Wednesday, July 14, 2010

The Outrageous Potential for Climate Change Agriculture

Imagine what could happen if close to 100% of Australia's agricultural soil was managed to sequester carbon and soil health levels rose across 450 million hectare. What tipping points would be reached? What emergent properties would emerge? No one can tell because it has never happened before. It seems like an outrageous suggestion, but some Australian farmers claim that they can slow, stall and even reverse the progress of Climate Change if given a chance. Members of the Carbon Coalition say they know how to turn Australia’s agricultural soils into a carbon sink large enough to play a major role in saving the world from the worst that climate chaos can inflict on us.
“Carbon Farming is already part of the Government’s policy on Climate Change. The decision we are looking for is a fast track to approval of soil carbon offsets under the National Carbon Offset Standard so we can get on with the job of saving the world,” says Michael Kiely of Carbon Farmers of Australia (the not-for-profit commercial arm of the Coalition.)
The world’s most highly awarded soil carbon specialist Professor Rattan Lal has announced that the world’s agricultural soils and vegetation can capture and hold enough CO2 from the atmosphere to stabilise Global Warming while the world makes the change to renewable energy. “It buys us time”, he says. Adviser to the US Government on soil carbon, Dr Lal believes plants and soils can be a bridge to the future because of their capacity to ‘draw down’ or absorb via the process of photosynthesis a massive amount of CO2, equivalent to 50ppm. In the race to contain global mean temperature below 2°C increase, we are told we must limit airborne carbon to below 450ppm – as the needle rockets through the 400ppm point.
Australian scientists agree. The Wentworth Group of Concerned Scientists announced that it is now too late to hope that setting targets for reductions in emissions will meet the 450ppm limit. It too advocates agricultural soils as an essential ingredient in the world’s survival plan.
Soils are the largest carbon sink mankind has the ability to influence – holding 1500 gigatonnes of CO2 vs 650Gt held in vegetation and 750Gt in the atmosphere. Photosynthesis is the only known process that can extract CO2 from the air and transform it into soil or plants. The world’s farmers control 5 billion hectares of soil which can start absorbing airborne carbon at a faster rate tomorrow if they are willing to change the way they farm. They need an incentive to grow a new commodity: carbon. They need a market.
The potential of soil carbon sequestration is uncharted by Science because no one alive has witnessed a landscape in which soil carbon levels were rising. Modern agriculture is carbon emitting by nature.
The upside potential is dramatic if there is widespread adoption of “Carbon Farming” practices. There will be more vegetation providing more ground cover and consequently less bare earth. This will have two outcomes: the landscape will capture and hold more of the rain that falls (which would otherwise rush off the bare earth carrying top soil into creeks and rivers and further baring the earth) and the landscape will be cooler as the darker surface provided by vegetation reflects less sunlight than bare earth.
Scientists call this the ‘albedo effect’ – lighter, harder surfaces reflect sunlight, heating the air above them. The ‘reverse albedo effect’ cools the air above. This cooler environment is likely to attract more rainfall than locations reflecting heat skywards as clouds are attracted to cooler air. There is the possibility of the “reverse albedo effect” creating “micro-climates” on individual farms. A micro-climate is a localised climate pattern that is caused by local conditions (can be man-made) that have an effect that is different to the general climate of the district. Vineyards are often sited to capture the effects of a micro-climate. Carbon farmers report increases in moisture in paddocks revegetated by trees on fencelines or scattered across the pasture.
Can the micro-climate effect be generalised to cover districts and whole regions as individual farms make the transition to carbon farming? The cumulative effect cannot be predicted because no one alive has experienced it. But outcomes could be dramatic as feedback loops kick in and new patterns emerge. Scientists do not speculate on the extreme upside, but do concede that conservatively it can be expected that Carbon Farming will provide farms with a ‘buffer’ against higher temperatures and lower rainfall.
Buffer or better than buffer, all is speculation. The simple fact remains that more vegetation and less bare soil means more soil carbon, less erosion, more effective rainfall, and cooler landscapes. Multiply these effects over 450 million hectares in Australia and the impact must be dramatic. Extended across 5 billion hectares around the globe, and we have Professor Lal’s Carbon Bridge to the Future.
Reference: Rattan Lal, The Potential for Soil Carbon Sequestration, International Food Policy Research Institute, Focus 16, Bri eF 5, May 2009 Rattan Lal ( is Director of the Ohio State University’s Carbon Management and Sequestration Center and Professor of Soil Science in the School of Environment and Natural Resources.

"Some men see things as they are and say, 'Why'? I dream of things that never were and say, 'Why not'?" (Senator Robert Kennedy)

No comments: