ROME--In a rare report related to climate change, the United Nations Food and Agriculture Organization (FAO) March 28 said that improved farming techniques could bury around 10 percent of the world's human-caused atmospheric carbon emissions over the next 25 years. The report, titled Soil Carbon Sequestration for Improved Land Management, said that the modernized techniques would also lead to improved soil and crop quality while slowing erosion and enhancing biodiversity.
The techniques are based on the accumulation of plant matter in the soil, which would pull carbon dioxide out of the air and convert it into new plant matter--a process called carbon sequestration.
"Rarely has there been a step that can be taken so easily that would have so many positive results with little drawback," Jacques Antoine, an FAO soil scientist who helped author the report, told BNA April 3.
Though the technique would have an effect only on carbon dioxide emissions, it would reduce them by more than twice the rate of reduction required over a similar length of time by the 1997 Kyoto Protocol, the mechanism for implementing the U.N. Framework Convention on Climate Change.
The protocol aims to reduce the emissions of six key greenhouse gases from developed countries by an average of 5.2 percent between 2008-2012, based on 1990 levels (INER Reference File 1, 21:3901 and 3951).
Effects in Developing World
Based on FAO figures, a 10 percent reduction in worldwide greenhouse gas emissions over 25 years starting in 2002 is roughly the equivalent of a 13.1 percent reduction in 1990 carbon dioxide emissions from industrialized countries. This is because the reductions would be based on a year with higher emissions levels and reductions are not limited only to developed economies.
Carbon dioxide is the most prominent of the gases limited under the Kyoto agreement, accounting for around 80 percent of total emissions referred to in the protocol, although other less-prominent gases are thought to cause far more damage by volume than carbon causes.
"In many ways it is not fair to compare this technique with the Kyoto Protocol, since this results only in a reduction in CO2," Antoine said. "But the reductions [from sequestration] are very significant."
The Kyoto Protocol's Clean Development Mechanism (CDM) allows developed countries to offset some of their emissions by funding climate-friendly projects in the developing world. According to the FAO report, projects aimed at improving farming methods in the developing world that are paid for by richer countries will be eligible for credits under the CDM.
An Important Development
One of the characteristics of carbon sequestration, according to experts, is that carbon dioxide absorbed by plants is later released when the plant dies and decomposes. It has long been seen as an important way for carbon emissions to be reduced for periods of time during which other methods can be developed to more permanently remove the emissions from the atmosphere. But the 10 percent figure over 25 years is far more ambitious than any previous estimates regarding the effectiveness of the method.
"Reducing carbon emissions by a tenth by the use of agricultural techniques is a far higher figure than any previous models have shown," one scientist working on climate change issues for the Italian government told BNA April 4. "If the [report's] results are backed up by further tests, it could be a very important development."
Techniques Available
According to the report, increasing the amount of organic matter in soil and reducing tillage to protect the organic matter once it is there--a technique known as conservation agriculture--can dramatically reduce the amount of soil-based carbon released into the atmosphere while also improving soil structure and protecting valuable topsoil from being drained or blown away. "The best way to bury carbon productively is agroforestry--combining trees and crops, together or in sequence," the report said.
Agroforestry can replace slash-and-burn agriculture, which accounts for much of the deforestation in the developing world, and the trees provide income.
Agroforestry could be suitable for up to 300 million hectares of degraded farmland in the tropics--enough to account for a large part of the carbon reductions the report says are possible.
"Buildup of soil organic matter can be encouraged through better crops and agronomic practices, including minimizing tillage, leaving crop residues in place, mulching, and using manure and even sewage sludge as fertilizer," the report said.
In its conclusion, the report calls for cooperation between the United Nations and other organizations and the bodies responsible for implementing U.N. conventions on climate change, desertification, and biodiversity to help implement these techniques worldwide.
Text of Soil Carbon Sequestration for Improved Land Management, which was produced by FAO in cooperation with the International Fund for Agricultural Development, is available at http://ftp.fao.org/agl/agll.docs/wsrr96e.pdf.:
