Dr. Drew Shindell

Dr. Shindell has left NASA and is now on the faculty at Duke University. Please see his university page for current information.

Scientific Research

Dr. Shindell's research is concerned with global climate change, climate variability, and Atmospheric Chemistry. He uses mathematical models of the atmosphere and oceans which run on supercomputers to investigate chemical changes such as increased pollution from human activities, climate changes such as global warming, and the connections between these two. Within these general topics, his research can be grouped into several specific main areas.

Papers on these topics are available at Dr. Shindell's bibliography.

He is also a co-leader of the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP).

Climate, health and agricultural benefits of methane and black carbon emissions control measures

Dr. Shindell has been a leader in promoting actions that simultaneously reduce climate change and improve air quality. Many years of research by Dr. Shindell and others have led to a broader appreciation of the benefits of pursuing such actions alongside efforts to reduce carbon dioxide emissions, opening what the New York Times referred to as "A Second Front in the Climate War".

Science Paper: One of the key papers describing the benefits of emissions controls is the journal paper "Simultaneously Mitigating Near-Term Climate Change and Improving Human Health and Food Security", Shindell et al., Science, 2012, which can be freely accessed without a subscription courtesy of Science. Click on the link to get a reprint or to be taken to the full text. Additional technical information is available in the UNEP/WMO Integrated Assessment of Black Carbon and Tropospheric Ozone below.

Interactive Graphics: A web-based set of interactive graphics showing the climate, health and agricultural impacts of the measures is available here. A NASA Feature story showing a gallery of images associated with these pollution control measures is available here.

Presentation: Dr. Shindell delivered the honorary Charney Lecture on this topic at the Dec. 2012 meeting of the American Geophysical Union. Video of that presentation can be viewed here. The presentation itself can be downloaded as powerpoint or pdf.

Policy Response: In Feb. 2012, Secretary of State Hillary Rodham Clinton announced an international initiative to reduce methane, black carbon, and hydrofluorocarbons called the Climate and Clean Air Coalition to Reduce Short-Lived Climate Pollutants. The initial participants were Bangladesh, Canada, Ghana, Mexico, Sweden, the United States, and the United Nations Environment Programme. Transcript and video of the announcement are available from the US State Dept here. As of Dec. 2012 the Coaltion has grown to 25 nations.

Bringing Climate Science to Society

Dr. Shindell engages in efforts to bring scientific knowledge to the public and to decision makers. This includes participation in national and international assessments, providing expertise to Congress, federal agencies, or bodies such as the Arctic Council nations, educational talks and coursework, etc. He taught at Columbia University for 14 years. Some of those efforts and/or their products can be accessed below.

Interactions between atmospheric composition and climate change

Although carbon dioxide increases are the largest driver of modern climate change, changes in the abundance of many other compounds also play a role. Among these are the gases methane and ozone, and several types of particles (aerosols). Atmospheric chemistry governs the formation and removal of these gases and particles (unlike carbon dioxide, which is not reactive in the lower atmosphere). Our current research focuses on how changes in emissions of these compounds or their precursors influence climate, how changes in climate influence both emissions and atmospheric lifetimes of these compounds, and how changes in their abundance in the atmosphere influences society by affecting human health and ecosystem productivity.

While recent trends in stratospheric ozone have been driven largely by increases in halogen abundance resulting from chlorofluorocarbon (CFC) emissions, climate change will play an increasing role in governing ozone amounts in the future, and ozone changes will feed back on climate as ozone is itself a greenhouse gas. Current research combines the climate and chemistry changes in the GISS model to predict future stratospheric ozone amounts both over the polar regions and at lower latitudes. Changes in stratospheric water vapor, also a greenhouse gas, and in transport between the troposphere and stratosphere are also current research topics.

Our model seamlessly represents atmospheric composition from the surface to the model top (above the stratosphere). The composition simulated in the model is evaluated against a range of observations, including aircraft, balloon and satellite measurements.

Climate Change From Short-Lived Emissions Popular summary.

Modeling Carbon Monoxide Popular summary.

Reaction of Ozone and Climate to Increasing Stratospheric Water Vapor. Popular summary.

