Workers fighting to keep floodwaters out of a residential neighborhood in Cedar Rapids.

Even though the First Floor is on a de facto summer hiatus, I had some thoughts on the flooding.  Thesis: if you or someone you care about lost a home or business in the 2008 flooding, you should consider supporting political candidates who strongly support controlling greenhouse gas emissions, because global warming caused at least a few people to lose their property.

I’m sure most people, even those who are concerned about the environment, have the same initial response.  It’s true that global warming was not the “but-for cause” of the floods in the sense that there would have been no flooding at all but for global warming.  We cannot know whether the floods would have happened without climate change, but we do have serious scientific evidence that global warming dangerously increased the amount of rainfall in Iowa this year and is creating all sorts of meteorological problems.

So assume for the sake of argument that you owned a one-story house in Cedar Rapids on the very edge of the 500-year floodplain.  Your home took an inch of water, destroying your furniture, walls, and carpeting.  Now think back to first-year torts.  Is global warming “legally” responsible?  Yes.

To win in a tort action, a plaintiff has to prove, among other things, that the defendant was the cause-in-fact of the injury.  Generally, this means that the harm would not have occurred “but for” the defendant’s action.  The flood victims who live right up along the rivers that flooded might have lost their homes whether or not global warming is taking place.  That is, even if the atmosphere had normal levels of CO2, there might have been some flooding anyway.  We just don’t know.

But consider the hypothetical one-story house out near the 500-year floodplain boundary.  We have evidence that global warming caused a lot more rain to fall this year in Iowa than what normally would have fallen.  Perhaps that little bit of extra rain caused the floodwaters to rise an extra six inches, and it was that extra six inches of water that flooded your home.  In that sense, global warming was the but-for cause of the serious damage you suffered.

Even if we are not comfortable calling global warming a “but-for cause,” we can apply another legal doctrine: substantial-factor causation.  Under the Second Restatement of Torts, we can also find that the defendant was a cause-in-fact of the injury if their actions were a “substantial factor” in causing the harm.  This only requires that the cause was “significant” or “recognizable.”  Because climatology is so complex, and the weather is so hard to understand, we could at least say that global warming was a substantial factor in causing the people on the edge of the floodwaters to suffer tremendous losses. 

But although we might argue about whether climate change is contributing to individual events like Hurricane Katrina or the Iowa floods, we do know that in the long run a hotter Earth will disrupt our lives more and more.  As we pollute the Earth, the likelihood that the weather will destroy peoples’ livelihoods and threaten their safety will only increase.