Rising CO2 due to climate change may not improve agriculture, model shows

March 8, 2017, Purdue University
Modeling the effects of increased CO2 on global crop production at Purdue University shows that because of the complex effects and feedback behaviors that connect plant life and the atmosphere, many areas may suffer due to increased heat and reduced rainfall, despite the increase in the plant nutrient. Credit: Qianlai Zhuang

Although many people have argued that rising carbon dioxide levels would benefit crop production, a recent model of the effects of increased CO2 shows that it's not that simple and that elevated levels could have a much less positive effect on plant photosynthesis than previously predicted.

Purdue University researchers tested the effects of increased CO2 and warmer temperatures on plant water use. Although increased carbon dioxide and warmer temperatures generally improve photosynthesis, in these experiments the researchers found that pores on plant leaves, known as the stomata, were predicted to narrow in these conditions, reducing the amount of moisture plants release into the air.

Although this change may mean some plants are more efficient in their water use in some arid regions, overall this change in plant physiology will have its own climate effects, resulting in less rainfall in some regions, damaging plants and crop yields, says Qianlai Zhuang, professor of earth and atmospheric science.

"This study reveals that while increasing can directly strengthen plant uptake of CO2, it can also reduce plant transpiration, influence global precipitation patterns, and increase warming locally," he says.

The research was published in a recent issue of Geophysical Research Letters. Zhuang's graduate student Zhu is the lead author on the paper.

Lisa Welp, assistant professor of biogeochemistry in Purdue's Department of Earth, Atmospheric, and Planetary Sciences, and a co-author on the paper, says that in many terrestrial ecosystems, precipitation is from water recycled to the atmosphere by plants upwind, affecting both precipitation and temperatures.

"The role that terrestrial vegetation plays in rainfall recycling on land is often simplified or overlooked, but it's a key player in determining regional and, therefore, productivity in water-limited ecosystems," Welp says. "If some reduce their transfer of water to the atmosphere by reducing transpiration rates, this results in regional declines in precipitation. It also results in local heating because evaporating water from plant leaves acts like an air conditioner, keeping surface temperatures cooler."

Overall, the effect is strong enough that there is no net increase in global agricultural production, Zhuang says. In fact, as carbon dioxide increases globally, the modeling showed that plant life in most regions of the world suffers considerably due to rising temperatures and decreased precipitation.

"You cannot look at just one effect in isolation, such as photosynthesis, and make a determination of how it will affect global ," Zhuang says. "There are both direct and indirect effects, and both should be considered."

Atmospheric has increased from 280 parts per million before the Industrial Age, which began in the late 1700s, to the current level above 400 parts per million.

Zhuang and graduate student Peng Zhu devised six model experiments using historic climate data from 1850 to 2011. They found that although a few areas would see improved plant growth - including parts of Canada, most of Madagascar, and the southern tip of India - other regions on the planet would suffer.

"This study indicates that the net CO2 fertilization effect will be overestimated unless vegetation-climate feedback effects are taken into account," Zhu says.

Explore further: Indirect effects of rising CO2 levels on ecosystems more important than previously thought

More information: Peng Zhu et al. Elevated atmospheric COnegatively impacts photosynthesis through radiative forcing and physiology-mediated climate feedback, Geophysical Research Letters (2017). DOI: 10.1002/2016GL071733

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17 comments

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HeloMenelo
4.4 / 5 (10) Mar 08, 2017
And yet we still have a baboon (antigoracle and his 40 goon sockpuppets) bouncing about the comment section chest thumping saying, co2 is not harmful, i wonder if he can smell his head from his @rse apart ? ? No really.. i do wonder.
gkam
Mar 08, 2017
This comment has been removed by a moderator.
Shootist
1.9 / 5 (14) Mar 08, 2017
There goes the last "yeah, but" of the Deniers.


hardly. Until barley, wheat and cattle have been raised on Greenland for 400 years, Man caused global warming will remain either a hoax or a gross misunderstanding of what is normal (probably a hoax, what better way to control the means of production than to frighten the prols with Fake News, convincing them into giving up their power?).

It has been both warmer and colder than it is today and THAT within historical times.
Pumastar
4.3 / 5 (11) Mar 08, 2017
Except that the news is real based on science, and your airhead comments ? is based on the air inside your head. Fake is you first middle and last name, and clearly everyone reading it sees how pathetic your understanding is wrt climate change.
HeloMenelo
5 / 5 (7) Mar 08, 2017
aaah the bait worked, see now how shooty (antigoracle sock) will go on a spree rubbing in self inflicting insults, not that he has not done it enough, but hey, who cares the world get's to see through all his stupid lies on a daily basis lol, not complaining at all :D
novaman
Mar 08, 2017
This comment has been removed by a moderator.
snoosebaum
not rated yet Mar 08, 2017
from another study highlighted above ,''For example, when plants close their stomata, they use less soil water, changing the amount of soil water available to other plants.''

Read more at: https://phys.org/...html#jCp
unrealone1
3.2 / 5 (6) Mar 08, 2017
Plant Growth Surges As CO2 Levels Rise..
http://climatenew...ls-rise/
Rise in CO2 has 'greened Planet Earth'
Carbon dioxide emissions from industrial society have driven a huge growth in trees and other plants.
http://www.bbc.co...36130346
unrealone1
2.1 / 5 (7) Mar 08, 2017
This article is trying to prove the Green house Effect is bad for plants? and the Jurassic period was?
Solon
2.7 / 5 (9) Mar 08, 2017
Why use a model when there is lots of info on the results of increased CO2 with tomatoes for instance? They thrive at 900 ppm. Cannabis too, from what I read.
Shootist
2.7 / 5 (3) Mar 09, 2017
Tell the growers of cannabis that their 30% increase in yield is NOT due to their doubling and tripling of the CO2 in their grow rooms.
Zzzzzzzz
3.5 / 5 (6) Mar 09, 2017
Another piece of cover for deniers destroyed. But this is the Trump era - if you're delusional you can be proud of it. Flaunt your delusions - after all, the President of the USA does it routinely!
gkam
1 / 5 (5) Mar 09, 2017
Tell the growers of cannabis that their 30% increase in yield is NOT due to their doubling, . .
---------------------------------
Know any professional cannabis growers? I do.

They do not use CO2.
Uncle Ira
4.3 / 5 (6) Mar 09, 2017

Know any professional cannabis growers? I do.

They do not use CO2.


Skippy, why you never use the Google before you make your stupid blurts? It only takes a couple of seconds and would save you from looking as foolish as you do.
gkam
1.5 / 5 (6) Mar 09, 2017
Are you telling me my licensed provider uses CO2?

You need to stick your nose into something you know about, and do not have to "look up".
Uncle Ira
3.9 / 5 (7) Mar 09, 2017
Are you telling me my licensed provider uses CO2?
Non, I am not telling you that. But I would suggest to him he should cut you off. His stuff is making you stupid and it's got to be bad for business (especially when you are riding your Hover-Around up and down the neighborhood with that silly looking pointy cap on your head, yeah, the one with the stars and moons on him.)
gkam
1 / 5 (4) Mar 09, 2017
Okay, I had gotten out the pics of the car, inverter, and PV panels, but now you will have to wait and keep on shooting off your mouth until the new Google pics come out and show everybody who is the liar.

Don't stop.

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