Why do the Ozone Holes Vary in Size? Popular summary.

Are Increasing Greenhouse Gases creating an Arctic Ozone Hole? Popular summary.

Climate and air quality linkages and public policy

We are investigating the effects of long-term emissions trends using a version of the GISS climate model that includes atmospheric chemistry. Characterization of how societal choices influence long-term trends in climate and air pollution (having adverse affects on human health in urban areas, and on agriculture in farming areas) are our primary goals.

Looking Both Ways at Pollution Popular summary.

Natural modes of climate variability and detection/attribution of climate change

While the average temperature of the Earth has been slowly increasing over recent decades, much larger warming trends have been seen over the Northern Hemisphere continents during winter (as shown in the figure below, based on the GISS Global Surface Air Temperatures. At the same time, the wintertime stratospheric vortex over the Arctic seems to have been increasing in strength. Observations indicate that the two trends are closely related via dynamical coupling between the stratosphere and the troposphere. Similarly, changes in atmospheric circulation appear to have played a major role in the cooling seen over Antarctica during recent decades (see the figure below). We have been investigating the causes and impacts of these trends, with a focus on determining if the regional warming and cooling patterns result from natural variability or are due to human activities. Simulations have explored the response to volcanic eruptions, solar variations, greenhouse gas increases and polar ozone depletion.

One of the natural forces affecting climate is variations in the strength of solar radiation, though their degree of influence is a subject of intense debate at present. Solar output varies both over the long-term (centuries), which will impact long-term climate trends, and over the shorter-term (the 11 year solar cycle). To understand if climate models are capable of simulating the long-term atmospheric and climate response to solar irradiance changes, we first test their ability to simulate the roughly 11 year solar cycle changes, which have been observed from satellites over the past few decades. Variations in temperatures, ozone amounts, and the altitude at which the atmosphere has a given pressure have been correlated with the solar cycle. We test how well our model can reproduce these observations, and thus gauge its ability to simulate long-term climate responses to solar variations. A particularly interesting aspect of this research is that variations in solar output appear to cause changes in some existing natural modes of climate variability. Studies of the response to solar forcing can thus provide a way to gauge how sensitive these modes are to being amplified or surpressed by external factors.

In addition to regional climate change being strongly affected by natural modes of variability, geographic differences in climate change are related to the uneven spatial distribution of aerosols and tropospheric ozone. A key of our research seeks to understand how the regional distribution of forcing affects the geographic pattern of the resulting climate change. This has implications for attributing observed climate changes in the recent past as well as for designing effective climate change mitigation policies.

Map: Observed surface temperature trends, 1965-1995. December to February average

The Sun vs the Volcano: Drivers of regional climate change. Popular summary.

Glaciers, Old Masters, and Galileo: The Puzzle of the Chilly 17th Century. Popular summary

Greenhouse Gas Influence on Northern Hemisphere Winter Climate Trends. Popular summary

Solar Variability, Ozone, and Climate. Popular summary.

Historical and paleoclimate

Historical datasets show large regional variations in climate changes over the past millenium. For example, from the mid-1600s to the early 1700s, there is believed to have been a minimum in solar irradiance, called the Maunder Minimum. Concurrently, surface temperatures appear to have been at or near their lowest values of the last millenium in the Northern Hemisphere, and European winter temperatures were reduced by 1-1.5 C. We have simulated the difference between that period and both a century later, when solar output remained relatively high over several decades, and during the Medieval Climate Anomaly when solar output was comparatively high. We find that changes in naturally occurring climate variability patterns can play a major role in large regional changes (especially cooling over North America and Europe as solar output decreases). Volcanism is another key driver of historical climate changes, and we have compared the modeled response to large volcanic eruptions with historical data as well.

On longer timescales, atmospheric composition and climate have been intertwined for billions of years, especially via methane, which is both a powerful greenhouse gas and is chemically reactive. Simplified versions of our climate model have been used to study composition-climate interactions during the distant past (paleoclimate), providing information about the climate system's response to changes which provide insight into our potential future.

Super-Eruptions, Climate and Human Survival. Popular summary.