EPA Climate Change Adaptation Plan sees likely increase in tropospheric ozone, with more difficulty in attaining NAAQS in many areas
Among the many climate-related vulnerabilities that can impact its mission, the US Environmental Protection Agency (EPA) cites a likely increase in tropospheric ozone pollution as potentially making it more difficult to attain National Ambient Air Quality Standards (NAAQS) in many areas with existing ozone problems. The analysis comes in a draft Climate Change Adaptation Plan that the agency has released for public comment.
In the plan, EPA examines the different ways in which its programs are vulnerable to a changing climate and how it might adapt to continue meeting its mission of protecting human health and the environment. Every program and regional office within the EPA is currently developing an Implementation Plan outlining how each considers the impacts of climate change in its mission, operations, and programs, and carrying out the work called for in the agency-wide plan.
Many of the outcomes EPA is working to attain (e.g., clean air, safe drinking water) are sensitive to changes in weather and climate. Until now, EPA has been able to assume that climate is relatively stable and future climate will mirror past climate. However, with climate changing more rapidly than society has experienced in the past, the past is no longer a good predictor of the future. Climate change is posing new challenges to EPA’s ability to fulfill its mission.
It is essential that EPA adapt to anticipate and plan for future changes in climate. It must integrate, or mainstream, considerations of climate change into its programs, policies, rules and operations to ensure they are effective under future climatic conditions. Through climate adaptation planning, EPA will continue to protect human health and the environment, but in a way that accounts for the effects of climate change.
EPA has not yet conducted a detailed quantitative assessment of the vulnerability of its mission to climate change. This Climate Change Adaptation Plan uses expert judgment, combined with information from peer-reviewed scientific literature on the impacts of climate change, to identify potential vulnerabilities. It then presents priority actions the Agency will take to begin integrating climate adaptation planning into its activities.—Draft Climate Change Adaptation plan
|The Clean Air Act (CAA) requires EPA to set National Ambient Air Quality Standards (NAAQS) for pollutants considered harmful to public health and the environment.|
|EPA has set National Ambient Air Quality Standards for six principal pollutants, which are called “criteria” pollutants: carbon monoxide (CO); lead; nitrogen dioxide (NO2); ozone; particulate matter (PM10 and PM2.5); and sulfur dioxide (SO2).|
|Under the CAA, each state must develop a plan describing how it will attain and maintain the NAAQS—the State Implementation Plan. In general, the SIP is a collection of programs (monitoring, modeling, emission inventories, control strategies, etc) and documents (policies and rules) that the state uses to attain and maintain the NAAQS. A state must engage the public in approving its plan prior to sending it to EPA for approval.|
|In some cases where the EPA fails to approve a SIP, the Agency can issue and enforce a Federal Implementation Plan (FIP) to ensure attainment and maintenance of the NAAQS.|
The relationship between temperature changes and tropospheric ozone formation is well understood, EPA notes in the draft. Higher temperatures and weaker air circulation will lead to more ozone formation even with the same level of emissions of ozone forming chemicals. Studies project that climate change could increase tropospheric ozone levels over broad areas of the country, especially on the highest-ozone days.
Climate change might also lengthen the ozone season and increase individuals’ vulnerability to air pollution.
Increases in ozone due to climate change may make it more difficult to attain or maintain ozone standards that the EPA establishes; this will need to be taken into account when it designs effective ozone precursor emission control programs, the agency noted.
A related concern in terms of air quality is potential that climate change will affect PM levels through changes in the frequency or intensity of wildfires. The potential increase in PM resulting from wildfires may increase the public health burden in affected areas and also complicate state efforts to attain the PM NAAQS and address regional transport of air pollution.
Additionally, climate change may alter the effects of and strategic priorities within EPA’s regulatory and voluntary programs to help restore the stratospheric ozone layer, the agency notes. Climate change affects the ozone layer through changes in chemical transport, atmospheric composition and temperature. In turn, changes in stratospheric ozone can have implications for the weather and climate of the troposphere.
EPA recognizes that the integration of climate adaptation planning into its programs, policies, rules, and operations will occur over time. This change will happen in stages and measures should reflect this evolution. The earliest changes in many programs will be changes in knowledge and awareness (e.g., increase in the awareness of EPA staff and their external partners of the relevance of adaptation planning to their programs). Building on this knowledge, they then will begin to change their behavior (e.g., increase their use of available decision support tools to integrate adaptation planning into their work). As programs mature, there will be evidence of more projects implemented as a result of increased attention to climate-related programmatic issues. Finally, in the long-term, adaptation planning efforts will lead to changes in condition (e.g., percentage of flood-prone communities that have increased their resilience to storm events) to directly support EPA’s mission to protect human health and the environment.—Draft Climate Change Adaptation plan