It also comes at a crucial time. With a presidential election in the United States this year, activists had hoped to raise the profile of climate change on the public agenda. And, just days after the election, world leaders are scheduled to gather in Glasgow for United Nations-led climate talks where presidents and prime ministers will face pressure to get more ambitious about reining in greenhouse gas emissions.

Fridays for Future called preliminary online protests last week a success. Activists posted from bedrooms, gardens and balconies overlooking empty streets. Families joined in. In one video posted on TikTok, a father tucked his daughter into bed, leaving her alone with a climate monster in her closet.

Some experts, however, said reaching world leaders and the general public would be more difficult now as the pandemic shuts down large parts of public life.

“What you’re going to end up doing is amplifying within an echo chamber, which is really different from what the movement wants,” said Dana Fisher, a professor of sociology at the University of Maryland whose research focuses on activism. Twitter hashtags, like #ClimateStrikeOnline and #DigitalClimateStrike, are far less visible than huge crowds in the streets, she said.

Still, Dr. Fisher noted, the young people leading climate protests are highly effective at using social media to build their movement.

That was echoed by Ms. O’Connor, the Irish activist, who said she had noticed new faces in online protests messages that she hadn’t seen at her group’s weekly gatherings in Cork. She said Fridays for Future organizers were adaptable and prepared to adjust strategy as necessary. “Intersecting crises will be a feature of our times,” Ms. O’Connor said. “We can’t let one stop action on the other.”

Ms. Palmer said she hoped public demonstrations would resume before the United Nations conference in November. If not, she said, respecting advice to stay off the streets for the sake of older people, for whom coronavirus exposure is especially dangerous, would still come first.

“And that’s also how we want the older generation to feel toward young people,” Ms. Palmer said. “We want them to make the effort to save the planet for us in that same way.”

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