17
Nov
Synthetic Fertilizers Accelerate Climate Crisis; The Way We Feed People Conflicts with Stabilizing Climate
(Beyond Pesticides, November 17, 2020) Excessive use of nitrogen fertilizers in agriculture is driving global nitrous oxide (N2O) emissions higher than any projected scenario, putting the world at greater risk of a climate catastrophe. According to research published by an international team of scientists in the journal Nature, failure to adequately address nitrous oxide emissions has the potential to impede the ability for the world to keep warming below the 2°C target established under the Paris Climate Agreement, necessitating further cuts in other greenhouse gasses. The paper is a clarion call for greater attention to agriculture’s role in generating and mitigating the climate crisis.
“The dominant driver of the increase in atmospheric nitrous oxide comes from agriculture, and the growing demand for food and feed for animals will further increase global nitrous oxide emissions,” explains study lead author Hanqin Tian, PhD, director of the International Center for Climate and Global Change Research at Auburn University in Alabama. “There is a conflict between the way we are feeding people and stabilizing the climate.”
Nitrous oxide both damages ozone and warms the atmosphere, as it is roughly 300x better at capturing heat than carbon dioxide. To account for global nitrous oxide emissions, the research team synthesized emission data from a wide range of both anthropogenic and natural sources, including consideration of the biogeochemical processes that influence N2O release into the atmosphere. In sum, it covers 21 natural and human related sectors between the years 1980 and 2016.
Growth in nitrous oxide emissions over these last four decades has been considerable, with human-caused release, mostly from fertilizer use on cropland, increasing by 30%. Compared to pre-industrial levels, nitrous oxide levels increased 20% from all sources.
“Current emissions are tracking global temperature increases above 3 degrees Celsius — twice the temperature target of the Paris Agreement,” said study co-author Robert Jackson, PhD, a Stanford University professor and chair of the Global Carbon Project.
The highest level of anthropogenic nitrous oxide came from East Asia, with North America, Africa, and Europe following in turn. The study indicates, “High direct agricultural N2O emissions can be attributed to the large-scale application of synthetic nitrogen fertilizers in East Asia, Europe, South Asia and North America, which together consume over 80% of the world’s synthetic nitrogen fertilizers” The bulk of emissions in South America and Africa can be attributed to animal agriculture. Use of nitrogen fertilizers in aquaculture farming, primarily in East Asia, also contribute significant emissions. Industrial chemical production also makes up a sizable share of N2O release in both emerging economies in Africa and East Asia, as well as in more developed North American and Europe.
Only Europe and Russia (investigated separately by researchers) displayed a downward trend in nitrous oxide emissions. For Russia, the decrease was explained by the collapse of the Soviet Union and its agricultural co-op system in the early 1990s. Europe’s decrease can be owed to agricultural policies that successfully addressed excessive nitrogen use.
“Europe is the only region in the world that has successfully reduced nitrous oxide emissions over the past two decades,” said study coauthor Wilfried Winiwarter, PhD. “Industrial and agricultural policies to reduce greenhouse gases and air pollution and to optimize fertilizer use efficiencies have proven to be effective. Still, further efforts will be required, in Europe as well as globally.”
Synthetic fertilizers were developed in the early 1900s by chemists Fritz Haber and Carl Bosch. They developed a process to fix nitrogen from the air into ammonia, which could be applied as a plant fertilizer. While new synthetic fertilizers work quickly, they come with a range of downsides.
Any synthetic fertilizer that is applied to land, but not immediately taken up by plant roots, can make its way into rivers, lakes, streams, or back into the air as harmful nitrous oxide through the nitrogen cycle. Eutrophication, or oxygen depletion, is a major environmental problem resulting from synthetic fertilizer use. It occurs when excessive nutrients runoff into local waterways, causing algae blooms that consume oxygen in the water as they decay.
Runoff from synthetic sources of nitrogen can also cause nitrate and nitrite pollution that contaminates drinking water. Elevated nitrate concentrations in drinking water has been linked to methemoglobinemia (“blue baby syndrome”), birth defects, cancers, and thyroid problems, even at levels below EPA allowable limits.
Synthetic nitrogen applied to cropland can also be emitted from agricultural soil in the form of harmful nitrogen oxides (NOx, NO, NO2). In this form, nitrogen compounds not only damage the ozone layer and contribute to climate change, but also lead to the creation of smog and acid rain, increasing public health risks for asthma and other respiratory illnesses. A 2018 study determined that the state of California was woefully underestimating nitrogen oxide emissions from agricultural sources.
Changes in policy and regulation are critical to addressing the warming effects of nitrogen pollution, as evidence shows that farms can be either a source or a sink for greenhouse gasses. “This new analysis calls for a full-scale rethink in the ways we use and abuse nitrogen fertilizers globally and urges us to adopt more sustainable practices in the way we produce food, including the reduction of food waste,” said study coauthor Josep ‘Pep’ Canadell, PhD.
A 2018 study from the University of Virginia and The Organic Center found that “reactive” nitrogen, in the form readily available to be taken up by plants, is conserved in organic systems. Jessica Shade, PhD of The Organic Center, noted that the research was “significant and timely because its findings show that many common organic farming practices—like composting and the use of manure fertilization in place of synthetic fertilizers—can recycle reactive nitrogen that is already in the global system, rather than introducing new reactive nitrogen into the environment, and thus have a much smaller environmental impact.”
In addition to reducing the influx of dangerous nitrogen compounds into the atmosphere, organic systems sequester significant amounts of carbon from the atmosphere into on-farm soil carbon. A report from the Rodale Institute expounds on these benefits. It reads, “Simply put, recent data from farming systems and pasture trials around the globe show that we could sequester more than 100% of current annual CO2 emissions with a switch to widely available and inexpensive organic management practices, which we term ‘regenerative organic agriculture.’ These practices work to maximize carbon fixation while minimizing the loss of that carbon once returned to the soil, reversing the greenhouse effect.”
The convenience of chemical-intensive agriculture is balanced by costs to public health, the planet, and future generations that are rapidly becoming insurmountable. Help effect a shift to safer organic practices through your buying practices by purchasing organic whenever possible. For a run-down of safer fertilizers to use in an organic system, see Beyond Pesticides page on Organic Compatible Fertilizers. Take action today to make certain the next administration prioritizes organic practices at the United States Department of Agriculture.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: Science Daily, Greenbiz, Nature
