What agricultural ’ecosystems on steroids’ are doing to the air

ANN ARBOR-In a study that identifies a new, "direct fingerprint" of human activity on Earth, scientists have found that agricultural crops play a big role in seasonal swings of carbon dioxide in the atmosphere. The new findings from Boston University, the University of Michigan and other institutions reveal a nuance in the carbon cycle that could help scientists understand and predict how Earth's vegetation will react as the globe warms. Agriculture amplifies carbon dioxide fluctuations that happen every year. Plants suck up CO2 in the spring and summer as they blossom. Then they release it in the fall and winter as they decompose. The study authors point out that these seasonal effects are distinct from the overall upward trend in CO2 levels that's the main culprit of climate change. While farming does contribute to that upward trend, the seasonal swings themselves don't.