U.S. cities and towns should ensure that every resident lives within 10 minutes' walk of a park as part of their climate action strategies, an advocacy group for open spaces said.
According to The Trust for Public Land, a San Francisco-based non-profit, 100 million U.S. urbanites lack such access.
"Parks are one of the few ways we can invest right now in the human impacts of climate change," said Diane Regas, CEO of the trust, which works to protect and conserve public spaces.
The United States could boost the number of people living close to parks by 15-20 million over the next 10-20 years on current funding trends, she told the Thomson Reuters Foundation.
As cities endeavor to meet their commitments under the Paris Agreement to curb climate change, parks are a popular investment, experts said at the Global Climate Action Summit in California, an international gathering highlighting local government efforts to tackle climate change.
Regas contrasted parks with other climate-friendly measures, like promoting electric cars and adopting clean energy, which reduce planet-warming emissions but provide no respite from the impacts of climate change such as rising heat.
"People are hungry for more spaces to recreate in," said Josh Alpert of C40 Cities, an urban alliance tackling climate change.
Parks tend to be more politically popular than other climate measures because they bring tangible benefits for residents' quality of life, he added.
"That's a home run because our mayors are struggling to communicate and implement climate action," he said.
Advocates believe the best parks are not only pleasant places to spend an afternoon but also serve infrastructure needs, from soaking up heavy rainfall to reducing city heat and acting as a coastal buffer during storms.
Hawaii's Honolulu is discussing with government engineers how to rebuild its seawall as open space that could withstand storm surges, rather than constructing high concrete walls.
Lower Manhattan may eventually be encircled by a berm called The Big U that provides a waterfront promenade and doubles as protection against hurricanes like Superstorm Sandy, which flooded New York's financial district in 2012.
"We can't do mono-functional infrastructure in cities anymore," Alpert said.
In June, California voters approved a $4.1-billion bond issue to fund conservation and open space.
Meanwhile, in 2016, rural Grand County, Colorado, secured support for a 10-year, 0.3 percent sales tax hike to fund trails and wildlife habitat protection on the same ballot where a majority voted for U.S. President Donald Trump.
"There is broad support across partisan lines for parks and open space," Regas said.
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In support of another nature-based climate change solution, 45 cities around the world committed Wednesday to using their municipal power to preserve and restore forests inside and outside their boundaries.
The Cities4Forests initiative, announced at the San Francisco summit, will help cities measure their tree canopy and plan where to locate trees.
It will also assist with drafting procurement guidelines for wood and paper products, and advise on carbon credits that offset emissions by protecting tropical forests far away.
Honolulu, one of 16 U.S. cities to sign up, is surrounded by rainforest, but has seen its trees decrease in recent years.
The Hawaiian capital committed to planting 100,000 new trees by 2025, and increasing tree cover to 35 percent of its land area by 2035.
Norway's climate minister, Ola Elvestuen, said forests contribute to the rainfall needed for food production, and combat climate change by storing massive amounts of carbon.
"Halting and reversing tropical deforestation is critical to retain these benefits, and only with cities and their citizens onboard can we succeed," he said.