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After years of decline, US carbon emissions are rising again

That’s alarming.

Transportation is once again the largest source of greenhouse gas emissions in the United States. An increase in air travel helped drive up US carbon output in 2018.
Transportation is once again the largest source of greenhouse gas emissions in the United States. An increase in air travel helped drive up US carbon output in 2018.
Robert Alexander/Getty Images
Umair Irfan is a correspondent at Vox writing about climate change, Covid-19, and energy policy. Irfan is also a regular contributor to the radio program Science Friday. Prior to Vox, he was a reporter for ClimateWire at E&E News.

The Trump administration has frequently deflected responsibility for regulating greenhouse gas emissions to limit climate change by arguing that emissions are on the decline in the US anyway.

“Thanks to President Trump’s regulatory reform agenda, the economy is booming, energy production is surging, and we are reducing greenhouse gas emissions from major industrial sources,” said acting Environmental Protection Agency Administrator Andrew Wheeler in a statement last year. “The Trump Administration has proven that federal regulations are not necessary to drive CO2 reductions.”

According to new data, that’s no longer true.

The Rhodium Group on Tuesday reported that US energy-related greenhouse gas emissions rose in 2018 by 3.4 percent, the second-largest margin in 20 years, reversing a three-year decline. It’s an alarming shift, especially given that scientists recently warned that we are running out of time to limit global warming to 1.5 degrees Celsius this century.

For the third year in a row, the largest source of US greenhouse gas emissions, Rhodium reports, is the transportation sector, fueled by greater demand from industry, diesel trucks, and air travel. It’s followed by power generation, industry, and buildings.

Transportation is the largest source of energy-related greenhouse gas emissions in the United States.
Transportation is the largest source of energy-related greenhouse gas emissions in the United States.
Rhodium Group

Even though cleaner energy sources like wind and solar are expanding rapidly, it’s not enough to keep emissions overall from rising: Power sector emissions still grew by 1.9 percent last year. That increase came even though the United States retired 16 gigawatts of coal-fired power capacity and saw coal consumption dip to its lowest levels in 39 years. The reason? Energy demand still rose, and natural gas largely filled the void. Natural gas emits about half the carbon dioxide of coal, so the emissions intensity — the amount of carbon dioxide released per unit of energy — still fell.

There are several additional factors that led to this spike.

2018 started out with unusually cold weather that led to more demand for heating than expected, increasing the carbon dioxide footprint of homes, offices, and other buildings. High demand for natural gas in the winter raised its price and made burning coal and oil for electricity more competitive in comparison, leading to more emissions from electricity production.

In addition, the US economy as a whole grew throughout 2018. A consequence of that is industry — from factories, steel mills, chemical plants, and the like — using more energy too.

“Absent a significant change in policy or a major technological breakthrough we expect the industrial sector to become an increasingly large share of US greenhouse gas (GHG) emission in the years ahead (including non-CO2 gases),” the authors wrote. “We expect it to overtake power as the second leading source of emissions in California by 2020 and to become the leading source of emissions in Texas by 2022.”

The United States is already off course for its commitments under the Paris climate agreement to cut its greenhouse gas emissions 26 to 28 percent below 2005 levels by 2025, and now the gap is even wider. President Trump announced in 2017 his intent to withdraw the United States from the Paris agreement, which can’t happen until 2020.

The bitter truth is that cost declines in renewables, technology improvements, and market forces won’t make a meaningful dent in greenhouse gas emissions without federal policy.

And the Trump administration is running in the opposite direction, advancing policies that would increase emissions, including freezing fuel economy standards for cars and trucks, rolling back the Clean Power Plan which limits emissions for existing power plants, and relaxing carbon dioxide emissions restrictions on new coal power plants. And despite the ongoing government shutdown, the Interior Department is still advancing fossil fuel extraction, including drilling in the Arctic.

However, more states are stepping up with aggressive carbon dioxide reduction goals of their own. Democratic Pennsylvania Gov. Tom Wolf announced Tuesday that his state is aiming to cut its greenhouse gases 80 percent below 2005 levels by 2050. Pennsylvania is the third-largest greenhouse gas-emitting state and is now the second-largest state with a climate change target.

After the midterm elections, several new governors have also vowed aggressive action on climate change, bolstered by state legislatures with Democratic majorities that want to curb emissions.

In Congress, some Democrats are mounting a campaign for a Green New Deal. The specifics are still up in the air, but the proposal broadly aims to fight climate change via a massive buildout of clean energy and infrastructure with government investment. It’s unlikely to pass a Republican-controlled Senate, but it could emerge as a key issue in the 2020 elections.

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