Monbiot: How much fossil fuel can we burn?

Governments need to cap the amount of coal, gas and oil we extract if they are serious about fighting global warming

Two papers on carbon emissions published in the scientific journal Nature last week were ground-breaking: they show us how much carbon dioxide we can produce if we’re to have a reasonable chance of preventing two degrees of global warming. It’s a completely different approach from the UN’s and national governments’. They set targets for reductions by a certain date but have nothing to say about the total amount of carbon we can release.

One of the papers, by Myles Allen and others, suggests that we can burn, at most, another 400-500 billion tonnes of carbon at any time between now and the extinction of humanity if we want to avoid 2C of warming.

The other, by Malte Meinshausen and others, suggests that producing 1,000 billion tonnes of CO2 between 2000-2050 would give us a 25% chance of exceeding two degrees. That’s a lot less than Allen’s estimate, as one tonne of carbon produces 3.667 tonnes of CO2 when it’s burnt: 1,000 billion tonnes of CO2 arises from 273 billion tonnes of carbon.

But let’s err on the side of valour and use Allen’s figures. Moreover, let’s disregard all other greenhouse gases (which, he suggests, should reduce the total CO2 budget to under 400 billion tonnes). How does his maximum allowance of carbon compare with known reserves of fossil fuel?

Guardian