Soil Organic Carbon is the Future Beneath Our Feet
26 January 2009
Grassland Carbon Working Group
To: Intergovernmental Panel on Climate Change
c/o Dr. R. K. Pachauri, Chairman
Civilizations rise and fall with the quality of their soils. Soil organic carbon is essential to soil health. We are given one more chance to learn the lesson of history. This time the stakes are higher ” soil degradation is endemic to every continent and we have created a new, atmospheric, carbon crisis.
The presence of soil organic carbon can be the difference between
life and death. Soils store twice as much carbon as global vegetation and the atmosphere combined. Loss of historic soil organic carbon due to degradative land use has been dramatic, resulting in poor soil fertility, environmental pollution, food insecurity and poverty. Soil organic carbon can and must be restored.
Excess carbon in the atmosphere is a pollutant; carbon in the soil is a valuable ecosystem commodity. Healthy plants are the agents of transformation, converting the former to the latter. We consider grasslands in order to illustrate the potential of soil carbon sequestration in all agricultural soils. Grasslands cover one third of the planet”™s 149 million km2 of land surface. A small change in soil carbon across this vast sink will have an enormous effect on atmospheric carbon. A 1 percent absolute increase in organic matter of grassland soils would sequester 102 Pg of carbon, removing 375 Pg of CO2 from the atmosphere.
Assuming 20% adoption of improved grassland management systems and that it would take 20 years to achieve the above increase, grasslands can sequester 1 Pg of carbon or 3.75 Pg of CO2 per year in the form of soil organic carbon. This would be the equivalent CO2 sequestration from 1000 medium”¢sized coal”¢fired power plants! The changes in grassland management required to achieve this change are already known (optimized stocking rates, improved fertility management, management intensive grazing, etc.), are relatively inexpensive to implement, and are ready to be deployed across the globe.
The same 1 percent increase in soil organic carbon would increase soil water holding capacity by 144,000 liters per hectare, an increase in soil water storage that would dwarf the capacity of the world”™s dams. As the driver of critical ecosystem functions, soil organic carbon is the gateway to other ecosystem services markets, which have the potential to drive human management activities towards global sustainability. The recently created USDA Office of Ecosystem Services and Markets is a signal ” the time for action is now.
Poor soils result in poor people, many of whom live in places where climate change is already having the most extreme effects. Crucially though, the most degraded soils have the greatest potential for remediation. Soil carbon sequestration will have the greatest effect in places where humanity is most desperate. Poverty, climate change, and food security are inseparable issues. Mechanisms are in place to feed the hungry, restore ecosystems, and build economic resilience; we are morally obliged to use them. It is time to mitigate misery and improve the health of our planet.
A lesson requires a teacher. This lesson requires strong leadership from the Intergovernmental Panel on Climate Change (IPCC). The Fourth Assessment Report and other IPCC documents recognized that sustainable management of grasslands could increase sink activity, but conclude there are barriers to implementation. It is time to find solutions. One person”™s barrier is another person”™s design constraint. Many barriers can be viewed as factors in a decision”¢making process. For example, public”¢private partnerships can develop and initiate solutions to perceived hurdles. Defensible soil carbon sequestration values are likely to be discovered during and after project activities.
We do not have the luxury of observation nor the time to fathom the global consequences.
An urgent and pragmatic assessment of the role of soil carbon sequestration is overdue. Grasslands and all forms of agricultural soil carbon sequestration must be recognized as an important source of mitigation at the next meeting of the international conference of parties in Copenhagen, and this important mitigation strategy accordingly linked to financing mechanisms. We call on the IPCC to hold immediate talks to develop strategies for the implementation of soil carbon sequestration at full potential. On the basis of these talks, we encourage the formation of a new working group to meet prior to the meeting in Copenhagen in December and its action plan be reported at that time. We extend our assistance to the IPCC in this important matter.
Convergent crises provide unprecedented opportunities. The multi-functional nature of soil organic carbon provides answers to problems, which paradoxically in isolation may appear insurmountable.
Like the crisis, the opportunity is unprecedented.
The solution is in our hands.
1 Calculation: 4.9 billion ha x 10,000 m2/ha x 0.3 m soil (depth) x 1.2 Mg soil/m3 soil (bulk density) x 5.8kg carbon/Mg soil (soil organic carbon in 1% greater soil organic matter). This calculation assumes equal change among all grassland ecosystems, which is unlikely to occur, but used for simplicity and generality.