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Liquefied natural gas carriers under construction in South Korea in 2018. Some U.S. lawmakers say expanded American natural gas exports are the key to cutting global carbon emissions, but others see more costs than benefits. (AP) Liquefied natural gas carriers under construction in South Korea in 2018. Some U.S. lawmakers say expanded American natural gas exports are the key to cutting global carbon emissions, but others see more costs than benefits. (AP)

Liquefied natural gas carriers under construction in South Korea in 2018. Some U.S. lawmakers say expanded American natural gas exports are the key to cutting global carbon emissions, but others see more costs than benefits. (AP)

Jon Greenberg
By Jon Greenberg April 6, 2022

Does the US lead in cutting greenhouse gases? It depends on how you look at it

If Your Time is short

  • Carbon dioxide emissions in the U.S. fell by about 880 million metric tons in 2019 compared with 2005.

  • That was more than any other country, but as a percentage change, the U.S. ranks fifth worldwide.

  • On a per-person level, U.S. emissions remain twice that of China.

The latest United Nations climate change report had a grim forecast: If greenhouse gas emissions don’t peak within three years, then there’s little hope of limiting the global temperature rise to 1.5 degrees Celsius.

Sen. Dan Sullivan, R-Alaska, says one of the best moves the United States could make is to accelerate the shift in places such as China and India from coal to natural gas.

Sullivan has a plan to increase American natural gas production, liquify it and ship it overseas. His key supporting argument is the hefty 14% drop in American carbon dioxide emissions over the last 15 years.

"If every other country in the world had a record like this, where do you think we would be on global emissions?" Sullivan said at a March 23 Senate hearing. "We are the leader in the world by far."

Whether the U.S. is the world leader in cutting emissions depends on how you measure things. In total metric tons, Sullivan is right. But in relative terms, many economic peers achieved steeper declines. 

Sullivan’s chart requires a closer look

At the Senate hearing, Sullivan displayed a chart showing the change in carbon dioxide emissions in nine countries between 2005 and 2020. The U.S. stands out with a fall between those years of 970 million metric tons of carbon dioxide. Japan’s emissions went down 237 million metric tons. China, on the other hand, released an additional 4,689 million metric tons in 2020 than it did in 2005, while India’s emissions rose 1,315 million metric tons.

Chart used by Sen. Dan Sullivan, R-Alaska, to show carbon dioxide emission trends for nine countries. (Office of Dan Sullivan)

Sullivan’s staff pulled these numbers from the website Our World in Data, a reliable resource based at the University of Oxford in England. The numbers are accurate, although climate trackers warn against including 2020 numbers, because the COVID-19 economic shutdown distorted normal emission patterns. In our analysis, we looked at 2005 to 2019.

The first caveat to Sullivan’s approach is that he uses absolute numbers. Rob Jackson, an earth systems professor at Stanford University, said the chart is "conveniently misleading." The United States has the largest reduction because, in 2005, Jackson said, it had the highest emissions.

"Other countries, in Europe in particular, have done far more than we have to reduce greenhouse gas emissions," Jackson said.

Looking at the percentage change in carbon dioxide emissions, the United Kingdom made the greatest progress, with a reduction of 35%. Italy, France and Germany came next. The United States and Japan tied for fifth place with reductions of about 14%.


Sullivan spokesman Ben Dietderich agreed that the relative changes reshuffled the rankings, but he countered that the absolute number of tons mattered most. It’s the tons of carbon dioxide that affect the global climate, he said. At the end of the day, Dietderich said, the United States made the largest contribution to reducing carbon dioxide emissions.

Jackson raised another issue with Sullivan’s chart — it left out emissions per person. China’s emissions are enormous, but the country also has 1.4 billion people. Viewed through that lens, despite the decline in U.S. emissions, the United States remained the larger emitter per capita.

"Our per capita emissions are still twice China’s and eight times higher than India’s," Jackson said.


Sullivan’s focus on carbon dioxide doesn’t give the full picture of American emissions. There are other greenhouse gases, most importantly methane and nitrous oxide. The same website that provided the carbon dioxide numbers also has data for greenhouse gases across the board.

Factoring in all greenhouse gases, the U.S. trends are less dramatic. The total decline goes from a reduction of 879 million metric tons to 607 million metric tons. As a percentage, the decline goes from 14.3% for carbon dioxide alone to 9.5% for all greenhouse gases combined. The numbers work that way because it doesn’t take much of those other gases to put a lot of carbon into the air.

Although natural gas was the single largest factor in cutting U.S. emissions, major contributions also came from the rise in wind power and efficiency gains in American industry that lowered demand.

The limits of expanding natural gas production

Sullivan’s point was that if other countries followed the United States’ lead, global emissions would fall. Since the blossoming of natural gas production played a large role in the U.S., it makes sense, he said, to expand production further and export to coal-burning countries such as China and India.

Not so fast, say energy researchers.

Michael Young, a senior scientist at the University of Texas at Austin, said building the pipelines and processing plants to send natural gas overseas adds carbon to the atmosphere. It’s possible, Young said, that exports to Asia could reduce emissions there if they replaced coal or wood.

"But it’s also true that liquified natural gas from the U.S. will embed carbon dioxide emissions in the production and transportation of the fuel, reducing the benefits," Young said. "Whether the two balance out depends on many factors."

Ben King, a senior analyst at Rhodium Group, a private research center, said although industry is getting better at preventing the release of methane gas, it still happens in the liquefaction process.

More troubling, King said, is that building new plants to export natural gas is a 30-year investment.

"Locking in long-lived fossil fuel assets runs directly counter to the need, recently affirmed in the latest International Panel on Climate Change report, to quickly transition away from uncontrolled fossil fuel use," King said.

Our ruling

Sullivan said the United States is "the leader in the world by far" in cutting greenhouse gas emissions. 

In absolute terms, that is accurate — but it isn’t telling the full story. Relative to the scale of emissions in other leading economies, other countries show much deeper reductions. Sullivan also left out emissions per person in the United States. Although those have dropped, they’re still about twice as high as they are in China. 

We rate this claim Half True.

Our Sources

U.S. Senate Committee on Environment and Public Works, Promoting American Energy Security by Facilitating Investments and Innovation in Climate Solutions, March 23, 2022

Sen. Dan Sullivan, tweet, March 30, 2022

Sen. Dan Sullivan, The American Energy Jobs and Climate Plan, Feb. 8, 2022

Our World in Data, CO₂ and Greenhouse Gas Emissions, August 2020

International Panel on Climate Change, Climate Change 2022: Mitigation of Climate Change, April 4, 2022

Carbon Brief, Why US carbon emissions have fallen 14% since 2005, Aug. 15 , 2017

Center for Climate and Energy Solutions, U.S. Emissions, 2021

Reuters, Explainer: Cleaner but not clean - Why scientists say natural gas won't avert climate disaster, Aug. 18, 2020

PolitiFact, China and India’s carbon dioxide emissions, in context, Dec. 2, 2021

Email exchange, Rob Jackson, professor of earth system science, Stanford University, April 5, 2022

Email exchange, Michael Young, senior research scientist, Jackson School of Geosciences, University of Texas at Austin, April 4, 2022

Email exchange, Ben King, senior analyst, Energy and Climate, Rhodium Group, April 5, 2022

Interview, Ben Dietderich, spokesman, Sen. Dan Sullivan, April 5, 2022


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