New York Leads in Controlling Heat-Trapping Methane. That Could Change.

The gaseous power duo that is heating up the planet consists of carbon dioxide, which is the largest contributor to global warming, and methane, its fast-acting, hot-tempered sibling.

Carbon dioxide, which is mostly the result of burning fossil fuels, tends to get top-villain billing in climate policies. But in New York, methane — the stuff of cow burps, pipeline leaks and landfills — is getting its moment in the spotlight as legislators consider changing a metric for measuring greenhouse gases. It is part of an overhaul of the state’s 2019 climate law that Gov. Kathy Hochul has proposed.

The suggested metric, a common — and some say outdated — formula for counting emissions since the early 1990s, would play a crucial role in weakening what was once described as one of the most ambitious climate laws in the world. It would downplay the warming effects of methane, many scientists argue.

Methane can trap 80 times more heat than carbon dioxide over a 20-year period. So New York’s current climate law uses a metric that reflects this fact.

Unlike carbon dioxide, which can linger in the atmosphere for hundreds of years, methane disappears fast; half of its presence is gone after 12 years. This means its heat-trapping effects diminish over time — which is why, many scientists said, it’s important to measure its effects at shorter intervals. Over 100 years, for example, methane’s heat-trapping powers are reduced to being about 30 times more potent than carbon dioxide’s.

Now, Ms. Hochul wants to adopt a 100-year time frame to measure the effect of methane on the climate. That would be a significant shift from the current policy, which evaluates methane’s impact over 20 years. Doing that would dilute measurements of the planet-warming damage of methane, scientists argue.

But it would also keep costs down by putting less pressure on waste management facilities, farmers and natural gas companies to reduce their methane pollution, an expensive undertaking that other New Yorkers could end up subsidizing through higher bills and prices, Ms. Hochul’s office argues.

“This change will align New York with 48 other states and global standards in ensuring progress toward climate goals,” according to a statement from Ms. Hochul’s office.

Only New York and Maryland use the 20-year greenhouse gas metric, which makes it one of the most ambitious cornerstones of New York’s landmark 2019 climate law.

But Ms. Hochul, like other governors, must contend with the energy priorities of President Trump (oil, gas and coal) while navigating soaring gas prices from the wars in Ukraine and Iran. As a result, she appears prepared to tap the brakes on New York’s renewable energy transition until the federal government and the economy are more conducive to it.

“Reckless policies coming out of Washington, D.C., are driving prices up across the board, and struggling New Yorkers cannot be expected to shoulder higher costs,” said Ken Lovett, the governor’s communications adviser for energy and the environment.

Three years ago, Ms. Hochul proposed the same change but was met with an outcry from scientists and activists, so she reversed course. This time, the outcry remains. In March, more than 65 scientists — from institutions including the Massachusetts Institute of Technology and Columbia, Stanford and Beijing Universities — sent a letter to the governor imploring her to take methane emissions seriously.

“This is not the time for New York to back down,” they wrote, arguing that the climate law’s original 20-year time frame should become the new federal standard.

Drew Shindell, a professor of earth science at Duke University, said that the “global standard” mentioned by Ms. Hochul was arbitrarily set in the early 1990s, when the scientific understanding of methane was scant. United Nations officials proposed different time frames, including 20, 100 and 500 years, and in the end, they simply chose the one in the middle, he said.

But Ms. Hochul, a Democrat who is up for re-election this year and is embracing an affordability platform, seems more amenable to New York trading in its trailblazing climate leader status for what other states are doing. She has the support of some moderate members of her party, along with unions and business organizations.

Methane’s concentration in the atmosphere has doubled during the last 200 years. And because of its heat-trapping powers, humans can feel its effects fast. Cue the hottest 10 years on record.

Dr. Shindell compared the importance of mitigating carbon dioxide and methane to long-term and short-term budget planning at a town-hall meeting. The carbon faction wants to invest in schools “because they are really important for future generations,” he said, while the methane group wants a fire station, “because our houses might burn down tomorrow.”

Both time scales are important, he said.

Methane is the primary component of natural gas, a fossil fuel that is used in heating and cooking and in more than 40 percent of New York’s power plants. When natural gas burns, its emissions become carbon dioxide, and are counted as such.

But the production cycle of natural gas, from its extraction to its transportation, results in methane leaks. And as Ms. Hochul expands natural gas infrastructure in New York, the fear among activists and scientists is that more such leaks will occur.

Globally, about 40 percent of methane gas emissions come from natural sources such as the decay of organic matter from wetlands. Human activity, including agriculture, landfills and coal and natural gas production, is responsible for 60 percent. In New York, the waste industry — one landfill is nearly 300 feet tall — accounts for more than 50 percent of methane emissions, while agriculture accounts for up to 25 percent.

“If we had fully implemented the climate law as written, it would have placed an overwhelming financial burden on the state’s farmers and municipal taxpayers,” Mr. Lovett, the governor’s spokesman, said.

Ms. Hochul, laser-focused on pocketbook issues, is concerned that shifting away from natural gas too soon could be too expensive for New Yorkers, because so many continue to rely on it, and a limited supply would drive up costs, her office said. She has embraced an “all of the above” approach to energy, which includes gas and nuclear, in addition to renewables like solar and wind. Mikie Sherrill, the Democratic governor of New Jersey, recently announced a similar approach.

Because New York does not produce its own natural gas — it relies on other states, including Pennsylvania and West Virginia, for its supply — the 2019 climate law mandates that methane emissions from those states be included in New York’s greenhouse gas calculations. Ms. Hochul is proposing to stop that practice.

“That’s probably an even bigger issue than changing the time scale, because suddenly you’ll say, ‘Oh, this gas is really clean,’” Dr. Shindell said. “You’ve essentially wiped those emissions off your books.”

Mr. Lovett said that the changes are based on common sense and are in response to macroeconomic and federal headwinds such as supply chain issues during the coronavirus pandemic that delayed the construction of offshore wind projects, which were further delayed by Mr. Trump, who has attempted to stop them.

But many scientists argue that reducing methane emissions is the quickest fix to stop the planet from surpassing a temperature increase of 1.5 degrees Celsius (2.7 degrees Fahrenheit), in order to stave off the worst effects of climate change.

Reducing methane “will slow global warming faster than anything else,” said Robert W. Howarth, a professor of ecology and environmental biology at Cornell University and among the scientists who sent the letter of concern to Ms. Hochul.

He and Dr. Shindell warned that excess greenhouse gas emissions could create a dangerous “feedback” loop. Hotter temperatures wrought by fossil fuels could speed up the natural release of methane from wetlands, which would heat up the atmosphere even more, possibly triggering the disappearance of rainforests or the flooding of coastal cities.

“We’re talking about the future of civilization,” Dr. Howarth said. “I have a 30-year-old daughter. I don’t want to see the world go that way.”