Connecticut continues to lag behind its goal to slash greenhouse gas emissions by mid-century, according to a new report released Wednesday by the state's Department of Energy and Environmental Protection.
Emissions of carbon dioxide -- the most prevalent of the climate-altering greenhouse gases -- rose by 1.5% in 2023 to reach 35 million metric tons, according to the report.
That was largely driven by an increase of more than 1 million metric tons of CO2 from power plants, which the report attributed to a prolonged outage of one of the reactors at the Millstone Nuclear Power Station that necessitated the burning of more fossil fuels to meet electric demand. Smaller increases in emissions were also reported from industrial and agricultural sources, according to the report.
But Connecticut otherwise made progress toward reducing emissions from the state's two biggest sources: vehicle exhaust and heating for residential buildings.
"The evidence is in: greenhouse emissions in 2023 declined in transportation and buildings, as a result of strong federal and state programs that provide clean air, improve energy affordability, and protect public health," DEEP Commissioner Katie Dykes said in a statement included with the release of the report.
Dykes said the effects of climate change are being felt across Connecticut in the form of heat waves, wildfire smoke and increasingly intense storms -- all of which are likely to get worse if sufficient efforts are not made nationally and globally to reduce CO2. And the report came just days after the Trump administration ordered a halt to work on one of the state's largest planned renewable energy projects, Revolution Wind.
"Addressing these impacts continues to be an urgent challenge," Dykes said. "As we celebrate this progress in reducing emissions, we are concerned that recent actions by the (U.S. Environmental Protection Agency) to roll back power plant regulations, vehicle fuel economy standards, and even the Endangerment Finding, will remove critical federal tools that contributed to this progress."
The annual report, known formally as the Connecticut Greenhouse Gas Emissions Inventory, is required under the state's Global Warming Solutions Act. That law, passed in 2008, set a goal of reducing greenhouse gas emissions by up to 80% of 2001 levels by 2050.
The law also set several incremental targets on the path toward meeting that goal, which started in 2020.
While Connecticut was able to meet its initial reduction targets that year, the achievement was largely the result of a the steep decline in vehicles on the road during the COVID-19 lockdown. Overall emissions have steadily increased since then, though they remain below pre-pandemic levels.
If current trends continue, the report found that Connecticut will fall about 5 percentage points below its next target: a 45% reduction by 2030.
Lori Brown, the executive director of the Connecticut League of Conservation Voters, said the state's experience during the pandemic, when levels of air pollution dropped significantly, showcased the benefits of meeting its long-term goals.
"It's not just a theory, you know, it's proof," Brown said. "It's the kind of thing that's right in front of your face that shows we can really make a difference. It's not too big for us to change the air quality in our state."
Brown was also critical of President Donald Trump's rollback of many environmental and climate regulations, but she noted that data behind the most recently reported increase in emissions predated his current administration.
She also chastised local leaders, including Gov. Ned Lamont, for supporting a proposed expansion of natural gas pipelines into the state. "It's easy to point the finger at Trump right now, because essentially, he's doing everything he can to destroy clean energy," she said.
Prior to the pandemic, Connecticut's most significant decreases in emissions came from the power sector. Emissions there declined nearly 80% between 2001 and 2022 as the state retired a number of highly polluting coal and oil-fired power plants while making strides in energy efficiency and building new, cleaner sources of power generation such as solar.
(Connecticut is a net exporter of electricity, and the state's greenhouse gas inventory calculates emissions based only on the power consumed within the state.)
Still, the vast majority of the electricity produced in Connecticut comes from natural gas and the Millstone Nuclear Plant. In 2023, both of the plant's two active reactors experienced extended outages, according to the report, including one outage that was due to refueling.
As a result the plant produced less electricity than in 2022, and its output had to be picked up by other fossil fuel burning plants.
Susan Adams, the state director of government affairs and economic development for Millstone's owner, Dominion Energy, said in a statement Wednesday that the data highlighted the facility's role in producing carbon-free electricity and reducing emissions.
"While 2023 was an anomaly, with both a higher number of outages and longer-than-usual events, looking ahead Millstone will continue to operate with regularly scheduled refueling and maintenance outages, but we do not anticipate any extended or prolonged outages," Adams said. "These planned outages are carefully scheduled during periods of lower energy demand, typically in the spring and fall, to minimize any impact on the grid and to help reduce reliance on fossil fuels."
The state's largest source of CO2 emissions comes from the transportation sector, which includes fuels burned to power cars, trucks, trains and planes. Those emissions fell by 2% in 2023, despite an overall increase in vehicle miles driven.
Increased fuel efficiency across all kinds of vehicles were cited as "the predominant driving force" in reducing in transportation emissions, along with a growing number of electric vehicles, according to the report. In addition, the report said a relatively mild winter and greater energy-efficiency measures resulted in a 5.6% decrease in emissions from residential buildings.
Emissions from commercial buildings, wastewater, solid waste and natural gas leaks all fell slightly or saw no change.
In addition to the goal to gradually reduce emissions over the coming decades, Connecticut lawmakers earlier this year passed legislation pledging to achieve "net-zero " emissions by 2050. Net-zero emissions can be achieved when gases are sequestered or removed from the atmosphere through carbon-capture technology or more natural means such as planting forests and other green spaces.
In 2023, a total of 4.9 million tons of CO2 were sequestered in Connecticut, or about 14% of the state's total emissions that year.
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This story was originally published by CT Mirror and distributed through a partnership with The Associated Press.