Unfinding Endangerment - Rescinding the Endangerment Finding

In a discussion on a recent comment thread, one commenter stated that “EPA had the evidence” when it issued its 2009 Endangerment Finding regarding CO2 and other “greenhouse gases”. Now, eight years later, the Endangerment Finding is being questioned by a new federal Administration and a new EPA Administrator. The courts, including the US Supreme Court, were involved in the determination that US EPA had the authority to regulate CO2 and other “greenhouse gases”  (GHGs) under the Clean Air Act. It is a virtual certainty that the courts, including the US Supreme Court, would be involved in any effort to rescind the Endangerment Finding.

This raises two obvious questions regarding the “evidence”:

1. What evidence did EPA present in support of its Finding?
2. Is that evidence still valid?

The evidence presented in support of the Endangerment Finding is described in the EPA Technical Support Document (TSD) published on December 7, 2009 and the reference documents listed in the document and its appendices. The primary evidence, based on observations, is that:

• GHGs trap heat in the atmosphere.
• Atmospheric concentrations of GHGs have increased.
• Average ambient temperatures have increased.
• Average sea surface temperatures have increased.
• Average sea levels have increased.

From that evidence, the document proceeds to lay out “Projections of Future Climate Change With Continued Increases in Elevated GHG Concentrations”. These projections are largely based on scenarios produced by general circulation models of the global environment, which were not then and are not now verified.

There is no question that the primary evidence, as listed above, is factual. However, there is reason to question whether the details of that evidence, particularly the temperature and sea level evidence, are factual. The near-surface temperature data are routinely “adjusted”, for a variety of reasons, before they are used to produce the various near-surface temperature anomaly products. The sea surface temperature data are also “adjusted”; and, temperature estimates are “infilled”, where actual data are not available.

There are far greater bases to question the “projections” made and suggested in the TSD. The potential future “endangerment” envisioned in the TSD is based on the historical rates of change of near-surface and sea surface temperatures and of sea levels; and, “projections” of future rates of change of these temperatures and sea levels, based on projections of future GHG emissions and their residence times in the global atmosphere.

The most widely recognized general circulation model, at the time of the Endangerment Finding, was the model developed by Dr. James E. Hansen of NASA GISS. The data input to this model is now 30 years old, the typical period identified by the World Meteorological Organization as the timeframe for “climate”. Therefore, it forms a reasonable basis for determining the accuracy of the “Predictions of Future Climate Change …” contained in the EPA TSD. A review of the scenarios produced by Hansen’s climate model can be found here.

Clearly, while GHG emissions have followed Hansen’s Scenario A, the temperature anomaly response has more nearly followed Hansen’s Scenario C, which envisioned a rapid cessation of global GHG emissions. Therefore, the “endangerment” envisioned in the 2009 Endangerment Finding is far less than was portrayed in the document. As a result, the regulations imposed and proposed by EPA might well be far more stringent that is justified by the actual impending “endangerment”, if “endangerment” actually impends.