Unburnable Carbon: Ca. 90% of Fossil Fuel Reserves Need to Be Left Underground

Various sources noted last year that proven fossil fuel reserves are much greater than what may be burned if we want to keep a reasonable chance of keeping the increase of global average temperatures below 2°C. For example, the International Energy Agency noted in its 2012 World Energy Outlook that

“No more than one-third of proven reserves of fossil fuels can be consumed prior to 2050 if the world is to achieve the 2 °C goal, unless carbon capture and storage (CCS) technology is widely deployed.”

The “Carbon Tracker Initiative” even put the ratio at 1:5,

“Only 20% of the total reserves can be burned unabated, leaving up to 80% of assets technically unburnable.”

Bill McKibben brought this little problem to the attention of a broader audience with his article “Global Warming’s Terrifying New Math” in Rolling Stone magazine (see earlier post).

“Think of two degrees Celsius as the legal drinking limit – equivalent to the 0.08 blood-alcohol level below which you might get away with driving home. The 565 gigatons is how many drinks you could have and still stay below that limit – the six beers, say, you might consume in an evening. And the 2,795 gigatons? That’s the three 12-packs the fossil-fuel industry has on the table, already opened and ready to pour.”

I finally had an opportunity to look up why the sources give different ratios, 1:3 vs. 1:5. Turns out IEA and CTI have nearly the same figures in their analysis, the IEA is just more generous in its interpretation of the 2°C target.

Both sources have almost exactly the same figure for the amount of CO2 emissions that would be released from burning the proven fossil fuel reserves: ca. 2,800 Gt. But they differ in what amount of emissions they see as compatible with the 2°C target.

Funnily, they both rely on the same source regarding what amount of emissions is still allowable, a Nature article by Meinshausen et al. from 2009 that did a probabilistic analysis of emission budgets for the 2000–50 period. Such a probabilistic analysis is necessary since it is not known exactly how sensitively the climate system will react to the increasing GHG concentration in the atmosphere.

The CTI based its analysis on a stringent budget with only 886 Gt CO2 of emissions from 2000 to 2050, which according to Meinshausen et al. would give an 80% chance of achieving the 2°C target. As McKibben put it, “somewhat worse odds than playing Russian roulette with a six-shooter.”

The IEA based its analysis on a more generous budget of 1440 Gt, which according to Meinshausen et al. gives only a 50% chance of achieving 2°C. So, Russian roulette with a six-shooter and three bullets.

According to the IEA 420 Gt have already been emitted between 2000 and 2011, so only ca. 1000 Gt are left from the more generous budget and only 466 Gt from the more stringent budget. And the IEA estimates that 136 Gt will be emitted from non-energy sources  such as deforestation until 2050, leaving 870 Gt of the generous budget and 330 Gt of the stringent budget for energy uses. And 870/2800 is ca. 1/3. The CTI had based its analysis on an estimate of 320 Gt having already been emitted, giving 565/2800 = ca. 1/5.

Taking the more recent IEA figures and considering that I personally prefer less rather than more bullets gives 330/2800 = 11.8%. So unless carbon capture and storage saves the day, which does not seem too likely at the moment, ca. 90% of proven fossil fuel reserves would need to be left underground to achieve the 2°C target with a likelihood of 80%.

Interestingly, the issue seems to be making the rounds among financial institutions. A recent analysis by HSBC concluded that meeting the 2°C target could strip as much as 60% of the market value off fossil fuel companies. Based on the 1440 Gt budget.

Meanwhile, in the world of Realpolitik the German environment minister is right now very proud to put some restrictions on fracking, the stringency of which is being hotly debated, instead of demanding an outright ban. And the restrictions that are foreseen are based on concerns about drinking water safety etc. No consideration of maybe not opening further carbon pools as a general principle.

And a brilliant NGO action made European Investment Bank (EIB) representatives say this morning that they were not ready to drop coal and that gas would continue to be a central focus of lending.

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