Climate Change Goes to Court

Several lawsuits filed by California cities and counties and a similar lawsuit filed by New York City against major oil companies seek billions for current and potential future damages resulting from climate change caused by CO2 emissions from their products. Another lawsuit, filed by a group of children against the US federal government, claims that “government's actions and failures to act have caused climate change, thus violating the youngest generation's constitutional rights to life, liberty and property, and have failed to protect essential public trust resources.”

The California and NYC lawsuits focus primarily on sea level rise caused by climate change. However, sea level has been rising, at a relatively constant rate, since before human emissions of CO2 are believed to have begun having an impact on climate. While changes in sea level are measurable, there is no scientific method to measure any incremental contribution of increased atmospheric CO2 concentrations to natural sea level rise in the period following the trough of the Little Ice Age. Therefore, there is no scientific basis on which to allocate some percentage of current and possible future adverse impacts of continued sea level rise to anthropogenic climate change.

The children’s lawsuit against the government is broader in scope, but probably less defensible scientifically. There is no documented evidence of loss of life or liberty in the US attributable to climate change. Sea level rise arguably results in a loss of property, but there is no scientific basis on which to attribute that loss of property to climate change resulting from government action or inaction.

There have been broad accusations in the media that climate change made the impacts of tropical storm Sandy and hurricanes Harvey, Irma and Maria greater than they would otherwise have been. However, none of these accusations are based on measured data. These storms, while unusual, were not unprecedented. The storms were not as unusual as the twelve-year hiatus in major hurricane landfalls which preceded them. Recent analysis of global weather-related damages by Dr. Roger Pielke, Jr. demonstrates that global damages have declined as a percentage of global GDP since 1990, despite peaks in 2005 and 2017.

Proving responsibility for some fraction of current damages on anthropogenic climate change will be difficult, since it is not currently possible to measure any incremental impact. However, proving responsibility for potential future damages will be even more difficult, as well assigning some potential future costs to those damages.

Scenarios describing potential future climate change resulting from increased anthropogenic CO2 emissions are based on unverified climate models, which can hardly be considered to constitute evidence. The potential future financial impacts of those modeled scenarios are based on unverified assumptions applied to those scenarios produced by the unverified climate models, which can hardly be considered to constitute evidence.

We can expect some interesting discussions regarding the rules of evidence as these lawsuits proceed. These discussions will likely include whether “adjustment” of measured temperatures and measured sea level rise represents evidence tampering; and, whether “infilling” temperatures where no data exists represents manufacturing evidence.