Alan Savory proposes that controlled livestock grazing can protect grasslands and even reclaim degraded land that was once desert. He proceeds to make grand claims for applying his method at a global scale to address climate change.
Tony Watts of climate-change naysayer site Watts Up With That, and Willis Eschenbach, perhaps Watts’ most interesting contributor, are enthusiastic supporters. That isn’t an especially good sign.
Chris Clarke, writing at Pharyngula, is unconvinced to say the least, and has a more detailed anti-Savory diatribe at KCET.
Despite the temptation to pile on, and despite the risk of being seen as Very Serious, Planet3.0 will take the opportunity to stake out a moderate centrist position. The truth, this time, may lie somewhere in between.
Or not. *sigh* More later.
Although in the meantime you might consider tracing the provenance of Savory’s assertion of scientific backing for his sequestration claim.
The thing that strains credulity for me is that he asking the grasslands and deserts to draw down not just their initial “desertification” contribution to the excess atmospheric (and marine) carbon, but to actually absorb *on top of that* all that contributed by deforestation, fossil fuel emissions, cement, etc.
Here is a far less dramatic clip from Tom Lovejoy – and he seems to be working more off the current state of the standard scientific literature.
He is saying that about 40% of the current excess atmospheric carbon dioxide has come from biologic sources – deforestation, “desertification”, loss of soil carbon, etc. So, call it 40% of 115 ppm… And, that therefore there should be “at least” 50ppm possible to draw down from the atmosphere using three main strategies: reforestation, restoring grasslands and degraded grazing lands, and by modifying agricultural practices to build up soil carbon.
But even though he is saying “at least” 50ppm, he is suggesting that there is some upper bound to what these strategies can deliver that is not much above that. And, he suggests that the way that they could ambitiously achieve this would be if each strategy could draw down half a billion tons of carbon (?) per year for 50 years*.
But note, even if you generously grant Savory all the reductions from restoring grass/grazelands AND restoring agricultural soil carbon, you would only get a 2/3 * 50ppm = 33ppm reduction. Whereas Savory is suggesting that you could get at least 115ppm reduction. Colour me skeptical.
* Lovejoy doesn’t stipulate there whether he is talking about carbon or CO2, but it must be carbon. But I think he may be a little light on his estimate. He is probably saying, ok, about 750 GtC in the atmosphere, of which ~ 218 is from post-industrial increase. So, if I can pull 75 GtC out and into biomass as above, that I have decreased excess atmospheric carbon by about 33% to 40%… or about 50ppm. But my understanding is that there would be a rebound effect from the ocean carbon, which would start to move back into the atmosphere as well, so you actually have to draw down *more* from the atmosphere…
I’d like to see a paper by Lovejoy on this, but I don’t see any.
The guy isn’t speaking about CO2 sequestation, he is speaking about something else: land management. He unfortunately employs AGW terminology, maybe by accident, maybe to get government grants, maybe to be accepted to the nicest possible bourgoius dinner parties. BUT, his thesis has nothing to do with the evil CO2.
@ Robert of Ottawa: Huh? Did you not listen to the presentation?
Savory most definitely is speaking about drawing down atmospheric CO2 and sequestering it. Specfically, at 19:46 of his talk he says:
“And people who understand far more about carbon than I do, calculate that – for illustrative purposes – if we do what I am showing you here, we can take enough carbon out of the atmosphere and safely store it in the grasslands soils for thousands of years. And if we just do that on about half of the world’s grasslands that I have shown you, we can take us back to pre-industrial levels, while feeding people.”
Without at least some irrigation not much will come of this. With irrigation (say by desalinated sea water) one can do quite a bit.
However, the land committed is rather extensive; think most of the Sahara plus much of the Australian outback.
Glanced at the Lovejoy video, and one thing I notice is that he way overstates the role of plants in the Neogene CO2 drawdown, although I don’t know how that would affect his calculations. But rust, is he the scientific backing claimed by Savory?
I can’t imagine that Lovejoy would have been his source, but I don’t know. Nevertheless, their numbers don’t reconcile.
I am skimming a video of Savory doing a Q&A at Tufts. He seems to dodge some on the quantification of the carbon drawdown potential. It starts href=”http://www.youtube.com/watch?v=QxPNPXbVtfI#t=8m41s”>8:41 and going for about 5 minutes… He does eventually state again that he thinks this could draw down all of the post-industrial increase… but says that there is some dispute about that.
A soil biologist in the audience does some hand-waving about potential, but in the end says “we just don’t know”…
Tufts Q&A with Savory clip href=”http://www.youtube.com/watch?v=QxPNPXbVtfI#t=8m41s”>here.