One view advanced in some studies attempting to model future climate is that cleaning up fossil-fuel air pollution rapidly will unintentionally lead to a near-term rise in atmospheric warming of about a half-degree Celsius, which might take up to a century to reverse. The foundational idea is that the sun-obscuring aerosols fossil fuel consumption puts into the atmosphere would clear relatively quickly, but long-lived greenhouse gases such as carbon dioxide would persist and create a net warming.

Now, new analysis by researchers at Duke University and the University of Leeds finds that reducing fossil fuel emissions steadily over coming years will prevent millions of premature deaths and help avoid the worst of climate change without causing the large spike in short-term warming that some studies have predicted.

We analyzed 42 scenarios presenting different timescales for a very rapid worldwide transition from fossil fuels to clean energy. Under all of these scenarios there is no significant spike in warming, no climate penalty, and we actually see a decrease in warming rates within two decades of the start of the phase-out.

The only scenarios that result in a significant warming spike are implausible ones in which worldwide emissions are halted instantaneously or over a very short timescale. But in the real world, that’s not going to happen. It will take decades to transition to clean energy.

—Drew Shindell, Nicholas Professor of Earth Science at Duke’s Nicholas School of the Environment

Our finding shows these fears are unfounded. Under a realistic rate of fossil-fuel phase-out, we do clean up the air, unmasking historically suppressed cooling. But we would also reduce the rate of further greenhouse gases put into the atmosphere, slowing down future warming. These competing effects will approximately balance out, and any increase in the rate or level of near-term warming will be quite small compared to what we would see if we allowed emissions to remain at current levels.

—Christopher J. Smith, research fellow at the School of Earth and Environment at Leeds

The new finding is good news on the public health front, too, Shindell noted, because aerosol particulates are highly toxic when inhaled and cause millions of premature deaths each year.

Shindell and Smith published their study in Nature.

By showing an alignment between climate and public health policy goals, Shindell and Smith hope their finding will spur progress in climate negotiations and add momentum to the discussions and presentations taking place at the UN Climate Action Summit in New York City on 23 September.

This research dispels the misconception that the air-quality and climate benefits of transitioning to clean energy play out at different timescales. Climate change mitigation does not come at the expense of air pollution reductions.

—Christopher Smith

Resources

• Drew Shindell and Christopher J. Smith (2019) “Climate and Air-Quality Benefits of a Realistic Phase-Out of Fossil Fuels,” Nature doi: 10.1038/s41586-019-1554-z