Policy Peril Segment 2: Air Pollution

Last Friday, I launched a blog series on CEI’s film, Policy Peril: Why Global Warming Policies Are More Dangerous Than Global Warming Itself.  The film is our antidote to Al Gore’s Scare-U-Mentary, An Inconvenient Truth. The blog series highlights 10 short segments of the film, one each day this week and next.

Yesterday’s blog was on the hype about heat waves–the claim that people will drop like flies from heat stress in U.S. cities unless urgent action is taken to cut carbon dioxide (CO2) emissions.

Today’s segment rebuts a related scare–the claim that global warming will sicken and kill thousands of us by increasing air pollution. Click here if you want to watch Policy Peril in its entirety. Click here to watch the segment on air pollution.

Here’s the text:

Narrator: But maybe the heat will get us by creating more air pollution. That’s what the Natural Resources Defense Council, or NRDC, said in a report titled Heat Advisory. It sounds plausible because smog forms when emissions of nitrogen oxides and volatile organic compounds bake in the heat of the Sun. However, the NRDC report is fundamentally flawed.

Joel Schwartz (American Enterprise Institute): NRDC uses emissions from 1996 to “predict” ozone levels, smog levels, in the 2050s. So we’re already below the emissions of 1996, and emissions continue to drop because of fleet turnover to cleaner vehicles, because power plants are getting cleaner. And most of those emissions are going to be gone even in about 20 years. And in the 2050s there’s going to be hardly any pollution in the air. But NRDC assumes we’re going to have 1996 emissions levels in 2050.

Narrator: Like heat-related mortality, air pollution levels have fallen as cities have warmed. U.S. air quality should keep improving regardless of climate change.


NRDC’s Heat Advisory report (September 2007) claims that, under a likely global warming scenario, the number of “bad air” days” (days when ozone levels exceed the 8-hour health-based air quality standard set by the U.S. Environmental Protection Agency) would increase by as much as 155% in some of the 10 cities studied. NRDC further states that, “by mid-century, people living in 50 cities in the eastern United States would see a 68 percent (5.5 day) increase in the average number of days exceeding the health-based 8-hour ozone standard established by EPA.” This means the number of unhealthy (“Red Alert”) days would “double.”

Joel Schwartz masterfully debunked Heat Advisory in two columns published in National Review. In the first column (September 14, 2007), Joel showed that NRDC used 1996 emissions to “predict” ozone levels in the 2050s and 2080s, even though “actual emissions of ozone-forming pollutants are already more than 25% lower than they were in 1996 and will drop another 70%-80%  in just the next 20 years, based on already-adopted and implemented federal requirements.”

Could this be an innocent mistake? Does NRDC not know that laws and regulations already on the books have cut emissions since 1996 and will keep on doing so for decades to come? No way.

As Joel documents, in press release after press release, NRDC enthusiastically applauds various new EPA rules that will dramatically reduce smog-forming emissions from automobiles, diesel trucks, off-road diesel engines, diesel fuel, and power plants.

“Most egregious of all,” Joel comments, “the NRDC report was authored by prominent university and government climate and public health scientists.” These seemingly non-political researchers (Joel names names) lent “the color of their scientific credentials and government and university affiliations” to NRDC’s effort to mislead the public.

Joel also cites a more realistic appraisal of global warming’s impact on air quality–an article in the Journal of Geophysical Research by researchers from NESCAUM (Northeast States for Coordinated Air Use Management) and Georgia Tech. These analysts project that, from the year 2000 to 2050, “The combined effect of climate change and emissions reductions lead to a 20% decrease (regionally varying from -11% to -28%) in the mean summer maximum daily 8-hour ozone levels over the United States.” They also project a 23% decrease in mean annual fine particulate (PM2.5) concentrations. Joel comments that these estimates are conservative, because “pollutant emissions and ambient levels are dropping much faster than they assume in their study (a fact which I show here). 

The decline in polluting emissions, despite increases in urban summer air temperatures, is quite dramatic, as Joel illustrates in the figures below.


