Study: Climate Change Will Likely Increase DFW Smog

by jim on June 26, 2014

Orange smog in DallasJust last week at the June regional air quality planning meeting the Texas Commission on Environmental Quality was bemoaning the fact that the weather too often determines how bad an "ozone season" DFW will have. And it's true. When we have really hot, dry, and windless summers, ozone levels soar as they did as recently as 2011-2012 when the recent drought seemed to reach its most awful heights in DFW. Conversely, when we have relatively cool, wet and windy summers, ozone levels abate, as they seem to be doing this year – at least so far.

Of course, the TCEQ spokesperson was using weather as an excuse why DFW hadn't yet achieved compliance with the 1997 ozone standard after two tries that fell short. Completely overlooked was the fact that the last state air plan for DFW in 2011 promised historically low ozone levels by 2013 without any new pollution controls on major sources of pollution. Combine that lack of action with a really hot, dry summer like we saw in 2011, and you get the first clean air plan ever to leave ozone levels higher after it ended than when it started.

That's why it's important to think about the weather when you're trying to build new clean air plans for DFW that stretch years into the future. Air quality planners have to ask themselves if between now and the next federal clean air plan deadline of 2018, will there be more summers like this seemingly anomalous one, or will they more like the summer of 2011 when we had a constant barrage of 100 degree plus days as early as March?

Currently, the TCEQ is using a stretch of bad air days from 2006 to predict ozone levels between now and 2018 in their computer model for the DFW air plan to comply with the new, tougher 2008 ozone standard. But 2006 was pre-drought. Although they say they're "adjusting" the meteorology to compensate for weather changes since then, do you really trust TCEQ to assume worst-case weather scenarios when they're still trying to hide the smog impacts of gas pollution from the public? Us either.

So it's with more than a little self-interest that we note a new Stanford study with the too-sexy title of "Occurrence and Persistence of Future Atmospheric Stagnation Events" concluding that the Western US, including Texas, should expect hotter and therefore smoggier summers thanks to climate change. Why? Because hotter temperatures will slow the flow of air around the globe. That means less wind, and less wind means more time for smog-forming chemicals to sit and bake in the hot sun and form harmful levels of ozone. Historically, most of our worst ozone days are when winds are blowing less than 5 mph – stagnate air.

DFW isn't like Denver or LA where mountains form bowls around the urban areas and trap pollution in inversions. But the new study concludes the impact from global warming could have the same effect on the Texas prairie by stagnating air currents:

"Our analysis projects increases in stagnation occurrence that cover 55% of the current global population, with areas of increase affecting ten times more people than areas of decrease. By the late twenty-first century, robust increases of up to 40 days per year are projected throughout the majority of the tropics and subtropics, as well as within isolated mid-latitude regions. Potential impacts over India, Mexico and the western US are particularly acute owing to the intersection of large populations and increases in the persistence of stagnation events, including those of extreme duration. These results indicate that anthropogenic climate change is likely to alter the level of pollutant management required to meet future air quality targets."

And who's more prepared to deal with the "pollution management required to meet future (re: tougher) air quality targets than the Texas Commission on Environmental Quality?  Almost any one, including your 13-year old niece who's done so well in 8th grade science this year. Because not only is it the TCEQ's official position that smog isn't all that bad for you, but that there's really no such thing as climate change. It's why you should bring a boatload of skepticism to the computer model that's driving the currently proposed DFW clean air plan. To plug hotter and hotter temps into the DFW smog model for coming years would be admitting to a phenomena that the Rick Perry administration in Austin just can't bring itself to concede. One more example of how the DFW plan is being driven by politics, not science.

As the TCEQ's own staff admitted last week, DFW's ozone levels are often hostage to the weather. If you're model isn't correctly estimating the weather during future ozone seasons, chances are your estimates of future ozone levels will be off as well. But of course, since smog isn't really bad for you there's no downside to being wrong about these things at TCEQ HQ, and only an upside in GOP primaries.

For the rest of us who believe what the science tells us, the consequences are more dire. As the VICE magazine take on the Stanford study said:

"….one reason this study is so important to the climate change conversation—it underlines the public health threat posed by climbing temps. When Obama was touting the EPA's new carbon regulations, he emphasized the public health benefits of drawing down emissions: It would reduce asthma and respiratory illness, he pointed out. But that's largely because shuttering dirty power plants cuts both carbon and particulate pollutants simultaneously; fighting climate change also means fighting asthma.

Now, scientists have demonstrated there's an additional layer of concern to grapple with on the pollution front; climate change is going to begin blocking cities' toxic release valves. If we don't work to slow carbon emissions, these steamier cities will find their streets clogged with stagnant smog. Scrubbing that pollution and finding novel ways to clear the air, too, then, will prove to be a pressing concern in the not-so-distant future. 

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