"They feel they have the right to degrade us," said Theresa Sebastian, 15, from Cork, in the Republic of Ireland.
The consequences of rising temperatures for the planet and ecosystems are becoming increasingly apparent, yet less noticed is the vile backlash and abuse being thrown at the young green activistswho have successfully pushed the climate agenda into the mainstream.
NBC News has spoken to three young climate activists, all female, and their families who now find themselves in the center of a digital culture war and have to contend with hateful messages from skeptics, misogynists and far-right agitators.
Swedish teen Greta Thunberg, who founded the Fridays for Futureweekly school strikes and has become a figurehead of a climate change youth movement, has borne the brunt of the attacks, particularly on messaging platforms including Telegram and forums such as 8chan, security and technology experts say.
But she is far from alone.
"It's shocking to me that people go after anyone and everyone just to bring them down, and I don't understand what they get out of it," said Theresa Sebastian, 15, from Cork, in the Republic of Ireland. "They feel they have the right to degrade us."
Despite lacking an international profile as a climate change activist, Sebastian has endured abuse from accounts that appear to belong to teenage boys and grown men. Some messages criticize her campaigning, while others are hateful comments about her appearance.
Sebastian said she frequently receives racial slurs due to her Indian heritage — she is among the few climate strike organizers of color in Ireland.
"Racism is something that happens on a daily basis," she said.
Abuse directed at climate activists isn't just a reaction to stark warnings — some experts think it is also a reaction to the call for social upheaval to avoid ecological collapse. And it matters that the climate change movement has so many notable women.
Martin Hultman, a professor of technology, science and environmental studies at the Chalmers University of Technology in Sweden argues that men have benefited in an economy that is propelled by fossil fuels and related industries
"This kind of industrial bread winner ideal of nature being there for us to grab and use and can handle all types of risk is no longer possible to uphold if you take the science into account but these groups still want to keep it in that way," he said.
Women entering fields traditionally dominated by men — such as science or energy, which intersect with climate change — are often met with criticism and outright hate speech, Hultman said: "It is both a historical and present phenomenon where women who take a stand based on science are getting attacked."
The age of the activists is also triggering backlash, as it flies in the face of ideals that children should be taught and supervised, not the other way around, Hultman said. "It has become a generational issue."
"It is misogyny. This movement is led by girls and somehow this triggers people, or men, to spout this abuse at them," said Eleanor Platt, the mother of 11-year-old climate striker Lilly.
Lilly has become well-known in her hometown of Zeist in the Netherlands, and further afield, for launching a plastic litter pickup campaign. She's gained more than 11,000 followers on Twitter with her message of fighting climate change and protecting wildlife.
Lilly's account has been spammed by pornography and hateful messages criticizing the way she speaks and conspiracy theories that her activism is part of a money-making scheme, Platt said.
"The first lot used to really upset me. It was like a physical kick in the stomach because I love my daughter and I can't believe anyone would hate her like this," she said.
Several members of the family have been targeted. Platt herself has been accused of child abuse for forcing Lilly into activism. The family once had all their computers and phones linked to the account hacked.
Tweets directed at Lilly's grandfather — who ran a campaign encouraging seniors to vote in the European election on behalf of their grandchildren— suggested he should be killed with a dose of morphine, Platt said.
The sexism ingrained in these attacks is not unique to those directed at climate activists, experts say. A pervasive culture of mockery and abuse is present across online cultures, often manifested in attacks on women and girls.
Thunberg has become a "fun target" for the far-right online, according to Alex Kobray, director of physical security and counterterrorism for Flashpoint Intelligence, a global security firm and an NBC News partner.
"Anyone who doesn't fit into their narrow view of the world is fair game for them," Kobray said. "They view her as liberal, left-leaning, which to them is obviously inherently negative.
"It becomes a pile-on where once these people start on something, they all try to one-up and try to be the most hateful one in the room," she said.
Apart from satisfying their own "twisted humor" there isn't a specific audience the group appears to be attempting to sway with their manipulated images of Thunberg and ill-meaning humor.
Instead, this behavior helps to solidify the beliefs of climate skeptics and extreme right-wing critics and build camaraderie, Bernhard Forchtner, a media and communications professor at England's University of Leicester, said.
"It's an identity issue. It helps them reproduce their wider hostility or rejection of what they perceive to be a liberal, more cosmopolitan, mainstream view," he said. "Through Greta, they can reject what they see as liberal hysteria."
Many have come to Thunberg's defence. Australian satirists Mark Humpries and Evan Williams made a mockery at the attackers, launching a video advertisingan imagined "Greta Thunberg helpline for adults angry at a child" that went viral, being shared over 115,000 times on Twitter.
Still, in a Facebook post, Thunberg mused shutting down her account because of the extent of the hate speech on the platform. It's a route some activists have been forced to take.
Ariadne Papatheodorou, a Fridays for Future organizer in Athens, Greece, said she keeps most of her social media accounts private to avoid attacks.
"Through life, people will hate on you and you have to overcome that," she said. "Our movement is trying to save our world from destruction, so we can't focus on these people who are literally screaming out hate."
As an extra precaution, the Greek teens who organize weekly demonstrations avoid releasing any information about what schools they attend or where they live and don't always provide their full name to the media, she said.
Other teens told NBC News they periodically switch their accounts to private settings around the time of major protests, when the backlash is most extreme.
For Platt, it means spending hours every day cleaning up Lilly's social media accounts before allowing her access. She also answers other parents' questions about how to protect their children online.
Despite the effort feeling like another job, Platt said she wouldn't consider shutting it down.
"We couldn't be more proud of her," Platt said, listing off Lilly's busy schedule of media interviews and invitations to environmental events and conferences along with her weekly climate strikes. "People can tell us 'get that child back to school,' but really this education from what she is doing is just immense. I will always champion this."