Zimbabwean biologist Allan Savory proposed in a TED talk in March that getting more cows grazing on rangelands worldwide would soak up carbon dioxide. His suggestion has been a huge hit with online viewers and the media and it’s no wonder: in a nutshell, Savory says grazing provides a simple solution to climate change.
If only ecology was that easy.
Understanding how ecosystems are responding to climate change is an enormous intellectual challenge for a very young and inexact science – ecology. Ecology seeks to understand life on Earth. To say this remit is complicated is an understatement: we don’t even have answers to many basic questions such as why plants and animals are found where they are!
Such yawning knowledge gaps are fertile ground for promoting simplistic solutions to complicated problems. Savory’s talk on the potential of grazing to “solve” greenhouse gas pollution is a classic example of this.
In a nutshell, Savory argues that more intensive cattle ranching could simultaneously improve meat production, reverse desertification and turn vast areas of the Earth into massive carbon sinks that would soak up carbon dioxide. This would save the world from climate change. His argument links lots of ideas about ecology that makes for a very inspirational, and for the uninitiated very sensible, narrative.
At the very core of the talk is the idea that rotating grazing animals across rangelands can mimic the migrations of wild animals. This would improve the productivity of pastures and the health of soils. Savory’s message is very positive, a rare a win-win for the environment and the economy.
The catch is Savory’s TED talk is littered with rhetorical devices that paper over problems and exaggerate the effect of grazing. Worse there are just plain errors of fact. In 2008 rangeland scientists undertook a review to determine if “rotation grazing” increased plant and animal productivity compared to other styles of grazing and they could not find any difference.
These authors concluded that “continued advocacy for rotational grazing as a superior strategy of grazing on rangelands is founded on perception and anecdotal interpretations, rather than an objective assessment of the vast experimental evidence”.
Savory’s TED talk builds to the truly astonishing claim that the least biologically productive landscapes on Earth could store so much greenhouse gas pollution it would restore CO2levels to near pre-industrial levels! This is a dangerous fantasy.
Rangelands are used for cattle grazing for the simple reason there is insufficient water for other more intensive forms or agriculture; more often than not, the soils are infertile. They are some of the least carbon-rich ecosystems on Earth, and no amount of management can get around that fact.
Climate change demands new ways of managing ecosystems, so one positive aspect of the Savory TED talk is that it stimulates discussion and debate about options for improving animal productivity, soil carbon storage and biodiversity conservation.
The future of rangeland management no doubt will be different – for example increased use of fire to boost productivity may be pivotal in some settings. Conversely, it is possible to dramatically increase woody cover, and thereby carbon storage, by completely eliminating grass and fire – this has occurred on severely overgrazed rangelands.
Careful evaluation of what works and what doesn’t is required to discover the best way of sustaining rangelands, and of combating climate change. But this is a job for applied scientists.
No matter how motivational, rhetoric can only get you so far in the real world of nature.
Source: The Conversation, story by David Bowman