Our research is interdisciplinary in nature, with broad concerns encompassing climate change, air quality, and the links between science and policy.

 

Co-benefits of climate or air quality policies: Most emission sources of the greenhouse gases that drive climate change also produce other pollutants that are harmful to humans and agriculture. Therefore, climate policy has the capability of simultaneously reducing deleterious air quality, and air quality policies will likewise affect climate. “Co-benefit” studies assess these complex relationships through modeling of the energy system, atmospheric chemistry, and subsequent climate changes and exposure to pollution. The two figures below show co-benefit results from Shindell lab members.

Annual average change in surface PM2.5 due to US clean energy and transportation related climate policies in line with 2°C temperature targets. From Shindell, D., et al (2016) Nature Climate Change.

Total air quality co-benefits from worldwide greenhouse gas mitigation in 2050 for annual average PM2.5 and 6-month ozone-season average
of 1 hr daily maximum of O3. From Zhang, Y. et al (2017) ERL.

These “co-benefits” can be assessed in reverse, extending the Social Cost of Carbon (SCC) framework to include the air quality based externalities in total costs. A multi-impact economic valuation framework called the Social Cost of Atmospheric Release (SCAR) was developed that extended the SCC to a broader range of pollutants and impacts. Shown below is the levelized costs of various primary energy sources, after factoring in environmental damages (externalities) that are not typically considered in the market.

Levelized generation costs for new US electricity generation by fuel type. From Shindell, D. (2015) Climatic Change.

Accelerated reduction of fossil fuel use: Scenarios that limit global warming to 2 degrees C often rely on heavy implementation of negative emission technologies, such as biofuel energy with carbon capture and sequestration (BECCS). These assumptions do not account for the added societal risks that accompany relatively high levels of near-term emissions, such as reduced air quality. If future negative emissions were instead replaced with near-term reductions, dramatic improvements in air quality would occur, reducing premature mortalities by millions. A Shindell lab project concluded that  a ‘standard’ 2 °C scenario without negative emissions would lead to 153 ±  43 million fewer premature deaths worldwide, with ~40% occurring during the next 40 years, and minimal climate disbenefits.

Reduction in premature deaths due to PM2.5 and ozone over the period 2020–2100 from co-emissions accompanying accelerated CO2 emissions reductions. From Shindell, D., et al (2018) Nature Climate Change.

Modeling of human-health impact metrics: The quantification of impacts due to policy simulations utilize many tools. The Shindell lab is actively evaluating common models that simulate changes in air quality and how well they are able to reproduce various impact metrics. Not only do these results determine model performance, but drivers of bias can be elucidated. In addition, techniques to correct for bias and improve simulations are being utilized. In concert with these efforts, ground-based monitoring networks are being used to constrain estimates of air quality impacts.

Modeled bias in the change of annual average PM2.5 (μg m−3) between 2004–2006 and 2009–2011 in the United States at CSN/IMPROVE network locations. From Seltzer, K.M. et al (2017) JGR:Atmospheres.

Climate and Aerosols: Aerosols are important drivers of global and regional climate. Either through primary emission or secondary formation via chemical processes in the atmosphere, these microscopic particles may induce warming or cooling effects. Output from the Precipitation Driver and Response Model Inter-comparison Project (PDRMIP) is being used to study how perturbations of greenhouse gas, aerosols and solar insolation individually cause regional climate responses. This information can then be used to determine regional temperature and precipitation responses to these drivers.

Normalized change in precipitation due to incremental perturbations of CO2, BC, and SO4 forcing. From Tang et al., ACP, 2018.

Understanding of Emission Trajectories:

The relationship between income and emissions has been extensively examined and debated by economists. Members of the Shindell lab have characterized the relationship between per capita income and emissions of SO2, CO2, and black carbon (BC) from the power, industry, residential, and transportation sectors using a global country-level emission inventory to assess the existence of the Environmental Kuznets Curve (EKC) in the trajectories.

 

From Ru et al., ERL, 2018.

 

 

 

 

 

 

Impacts of Emissions on Agriculture via Climate and Air Pollution:

Field measurements and modeling have examined how temperature, precipitation, and exposure to carbon dioxide (CO2) and ozone affect major staple crops around the world.  We have examined how emissions of each individual pollutant driving changes in these four factors affect present‐day yields of wheat, maize (corn), and rice worldwide. Such information will be incorporated into decision-making support tools to enable better evaluation of the effects of policies related to energy and transportation on crop yields.

Annual production changes in 2010 due to historical emissions of all pollutants by country. From Shindell et al., Earth’s Future, 2019.