Could there be an upside to rising carbon dioxide levels? Increasing CO2 levels in the atmosphere could actually assist in plant growth in some areas, a new study reveals.
While climate change is generally believed to hit food crops hard due to extreme heat and water shortages, CO2 levels could somehow mitigate the effect and particularly boost plant productivity and reduce water consumption, according to 16 international researchers who used newly accessible crop models and data from current large-scale experiments.
"Most of the discussion around climate impacts focuses only on changes in temperature and precipitation. To adapt adequately, we need to understand all the factors involved," says lead author and Columbia University environmental scientist Delphine Deryng, who clarified that while a rise in CO2 levels may be bad news, its direct effects should also be studied.
The team from half-dozen countries estimated the growth rates of four crops: wheat, maize, rice, and soybeans. They simulated two conditions: one with rising CO2 levels and climate change, and another with CO2 levels at current rate but with continuing climate change.
In the scenario of global temperatures and carbon dioxide rising at the same time, crop yields stayed the same or had losses mitigated by the CO2 increase. Heat and water stress alone – no rise in CO2 in the atmosphere – were predicted to damage yields, but with CO2 accounted for, all crops were seen to have more efficient water use by 2080.
Crop yields, however, could go down, specifically by over 8 percent for maize and by 4 percent for wheat. Deryng says little is known about how changing CO2 rates are affecting crop nutrition in particular.
It could get more complicated, she proceeds, as field experiments have been conducted only at sites in the U.S., Australia, Germany, China, and Japan, not in areas of subsistence farming such as Africa or India.
However, she believes this new study is stronger than the initial proof of so-called “CO2 fertilization” since the former combines field tests with lab experiments and accounts for potent environmental factors. While it will not fully counter climate change’s negative effects, it will aid in preparing for the future, Deryng tells The Christian Science Monitor.
Bruce Kimball, retired USDA researcher, echoes the findings’ accuracy on a large scale, but urges further research on more crops from more locations.
At any rate, human activity has led average global CO2 levels in the atmosphere to climb by over a quarter since 1960, now standing at about 400 parts per million. This rate is expected to steadily increase along with temperature.
The findings were published in the journal Nature Climate Change.
Photo: Miran Rijavec | Flickr
