopping global climate change, it's nice to see one new weapon that environmentalists may be able to bring to bear in this struggle.