Update: Fixed article to reflect increases in fluctuations, not CO2 levels. Thanks to the commenters for pointing out I’m an idiot. I blame Friday 🙂
Earlier this week, NASA released a stunning visualization of the carbon cycle for the entire globe. It showed the rise and fall of CO2 levels in the atmosphere throughout 2006. NASA gave us a chance to see the Earth effectively ‘breathe.’
With the visualization, we are now getting independent research suggesting high yield farming in the northern hemisphere is partially responsible for the fluctuations in long-term CO2. New studies show that farming is behind 20 to 50 percent of the long-term increases in the amount of CO2 absorbed during the growing season, and in the amount given back during the dormant period.
It isn’t the number of acres farmed that is increasing farming’s influence, but the sheer jump in productivity of farms. New crop breeds, fertilizer blends and better irrigation are being pointed out as increasing the fluctuations of carbon dioxide. Productivity has been fingered as a bigger concern than the longer growing season attributed to climate change.
Published in Nature, study author Josh Gray said researchers are still trying to parse what the influence means. At minimum, it shows that we have undervalued humans’ influence on the Earth’s carbon cycle.
Taking just corn alone, the rise in yield has been explosive. A fivefold increase has been recorded in the time period before WWII and today. New carbon models should be more accurate thanks to researchers assigning bigger values to forests as being responsible for the ‘breathing.’ Instead, if the new studies hold up, researchers could reassign values.
Still, compared to the overall increase of carbon dioxide, the increased fluctuations attributed to plants is small. That’s not to say that as farm productivity increases, its contribution to the carbon cycle should not be acknowledged.
Gray’s team used carbon-accounting tools to rank the top four crops behind the fluctuations. Corn was the big player, accounting for two-thirds, Wheat, rice and soybeans rounded out the top four.
With corn production tripling globally, the increases were confined to a relatively small area. Production zones exist in China and the US Midwest. Land usage has increased slightly, but the overwhelming fluctuation has come from productivity increases.
Even with corn and other crops contributing more to the seasonal carbon fluctuations, yields are going to have to increase dramatically. Populations are exploding, and arable land is in short supply. Researchers are scrambling to develop models to predict the changes that will inevitably occur to the carbon cycle.
Check out the current issue of Nature to read the studies.
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