Intersections were blocked across Washington during the Monday morning commute as activists sought to bring attention to climate policy issues. (Video: Jon Gerberg, Alice Li, Zoeann Murphy, Whitney Shefte/The Washington Post)

Climate change protesters shut down several intersections from Capitol Hill to downtown Washington during Monday’s morning rush, the latest of rallies around the world designed to force policymakers to respond to Earth’s rising temperatures.

D.C. police said they arrested 26 protesters across the city for blocking traffic, while U.S. Capitol Police arrested six others near the Capitol. Authorities noted 15 locations that were blocked at various times, forcing motorists to navigate blockades at some of the city’s busiest intersections as the workweek began.

Shut Down DC organizers urged “climate rebels” to flood the District’s streets to bring “the whole city to a gridlocked standstill,” according to the group’s website. Sites were chosen for traffic volume and also their proximity to the offices of “climate criminals,” organizers said, such as petroleum companies and lobbyists for the oil and gas industry.

The protest comes after youth-led demonstrations in more than 150 countries Friday and began ahead of a U.N. climate summit Monday, where policymakers were urged to aggressively take up climate change.

The scene as climate change activists shut down intersections across D.C.

Sept. 23, 2019 | Protesters block the intersection of K Street NW and 16th Street NW with a boat during a climate protest. (Matt McClain/The Washington Post)

Among other locations, protesters shut down parts of K Street, Dupont Circle and Connecticut Avenue, as well as Fourth Street and New York Avenue NW — forcing police to divert traffic at the Third Street Tunnel. Kaela Bamberger, a spokeswoman for the coalition behind the demonstration, said the protest was an escalation in tactics to draw attention to a warming planet.

“I think that we were very successful in holding the majority of the blockades people had planned,” she said. “We significantly impeded traffic in some of the main areas we were in for about three hours.”

Transportation officials had warned commuters to allow extra time and expect delays on their normal routes. Commuters also were advised to try other modes, including biking or taking Metro — or telework, transportation experts suggested.

Protesters shut down D.C. traffic before. It helped end the Vietnam War — and reshaped American activism.

Shut Down DC organizers said protesters had set up blockades at 22 District locations at various times. The 32 people arrested were released later in the day, organizers said.

Protesters chained themselves to a boat to block the intersection of 16th and K streets NW in downtown Washington, three blocks north of the White House grounds. D.C. police used power tools to cut the bonds, covering protesters with riot shields and fire blankets as sparks flew.

Waiting to be cut from the boat, a 22-year-old protester who identified himself only as George, as he risked arrest, shouted to a reporter outside the police cordon that he had chained himself to the boat about 7 a.m. and wasn’t sure when he would be cut free. He said the action was necessary to bring attention to the “climate crisis.”

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“I’m doing something that’s right, moral and just,” he said. “I’m doing this so I can look my kids in the eye one day.”

Jeffrey Johnson watched as a protester was being cut from the boat about 8:20 a.m. The protest hadn’t disrupted his commute — he’s an “early bird,” he said, starting work about 6 a.m. at a high-end downtown hotel.

“I don’t even know what the message is,” he said. “They need to get some signs up.”

But Johnson appeared broadly supportive of any critique of the current occupant of 1600 Pennsylvania Avenue.

“They’re protesting in the wrong place,” he said. “It should be two blocks up, where that knucklehead is at.”

Other commuters seemed to take the delays in stride.

Sitting in a car at 16th and L streets NW, Jackie Hilliard tried to remain philosophical about her delayed commute.

She had been “detoured,” she said, circling through downtown after a failed attempt to make a right on Rhode Island Avenue on the way to her job at a law firm. The net effect on her commute wouldn’t be that bad — an 11-minute delay — but she didn’t like being late.

She also didn’t want to get too distraught about it.

“I don’t care,” she said. “It is what it is. There’s no use getting upset over something I have no control over.”

At least one D.C. school opened later Monday because of the expected gridlock. Basis DC, a downtown charter middle and high school, informed families Friday that the school would open two hours late because of possible delays stemming from the protest.

By 7 a.m. Monday, health-care workers and other activists had gathered at Folger Park on Capitol Hill. They marched toward Independence and Washington avenues SW, intermittently blocking traffic. After being pushed back by police onto the sidewalk, they set up a tent outside the Department of Health and Human Services, where nurses and physicians conducted high blood pressure and glucose screenings for a few passersby. The tents were taken down by 9:30 a.m.

Southeast Washington resident Jerry Griffin was on his way to work downtown when he got caught in the Capitol Hill traffic snarl. After getting stuck at Independence and Washington avenues, followed by further delays elsewhere, he missed an 8:30 a.m. meeting and decided to drive back home.

While Griffin said he agreed with protesters that action is needed on climate change, he didn’t like the disruption to the District’s already-messy traffic. He said protesters were inconveniencing “the everyman” rather than those in positions of power.

“Do I approve of efforts to address climate change? Yes,” Griffin said. “Do I approve of a sit-in on a main thoroughfare during rush hour on Monday? People can be terminated because of this — not so much.”

Don Smith, a small-business owner in the District, also missed a meeting and texted clients to apologize. Even though it affected his work, he said he was glad the strike occurred.

“I’m inconvenienced, but I’m all for it,” he said. “Civil unrest is how this country was founded. As an American, I’m proud of them.”

One group of protesters said they were concerned about the disproportionate impact of environmental degradation on low-income and minority groups in the District.

“This is directed toward Mayor Bowser,” said Nee Nee Taylor, a Black Lives Matter core organizer, adding that issues faced by black communities in the city, from gentrification and poor living conditions to the lack of access to adequate health care in Ward 7, are exacerbated by the effects of climate change.

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As the crowd marched down Second Street NE toward Independence Avenue, their voices rang loudly in the empty streets. Some bleary-eyed townhouse residents peered out from their windows; several passing joggers cheered them on.

“The house is on fire!” the group chanted. “Put the fire out!”

A D.C. police spokeswoman said that no specific street closures were planned ahead of the protests but that rolling closures occurred where protesters showed up. Authorities didn’t respond Monday to questions about police procedures during the event.

Jude, a Lyft driver who declined to give his last name, said Monday that he didn’t know about the protests beforehand.

“I haven’t gotten an alert on my phone or anything,” he said at 8 a.m. as he drove south from Petworth. “But I’ve also been paying less attention to the news.”

He said he wasn’t worried about hitting roadblocks from demonstrations and would call passengers who might be waiting for him to inform them of delays. During a recent Women’s March demonstration, Jude said, he had five cancellations from passengers who waited 20 minutes or longer for a ride.

While he hates lost business, he said, he also saw opportunity. The Women’s March provided some of his best fares, the result of the upcharge Lyft instituted because of demand, he said.

He and other motorists who began the week with citywide protests could end the week in similar fashion.

Bamberger said activists decided Monday afternoon to return to District streets on Friday — the final day of coordinated climate change strikes worldwide. Specific protest sites haven’t been selected, but she called Monday’s demonstration “a huge success.”

“I might remind the disgruntled drivers that we are responding to the youth call for action on climate change,” she said. “Their futures are at stake.”

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Justin George, Perry Stein and Teddy Amenabar contributed to this report.