Peter Kareiva on Why the Ozone-Reforestation Study is Important

September 9, 2014

The Roy E. Larsen Sandyland Sanctuary in East Texas. Photo by Lynn McBride.

Sustainability is big for big business. A recent McKinsey survey of 2,632 CEOs revealed that 36% see sustainability as one of their top three priorities, and 13% declared it their #1 priority. More than 50% of the Fortune 500 companies now issue sustainability reports. Meanwhile, almost every major environmental NGO now embraces corporate partnership as a means of making progress on their environmental agenda.

Yet these efforts are often criticized as greenwashing. New research also shows that, beyond reducing energy use and emissions, corporations themselves are not sure what it means to be environmentally sustainable or pro-conservation. The corporate world clearly has a new fondness for the environment, but how much of this effort is symbolic or image burnishing and how much is real? And why should companies care about habitats and conservation, anyway?

One reason companies are embracing conservation is the recognition that nature can help them solve problems at a price tag that makes good business sense. Marshes and near-shore reefs, for instance, are known to reduce storm surge and could help protect coastal facilities. Forests can help purify water and may take the place of in-plant treatment.

To this list of nature as problem solver, we can now add the role of forests in helping to mitigate air pollution as reported in a new paper by Nature Conservancy environmental economist Timm Kroeger and colleagues through the The Dow Chemical Company-Nature Conservancy collaboration published in the Proceedings of the National Academy of Sciences (PNAS). The paper suggests that large-scale peri-urban forest restoration can cost-effectively reduce ground-level ozone and ozone precursor levels and thereby should qualify for ozone precursor mitigation credits if a company pays for the restoration.

Adding Forests to the Engineering Solution for Reducing Ground-Level Ozone

In the United States alone, 46 areas with a total population of 123 million people currently (2013) are designated by the U.S. EPA as ozone nonattainment areas because their ambient ozone levels exceed the federal air quality standard for ozone. Nonattainment areas impose area-wide emission caps on ozone precursors coupled with individual emission limits for major emitters. Those sources then implement emission controls — permanent or intermittent plant shutdowns, conversion to lower-emitting fossil fuels, production and combustion process changes and end-of-pipe controls — or purchase emission credits on local cap-and-trade markets.

While these conventional measures often have helped reduce ozone pollution, the problem of high ozone levels remains widespread. Furthermore, climate and land cover change threaten to counteract some of the historic gains in ozone control, leading to predictions of future increases in ozone levels for many areas of the world.

Kroeger and colleagues show that forests can be added to the engineering solutions in a significant way, and do so at a cost commensurate with conventional control approaches. And unlike the engineering solutions, forests bring numerous extra benefits as a bonus — they sequester carbon and help to mitigate climate change, they can cool air temperatures, they can help improve water quality and reduce flood risk, and they are habitats for wildlife and sites for recreation.

Innovative Ecosystem Science from the Dow-TNC Collaboration

The origin of this research is itself a story: the team of researchers comes from University of Florida, Department of Interior, Dow and the Conservancy. This article is the first of perhaps many peer-reviewed publications featuring research conducted as part of a collaboration between Dow and TNC.

The work that resulted involved ecologists and economists from the conservation community identifying and jointly solving problems with engineers from Dow on how conservation gains could also make business sense for a Fortune 500 corporation.

The convergence of these science fields has yielded surprising questions and innovative results. Large-scale reforestation as a partial solution to ozone pollution was mentioned as a possibility in a 2004 EPA report, but not under any sort of serious consideration until Dow and TNC started having brainstorming sessions together to explore possible ways nature might be of business value. The entire field of ecosystem science has much to contribute to the business world — but making that contribution will require sometimes uncomfortable and difficult partnerships that cut across strikingly different cultures and languages.

Global Implications for Ozone Mitigation

The implications of this new research extend far beyond any NGO-business partnership. While Kroeger and colleagues did their analyses for ozone mitigation in the Houston area, the opportunity and need is truly global. Worldwide, ground-level ozone has been linked to 152,000 deaths annually.  In the United States alone, an estimated 10 million cases of acute respiratory symptoms each year would be avoided if ground-level ozone concentrations could be reduced everywhere to less than 60 ppb.

Locations with the potential to use reforestation for ozone abatement are shown in green. They have ozone levels that exceed federal standards, were once forested but are not currently, and have NOx-limited formation of ozone. (Fig 2)
Locations with the potential to use reforestation for ozone abatement are shown in green. They have ozone levels that exceed federal standards, were once forested but are not currently, and have NOx-limited formation of ozone. (Fig 2)

And reforestation is a significant option in many of the areas with high ozone levels, as can be seen by mapping non built-up areas in the United States that used to have forests but have been cleared and in which ozone has exceeded 80 ppb (figure 2 from their paper). Forests around the world have been cleared at the expense of biodiversity — and, we now know, at the expense of clean air.

If the EPA would allow companies to receive credit for forest restoration as an ozone control measure, that move could be good for companies, for forests and for communities. A skeptical environmental purist might argue that allowing companies to use forest restoration to mitigate their polluting emissions is simply allowing them to pay-to-pollute. There is no question that air and water pollution warrant technical innovations that reduce the emissions from industrial processes. But the fact forests can also help should be viewed as a wonderful opportunity for nature.

We can imagine a dystopian world with no trees and no forests — just the concrete and steel edifices of human activity — suitably embellished with the latest in smokestack pollution controls. Or we can imagine a world that relies heavily on forests and floodplains, and coastal marshes mixed in with steel and concrete engineering solutions. There is no question which of these worlds offers the better life to people and nature.

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  1. Well said, Peter, in discussing these difficult but important innovations in how society approaches this issue. I appreciate that even as you urge the adoption of this approach, you note the complementary nature of it with other important traditional approaches.

    Given the several caveats noted in the study, I hope that the Conservancy will make a strong push to support the capacity of its foot-soldiers (and those of other organizations and agencies who are on the ground in places where the rubber meets the road, so to speak), so that implementation of the big idea is directed to appropriate places, and in ways that truly accomplish the multiple benefits that are possible.

  2. Hi Theresa,

    Great point. The national map just shows general enabling conditions (in terms of potential for trees to abate ozone, and general suitability for tree planting), and does not account for regional climatic variations like drought, nor microclimatic specifics that could complicate the value proposition at an individual site. So in short: we would certainly not recommend planting trees in California at the moment. If EPA does eventually allow this kind of reforestation to meet ozone abatement requirements, we would want to do the same kind of analysis we did in Texas in any other potential sites, at which point we would see whether a general potential translates into a real opportunity. It is possible that by then the drought will have abated, but it also likely that some of the areas on the map with potential (as identified by a coarse national analysis) are not actually workable.

  3. […] “Peter Kareiva on Why the Ozone-Reforestation Study is Important” — The Nature Conservancy The Nature Conservancy’s Peter Kareiva offers his perspective on the aforementioned ozone study, touching base on the social, health and economic benefits of mitigating ozone pollution through tree-planting initiatives. […]