Global warming and the attendant changing climate is caused mainly but not entirely by burning fossil fuels. This releases carbon dioxide, the principle greenhouse gas, to the atmosphere which traps heat by absorbing infrared radiation. Close to 25 per cent of the greenhouse gasses produced in the United States is due to agriculture.
Fuel, mostly oil derived gasoline and diesel fuel is used in tractors and other farm equipment to produce and haul food and fiber. Additional fossil fuels are used to produce fertilizer and a bevy of “cides” – insecticides, herbicides, etc. .
Nitrous Oxide and Methane are two more greenhouse gasses released to the atmosphere and have agricultural sources. Nitrous Oxide comes mainly from application of nitrogen fertilizers. Methane comes from the action of anerobic bacteria on plant matter. This can occur in wet soils such as occur in rice farming. Sewage lagoons where the wastes from confined animal operations also produce methane. Last but not least the stomachs of ruminants such as cows and sheep contain the same bacteria and produce the same methane emissions.
A final agricultural contribution to global warming comes from clearing timberland or more importantly rainforests for crop production. This is not particularly an issue here in the United States but is an issue on the global stage. The role the United States plays is as a consumer. Rainforests in the Amazon basin are being cleared to create pasture for cattle, aka hamburgers. In southeast Asia forests are cleared to create cropland for palm oil production, aka deep fried whatever.
Briefly that’s the impact of agriculture on climate change, how about the obverse, the impact of climate change on agriculture, especially here in the United States? The picture is not pretty.
Global warming is a cause, climate change is a result. Changing climate means a disruption of agricultural zones, not only based on temperature, but also rainfall. Crop production, whether for us to eat directly or for feed for livestock requires climatic stability. Any individual crop requires just the right combination of temperature, rainfall at the right time and proper soil conditions for that crop.
Climate change will disrupt all of the above. Consider our breadbasket, grain production in the upper midwest. Two factors impacted by global warming are a problem. First is the temperature. As the planet warms the growing zone will shift to the north. No problem you say, we will just grow our corn in Manitoba rather than Iowa. The problem is that the deep loam of Iowa doesn’t exist in Manitoba, and soil is a big deal.
Second is timely rainfall. Computer models of global warming predict that rainfall patterns will change in two ways. Rainfall will increase in the coastal areas, but decrease in the mid-continental regions. Not good. Also what rainfall that does occur will come in more intense storms. Even worse.
We have to eat, but we need to learn to produce our food in ways that lessen our carbon footprint, and at the same time decrease our dependence on crops that are too sensitive to climate. For starters, support your local small farmers. They generally have a smaller carbon footprint and can react more quickly to climate change.