Does More Carbon Dioxide Mean Increased Crop Water Productivity? (arstechnica.com)

An anonymous reader points us to an Ars Technica report: For the most part, we think of rising levels of carbon dioxide as an environmental problem. But atmospheric CO2 can also boost agricultural productivity by helping plants grow. How do these potential issues balance out? In an investigation recently published in Nature Climate Change, scientists have looked into the global implications of carbon dioxide's ability to enhance agricultural productivity. Increased levels of CO2 can enhance photosynthesis and reduce leaf-level transpiration, the process by which some of the water that plants draw from the ground gets released back into the atmosphere. These changes can reduce growing seasons and water loss. The result could be an increase in what's called "crop water productivity," i.e. the amount of food produced for each unit of water expended. If elevated CO2 levels increase crop yield and reduce water consumption at large scales, this could help ensure water and food security despite the climate disruptions. By combining data from a massive network of field experiments and global crop models, the scientists claimed that depending on the crop type, global crop water productivity will increase by 10 to 27 percent by the 2080s. Arid regions exhibited large increases that were based on crop type.

Comments

There are adverse effects from this

[Anonymous Coward]

It sounds good that crops will be more productive. So will other things, though. There was an experiment in which poison ivy was grown in higher CO2 conditions. It grew better and produced more urushiol (the stuff that causes you to have an allergic reaction). Crops may grow better, but so will weeds. It wouldn't surprise me if that included some invasive weeds like kudzu. If it stays warmer, pests might not die off in the cold; the mountain pine beetle is an example. Furthermore, there's not only increased temperatures and longer growing seasons; rainfall patterns will shift, too. Areas that currently grow crops might become arid and either have to grow different crops or not be productive at all. Other areas, such as the northern US, are likely to become wetter. Maybe you have longer growing seasons in some areas, but I'm not sure how much of a real gain there will be if the rainfall moves poleward with the warm temperatures.

That is stupid

[aepervius]

Increased plant growth does not mean increased yield in food stapple, if we are still limited in Phosporus and nitrogen fixation. But even if it did, the water increase and climate chaotisation would far more offset that. What good is it that Florida could produce more orange, if it loses its coastal city and vast swath of the everglade, or land ? Or if the ocean pH changes destroy the food stapple (fishing) of many countries ? And that is only on top of my head. There are so many factor at play that your typical "AGW is not that bad" is sad.