Chevron, Occidental Petroleum and the Australian mining giant BHP this year have invested in Carbon Engineering, a small Canadian company that claims to be on the verge of a breakthrough in solving a critical climate change puzzle: removing carbon already in the atmosphere.
NYT
At its pilot project in Squamish, an old lumber town about 30 miles north of Vancouver, the company is using an enormous fan to suck large amounts of air into a scrubbing vessel designed to extract carbon dioxide. The gas can then be buried or converted into a clean-burning — though expensive — synthetic fuel.
One thing they don’t tell you is that CO2 is food for plants. As this NASA study says:
Studies have shown that higher concentrations of atmospheric carbon dioxide affect crops in two important ways: they boost crop yields by increasing the rate of photosynthesis, which spurs growth, and they reduce the amount of water crops lose through transpiration. Plants transpire through their leaves, which contain tiny pores called stomata that open and collect carbon dioxide molecules for photosynthesis. During that process they release water vapor. As carbon dioxide concentrations increase, the pores don’t open as wide, resulting in lower levels of transpiration by plants and thus increased water-use efficiency.
Global climate impact assessments for crops have focused primarily on the impacts of elevated atmospheric carbon dioxide on yields, said Delphine Deryng, lead author and a climate scientist at NASA’s Goddard Institute for Space Studies (GISS) in New York City. “There has been very little impact assessment analysis that looked at the dual effect on yield and water use and how they play out in different regions of the world, which is critical to anticipating future agricultural water demands,” she said. …Results show that yields for all four crops grown at levels of carbon dioxide remaining at 2000 levels would experience severe declines in yield due to higher temperatures and drier conditions. But when grown at doubled carbon dioxide levels, all four crops fare better due to increased photosynthesis and crop water productivity, partially offsetting the impacts from those adverse climate changes. For wheat and soybean crops, in terms of yield the median negative impacts are fully compensated, and rice crops recoup up to 90 percent and maize up to 60 percent of their losses. …
The larger spread for gains and losses in rainfed maize is attributed mainly to the drier growing conditions. “The impact on crop water productivity and yield is strongest in regions like southern Africa where water is a limiting factor,” Deryng said. “Maize in these regions experience the most relief from better water-use efficiency.” …
NASA
But Rosenzweig said that more field experiments are needed. “The uncertainty of carbon dioxide effects are greater in arid regions because experiments have been carried out mostly in temperate regions of the northern hemisphere,” she said. “We need field observations in these drier regions in order to validate and further improve our models.”
A lot depends on the models and how accurate they are. But at first glance less CO2 may actually be bad for Africa.