Figure description: Trends in Estimated U.S. Air Pollutant Emissions, 1970-2006. Data Source: U.S. EPA, Air Quality and Emissions – Progress Continues in 2006.


The same story of dramatic progress in reducing emissions “continues in 2008,” as EPA tells us on its Web site.

Percent Change in Emissions

                                                        1980 vs 2008           1990 vs 2008

Carbon Monoxide                              -56                                 -46

Lead                                                     -97                                 -60

Nitrogen Oxides                                -40                                 -35

Volatile Organic Compounds         -47                                 -31

PM 10                                                   -68                                 -38

PM 2.5                                                   NA                                -57

Sulfur Dioxide                                     -56                                 -50

Source: EPA, Emission Trends, http://www.epa.gov/airtrends/aqtrends.html#comparison

Dan Lashof, director of NRDC’s Climate Center, tried to rebut Joel’s critique. He did not challenge Joel’s central points–emissions are already well below 1996 levels, current policies ensure emissions will continue to drop, and, therefore, air quality predictions assuming that 1996 emissions will persist into the 2050s and beyond are completely unrealistic. Instead, Lashof argued that Heat Advisory presents “projections,” not “predictions,” and that the researchers had to use emissions data from an actual year, such as 1996, because “there are no reliable estimates of [ozone] precursor emissions extending to the mid-21st Century.” Moreover, holding emission levels constant is the only way to isolate the effect of global warming on ozone concentrations.

In the second of his National Review columns (September 26, 2007), Joel rips these lame excuses to shreds. He cites several statements in Heat Advisory and the accompanying press release in which NRDC clearly presents its findings as predictions of what will happen in a warming world.

Joel also pokes fun at Lashof’s excuse that NRDC had to use 1996 emissions because who the heck knows what emissions will be 50 years from now. This is emphatically not what NRDC says about the CO2 emissions that allegedly control our climate destiny. Can you even imagine NRDC saying that climate models must use 1996 CO2 emissions to estimate CO2 concentrations in 2050 or 2080 because mid-century estimates of CO2 emissions are uncertain? Joel comments:

Climate activists have no problem trying to force the people of the world to spend trillions of dollars for CO2 reductions based on the presumption that climate models are accurate. But when it comes to ozone, NRDC pleads uncertainty and then chooses increases in future ozone-forming emissions that are grossly at odds with any plausible future scenario. If anything, the statement that “there are no reliable estimates … extending to the mid-21st Century” is far more applicable to greenhouse gas emissions and climate models’ predictive skill than it is for smog-forming emissions.

What about the claim that researchers must hold smog-precursor emissions constant to isolate the global warming impact on future ozone concentrations? EPA offers the same rationale on p. 78 of the Technical Support Document (TSD) for its proposed finding that greenhouse gas emissions endanger public health and welfare (EPA’s official response to the Supreme Court’s decision in Massachusetts v. EPA, 2007). However, the only accurate way to isolate the “global warming effect” on ozone concentrations would be to compare ozone levels in warming and non-warming scenarios based on plausible projections of precursor emissions in the 2020s, 2050s, and 2080s.

Again, EPA would not pay any attention to climate change scenarios that assume 1996 or even 2009 CO2 emissions in 2020, 2050, 0r 2080. So why put any credence in “studies” that assume 1996 ozone precursor emissions in perpetuity even though today’s emissions are already significantly below 1996 emissions? By the 2050s and 2080s, the “global warming effect,” if any, on ozone formation, will likely be negligible. The real point of holding emissions constant is not to isolate a warming effect, but to scare the public.

Those interested in additional information should find the following items useful. The U.S. Chamber of Commerce provides an excellent literature summary on global warming and air pollution in its detailed review of EPA’s endangerment proposal and TSD. Joel Schwartz’s book, No Way Back, explains why air pollution will continue to decline in the decades ahead. Finally, Joel presents his critique of the warming-will-destroy-air-quality scare in this video from the Heartland Institute’s first annual International Conference on Climate Change.