Agriculture, including land-use changes for farming, is responsible for an estimated 17 to 32 percent of all human-induced greenhouse gas (GHG) emissions, the report notes. And massive overuse of fertilizers is the biggest contributor to these emissions within the industry. More than half of all fertilizer applied to fields ends up in the atmosphere or local waterways, according to Greenpeace, and each year, the equivalent of 2.1 billion tons of carbon dioxide in the form of nitrous oxide, a GHG some 300 times more potent, is emitted because of fertilizer use.
Methane from livestock is the second largest direct emitter in agriculture, Greenpeace says. And the clearing of forests and other natural cover to create land for grazing and crop production destroys important “carbon sinks” that absorb carbon from the atmosphere.
The report calls for more precise application of fertilizer, in appropriate amounts, to reduce excessive GHG emissions and pollution of water resources. Other recommendations include cutting the global demand for meat to decrease both the amount of methane-producing animals raised and the area of land cleared for them; growing cover crops to help soils be better carbon sinks; and keeping rice paddies dry in the off-season to reduce methane emissions.
In a 2005 article “The Irony of Climate,” Worldwatch Institute agriculture expert Brian Halweil observes that even as farmers contribute to global warming, they are also struggling with its effects, including subtle changes in temperature and rainfall patterns that can have devastating impacts on agricultural communities. But there are effective, eco-friendly coping strategies that can make communities more self-sufficient, Halweil writes. For example, farms that grow diverse crop varieties tend to be less vulnerable to unpredictable weather changes and less reliant on fertilizer and fossil fuel inputs than monoculture farms. And farms with strategically planted trees can protect crops and create larger carbon sinks.
The Greenpeace report notes that government policies that promote monocultures and discourage local self-sufficiency put farmers’ livelihoods at greater risk and contribute to climate change. “Governments must stop subsidizing environmentally destructive practices in agriculture,” van Aken said.