Earlier this week, for instance, the Trump administration began rolling back Environmental Protection Agency rules restricting methane emissions. Methane is a powerful greenhouse gas: A single molecule of methane can trap roughly 25 times as much heat as a molecule of carbon dioxide, even though the methane leaves the atmosphere faster.
As part of the Climate Alliance announcement, the 16 states resolved to reduce their emission of methane and other short-lived super-pollutants by 40 percent by 2030. The governments of Mexico and Canada joined them in making this pledge.
“It’s pretty remarkable to have the governments of Mexico and Canada issuing a statement with 17 U.S. governors, as opposed to the federal government,” says Dan Lashof, the director of the World Resources Institute in the United States. “That is not normal—and in this particular instance, it’s a very positive thing.”
Also in opposition to Trump, the states promised to implement a suite of utility policies that will reduce the costs of new solar-panel installation. After Trump imposed an import tariff on solar panels earlier this year, U.S. companies froze or canceled $2.5 billion in new large-scale solar projects.
“There’s a lot of tertiary or supply-chain ways we think states can continue to drive down the [solar] costs,” Inslee told me.
The states also pledged to adopt the same strict energy-efficiency guidelines for household appliances, which it says will save consumers $4 billion by 2025. Trump’s Energy Department has sometimes neglected or tried to close similar federal programs, such as Energy Star.
But some state programs seem to have little to do with the president. For instance, the governors pledged to better track how carbon dioxide is stored in ecosystems and soil. Forests in the United States absorb more carbon than they emit, offsetting 11 percent of the country’s greenhouse-gas emissions. But neither states nor the federal government have ever focused on better managing that bounty, Lashof told me.
Land use “is an area where we just aren’t doing a good enough job of tracking what’s going on,” he said.
David Ige, the Democratic governor of Hawaii, told me that the new land-use strategy was the most important policy to his state. He said that he looked forward to his state’s land managers sharing their expertise and learning from those in other states.
“In Hawaii, our people are connected to the land. And better managing nature and our working lands is just fundamentally a part of our culture,” he said. “We want to know what other states are doing, and we want to understand how to do it better.”
“A lot of these things—if you’re not a climate-policy wonk, then they seem really unsexy,” says Julie Cerqueira, the director of the U.S. Climate Alliance. “But if you have a handful of states that adopt the same energy-efficiency standards, you’re pushing the entire market in that direction, even if 30 other states don’t have these rules.”