I’ve recently finished reading George Monbiot’s Heat: How to Stop the Planet from Burning. It’s an interesting piece from a widely-syndicated journalist, and it left me both alarmed and unsatisfied. I’ve held back on writing about it until I had a chance to read up a bit more on the underlying science and discuss the topic with more knowledgeable types, but I think I’m ready to comment.
For the anonymous visitors to this page, let me preface this by saying that I have zero expertise in this topic; I have no climate science training, and this represents my first stab at investigating the area. I am interested in this subject largely in terms of its implications for transportation/land use policy: to decide suitable long-term policies, I need a reasonable idea of the likely long-term acceptable level of carbon emissions.
At its heart, I think the book must be understood in terms of its intended audience: the environmental movement. Monbiot’s book is a call-to-reason for the movement, a plea to avoid the “aesthetic fallacy” of pleasing but impractical solutions: think high-speed rail, biofuels, voluntary conservation, or exclusive reliance on solar/wind power. He also urges some revisiting of traditionally demonised technologies, such as nuclear power and carbon sequestration. On these terms, the book is a valuable shaking-up of traditional environmental viewpoints. After establishing a target for emissions cuts, he devotes most of his book to investigations of the feasibility of current technologies for achieving these targets. His discussion of air travel and “love miles” is particularly prescient. The context for his book is exclusively the United Kingdom, and the solutions he proposed cannot necessarily be directly transferred elsewhere.
In this posting, I want to focus more on Monbiot’s target. He based the book on a simple argument, originally published in a 2006 column he wrote for The Guardian, which you can read yourself.

1. A global temperature rise higher than 2°C would likely mean runaway positive feedbacks and unstoppable large amounts of warming.
2. If we want mean global temperature rises no higher than 2°C (with 70% probability), we need to aim for atmospheric concentrations of CO₂ to stabilise at ~380ppm (or CO₂-equivalent gases at 450ppm).
3. Stabilisation requires emissions (sources) to equal absorptions (sinks). Land-based ecosystems’ ability to absorb carbon drops at higher temperatures. This will reduce the total land+ocean sink from past levels (4 GtC/year) to 2.7 GtC/year. Note: 1 GtC means “Giga-tonne of carbon”.
4. Therefore, we need to cut annual global emissions by 60% to 2.7 GtC/year.
5. Furthermore, this cut needs to be completed by 2030.
6. Finally, if emissions are to be fairly distributed to individual nations on a per capita basis, then the UK needs to cut its emissions by 90%. Monbiot argues in favour of a carbon rationing system with an equal emission entitlement for each individual.

I’ve dug around a little to see how valid these assumptions are. Continue reading Monbiot & Climate Mitigation →