August 10, 2004

NRDC Cooks Up a Recipe For Disaster

Filed under: Health Effects, Ozone

One particularly favorite recipe for disaster that global warming alarmists concoct goes like this: Assume the status quo, add a pinch of (usually dramatic) climate change, agitate thoroughly, and voila, you’ve whipped up a great calamity—animals go extinct, forests die back, human mortality increases, and so on. Primary among the many problems with this ill-advised technique is the assumption that no adaptations take place.

In its July 2004 report Heat Advisory: How Global Warming Cause More Bad Air Days, the National Resources Defense Council (NRDC) ignores the observed downward trend in ozone concentration to conclude that global warming, over the course of the next several decades, will lead to ozone concentrations in eastern U.S. cities that are significantly greater than today. This lack of recognition of observed quantities—air pollution trends, temperature changes, precipitation patterns, and the like—characterizes the alarmist messages of groups like the NRDC. The conclusions of the NRDC report, like so many other aspects of the predictions of widespread ecological disruption linked to anthropogenic global warming, exist only in the output of computer models. Real world observations tell a completely different story.

The NRDC report serves as a case in point. Its purpose (aside from spreading global warming terror) is to estimate the effect of warming temperatures on ground level ozone concentrations in major cities across the eastern United States. Ground level ozone is produced when incoming ultra-violet radiation from the sun interacts with various air-borne chemicals known as ozone precursors—primarily nitrogen oxides (NOx) and volatile organic compounds (VOCs). The warmer the temperature, the faster the reactions leading to ozone formation occurs. The ozone precursors are emitted both by human activities (e.g., vehicle exhaust, industrial emissions, combustion for electrical production) and by natural systems (biogenic emissions mainly from woody plants).

The NRDC decided to see what might happen to ground level ozone concentrations in the future under an Intergovernmental Panel on Climate Change (IPCC) medium-to-high range scenario of climate change (IPCC scenario A2, to be exact—with a global average temperature rise of 3.79ºC by 2100). To do so, they took the output from the Goddard Institute for Space Studies (GISS) climate model, fed it into a regional climate model that produced daily weather conditions for the eastern United States, and then fed this output into a model that produced ozone concentrations based on the daily weather conditions and the average NOx and VOC emissions during the period 1993-1997. Let us repeat that the NRDC coupled future climate predictions with the average NOx and VOC emissions during the period 1993-1997 to produce future ozone concentrations! In other words, the NRDC assumed that the anthropogenic NOx and VOC emissions in the mid-2050s would be identical to what they were in the mid-1990s.

It comes as little surprise that, all else being equal, warmer temperatures lead to higher ground level ozone. It didn’t take the NRDC modeling effort to prove that: a simple lesson in organic chemistry in front of a blackboard would have shown the same thing, and, in fact, such lessons occur each semester in innumerable college classrooms across the country.

What would have made the NRDC report marginally useful would be for them to have incorporated projections of the NOx and VOC emission levels in the mid-21st century into their ozone modeling scheme. The reason they did not do this is that by most accounts, anthropogenic NOx and VOC emissions in the United States are expected to be significantly lower in the future than they are currently. Through a series of restrictions starting with the Clean Air Act of 1970 and continuing with the Acid Rain Program and vehicle exhaust programs of the 1990s, the EPA projects that by 2015 the U.S. emission of VOCs will decrease by nearly one-fifth and NOx emissions will decline by nearly one-third. This projected decline will continue a trend that has been ongoing for more than 25 years (Figures 1 and 2). Through the EPA’s own modeling efforts, they project that these declines in the emissions of ozone precursors will result in declines in ozone concentrations of 10% to 20% by 2015! Granted, the EPA models don’t include climate change, but considering that the NRDC reports increase in average ozone concentrations due to climate change on the order of 8% to 9% by the year 2050, it is obvious that the projected declined in NOx and VOC emissions overwhelm the projected increases due to warming temperatures. The net result is a continued decline in ground level ozone concentrations in the United States.

NOx Trends

Figure 1. U.S. national trend in NOx emissions, 1970-2003 (source:


Figure 2. U. S. national trend in VOC emissions, 1970-2003 (source:

Nowhere is such a conclusion to be found in the NRDC report. Simply put, the NRDC must ignore current trends and existing and proposed emissions control programs in order to arrive at their conclusions. Such practice produces neither reliable nor in any way usable results. It is simply wasted effort aimed at regulating anthropogenic emissions of greenhouse gases produced by the burning of fossil fuels—the fuel source that powers the daily lives of all of our citizens.


Environmental Protection Agency, 2004. The Ozone Report: Measuring Progress through 2003. EPA 454/KJ-04-001, Office of Air Quality Planning and Standards, Emissions, monitoring and Analysis Division, Research Triangle Park, North Carolina,

Patz, J.A., et al., 2004. Heat Advisory: How global warming causes more bad air days. National Resources Defense Council,

No Comments

No comments yet.

RSS feed for comments on this post. TrackBack URI

Sorry, the comment form is closed at this time.

Powered by WordPress