It has been the sole silver lining in the coronavirus pandemic -- cleaner air and water on the planet. But will it continue?
A new study says that isn't yet clear.
"The pandemic raises two important questions related to the environment," said study author Christopher Knittel, from the MIT Sloan School of Management in Boston. "First, what is the short-run impact on fossil fuel consumption and greenhouse gas emissions? Second -- and more important but harder to answer -- what are the longer-term implications from the pandemic on those same variables?
"The health impacts from the pandemic could stretch out for decades -- if not centuries -- depending on the policy response," he said.
"If the pandemic leads to a persistent global recession, there is a real threat to the adoption of clean technology, which could outweigh any 'silver lining' in environmental benefits," said study co-author Jing Li, also from the MIT Sloan School of Management.
For the study, the researchers analyzed the effect of the pandemic on carbon dioxide (CO2) levels from late March to June 7.
They found reductions in the use of jet fuel (50%) and gasoline (30%). Natural gas use also dropped by nearly 20% and the demand for electricity dropped by less than 10%.
"Overall, these reductions reflect a 15% total reduction in daily CO2 emissions, which is the largest annual percentage decline for the U.S. in recorded history," Knittel said in a MIT news release. "We estimate that the shutdowns saved about 200 lives per month, primarily driven by the lower emissions from transportation."
However, the researchers noted that due to the pandemic, investment in the transition to low-carbon energy has halted. For example, worldwide sales of electric cars are estimated to drop 43% in 2020, as all car sales fall.
Also, rooftop solar and storage installations have declined, and clean energy jobs dropped by nearly 600,000 by the end of April.
"The short-term impact of the pandemic is clear, but the long-term impact is highly uncertain," Li said. "It will depend on how long it takes to bring the pandemic under control and how long any economic recession lasts."
In the best case, investment trends before the pandemic will continue, the researchers said.
"Unfortunately, we view a second scenario as more likely," Knittel said. "In this scenario, the consequences of the pandemic will be greater, with many more deaths and deeper disruptions to supply chains, and a persistent global recession. The need to backpedal on the reopening of the economy due to flare-ups could destroy rather than defer the demand for goods and services."
In the long-run, the effect on CO2 and local air pollution could outweigh the short-run reductions.
"Our findings suggest that even just pushing back all renewable electricity generation investments by one year would outweigh the emissions reductions and avoided deaths from March to June of 2020," the researchers wrote. "However, the energy policy response to COVID-19 is the wild card that can change everything."
"Just stabilizing the economy can go a long way to putting clean energy trends back on track," Knittel added. We need to solve the pandemic and continue to address climate change. Otherwise, it will lead to even more tragedy."
The report was published July 9 in the journal Joule.
For more on air pollution, head to the Natural Resources Defense Council.