Are modern farms a big player in the carbon dioxide cycles that influence global warming? Two teams of researchers have uncovered evidence that suggests that this may be the case.

Research teams in California and Massachusetts found that the seasonal breathing pattern of terrestrial plants — shown in a dramatic NASA video of carbon dioxide distribution in the Northern Hemisphere — is heavily influenced by farming, which could be responsible for 20 to 50 percent of the long-term increases in the amount of CO2 absorbed during growing season and given off during the dormant season, according to the Christian Science Monitor.

It’s not because more farms are being planted, but rather because farms are seeing massive jumps in productivity due to technology, including better fertilizers, improved crop breeds, and more efficient irrigation. Scientists estimate that these factors have been twice as influential as the fertilizing effect on rising CO2 levels, as well as longer growing seasons.

What the broader implications of these results are remains to be seen, but the research reveals a level of human influence on the Earth’s carbon cycles that weren’t recognized before.

A research team in La Jolla, Calif., with the Scripps Institution of Oceanography reported last year on CO2 exchanges between the atmosphere and plants.

The large fluctuations in CO2 levels appears to be as a result of an increase in the size of forests and the trees within, as well as young, fast-growing species in areas destroyed by logging or fire, and finally to vegetation that has migrated north as the planet has warmed.

The studies could show that current generation models are close to being correct, as a significant portion of the plants that are affecting the atmosphere are coming from farming.

However, scientists acknowledged that the CO2 seasonal fluctuations from plants is tiny compared to the overall increase in carbon dioxide in the atmosphere in the past five decades.

Researchers use sophisticated tools to account for carbon, as well as crop statistics, to examine common farm products such as maize, rice, soy beans, and wheat. They noted that improved production accounted for a nearly 25-percent increase in season CO2 swings. Corn was the biggest influencer on that number, accounting for two-thirds of the increase. U.S. corn yields are now five times higher than the pre-World War II era. Globally, corn production has tripled. It is mostly produced in the U.S. Midwest and in China.