Viral Posts Distort Greta Thunberg Tweet Warning About Climate Change


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A Harvard University professor warned in 2018 that steps were needed over the next five years to reduce carbon pollution to preserve Arctic ice. Climate activist Greta Thunberg then shared a tweet that misquoted the professor. But recent social media posts have distorted Thunberg’s tweet to falsely claim she predicted human extinction by 2023.

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James G. Anderson, a professor of atmospheric chemistry at Harvard University, delivered a lecture in 2018 at the University of Chicago about the effects of climate change on the planet. Among the dangers Anderson highlighted was the depletion of floating ice in the Arctic

Anderson warned that an urgent effort is needed to stop producing carbon pollution and remove it from the atmosphere within five years to preserve any permanent ice in the Arctic, Forbes reported.

The following month, the now-defunct news website Grit Post cited the Forbes piece in an article that misinterpreted Anderson’s lecture and had the inaccurate headline, “Top Climate Scientist: Humans Will Go Extinct if We Don’t Fix Climate Change by 2023.” 

Greta Thunberg speaks about climate change at the United Nations in 2019. Photo by Spencer Platt via Getty Images.

Greta Thunberg, a young climate activist from Sweden who rose to prominence when she organized the 2018 School Strike for Climate movement, quoted from the Grit Post article in a since-deleted June 2018 tweet.

Thunberg’s tweet said: “A top climate scientist is warning that climate change will wipe out humanity unless we stop using fossil fuels over the next five years.” 

With the fifth anniversary of her tweet recently passed, social media posts have falsely claimed that Thunberg predicted human extinction would occur by 2023.

“Greta Thunberg’s apocalyptic tweet proves false exactly 5 years later to the day,” read a Facebook post from the Young America’s Foundation.

Donald J. Trump, Jr. shared a post to Instagram which read: “Greta Thunberg’s beginning of the end of the world prediction was for today, June 21st.” His post received more than 99,000 likes.

But Thunberg’s 2018 tweet did not say that humanity would be wiped out in five years, but rather that continued use of fossil fuels over the next five years would lead to human extinction at some point. The tweet was, moreover, quoting from an article and not her own words.

Thunberg has been the subject of viral false claims before, as we’ve written. These claims often target her credibility as a climate activist, such as the false claim that she is on the payroll of billionaire George Soros.

In this case, though, Thunberg has been both the subject and spreader of misinformation. According to Anderson — the “top climate specialist” in question — the quote from Grit Post that Thunberg shared was a “complete fabrication” of his words.

“The ‘.. wiping out of humanity by 2022’ is a total distortion of what I said, implied, or meant at the University of Chicago colloquium in 2018,” Anderson told us in an email on June 23. “I would never make such a statement.”

Rather, Anderson’s statement was that at the rate of floating ice loss in 2018, there would be no more floating ice within five years. In his email to us, Anderson said, “the only reason there is any floating ice on the Arctic Ocean remaining today is that the last 15 to 20% of that floating ice volume is protected by the existence of the Greenland glacial mass.”

“Ironically, of course, for the past 10,000 years it was the Arctic Ice Cap on the Arctic Ocean that protected Greenland through the summer melt season,” Anderson said. “Now there is virtually no protection of the Greenland glacial system via the floating ice on the Arctic Ocean. This is a profound concern for the increasing rate of sea level rise. Another key point of context is that the volume of floating ice on the Arctic Ocean was essentially stable over the past 10,000 years, yet in just the past 40 years approximately 80% of that floating ice volume has been lost.”

Editor’s note: is one of several organizations working with Facebook to debunk misinformation shared on social media. Our previous stories can be found here. Facebook has no control over our editorial content.


Alden, Scott. “Top Climate Scientist: Humans Will Go Extinct if We Don’t Fix Climate Change by 2023.” Grit Post. 19 Feb 2018. 

Anderson, James G.. Email to 23 Jun 2023. 

Hoft, Jim. “SURPRISE! The Official Escort for 16-Year-Old Global Warming ‘Expert’ Greta Thunberg Is a Leftist Hack Funded by George Soros Org.” The Gateway Pundit. 22 Sep 2019.

McMahon, Jeff. “We Have Five Years To Save Ourselves From Climate Change, Harvard Scientist Says.” Forbes. 15 Jan 2018.

Thunberg, Greta (@GretaThunberg). “A top climate scientist is warning climate change will wipe out humanity unless we stop using fossil fuels over the next five years.” Twitter. 21 Jun 2018. 

United Nations. “Greta Thunberg tells world leaders ‘you are failing us’, as nations announce fresh climate action.” 24 Sep 2019.

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