Despite the Trump administration’s environmental rollback, U.S. states are forging ahead with initiatives to combat climate change. Now, a coalition of states – from California to Colorado to North Carolina – are banding together to slash emissions and boost renewable energy.

Just hours after President Trump’s Rose Garden speech in June announcing plans to withdraw from the 2015 Paris climate agreement, the governors of three states — California, Washington, and New York — announced their remedy. They formed the U.S. Climate Alliance, and called on other states to join them in continuing to push ahead on fighting climate change. “It only took two nanoseconds,” Washington Governor Jay Inslee said in an interview with Yale Environment 360. “We heard the president wanted to run up the white flag of surrender. We wanted to send a strong message to the world: We’re not going to surrender.” The Trump administration was already in the midst of an aggressive effort to roll back nearly every climate change initiative of President Barack Obama, including the Clean Power Plan, designed to reduce emissions from the nation’s electricity sector 32 percent below 2005 levels by 2030. In Virginia, Governor Terry McAuliffe responded by ordering state officials to draft a rule to create a cap-and-trade program for carbon pollution from the state’s power sector. “Virginia cannot and will not stand idly by while the federal government abdicates its role,” he said.

Washington Governor Jay Inslee (center) flanked by then-Vermont Governor Peter Shumlin (left) and California Governor Jerry Brown at the Paris climate summit in 2015. COP Paris/Flickr

In the void created by Trump, states are stepping up to become bigger players in the climate battle, both individually and by joining together. The U.S. Climate Alliance, which has grown to include 14 states and Puerto Rico, plans to collaborate on a broad range of greenhouse gas-cutting initiatives, such as creating new mechanisms for financing clean-energy projects, updating electric grids to better accommodate wind and solar power, improving construction standards to reduce electricity use by buildings, and hastening the transition to electric vehicles. The alliance states also plan to boost communities’ resilience to the more damaging natural disasters that are a consequence of climate change, including mapping the risks posed by sea level rise, storm surge, and extreme precipitation. These efforts will add to momentum already underway in alliance states, such as California’s recent extension of its economy-wide cap-and-trade program and a proposal by nine Eastern states to continue their Regional Greenhouse Gas Initiative (RGGI) until 2030. RGGI states have cut electricity-related greenhouse gas emissions nearly in half since 2009, and under the proposal, they would further reduce greenhouse gas emissions from electricity 30 percent below 2020 levels by 2030. Without federal leadership, such state-level initiatives have become much more important, both for constraining carbon emissions and for discouraging other countries from following Trump’s lead. “The way I think they’re most significant is as a signal to the rest of the world,” says Robert Stavins, a Harvard University professor of environmental economics. “What would be disastrous is if China, India, and Brazil … decide to be less ambitious, rescind, or drop out.”

Without federal leadership, these state-level initiatives have become much more important in constraining carbon emissions.

Stavins was in Shanghai last month working with Chinese officials and academics to develop a cap-and-trade program, which China hopes to launch by year’s end. China is keenly aware of California’s leadership and the RGGI collaboration. According to Stavins, the alliance and individual state actions are helping the rest of the world see the U.S. as a place where action on climate change continues, despite the actions — or inaction — of the Trump administration.

“That strikes me as very important at this stage,” he says. Most of the states in the alliance — California, Colorado, Connecticut, Delaware, Hawaii, Minnesota, New York, North Carolina, Oregon, Rhode Island, Virginia, and Washington — have Democratic governors. The exceptions are Vermont and Massachusetts, whose governors are Republicans. The group had its major debut last month when world leaders gathered in New York City for the annual United Nations General Assembly session. Inslee and California Governor Jerry Brown joined New York Governor Andrew Cuomo, the alliance’s three co-chairs, for a series of meetings with leaders from around the world. The governors released a report showing that their states collectively reduced greenhouse gas emissions by 15 percent between 2005 and 2015 and are on track to continue cutting and achieve a 24 to 29 percent reduction below 2005 levels by 2025. The governors emphasized that they have the authority to set stringent policies to reduce emissions and that they’re succeeding without sacrificing economic growth.

Past and future greenhouse gas emissions reductions by states in the U.S. Climate Alliance compared to other states. U.S. Climate Alliance

“This is about controlling our own destiny,” Inslee said. “There is nothing Donald Trump can do to stop us in our states from advancing these policies.” For instance, Inslee used his executive powers to set a mandatory cap on carbon pollution from large emitters in his state, such as oil refineries and power plants. Inslee says his meetings with leaders from around the world persuaded him that they remain committed to the Paris treaty. “The world is moving forward,” Inslee said in the interview. “They’re not swallowing Donald Trump’s bunk.”

