Climate change and agriculture Doreen Stabinsky Greenpeace International June 2009
Cool Farming: major climate impacts of agriculture January 2008 Report Based on IPCC numbers and additional research
Sources of Agricultural l GHG Total: 8.5-16.5 billion tonnes of CO 2 equivalent 17-32% of all humaninduced GHG (direct and indirect contributions)
Sources of agricultural GHG emissions
Key mitigation strategies to reduce GHG emissions in agriculture Making agriculture part of the Making agriculture part of the climate solution
Mitigation Potential Estimates of mitigation potential of agriculture vary. (Smith 2007) Technical potential = 6 Gt CO 2 -eq Economic potential, at a carbon price of $100 US/ton = 43GtCO 4.3 2 -eq Soil carbon sequestration accounts for 89% of the potential. t Nitrous oxide and methane emissions can also be considerably reduced.
Global trends in synthetic fertilizer use
Global trend in overuse and inefficiency in the use of nitrogen fertilisers Globally, an average 50% of the nitrogen used in farming is lost to the environment: -as N 2O to the air as a potent GHG (296-320x the warming potential of CO 2 ) - as nitrate, polluting wells, stream and rivers, and oceans Very inefficient use of nitrogen fertilisers: - Farmers overuse: cheap, lack of good guidelines, soil analysis - Lack of precision: wrong amount, wrong time
Nitrous oxide: fertilisers Nitrogen applied as fertilizer Volatilization lost 25-33% Chowdary et al 2004 Leaching lost 20-30%
Emissions from fertilisers CO 2 + N 2 O N 2 O
emissions from 1 kg synthetic urea 4.1 kg CO 2 -eq 3.8 kg CO 2 -eq
Carbon sequestration in soils Carbon sequestration in cultivated soils: -store carbon - recycle nutrients - improve soil fertility - improve water conservation
Soil-related mitigation strategies Fertilizers and N 2 O emission reduction Avoid overuse (precision fertilization) Reduce reliance on synthetic fertilizers by adopting cropping systems such as use of rotations with legume crops More closely integrate animal and crop production to take advantage of fertility provided by animal manures
Soil-related mitigation strategies Increase soil carbon sequestration Avoid leaving land bare, using mulch and cover crops. Reduce tillage, coupled with organic production methods (no herbicide id use) Reduce grazing intensity Shift land use from annual crops to perennial crops, pasture and agroforestry Restore organic soils and degraded lands to increase carbon sinks
A key lesson regarding agricultural soils: Stop treating soil like dirt. Healthy soil with increased organic matter (i.e., carbon): Has better soil structure and water-holding capacity and therefore is drought- and flood-resistant Has better nutrient absorption capacity, so N 2 O emissions are reduced Removes carbon dioxide from the atmosphere
Please eat less meat meat is a very carbon intensive commodity Dr. Rajendra Pachauri, IPCC chair
Cattle are responsible for about 80% of all deforestation in the legal Amazon Plan of action for the prevention and control of deforestation in the legal Amazon. Brazilian government Casa Civil, 2004.
Reducing Annex I meat foodprint Reducing BAU 2050 emissions from cattle and manure to 2000 levels would reduce GHG emissions by 1594 Mt CO 2 -eq a year by 2050. How? Bi Bring consumption of meat and ddairy in Annex I countries down to the global per capita average of 25 kg and 53 kg respectively. Reduction in the associated forest conversion will bring additional GHG reductions!
Conclusions Soil is a critical resource. Increasing carbon sequestration is only one reason (but a very good one) to be good to our soils. Meat consumption in industrialized countries must move downward to global average consumption levels.