The Guardian warned the “next three months are crucial for the future of the planet.”

Of course, we’ve heard this argument many times in the past.

Here are nine previous instances activists and politicians warned time was running out to save the world.

As the United Nations prepares to issue a dire warning about future global warming and hold summits on the matter, activists are already warning that time is running out to stop catastrophic climate change.

For example, The Guardian newspaper warned on Friday the “next three months are crucial for the future of the planet” and that the U.N.’s “[t]wo forthcoming major climate talks offer governments an opportunity to respond to this year’s extreme weather with decisive action.” (RELATED: New York City Filled With Road Signs Flashing Climate Warnings, Including ‘Climate Denial Kills’)

It’s only the latest warning from climate activists about the supposed importance of upcoming U.N. meetings stemming future temperature rise. Environmental economist Richard Tol quipped that “[i]f we miss this final chance, there will be another final chance in a little while.”

It’s our final chance to save the planet. Just like last time. If we miss this final chance, there will be another final chance in a little while. https://t.co/M5Dcov619v — Richard Tol (@RichardTol) October 5, 2018

Tol’s remarks inspired The Daily Caller News Foundation to reprise its list of warnings from politicians and activists that time was running out to avoid catastrophic global warming. Enjoy.

1. Was 2015 The ‘Last Effective Opportunity’ To Stop Catastrophe?

World leaders meeting at the Vatican last week issued a statement saying that 2015 was the “last effective opportunity to negotiate arrangements that keep human-induced warming below 2-degrees [Celsius].”

Pope Francis wants to weigh in on global warming, and is expected to issue an encyclical saying basically the same thing. The head of the Catholic Church will likely reiterate that 2015 is the last chance to stop massive warming. However, the U.N. said basically the same thing about 2014’s climate summit.

2. French Official Warned We Only Had ‘500 Days’ To Stop ‘Climate Chaos’

When French politician Laurent Fabius met with former Secretary of State John Kerry on May 13, 2014 to talk about world issues, he said, “We have 500 days to avoid climate chaos.”

Ironically, at the time of Fabius’ comments, the U.N. had scheduled a climate summit to meet in Paris in December 2015 — some 565 days after his remarks. Looks like the U.N. is 65 days too late to save the world.

3. Obama Was Apparently Our Last Chance

When former President Barack Obama promised to “slow the rise of the oceans” some environmentalists may have taken him quite literally. (RELATED: 25 YEARS OF PREDICTING THE GLOBAL WARMING ‘TIPPING POINT’)

The United Nations Foundation President Tim Wirth told Climatewire in 2012 that Obama’s second term was “the last window of opportunity” to impose policies to restrict fossil fuel use. Wirth said it’s “the last chance we have to get anything approaching 2 degrees Centigrade,” adding that if “we don’t do it now, we are committing the world to a drastically different place.”

4. Hours, Yes Hours, To Stop Global Warming

In 2009, world leaders met in Copenhagen, Denmark, to potentially hash out another climate treaty. That same year, the head of Canada’s Green Party wrote that there was only “hours” left to stop global warming.

“We have hours to act to avert a slow-motion tsunami that could destroy civilization as we know it,” Elizabeth May, leader of the Greens in Canada, wrote in 2009. “Earth has a long time. Humanity does not. We need to act urgently. We no longer have decades; we have hours. We mark that in Earth Hour on Saturday.”

5. 50 Days Left To Save The Earth?

Former U.K. Prime Minister Gordon Brown warned in 2006 there was only “50 days to save the world from global warming,” the BBC reported. There was “no plan B,” according to Brown.

Brown has been booted out of office since then. What would he say about global warming today?

6. Prince Charles Warned We Only Had 96 Months To Save The Planet

U.K. Prince Charles said in July 2009 that there would be “irretrievable climate and ecosystem collapse, and all that goes with it.” Charles gave humanity 96 months to save the world. That deadline passed in July 2017.

7. In 2007, We Only Had Four Years To Save The World

Rajendra Pachauri, the former head of the Intergovernmental Panel on Climate Change, said in 2007 that if “there’s no action before 2012, that’s too late.”

“What we do in the next two to three years will determine our future. This is the defining moment,” he said.

Pachauri was forced to resign in 2015 amid accusations he sexually harassed multiple female coworkers.

8. Only A Decade To Go Green?

Environmentalist writer George Monbiot wrote in the U.K.’s Guardian in 2002 that within “as little as 10 years, the world will be faced with a choice: arable farming either continues to feed the world’s animals or it continues to feed the world’s people. It cannot do both.”

9. Tipping Point 2000?

The U.N. was already claiming in the late 1980s the world had only a decade to solve global warming or face the consequences.

The San Jose Mercury News reported on June 30, 1989 that a “senior environmental official at the United Nations, Noel Brown, says entire nations could be wiped off the face of the earth by rising sea levels if global warming is not reversed by the year 2000.”

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