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Amount of meat we eat will barely affect future climate change

Look at the numbers, forget the spin

Opinion For the last few days, the mainstream British media have been assuring us that rich westerners must seriously cut down the amount of meat we eat - and the rest of the world must keep to its current meat-light diet - in order to stave off planetary apocalypse. But what are the facts?

The reports are all based on this paper in the journal Energy and Environmental Science. It was actually published a couple of weeks ago, but nobody noticed: the flurry of interest, as is normal in "science news", stems from a press release issued this week. The press release offers a clear message:

New research from the University of Exeter shows that if today’s meat-eating habits continue, the predicted rise in the global population could spell ecological disaster.

This has generally been simplified along the lines of "Eat less meat to save planet, researchers warn". And to be fair, that does indeed seem to be in line with the personal agenda of the researchers who wrote the paper.

"By focusing on making agriculture more efficient and encouraging people to reduce the amount of meat they eat, we could keep global temperatures within the two degrees threshold,” says geography PhD student Tom Powell, lead author. Mr Powell has a master's in Ecology.

So what has Powell got to back this up?

Well, he and his co-author used modelling to examine the impact on atmospheric CO2 levels of four possible scenarios for human agriculture. These assumed that agriculture will become more efficient (in line with methods already used in Western nations) or continue largely inefficiently (as seen in many other places). Then, the world's population in general - as it is beginning to do - could start to eat more meat as Westerners already do, or it could slightly reduce meat consumption overall (this would almost certainly involve Westerners eating a lot less meat).

If agriculture doesn't increase in efficiency there's big trouble ahead no matter what, with population set to climb by a billion and more in the coming decades. There's no reason to think this will happen, however - agriculture has been improving its game for a long time, one reason why the doom of mass starvation so long foretold has failed to materialise despite population increases to date.

So let's look at the two more realistic scenarios where efficiency increases. Powell's research assumes in these cases that any cultivated land which can be spared from food production can then be used instead to suck CO2 out of the air using methods such as biochar etc. He finds:

If there is also a return to lower meat diets, biomass energy with carbon storage (BECS) as CO2 and biochar could remove up to 5.5 PgC yr-1 in 2050 and lower atmospheric CO2 in 2050 by 26 ppm. With the current trend to higher meat diets there is only room for limited expansion of bio-energy crops after 2035 and instead BECS must be based largely on biomass residues, removing up to 3.7 PgC yr-1 in 2050 and lowering atmospheric CO2 in 2050 by 14 ppm.

In other words the difference between the high-meat future and the low-meat one is just 12 parts per million. The OECD thinks that atmospheric CO2 is likely to climb from present levels of 394 ppm to 685ppm on that timescale, a rise of nearly 300 - 25 times the saving Mr Powell is offering. There is a notional aspiration to hold the level to 450 ppm, but this is widely acknowledged to be a lost cause and much modelling in recent times has sought to predict the consequences of a doubling in CO2 to say 780 ppm.

Against this sort of picture, a paltry few-percent-at-best saving to be gained by somehow compelling most people in the world to remain on their present not-very-nutritious diets and (even more difficult) getting westerners to join them in this ... well, it hardly seems worth bothering with. If atmospheric CO2 is what bothers you, every scrap of political capital, every scintilla of goodwill and economic wherewithal, must be focused on just one thing - that is, getting people to burn less coal. Footling stuff like campaigning against meat is a waste of political resources which are probably insufficient to the task in the first place.

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