Nearly two years ago, University of Minnesota faculty and staff travelled to Paris to watch world leaders broker the Paris Climate Agreement.

Last week, President Donald Trump chose to start a withdrawal from the agreement. This makes the U.S. one of three countries outside of the pact that aims to slow Earth’s temperature climb before it reaches two degrees Celsius higher than its preindustrial average. The decision sparked speculation on possible negative effects it may bring for America’s international and economical stature and the environment.

As part of the backlash to Trump’s decision, some states formed the United States Climate Alliance and pledged to uphold the Paris Agreement. More than 200 mayors across the country pledged the same.

Gov. Mark Dayton made the pledge along with the mayors of Minneapolis and St. Paul, Betsy Hodges and Chris Coleman.

“We are literally all in this together because we’re all on the same planet and what one country does to have an impact on the environment has an impact on the entire world,” Hodges said.

There is no legal penalty if a country misses its climate goals in the agreement, Hodges said, but there is a sense of accountability for each country.

“If we can get enough local actors to do good work, we can still head toward that agreement and head toward those goals,” she said.

The U.S. is the world’s second largest greenhouse gas emitter and without it, the agreement’s temperature goal could be unreachable, said Jessica Hellmann, director of the University’s Institute on the Environment.

“The world could experience catastrophic climate change because the U.S. is being selfish and isolationist,” she said.

Hellman, who attended the original talks, said if the countries still in the agreement are able to achieve the goals alone it could leave the U.S. behind economically.

Countries that pledge to be green could move away from fossil fuels to renewable energy, said Gabriel Chan, assistant professor in the Humphrey School of Public Affairs.

Ellen Anderson, executive director of the University’s Energy Transition Lab, said the movement to a “clean energy economy” is an economic opportunity for the countries dedicated to it.

“Countries are not necessarily feeling like it’s going to be a sacrifice to transition to clean energy,” said Anderson, who attended the original Paris climate talks. “Instead … the ones that really lead the way are going to be the most successful in this new economy.”

Chan, who focuses on science and environmental policy, said while the U.S. cannot technically leave the agreement until 2020, many of Trump’s domestic policies could be environmentally damaging.

With the administration’s proposed budget to defund environmental policies like the Clean Power Plan — an Obama–era policy to cut carbon emissions — Chan said the 2020 exit timeline might not matter.

“I think the U.S. pledge was already in serious jeopardy based on a set of actions that the Trump Administration took over the last 130 plus days,” he said.

Trump’s decision to move out of the Paris Agreement was a mistake, said Humphrey School professor Robert Kudrle.

He said along with Trump’s past actions, like leaving the Trans-Pacific Partnership trade deal, are signs of America’s decline in international leadership.

“I think [Trump’s actions] suggest a complete collapse of American leadership in the world,” he said.

Tracy Twine, associate professor in the Department of Soil, Water and Climate, has done research showing how climate change could hurt future corn yields. Twine said the administration’s move is upsetting.

“It’s disappointing because it’s really taking us backwards instead of moving us forward through time,” she said.