(NEXSTAR) – As a deadly virus tore across the U.S. in 2020 the country’s greenhouse gas emissions fell more than 10 percent, according to a research group report Tuesday.

“Based on preliminary economic and energy data, we estimate that this historic shock to economic activity led to a 10.3% drop in US greenhouse gas (GHG) emissions in 2020,” economic research firm Rhodium Group said.

It’s the single largest drop in annual emissions since the post-World War II era, the group found, even greater than the 6.3% slide following the Great Recession of 2009.

“Across the US, measures put in place to slow the pace of infection affected all aspects of American life, reducing travel, altering demand for goods and services, and resulting in record-high unemployment,” the report said. “The emission reductions of 2020 have come with an enormous toll of significant economic damage and human suffering.”

The emissions reduction was 21% below 2005 levels – and would easily surpass the 2020 Copenhagen Accord target of a 17% reduction – but the Rhodium Group cautions that there isn’t reason to think the U.S. will fulfill 2025 Paris Agreement target of 25-28% below 2005 numbers.

“With coronavirus vaccines now in distribution, we expect economic activity to pick up again in 2021, but without meaningful structural changes in the carbon intensity of the US economy, emissions will likely rise again as well,” the group said.