Another human element to global warming was revealed in two studies showing that higher crop yields increase carbon dioxide to the atmosphere. One study surfaced from the University of Maryland and the other from Boston University. While using different methods, both studies came to the same conclusion.
The studies focused primarily on rice, corn, wheat and soybean agriculture, as those products make up for 64 percent of all calories consumed in the world. It was found that every winter they emit the highest amount of carbon dioxide, especially in the frigid regions of the North.
Advances in agriculture allow crops to grow in less-than-ideal environments thanks to irrigation and the use of fertilizers. More crops can also grow in smaller spaces. All these factors taken together increase the number plants that grow and later produce a harvest. With the increasing global population, food demands continue to create pressure and spur the development of these high-yield advancements.
However, this age of agricultural productivity also has unintended consequences. Like all plants, crops ingest carbon dioxide during photosynthesis, or plant respiration. They use it to grow all summer and produce their food products. After their life cycle is complete, they die in winter and emit carbon dioxide as they decompose.
Known as a “breathing pattern” this process causes the increase of atmospheric carbon dioxide that likely arises from higher crop yields. Since scientists started tracking atmospheric composition 50 years ago, carbon dioxide steadily increased each year as agriculture advanced. The latest results show an increase in concentration between 30 and 60 percent since 1960.
The study’s lead, Mark Friedl of Boston University, noted that crop fields monitored for the study have not increased in size but they all increased production. Josh Gray, assistant professor at Boston University indicated that the amount of carbon dioxide released into the atmosphere was “considerable” and could change ecosystems. “Just about everything is linked to the atmosphere,” he explained.
Atmospheric science professor at University of Maryland, Ning Zeng, was impressed when the two studies independently came to the same conclusion. “Essentially, we depend on, to a large degree a model and climatic CO2 surveillance,” he explained. “Their study dissected in more detail the particular agrarian change down to the particular crop species. Underlying our investigation, we did a similar thing. It’s extremely empowering.”
The teams conclude that farming in the northern hemisphere contributes to 20 to 50 percent of carbon dioxide increases each year. They have not predicted specific implications as the effects of farming on the atmosphere have not been thoroughly studied before. Similar links have also been made to replanting faster growing trees after a lumbar harvest and redistributing native plant species.
While a link between the increase of carbon dioxide and higher crop yields is confirmed, further research from this data will examine effects in more details. Researchers continue to examine how land use changes and climate affect carbon cycles. For now, the only firm conclusion is that farming must be considered a human activity that affects climate change.
By Jocelyn Mackie
Photo by Brian Smithson – Flickr License