Three terrifying numbers: that's we all need to understand what’s really at stake if we continue to burn fossils fuels.

These three numbers were originally published by the American environmentalist, Bill McKibben, in Rolling Stone in 2012. They were the same three shock numbers adopted by the Guardian’s 'Keep it in the Ground' campaign. They are also the three numbers that anyone can cite to explain how cutting-edge climate science underscores humanity’s need to switch to renewable energy .

Yesterday, I recounted them to a teenager, while my husband recounted them to a bunch of Oxford physicists - in both cases, they went down a treat. Here, then, are the three terrifying numbers.

  1. 2° Celsius. So far our fossil fuel habit has raised the average temperature of the planet by 0.8 degrees Celsius, and that has caused far more damage than most scientists expected. Scientists have figured out that 2 degrees Celsius would be far, far too much.
  2. 565 Gigatons. This is the amount of carbon dioxide humans can emit into the atmosphere by mid-century, and still have some ‘reasonable’ hope of staying below two the degree threshold mentioned above.
  3. 2,795 Gigatons.This is the minimum amount of carbon already contained in proven coal and oil and gas reserves, and is five times more than the safe amount to contain warming to Celsius.

Those who previously shunned or at least hushed the climate change facts because of vested interest in fossil fuel extraction or fossil fuel financing are now repeating these same terrifying numbers . We simply cannot burn all the oil and gas reserves that have been located. Now, even BP’s chief economist Spencer Dale (formerly at the Bank of England) is boldly echoing this. This week BP declared: “oil is not likely to be exhausted.”

Vast amounts of the Middle East’s oil, over 90% of US and Australian coal, almost all Canadian tar sands, and many other fossil fuel reserves in China and elsewhere must be left in the ground to prevent dangerous climate change.

Currently, the world is heading for a catastrophic C of warming. However, two immediate actions could steer us away from this climate catastrophe : a global climate deal at this year’s crucial UN summit in Paris; and burning no more than 565 gigatons of carbon dioxide. Adhering to these two actions could spare the Earth from warming beyond C, and untold planetary destruction.

Listen to the climate scientists, and now even the oil companies, and the economists : “Keep the oil in the soil, and the coal in the hole!”