The carbon dioxide absorbed by plants in the spring and summer as they convert solar energy into food is released back to the atmosphere in autumn and winter, in the northern hemisphere. Levels of the greenhouse gas fall, only to rise again, as summer crops in the south take up more CO2.
But the budget has gotten bigger. Over the last five decades, the magnitude of this rise and fall has grown nearly 50 percent in the Northern Hemisphere, as the amount of the greenhouse gas taken in and released has increased. Now, new research shows that humans and their crops have a lot to do with it, highlighting the profound impact people have on the Earth’s atmosphere.
In a study published Wednesday, Nov. 19, in Nature, scientists at Boston University, the University of New Hampshire, the University of Michigan, the University of Minnesota, the University of Wisconsin-Madison and McGill University show that a steep rise in the productivity of crops grown for food accounts for as much as 25 percent of the increase in this carbon dioxide (CO2) seasonality.
It’s not that crops are adding more CO2 to the atmosphere; rather, if crops are like a sponge for CO2, the sponge has simply gotten bigger and can hold and release more of the gas.
With global food productivity expected to double over the next 50 years, the researchers say the findings should be used to improve climate models and better understand the atmospheric CO2 buffering capacity of ecosystems, particularly as climate change may continue to perturb the greenhouse gas budget.
We need to remember that plants are a critical feature in the CO2 balance. Grow more of them!!
There is more here - [ where this info came from] - http://www.news.wisc.edu/23298
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