Since the decision, cities and states have stepped up to try to fill the gap

(Adds comment, updates throughout)

By Sebastien Malo

NEW YORK, May 30 (Thomson Reuters Foundation) - A year after President Donald Trump vowed to pull the United States out of a global pact to fight climate change, experts lamented the move but welcomed efforts by cities and states to fill the gap.

Trump's announcement of June 1 last year to ditch the deal agreed upon by nearly 200 countries came over opposition by U.S. businesses and the powerful nation's allies.

Trump said leaving the deal signed by his predecessor Barack Obama would boost domestic energy production and speed economic growth.

But it raised fears among supporters of the agreement that other nations would follow suit.

"That was a dark day," said Vicki Arroyo, executive director of Georgetown University's Climate Center. "A domino effect could have happened."

Instead two more countries - Syria and Nicaragua - signed on after Trump's announcement.

But Trump's decision means some U.S.-based businesses now have less incentive to move toward clean energy, said Christiana Figueres, the U.N. climate chief when the 2015 Paris Agreement was signed.

That will put them at a competitive disadvantage as global competitors shift away from polluting fossil fuels faster, she said.

Promoting the use of coal over renewable energy sources "is like prohibiting people from using cell phones and asking them to go back to landlines", she told the Thomson Reuters Foundation in an interview on Thursday.

"That's a pretty sad position to be advocating."

But growing public concerns about the health risks of air pollution from coal and other fossil fuels are also driving broader interest in curbing climate change, she said.

For a long time, people tended to think climate change was happening far away, to others, or would only affect future generations, she said.

Now more understand that "this is happening right now and we can do something about it", she added.

The 2015 Paris deal committed nations to reducing greenhouse gas emissions and keeping the global hike in temperatures "well below" 2 degrees Celsius (3.6F) above pre-industrial times.

In December, countries will meet in Poland to set rules for the accord's implementation, including how to monitor emissions.

Experts say momentum is compromised in the absence of the United States, the world's second-largest greenhouse gas emitter after China.

"We need the U.S. back at the table," said Selwin Hart, the ambassador of Barbados, at a panel in Washington organized by the World Resources Institute (WRI).

Andrew Norton, director of the London-based International Institute for Environment and Development, said Trump's decision to stop further U.S. payments into a major fund to help poorer countries adopt clean energy and adapt to climate threats also threatened climate action around the world.

"Without the money and support crucial to delivering the Paris Agreement, the global effort to address climate change may be fatally undermined," he warned in a statement.

Nevertheless, a deluge of state- and city-level policies adopted over the last 12 months in the United States, from emissions reductions targets to a push for electric cars, is a silver lining, said experts on the WRI panel.

The planned U.S. departure from the Paris pact "gave us a galvanizing point", said Angela Navarro, Virginia's deputy secretary of commerce and trade.

Former Virginia Gov. Terry McAuliffe last year ordered a push for a cap-and-trade system to cut emissions from power plants, citing the federal government's retreat from the climate debate.

California Gov. Jerry Brown is planning a global climate summit in September.

States, cities and businesses representing more than half the U.S. economy and population have adopted targets to reduce greenhouse gas emissions, according to WRI.

However, piecemeal regulation cannot match the policy reach of the federal government, Arroyo said.

"I don't think that anyone would argue that we're in a better position," she said. "The task definitely got harder." (Reporting by Sebastien Malo @sebastienmalo in New York and Laurie Goering in London, Editing by Ellen Wulfhorst and Megan Rowling. Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's rights, trafficking, property rights, climate change and resilience. Visit http://news.trust.org)

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