The lockouts and reduced social activity associated with the COVID-19 pandemic have impacted pollutant emissions in ways that have slightly warmed the planet for several months last year, according to a new study led by the National Center for Atmospheric Research (NCAR).
The counterintuitive detection illuminates the effect of airborne particles, or aerosolas, which block incoming sunlight. When aerosol emissions fell last spring, more of the sun’s warmth reached the planet, especially in highly industrialized countries, such as the United States and Russia, which usually pump lots of aerosol to the atmosphere.
“There was a sharp decline in emissions from the most polluting industries, which had a short-term effect on temperature,” said NCAR scientist Andrew Gettelman, lead author of the study. “Pollution cools the planet, so it makes sense that reducing pollution would warm the planet.”
Temperatures over parts of the Earth’s surface last spring were about 0.2-0.5 degrees Fahrenheit (0.1-0.3 degrees Celsius) warmer than expected by normal weather, the study found. The impact was more pronounced in regions typically associated with large aerosol emissions, with warming reaching around 0.7 degrees F (0.37 C) across much of the United States and Russia.
The new study highlights the complex and often controversial effects of different types of emissions from power plants, motor vehicles, industrial facilities and other sources. While aerosols tend to illuminate clouds and reflect heat from the Sun back into space, carbon dioxide and other greenhouse gases have other effects, trapping heat near the planet’s surface and raising temperatures.
Despite the short-term warming effects, Gettelman stressed that the long-term effects of the pandemic may be a slightly slower climate change due to lower emissions of carbon dioxide, which lies in the atmosphere for decades and will have a more gradual impact on climate. In contrast, aerosols – the focus of the new study – have a more rapid impact that will go away within a few years.
The study was published in Geophysical Research Letters. It was partly funded by the National Science Foundation, a NCAR sponsor. In addition to NCAR scientists, the study was co-authored with scientists at Oxford University, Imperial College, and Leeds University.
Removing the Effects
Although scientists have long been able to quantify the warming effects of carbon dioxide, the climatic effects of different types of aerosol – including sulfates, nitrates, carbon black, and dust – have been be harder to knock down. One of the main challenges for the future rate of climate change is to estimate the extent to which society will continue to emit future aerosols and the impact of different types of aerosols on clouds and temperatures.
To conduct the research, Gettelman and its co-authors used two of the world’s leading climate models: an NCAR-based Community Earth System Model and a model called ECHAM-HAMMOZ, developed by co- bondage of European countries. They ran simulations on each model, changing aerosol emissions and capturing real weather conditions in 2020, such as winds.
This approach allowed them to identify the effect of reduced emissions on temperature changes that were too small to be observed in real view, where they could be masked by the difference in conditions. atmosphere.
The results showed that the warming effect is the strongest in the central and upper latitudes of the Northern Hemisphere. The effect was mixed in the tropics and relatively small in much of the Southern Hemisphere, where aerosol emissions are less destructive.
Gettelman said the study will help scientists better understand the impact of different types of aerosols in different environmental conditions, helping to inform efforts to reduce climate change. While the research shows how aerosol counteracts the warming effects of greenhouse gases, he stressed that letting more of them into the atmosphere is not an operational strategy. low to slow climate change.
“Aerosol emissions have a huge impact on health,” he said. “It’s not practical to say we should pollute.”
###
About the article
Title: “Climate Impact of COVID-19 Stimulus Emissions Changes”
Authors: A. Gettelman, R. Lamboll, CG Bardeen, PM Forster, D. Watson-Parris
Iris: Geophysical Research Letters
This material is based on work supported by the National Center for Atmospheric Research, a major resource sponsored by the National Science Foundation and managed by the University Corporation for Atmospheric Research. Opinions, conclusions and conclusions or recommendations expressed in this material do not necessarily reflect the views of the National Science Foundation.
On the web: news.ucar.edu
On Twitter: @NCAR_Science
Disclaimer: AAAS and EurekAlert! they are not responsible for the accuracy of press releases posted to EurekAlert! by sending institutions or for using any information through the EurekAlert system.