Can the legal system catch up with climate science?
A few decades ago, it wasn’t realistic to attribute individual events—even heat waves—to the general warming trend driven by human-caused climate change. Now, there are peer-reviewed methods of rapidly detecting humanity’s fingerprints in the wake of weather disasters like hurricanes or climate-driven wildfires.
In today’s issue of Nature, Dartmouth’s Christopher Callahan and Justin Mankin argue that we’ve reached a similar level of sophistication regarding another key question: What are the economic damages caused by individual climate events? They argue that we can now assign monetary values to the damage caused by emissions that can be traced back to individual companies. They found that “The global economy would be $28 trillion richer … were it not for the extreme heat caused by the emissions from the 111 carbon majors.”
They argue that this method might provide legal ammunition for those interested in seeking climate damages in court: “By revealing the human fingerprint on events previously thought to be ‘acts of God,’ attribution science has helped make climate change legally legible.”
How attribution works
The method used by Callahan and Mankin is a variant on standard climate attribution studies. In the standard studies, climate models are run with and without the carbon dioxide that humanity has pumped into the atmosphere through fossil fuels and land use changes. You can then compare the frequency of specific weather events, like the intensity of rainfall from a hurricane or the peak temperatures of a heatwave, both with and without the added CO2. The difference in frequency is an indication of the impact of climate change.
But it’s possible to repeat the analysis with arbitrary amounts of carbon dioxide. So, the researchers could calculate the estimated emissions from different companies and compare the probabilities of events with and without those emissions. So, for example, Callahan and Mankin calculate the individual contributions of the companies responsible for the most carbon emissions (the “carbon majors” mentioned earlier), such as Chevron or Saudi Aramco. These include both the direct emissions during fossil fuel production, as well as the emissions that result when the products are burned.