The governors released a report showing that their states collectively are on track to achieve a major reduction in emissions by 2025.

The alliance has yet to unveil details of their joint initiatives, but the governors plan to do so at the major international climate change conference next month in Bonn, according to Chris Davis, Inslee’s senior policy advisor for climate and energy. The alliance states understand they will have to show tangible progress if they want their calls for climate action to continue to resonate in the U.S. and abroad. “Over time, if the Climate Alliance could not robustly show that we collectively are climate leaders, then all the messaging in the world would accomplish nothing,” says Reed Schuler, another senior policy advisor to Inslee.

Schuler’s resume reflects how the center of climate action has shifted to the states. Under Obama, Schuler worked for Secretary of State John Kerry and served on the U.S. negotiating team for the Paris agreement. He helped negotiate a bilateral emissions-reduction agreement with China, as well as voluntary emissions limits and financial transparency aspects of the Paris accord. “It’s a critical time for Washington (state) and the country,” he said. “We are working hard with other states and other countries to keep the momentum up.” Trump’s decision to take the U.S. out of Paris lit a “bonfire under the governors,” says Schuler.

California, which has long been a leader in policies to address climate change, has committed to generating 50 percent of its electricity from renewable sources and cut greenhouse gas emissions 40 percent below 1990 levels by 2030. In July, the state legislature extended its cap-and-trade program for reducing greenhouse gases through 2030, a major victory for Governor Brown. The nation’s financial capital, New York state, has created the NY Green Bank, which has funded $1.4 billion in clean energy projects, such as small-scale wind turbine installations for New York businesses and residents and a solar array at a former landfill in the town of Esopus, New York. “It’s hard often to finance clean energy… and that’s where the green bank can step in,” says Governor Cuomo. “We’re going to go national with it, so our Green Bank can work with all states on clean energy projects.”

Governor Jerry Brown recently pushed through an extension of California’s cap-and-trade program. JUSTIN SULLIVAN/GETTY IMAGES

The states’ climate efforts vary significantly. Some states have enacted mandatory measures to cut pollution, including Washington, California, and the nine Eastern states involved in RGGI (Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New York, Rhode Island, and Vermont.) Oregon is phasing out coal in its electricity pool and by 2030, will no longer import electricity generated by coal. Other states, like Colorado — the only Rocky Mountain state in the alliance — have opted for a hybrid of mandatory and voluntary approaches. In 2014, Colorado was the first state to require the oil and gas industry to cut emissions of methane, a potent greenhouse gas. When announcing plans to join the alliance in July, Governor John Hickenlooper signed an executive order declaring that the state would reduce greenhouse gas emissions 26 percent below 2005 levels by 2025, but he primarily outlined voluntary efforts. His initiatives include helping electric utilities install more renewable energy projects. Colorado also is working with other Western states to plot out key corridors for building electric vehicle recharging stations. Harvard’s Stavins is skeptical of such voluntary efforts. “I would take that much less seriously,” he said. “Maybe it’s real, maybe it’s not.” But Vicki Arroyo, director of the Georgetown Climate Center at Georgetown University Law School, says even voluntary goals like Colorado’s make a difference. “Having the governor make those statements emboldens staff to really roll up their sleeves and get to work on it,” said Arroyo, who has been working with states on climate issues for years.

Even some states unlikely to join the alliance are making significant strides. Texas and Iowa are the nation’s first- and second-largest producers of wind energy and biodiesel. Last year, more than a third of the electricity generated in Iowa was from wind, up from 8 percent in 2008. Illinois, which has a Republican governor, passed a major energy bill in December, fixing its broken renewable power mandate and further subsidizing its nuclear plants to keep them in operation. It’s also significant that states like North Carolina, which previously have not been leaders in climate action, have joined the alliance, even if they haven’t yet fleshed out plans to cut emissions. Arroyo said: “I’m impressed by how serious they are about trying to reach those goals. It obviously takes time to put actual policies in place to tell you exactly how they’re going to get there.” However, that is not a full substitute for federal action because states cannot force other states to clean up. “There are a lot of other states taking significant action — I’m heartened by it,” Arroyo added. “But it’s not the same as having a president who believes in climate change and wants to be a leader. It’s only a coalition of the willing that’s taking these actions.”

Even with a committed White House, the U.S. would have had difficulty meeting its emissions target under the Paris accord.