What Happened to that Ozone Hole Anyway?
NASA July 2022. Total ozone over the Antarctic pole. Purple and blue are areas there is the least ozone.
Climate Change experts are celebrating this week the potential deal to move forward with the largest US bill supporting climate change initiatives that includes methane emission programs. New Mexico is already years ahead on this project, and this week the New Mexico Environment Department is set to implement the new methane emission regulation called the Oil and Gas Sector – Ozone Precursor Pollutants. A quick search of their website about methane emissions comes up blank because they have chosen to not to regulate methane, but ozone instead. As confusing as it sounds, it turns out to be a broad solution to control emissions of Volatile Organic Compounds (VOC’s) and Nitrogen Oxides (NOx). Let me explain: In other posts, I’ve included methane emission reductions as one of “three-things” we should do now to mitigate climate change so I am planning a not too deep-dive into this new regulation in future posts. But first let’s take a shallow dive into ozone.
We don’t have to go too far back in history to learn about the 1987 Montreal Protocol on Substances that deplete the ozone layer, chlorofluorocarbons. They were commonly found in refrigerants. But wait, wasn’t that to increase ozone to patch the ozone hole, not decrease emissions of greenhouse gasses? It turns out ozone in the upper atmosphere (stratosphere) is a good thing because it blocks ultraviolet light which can cause skin cancer, cataracts and environmental calamities. But, ozone in the lower troposphere layer including the air we breathe causes throat and lung irritation aggravating asthma and emphysema. You can find your local ozone level by visiting the EPA site at www.airnow.gov. A quick scan this afternoon, most of the regions with high ozone in the lower atmosphere appear to be in regions impacted by wildfires. Tropospheric ozone even affects plants by inhibiting photosynthesis which reduces the desirable ability to convert carbon dioxide to oxygen.
OK, so now we know ozone in the stratosphere is good and the troposphere is a bad thing, where does tropospheric ozone come from? Ground level ozone, is not emitted directly into the air, but is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC). This happens when pollutants are emitted by cars, power plants, industrial boilers, refineries, chemical plants, and oil and gas production. All these sources chemically react in the presence of sunlight to produce ozone. Depending on your desire to study a little chemistry you can read this bulletin by Michael Sanderson to learn how ozone is created. https://www.envchemgroup.com/climate-change-methane-and-ozone.html, So by measuring ozone, regulators don’t focus on a single hydrocarbon like methane, but a whole number of hydrocarbon gas emissions. Remember from my previous posts that not all methane comes from the oil and gas industry. There are natural sources like wetlands, permafrost, the oceans and other man-made sources like cattle, rice paddies, and everything organic that we throw into the landfill. I keep focusing on the oil & gas industry because there is so much potential to reduce emissions economically.
So what happened to that ozone hole anyway? We are not out of the woods yet though the stratosphere ozone layer is expected to fully recover by about 2040, thanks to the Montreal Protocol of 1987, which phased out the use of CFCs. The international treaty that saved the Earth’s ozone layer is often considered one of the most successful environmental efforts. Maybe the new Inflation Reduction Act of 2022 will be the start of another.