WASHINGTON — On a sweltering day, tens of thousands of demonstrators joined the People’s Climate March in Washington on Saturday, one of about 375 such marches held across the country to oppose the environmental policies of the Trump administration.
The huge crowd made its way down Pennsylvania Avenue, where protesters surrounded the White House grounds. There the demonstrators let out a roar to symbolically drown out the voices of climate change deniers in the government.
“Resistance is here to stay; welcome to your 100th day,” the protesters chanted.
It was the latest installment of the regular protests that punctuate the Trump era. President Trump’s first 100 days in office have included rollbacks of environmental protections and Obama administration orders involving mining, oil drilling, and greenhouse gas emissions at coal-fired power plants, among other issues.
Organizers of the People’s Climate March, which originated with a massive demonstration in New York in September 2014, picked a symbolically appropriate day for their 2017 event. Temperatures hit 91 degrees in Washington, matching the record for the day set in 1974 and amplifying the movement’s message about global warming.
Organizers told the National Park Service that they expected 50,000 to 100,000 people to attend.
In downtown Tampa, Fla., a demonstration stretched for several blocks. Marchers there said they were concerned about the threat rising seas pose to the city.
In Los Angeles, protesters gathered near the port, where the oil refiner Tesoro wants to expand its operation.
On the eve of the marches, the Environmental Protection Agency announced that it was beginning an overhaul of its website, which included taking down a longstanding site devoted to the science of climate change, which the agency said was ‘‘under review.’’
‘‘Hang on EPA, the midterms are coming. 2018,’’ read one sign carried by Kathy Sommer of Stony Brook, N.Y, as the protest assembled on the National Mall.
‘‘There is no Planet B,’’ read another sign by Eva Gunther of the District of Columbia.
Many of the signs at Saturday’s climate march were ominous, warning of climate catastrophe, dying oceans, crop destruction, and planet degradation.
But the mood of the marchers was anything but somber. Thousands gathered all morning in the lush green Mall in front of the Capitol carrying signs, singing, and chanting as they prepared to march to the White House. It was a racially diverse crowd, with marchers of all ages.
The marchers came prepared with water bottles, hats, and sunscreen. They also arrived with sunny dispositions. ‘‘It’s beautiful,’’ said Allison Dale, a geologist from Conshohocken, Pa. ‘‘It’s so well organized and everyone is really friendly and in a really good mood.’’
Impromptu concerts broke out as protesters waited for the march to begin. A brass band played as a stiltwalker danced past. Tambourine shakers and drummers added to the joy. Their reason for marching was serious, but they were determined to have a good time, too.
The climate event differed from last week’s March for Science in its focus and also its participants — only 1 out of 8 contingents at Saturday’s protest had scientific researchers. The rest included labor activists, indigenous people already facing severe effects from climate change, and children and young people who will live with the effects of climate change longest as the Earth continues to warm.
But there was plenty of overlap between the marches. Ken Hunter, 78, traveled from Charlestown, W.Va., for Saturday morning’s march. He also came to Washington for the March for Science last weekend and the Tax March on April 15 — and attended a Women’s March in Florida.
The motivation for the current climate march is clear: The young Trump administration already has moved to roll back former president Barack Obama’s signature climate initiative, the Clean Power Plan, and Trump and his team have taken many other actions to weaken environmental protections of air and water, and to enable fossil fuel drilling on public lands and waters.
The administration is grappling with a major climate policy decision: whether to remain in the Paris climate agreement. Several of Trump’s Cabinet picks are advising against following through on his campaign pledge to ‘‘cancel’’ the accord.