American greenhouse gas emissions fell a record 10.3% last year—the largest annual decline since World War II, according to a report released today by the Rhodium Group.

But the emission reduction—which puts the U.S. temporarily into position to meet its obligations under the Paris climate accord—is likely to be fleeting without a major intervention by the incoming Biden administration and Congress.

The report attributes the vast majority of the decline in carbon dioxide emissions last year to behavioral changes associated with the COVID-19 pandemic. Rhodium said it expects emissions to climb in 2021 unless policymakers act.

“We’re seeing things we haven’t seen before, but it’s not for the right reasons,” said Hannah Pitt, a senior analyst on Rhodium’s climate and energy team. “In order to be on track for sustained reductions, there have to be structural changes to the underlying drivers of emissions.”

Rhodium’s findings weren’t a surprise. Analysts have been predicting a record drop in the United States’ emissions output almost since lockdowns began early last year (Climatewire, May 20, 2020).

The report was nevertheless a striking illustration of the virus’s toll on American life.

Driving plummeted 40% in April, when lockdowns reached their peak, before slowly recovering throughout the year. Vehicle miles traveled were still down 15% through October compared with the same period in 2019, a reflection of how many Americans remained confined to their homes last year.

But if some ventured a return to the roads, most Americans remained planted on the ground. Jet fuel demand remained 35% below 2019 levels in December.

The combined drop in driving and air travel helped produce a drop of 273 million metric tons in transportation emissions, the most recorded by any economic sector in the United States last year. The nearly 15% decline marked a sharp reversal from previous years, which have seen transportation emissions edged upward to overtake the power sector as America’s leading source of greenhouse gas emissions.

Overall U.S. emissions fell to 5,160 million tons in 2020. That left American greenhouse gas levels 21.5% below 2005 levels. The United States committed to a 26%-28% drop in emissions by 2025 under the Paris Agreement. President Trump pulled America from the international accord, but President-elect Joe Biden is expected to reenter it soon after assuming the White House.

Many analysts said they expect the United States to backtrack, as drivers return to roadways in greater numbers and the economy rumbles back to life.

“The emissions decrease shows us the degree of effort to get anywhere close to Paris,” said Melissa Lott, a senior research scholar at Columbia University’s Center on Global Energy Policy. “The degree of effort is huge and only gets more challenging the longer we wait.”

It remains to be seen what behavioral changes stick from the pandemic. While a greater number of Americans now work from home than in the past, potentially driving emissions lower, public transit ridership has plummeted. A large number of people also swapped cities, where public transit is widely available, for driving-centric suburbs.

Analysts said those trends could push emissions higher in future years and underline the challenges facing the United States as it seeks to build back from the pandemic.

The expected CO2 rebound points to the need for action in Washington, they said. The pandemic illustrated that behavioral changes can only reduce emissions so much. More important is changing the way America is fueled.

Investments in public transit, bike lanes, sidewalks and electric vehicle infrastructure are needed to encourage Americans to forgo gas-guzzling automobiles. Even more work is needed to further decarbonize sectors like long-haul trucking and aviation, such observers said.

“We need to ensure that when activity resumes, it is clean,” said Costa Samaras, an associate professor of civil and environmental engineering at Carnegie Mellon University. “The idea is to find opportunities where they present themselves and knowing every bill is a climate bill from now on.”

Indeed, transportation is only one part of the climate puzzle. The power sector is the only area of the economy to consistently reduce emissions in recent years.

That continued in 2020, as utilities swapped coal for natural gas and installed renewables in record amounts. Power sector emissions were down 10.3% thanks to an almost 19% drop in coal generation, Rhodium said.

The greening of power nevertheless needs to be accelerated if other parts of the economy are to follow, Lott said, noting most plans to clean up sectors like transportation and home heating involve trading fossil fuels for carbon-free electricity.

She argued America’s climate efforts would greatly benefit from a national standard for clean electricity. Biden campaigned on a pledge to decarbonize electricity by 2035. Some utility executives have called that pledge unrealistic (Climatewire, Nov. 13, 2020).

“One of the big struggles is we don’t have a clear requirement,” Lott said, noting some states have standards for clean electricity while others do not. “We have a patchwork but not a full quilt. They are pieces that need to be sown together. If we don’t have a standard, the transition will be slow.”

If progress is being made on power, industrial emissions present a different challenge. Many climate experts have long focused their efforts on greening power plants due to more readily available alternatives, like solar and wind.

Those alternatives are less common in industry, where climate policy needs to be balanced with concerns over international competitiveness and companies’ thin profit margins.

Rhodium’s report notes industrial emissions loom as a major challenge, with factories, refineries and other industrial operations poised to overtake the power sector as America’s second largest source of greenhouse gas emissions. Industrial emissions fell 7%, or 109 million tons, in 2020.

Analysts said more incentives are needed to deploy existing technologies, like carbon capture and sequestration, while federal research funding is required to pave the way for greener industrial processes.

“Let’s hope there are no more pandemic sources of emissions cuts and that it is us acting deliberately next time,” Samaras said.

Reprinted from E&E News with permission from POLITICO, LLC. Copyright 2021. E&E News provides essential news for energy and environment professionals.