Climate change

Climate change

• Agriculture is not only affected by climate change, but also contributes significantly to it. Greenhouse gas emissions from all sectors related to agriculture are estimated to contribute up to 30% of all greenhouse gas emissions.
• According to Dr. Timothy J. LaSalle, CEO The Rodale Institute, “…agriculture is an undervalued and underestimated climate change tool that could be one of the most powerful strategies in the fight against global warming”.
• Unfortunately, conventional agricultural practices exacerbate rather than alleviate the effects of climate change. Organic agriculture on the other hand – with its emphasis on closed nutrient cycles, biodiversity, and effective soil management – appears to have the capacity to mitigate and even reverse the effects of climate change.

How does conventional agriculture contribute to global warming?

• Many scientists now believe that conventional agricultural practices are unsustainable.
• Unlike organic agriculture, which emphasises effective soil management and biodiversity, conventional agriculture (also referred to as intensive agriculture) relies on farming a single crop year after year.
• To overcome the imbalance imposed upon a conventional farm’s ecosystem, harmful agents, such as pesticides and synthetic nitrogen fertilizers are used.
• In 2005, global nitrogen fertilizer consumption (produced by fossil energy) was 90.86 million tonnes (IFA, 2007; http://www.fertilizer.org/). It takes roughly 90 million tonnes of fossil fuel (diesel equivalents) to produce this nitrogen fertilizer. This alone represents about 1% of global fossil energy consumption.

Is conventional agriculture an unsustainable long-term option?

• The consequence of conventional farming’s ecological imbalance is a decline in soil organic matter, soil structure, fertility, microbial and faunal biodiversity.
• Combine these impacts with the nutrient overload that ultimately ends up in waterways, deforestation, and overgrazing that occurs due to changes in land use, and it’s not difficult to see why many are now stating that conventional agriculture represents an unsustainable long-term option.

How is the loss of soil carbon contributing to climate change?

• But from a climate change perspective, it is the loss of carbon from intensively farmed soils that is of most concern. Carbon is lost to the soil through mineralization, erosion (water and wind driven) and overgrazing.
• Soil testing conducted throughout the United States over the past sixty years indicates that soils, which in the 1950s were composed of up to 20 percent carbon, now contain only 1- and 2-percent carbon.
• This phenomenon is widespread and is routinely observed in soils that have been conventionally farmed.
• It is now understood that intensive agriculture breaks down soil carbon into carbon dioxide. When released into the atmosphere, this carbon dioxide contributes significantly to global warming.

Can organic farming help address climate change?

• Organic agriculture exhibits the potential to reduce emissions of greenhouse gases.
• Apart from being self-sufficient in nitrogen, organic farming has been found to reduce atmospheric carbon dioxide by pulling it from the air and storing it within the soil as carbon.
• In a major study undertaken by the Rodale Institute, which analysed 30 years of soil carbon data, organic farming has been found capable of substantially mitigating the impacts of global warming.
• While organic farmers have long understood the importance of establishing and maintaining healthy soils, it now appears that their understanding and emphasis on soil is set to become even more important than could reasonably have been envisaged.

How does organic farming lock carbon in the soil?

• Researchers have found that agricultural carbon sequestration has the potential to substantially offset the impacts of global warming.
• The Rodale Institute’s Farming Systems Trial – the longest-running side-by-side comparison of organic and conventional farming systems in the United States, has found that organic farming methods such as the use of cover crops, composting and crop rotation dramatically alter the carbon storage capacity of arable lands, building soil “humic” substances (also referred to as organic matter) that remain as stable carbon compounds for centuries.
• The Rodale study found that organic systems showed an increase of almost 30 percent in soil carbon over 27 years, while conventional systems showed no significant increases in soil carbon over the same period.

Coping with the future

• The OECD and Stern Review project that if no action is taken, concentrations of greenhouse gases in the atmosphere could reach 2 degrees Celsius higher than their pre-industrial levels by as early as 2035.
• The consequences of a 2 degree Celsius temperature increase would be catastrophic for millions of people. Death, injury, dislocation due to flooding, fire, disease, impaired water quality, species extinction and reduced agricultural yields are considered likely under such conditions.
• Some of the poorest countries in the world, such as those located in tropical and sub-tropical climes, are likely to be the hardest hit.

Why is organic farming a better option?

• There are a number of factors indicating that organic agriculture is far more future proof than conventional agriculture.
• Organic farmers apply traditional skills and knowledge. Rather than placing blind reliance on petroleum intensive agricultural inputs, organic farmers apply practical knowledge, observation, personal experience and intuition. This enables them to get the best out of complex agro-ecosystems. They are adept at breeding locally adjusted seeds and livestock, producing on-farm fertilizers (compost, manure, and green manure) and at devising relatively inexpensive natural pesticides.
• By preserving soil fertility, in addition to maintaining – and even increasing – the quantity of organic matter in soil, organic farms are more capable of maintaining productivity during climatic extremes culminating in drought, irregular rainfall, floods, and elevated temperatures.
• Extensive research (Mader et al., 2002) (Lotter et al. 2003) has concluded that soils under organic management retain significantly more rainwater due to the “sponge-like” properties of trapped organic matter.

Resources

Altieri, M., Ponti, L. and Nicholls, C. 2005. Enhanced pest management through soil health: toward a belowground habitat management strategy. Biodynamics (Summer) 33 – 40.
Hepperly, P., Seidel, R., Pimentel, D., Hanson, J., and D. Douds, Jr. 2007. Organic farming enhances soil carbon and its benefits. Pages 129 – 153 in Soil Carbon Management: Economic, Environmental, and Societal Benefits, J. Kimble, C. Rice, D. Reed, S. Mooney, R. Follet, and R. Lal eds. CRC Press, Boca Raton, 268 p.
Khan, S., Mulvaney, R., Ellsworth, T., and C. Boast. 2007. The myth of nitrogen fertilization for soil carbon sequestration. J. Environ. Qual. 36:1821 – 1832.
Lal, R. 2004. Soil Carbon Sequestration Impacts on Global Climate Change and Food Security. Science 11 June 2004, Vol 304. no 5677, pp. 1623 – 1627.
LaSalle, T.; and Hepperley, P. 2008. Regenerative 21st Century Farming: A Solution to Global Warming. The Rodale Institute
Lotter, D., Seidel, R. and Liebhardt, W. 2003. The Performance of Organic and Conventional Cropping Systems in an Extreme Climate Year. American Journal of Alternative Agriculture. 18 (3): 146 – 154.
Mader, P., Fliebach, A., Dubois, D., Gunst, L., Fried, P., Niggli, U. 2002. Soil fertility and biodiversity in organic farming. Science 296, S.1694 – 1697
Pimentel, D., Hepperly P., Hanson, J., Douds, D., and R. Seidel. 2005. Environmental, Energetic, and Economic Comparisons of Organic and Conventional Farming Systems. Bioscience 55 (7):573 – 582.