Quantcast
Environmental News for a Healthier Planet and Life

Pandemic Lockdown’s Clear Skies Have Warmed the Planet

Science
Pandemic Lockdown’s Clear Skies Have Warmed the Planet
Nepal's COVID-19 lockdown decreased air pollution levels in the Kathmandu Valley, seen here on March 29, 2020, and known as one of the world's most polluted cities. Narayan Maharjan / NurPhoto / Getty Images

When countries began going into lockdown last winter and spring, clearer skies from reduced traffic and industry were hailed as a rare bright spot during a difficult time.


But a study published in Geophysical Research Letters in December 2020 shows that those blue skies had an unexpected side effect: They made the Earth slightly warmer.

"There was a big decline in emissions from the most polluting industries, and that had immediate, short-term effects on temperatures," said Andrew Gettelman, lead author and National Center for Atmospheric Research (NCAR) scientist. "Pollution cools the planet, so it makes sense that pollution reductions would warm the planet."

Soot and sulfate air pollution had the biggest impact, the study authors explained. Known as aerosols, these types of pollutants release particles into the atmosphere that either scatter sunlight on clear days or brighten clouds, reflecting sunlight. Both of these impacts mean less sunlight reaches Earth and temperatures cool.

In 2020, a reduction of these pollutants warmed global temperatures by about 0.1 to 0.3 degrees Celsius, the press release explained. The effect increased in places with higher aerosol emissions. Temperatures over China, Russia and the U.S. were as much as 0.37 degrees Celsius warmer, The Associated Press reported. All told, aerosol reduction may have contributed to 2020 experiencing one of the warmest years on record, NASA Climate Scientist Gavin Schmidt, who was not involved in the research, told The Associated Press.

To reach their conclusions, the researchers compared the actual weather with climate models reproducing the same conditions without the lockdowns and subsequent emission reductions. This allowed them to calculate the impact of reduced aerosols on temperature changes that were too small to identify based solely on observations, the press release explained.

The study found that aerosol reduction had a bigger impact on 2020 temperatures than the reduction of greenhouse gas emissions such as carbon dioxide. However, that may change in the future. Because carbon dioxide stays in the atmosphere longer, the lockdown dip in greenhouse gases may still slow down the climate crisis in the long term.

Gettelman emphasized that the study's message is not that we should pollute more.

"Clean air warms the planet a tiny bit, but it kills a lot fewer people with air pollution," Gettelman told The Associated Press.

Instead, the value of the study involves understanding aerosols' impact on the climate, according to the press release. This can then help scientists more effectively combat climate change.

David Attenborough narrates "The Year Earth Changed," premiering globally April 16 on Apple TV+. Apple

Next week marks the second Earth Day of the coronavirus pandemic. While a year of lockdowns and travel restrictions has limited our ability to explore the natural world and gather with others for its defense, it is still possible to experience the wonder and inspiration from the safety of your home.

Read More Show Less
EcoWatch Daily Newsletter

By Michael Svoboda

For April's bookshelf we take a cue from Earth Day and step back to look at the bigger picture. It wasn't climate change that motivated people to attend the teach-ins and protests that marked that first observance in 1970; it was pollution, the destruction of wild lands and habitats, and the consequent deaths of species.

Read More Show Less
Trending
An Amazon.com Inc. worker walks past a row of vans outside a distribution facility on Feb. 2, 2021 in Hawthorne, California. PATRICK T. FALLON / AFP via Getty Images

Over the past year, Amazon has significantly expanded its warehouses in Southern California, employing residents in communities that have suffered from high unemployment rates, The Guardian reports. But a new report shows the negative environmental impacts of the boom, highlighting its impact on low-income communities of color across Southern California.

Read More Show Less
Xiulin Ruan, a Purdue University professor of mechanical engineering, holds up his lab's sample of the whitest paint on record. Purdue University / Jared Pike

Scientists at the University of Purdue have developed the whitest and coolest paint on record.

Read More Show Less

Less than three years after California governor Jerry Brown said the state would launch "our own damn satellite" to track pollution in the face of the Trump administration's climate denial, California, NASA, and a constellation of private companies, nonprofits, and foundations are teaming up to do just that.

Read More Show Less