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The Next Big Thing for Climate Change?
Tapping the Soil’s Huge Potential as a Carbon Sink

June 2009

Steadily increasing levels of carbon dioxide in the atmosphere is one of the main reasons for global warming. What few people realize is that soil has a tremendous untapped potential to re-absorb and store carbon dioxide.

Indeed, the Intergovernmental Panel on Climate Change (IPCC) has said that soil carbon sequestration has the greatest potential for mitigating the effects of global warming. Unfortunately, many modern farming techniques cause soils to lose, instead of increase, the carbon they hold. For example, tilling the soil not only releases carbon dioxide, it also becomes more vulnerable to erosion. Furthermore, the soil is often not replenished with organic matter and thus becomes degraded over time.

What are some ways to increase the soil’s carbon sequestration capacity?

	Do not till the soil as this disturbs the soil’s structure, releases carbon into the air and makes soil vulnerable to erosion.
	Put organic matter, especially post-harvest residues, back into the soil. As earthworms eat this organic matter, carbon is reintegrated into the soil through their droppings.
	Diversify and rotate crops to make sure soils’ nutrients are not depleted.

Many of the techniques used in conservation agriculture (CA) rapidly restore even depleted soils to health in 2-5 years, thereby increasing their overall carbon sequestration capacity. However, only 6% of agricultural land is currently farmed using these techniques. Furthermore, farmers wishing to switch to CA, should be supported by insurance schemes and other incentives over the 2-5 year transition period.

Benefits for farmers...and the environment

What is good for the earth also makes economic sense for farmers. Benefits include reduced labour and machinery costs since the land does not need to be ploughed or heavily manipulated. People’s time can thus be used for other income earning activities and for further schooling. Furthermore, when compared to other practices, CA techniques actually give better yields during dry years.

There are longer-term benefits for the environment too as the soil becomes more fertile and is able to store more moisture. Erosion is reduced and water quality in surrounding areas improves. Less soil erosion also makes it easier to maintain dams and roads. In addition, biodiversity increases both above and in the soil.

What exactly is soil carbon sequestration? Organic matter in the soil such as roots, plants, decomposing organic matter, soil life, etc. contain an estimated 2500 gigatons of carbon worldwide. This carbon is stored ( or “sequestered”) safely in the soil instead of being released into the atmosphere. Sequestering carbon in the soil helps compensate for the increasing amounts of carbon dioxide being emitted into the atmosphere by burning fossil fuels, industrial processes, etc. Indeed it has been estimated that better soil management practice could help offset up to 90% of carbon emissions.

Ignored by Kyoto?

The Kyoto protocol’s Clean Development Mechanism (CDM) allows industrial countries to invest in emission reducing activities in developing countries instead of in their own countries, where reducing emissions is usually more expensive. Unfortunately, the CDM does not recognize soil carbon sequestration as a suitable activity for investment - despite its enormous potential and the fact that it is inexpensive and environmentally friendly.

Climate Change Activities in the EC-FAO “Linking Information and Decision Making to Improve Food Security” Programme

The climate change component of the programme will help countries estimate the impacts of current and future climate variability. This will help identify areas that are particularly vulnerable and which could benefit from conservation agriculture (CA). They will also help assess climate related risks and crop insurance schemes which would make the transition to CA less risky for farmers.

This article was prepared by Denise Melvin, Communications Officer, who would like to thank Rene Gommes and Theodor Friedrich from FAO for their expert advice.