Tort liability of climate polluters for climate-related monitoring and preventive costs

Last year I did a series of posts on whether climate polluters could be found legally liable for damage to hurricane victims (here's the last post with the summary of the others). Basically I thought that it would be hard to show liability with the current understanding of the science that limits our ability to tie climate change to particular harm, even for class action suits for a large class of victims.

A conversation I had recently helped me rethink one aspect of this, though. To some (controversial) extent, legal liability for medical monitoring is part of current tort law in the United States. An example: a company negligently exposes a community to low levels of a carcinogen. While the court may not conclude that any community member will necessarily incur cancer as a result, the community members could recover the costs of increased medical monitoring they will need to try and detect cancers as early as possible.

The same reasoning should apply to climate change, and it avoids much of the problem of tying pollution to a particular injury. If an inland community now has to monitor hurricanes because the increased intensity and sea level rise means they crossed the threshold from not-too-vulnerable, and become vulnerable-enough-to-be-worried, the US legal system might assign the liability to the people that caused it.

Prevention of damages could also be an assigned cost. If sea level rise means your property is now in a 100-year flood plain and you need insurance, that could also be a recoverable cost. Tracing causation for this should be particularly easy.

One interesting aspect of this is how it fits into the current adaptation-versus-mitigation debate. While I tend to strongly favor a mix that emphasizes mitigation, the legal approach I've described would fund adaptation.

The crucial thing to me though is the one thing I've missed in spotty following of this debate: who do the adaptationists think should pay for the costs? Here, making the polluters pay for the costs of adaptation through tort liability will by itself help promote mitigation, making fossil fuels more expensive in relation to non-polluting alternatives. That's all the better, so long as no one gets confused into thinking this even approaches a substitute for a regulatory solution. It's only a single tool in the toolkit.

Part 3 (Katrina-specific): Legal theories of causation, hurricanes, and climate change

Part 1 of this series found that climate change easily satisfies the first required part of causation under the law, being a "but-for" cause of hurricanes. Part 2 found that the second required part, "proximate cause," couldn't be proven for the mere fact that a hurricane existed and injured someone, but probably could be found as a general matter for some as-yet undefined increase in hurricane intensity.

But can a court find that proximate cause exists for the increase in intensity of a specific hurricane, say Hurricane Katrina? This question is complicated, I think, because the but-for cause (multiple influences on chaotic weather systems) and proximate cause (increase in sea-surface temperatures) derived from global warming are different. Usually the law analyzes the same alleged mechanism to see if it satisfies both but-for and proximate cause. Remember, absent global warming, Hurricane Katrina would not have existed. It's difficult to ask how much of Katrina's damage is especially attributable when all of the hurricane's damages are attributable to warming, but not necessarily especially attributable.

Here's the closest I can get to an answer, using another thought experiment. Suppose it's late August 2005, and just as Hurricane Katrina crosses west over Florida, some technologically-advanced space aliens decide to conduct an experiment. Using means we don't understand, they remove all effects of anthropogenic global warming from sea-surface temperatures in the Gulf of Mexico. (I'm simplifying things to assume at this point in time, no other AGW-effects will do much to Katrina). This seems like a strange thought experiment, but it's the only way I can examine the issue. So what happens in this thought experiment?

If climatologists could say, "under this scenario, we're certain that the Gulf's sea surface temperatures in August-September 2005 would decrease," and given how the otherwise-unchanged conditions otherwise allowed Katrina to maximize intensity, then we could say it's likely that AGW-caused temperature increase made Katrina still more intense, and proximate cause has been satisfied. I doubt climatologists could deliver this certainty, though. Instead they'll say there's a range of probability that the Gulf was artificially-warmed. I doubt that probability, reduced by the large-but-not-100% probability that the sea temperature warming would also have the effect of intensifying Katrina, would be enough to show proximate cause.

This isn't the end of the story, though. Climatologists will be getting more certain about the specific, regional effects of climate change. And if you broaden your potential lawsuit from my single example of a newborn baby to a whole class of widely-distributed hurricane victims, then proximate cause becomes a lot easier to demonstrate. Similarly, showing proximate cause for increased insurance costs or inability to get insurance is also easier. Litigation on this type of issue is increasingly viable.

UPDATE: Welcome, readers from ExxonMobil's Internet Service Provider! That's an interesting blog search you've got going. Seriously, I am glad if oil companies are taking private litigation issues seriously. Oh, and please stop funding the inanity at the American Enterprise Institute.

Part 2: Legal theories of causation, hurricanes, and climate change

In Part 1 of this discussion, I argued that the "but-for" causation test used in American legal proceedings would find that global warming did more than make hurricanes worse in general - it would show that global warming specifically caused specific weather events like Hurricane Katrina.

The law requires more than this to find that causation has been demonstrated, however. The tricky, second part is called "legal causation" or "proximate cause". Nobody has a perfect definition of proximate cause that I know of. The idea though is that in addition to global warming being one of the necessary causes that preceded Hurricane Katrina, global warming must especially cause the hurricane - or at least to have especially caused harm to the newborn child in the hypothetical from Part 1.

Another hypothetical might help here. Suppose you're injured in a car crash caused by someone else's negligence. Rushing you to the hospital, the ambulance gets into an accident that was unavoidable because of the speed necessary to get you to the hospital, and you suffer further injuries. When you recover enough to leave, you are unfortunately injured a third time while driving away from the hospital a normal speed, in another unavoidable accident. What damages to you does the person who first injured you have to pay for?

The "but-for" test is satisfied in all three injuries, but proximate cause exists only for the first two. There is a special relationship between the ambulance's speed, caused by the need to respond by the accident that the defendant created, and the ambulance's crash. By contrast, it's basically coincidental that you were injured a third time while driving normally when leaving the hospital. "Proximate" used to mean what it sounds like - that the defendant was the last cause or nearly the last cause preceding the injury - and that closeness is still helpful, although not determinative, in satisfying proximate cause.

While the mere existence of Hurricane Katrina and any other specific tropical storm is sufficent to satisfy "but-for" causation, it's not enough to show proximate cause. There would have been a different set of hurricanes in 2005 folowing different tracks even without global warming, and it's just coincidental that global warming was one of countless necessary causes that ultimately sent Hurricane Katrina to Mississippi, just like it was coincidental that your first car accident ultimately led to you being in a place where you were injured, leaving the hospital.

That's not the end of the story, though. In addition to making Hurricane Katrina and other specific hurricanes happen, global warming as a general matter makes them worse. The IPCC found (pg. 9) that is "more likely than not" that anthropogenic global warming has already contributed to increasing intense tropical storm activity. I'll bet every lawyer for a fossil fuel company felt a chill when reading that IPCC description, because it closely matches the burden of proof needed to show causation in a civil trial - "the preponderance of evidence".

To the extent that AGW made hurricanes worse, that increase in damaging effect clearly satisfies proximate cause. There's this WMO statement (pg. 6):

A more appropriate question is whether the probability of an event happening in a particular basin has been increased by the ocean warming....The possibility that greenhouse gas induced global warming may have already caused a substantial increase in some tropical cyclone indices has been raised (e.g. Mann and Emanuel, 2006), but no consensus has been reached on this issue.

This basically responds to proximate cause issues, not just the but-for causation (which they get wrong in a preceding sentence, but we can let that pass). And the law doesn't require consensus, "more likely than not" is good enough for a verdict.

So the law would likely find both but-for and proximate causation as a general matter regarding an undefined level of increased damage from hurricanes. But the question people want to ask is whether AGW made a particular storm worse - so did AGW make Katrina worse than it would otherwise have been? I think from a legal perspective the question might not have an answer - not that we don't know the answer, but rather that the question doesn't make any sense. I'll discuss that in the next post, and see how close I can get to an answer if it's possible.

More information on legal causation/proximate cause is here.

UPDATE: softened my suggestion in the last paragraph that the question doesn't have an answer.

Legal theories of causation, hurricanes, and climate change (Part 1: But-for causation)

I'm going to apply the Dilbert Rule to the hurricane-global warming issue - that the only approach to a problem happens to be the only one you know. So let's take the legal approach to the question of the causal relationship of global warming and hurricanes, through a hypothetical:

A new-born baby in Mississippi was orphaned and injured in Hurricane Katrina. The court-appointed guardian decides to sue every corporation, entity, and individual she can reach for causing global warming and injuring her ward. What result?

Some preliminaries: first, I chose an orphaned newborn to dismiss the counter-argument that the victim actually benefits from the modern economy - no unclean hands here. Second, this isn't a full-scale legal analysis - in the real world, this lawsuit would face all kinds of procedural hurdles, some legit and some seized upon by judges looking for an excuse to push this judicial-career-consuming morass out of the courtroom. What I'm really focusing on is the causation.

The law requires two types of causation be satisfied before it will conclude that the defendant "caused" the injury to the plaintiff. First is the "cause-in-fact" requirement that global warming resulted in injury to the baby. This legal requirement can be simplified (in this case, anyway) to the "but-for" question. But for global warming, would the baby have not been orphaned and injured?

I'm now ready to finally say something halfway interesting, I hope: a judge could easily go beyond the current arguments about whether warming has intensified and find that anthropogenic global warming actually caused Hurricane Katrina. The way to determine this is with a thought experiment, imagining what the world would have been like without AGW.

Imagine some invention in 1850 had the incidental effect of absorbing all the excess carbon dioxide and methane we've produced since then. Would the baby have been injured in this thought experiment by Hurricane Katrina? Considering that Altantic hurricanes generally result from tropical waves, which themselves are the results of minor disturbances in African weather systems, and considering how different the no-warming world's weather would have been on a day-to-day level, it's nearly impossible to imagine that a hurricane like Katrina would have hit Mississippi at the same time in 2005 in the no-warming world. That world would have had hurricanes, but they would have been different hurricanes at different times taking different paths. But for global warming, Hurrican Katrina would not have happened.

This still leaves the second type of causation required in an injury claim like this one, called proximate cause or, confusingly, "legal causation". I'll save that for my next post.

More information on cause-in-fact is here.

Part 2 of this series is here.

Part 3 of this series is here.