November 19, 2008

Why the EPA should find against “Endangerment”

Filed under: Climate Politics

Back in July, as a result of last year’s Supreme Court ruling on Massachusetts v. EPA, the U.S Environmental Protection Agency (EPA) issued an “Advance Notice of Proposed Rulemaking: Regulating Greenhouse Gas Emissions under the Clean Air Act” and asked for public comment though November 28, 2008.

Aside from the massive bureaucracy that would be involved in trying to regulate greenhouse gas emissions under the Clean Air Act, the EPA primarily needs to determine whether or not greenhouse gas emissions from human activities are endangering the public health or welfare. The underlying analysis to support/deny an endangerment finding is provided in the EPA’s Technical Support Document for Endangerment Analysis for Greenhouse Emissions under the Clean Air Act (Endangerment TSD) which attempts to serve as review of the state to the science concerning the “vulnerabilities, risks and impacts” of climate change, primarily within the United States.

However, the Endangerment TSD is largely a dated document which relies heavily on the Fourth Assessment Report (AR4) of the U.N.’s Intergovernmental Panel on Climate Change (IPCC). The IPCC’s AR4 was published in the spring of 2007, but to meet the deadline for inclusion in the AR4, scientific papers had to be published by late 2005/early 2006. So, in the rapidly evolving field of climate change, by grounding its TSD in the IPCC AR4 the EPA is largely relying on scientific findings that are, by late 2008, nearly 3 years out of date.

And a lot has happened in those intervening three years.

• Global temperatures have declined (Figure 1a)—extending the current run of time with a statistically robust lack of global temperature rise to eight years (Figure 1b), with some people arguing that it can be traced back for 12 years (Figure 1c).

Figure 1. Monthly global temperature anomalies (ºC) as measured at the surface (filled circles) and in the lower atmosphere by satellites (open circles). Top (a), Last three years, January 2006-October 2008; Middle (b) Last eight years, January 2001-October 2008; Bottom (c), last 12 years, January 1997-October 2008. (sources: Hadley Center; University of Alabama-Huntsville).

• The consensus on past, present and future Atlantic hurricane behavior has changed. Initially, it tilted towards the idea that anthropogenic global warming is leading to (and will lead to) to more frequent and intense storms. Now the consensus is much more neutral, arguing that future Atlantic tropical cyclones will be little different that those of the past (e.g. Knutson et al., 2008; Vecchi et al., 2008).

• The alarmist notion that warming temperatures will cause Greenland to rapidly shed its ice has been silenced by new results indicating little evidence for the operation of such processes (e.g., van de Wal et al., 2008; Joughin et al., 2008).

These three developments should greatly influence any assessment of “vulnerability, risk, and impacts” of climate change within the U.S. Therefore, the extensive portions of the EPA’s Endangerment TSD which are based upon the old science are no longer appropriate and need to be revised.

In other portions of the Endangerment TSD, the logic is faulty and leads to unsupportable and ill-informed conclusions. Such is the case with the “Human Health” and “Food Production and Agriculture” sections. The TSD authors do not adequately factor in changing populations and changing technologies in projecting harm to health and agriculture from a shifting climate.

But perhaps the most glaring problem of all with the EPA’s Endangerment TSD is the nearly complete disregard of observed trends in a wide array of measures which by and large show that despite decades of increasing anthropogenic greenhouse gas emissions (as detailed by the EPA) the U.S. population has triumphed over any changes in “vulnerabilities, risks, and impacts” that may have arisen (to the extent that any at all have actually occurred as the result of any human-induced climate changes).

For instance, despite the overall rise in U.S. and global average temperatures for the past 30 years, U.S. crop yields have increased (Figure 2), the population’s sensitivity to extreme heat has decreased (Figure 3), and our general air quality has improved (Figure 4). Further, there has been no long-term increase in weather-related property damage once changes in inflation, population size, and population wealth are accounted for (an essential step in any temporal comparison). All of these trends are in the opposite sense from those described in the EPA’s Endangerment TSD.

Figure 2. Yields of major cash crops such as corn and wheat show annual fluctuations as a result of weather conditions, but overall, they exhibit an upwards trend (data sources: NCDC, USDA).

Figure 3. Average annual heat-related mortality per standardized million people in the U.S. (source: Davis et al., 2003).

Figure 4. Trends in ozone air quality (source: US EPA)

Perhaps, most significant of all, the average lifespan of Americans has increased (Figure 5).

Figure 5. Life expectancy at birth in the U.S. (source: Centers for Disease Control)

What better measures of human health and welfare are there?

In fact, there is no better way to obtain a good picture of how human health and welfare may trend in the future under increases in greenhouse gas emissions than to assess how we have fared in the past during a period of increasing greenhouse gas emissions. As we used to say in group weather forecasting discussions when the forecast models projected an uncertain future “Let’s just look out the window” because what is happening now provides a strong clue as to what will happen at least in the near future.

A look out of the window today shows an America that has greatly reduced its vulnerability to climate, much less climate change (which accounts for only a small portion of our overall climate).

True, hurricanes will strike again in the future and cause a great deal of damage and suffering. But that will largely occur because our climate is one which includes hurricanes. The same is true for tornadoes, droughts, floods, heat-waves, cold outbreaks, strong thunderstorms, heavy rains, hail, lightning, snowstorms, blizzards, freezing rain, etc. Those are all aspects of our climate.

Climate change may alter the strength, path, or frequency of these events—lessening some and increasing others. But to the large part, our nation’s climate in the future will be made up of the same characteristics as it is today.

As America moves forward, we develop technologies that help us better respond and adapt to the prevailing climate and better protect ourselves from climate extremes. Thus, climate has become, and will undoubtedly continue to become, less and less of an “endangerment” to our general health and welfare. It would be foolish of the EPA to ignore history in reaching its ultimate conclusion.


Davis, R.E., et al., 2003b. Changing heat-related mortality in the United States. Environmental Health Perspectives, 111, 1712-1718.

Joughin, I., et al., 2008. Seasonal speedup along the western flank of the Greenland Ice Sheet. Science, 320, 781-783.

Knutson, T.R., et al., 2008. Simulated reduction in Atlantic hurricane frequency under twenty-first-century warming conditions. Nature Geosciences, doi:10.1038/ngeo202

Vecchi, G. A. et al., 2008. Whither Hurricane Activity? Science, 322, 687-689.

van de Wal, R. S. W., et al., 2008. Large and rapid melt-induced velocity changes in the ablation zone of the Greenland ice sheet. Science, 321, 111-113.

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