Rising CO2 levels not as good for crops as thought

A FACE soybean field trial in which CO2 is released from pipes above the crop Copyright: Science

By: Kimani Chege

We encourage you to republish this article online and in print, it’s free under our creative commons attribution license, but please follow some simple guidelines:

You have to credit our authors.
You have to credit SciDev.Net — where possible include our logo with a link back to the original article.
You can simply run the first few lines of the article and then add: “Read the full article on SciDev.Net” containing a link back to the original article.
If you want to also take images published in this story you will need to confirm with the original source if you're licensed to use them.
The easiest way to get the article on your site is to embed the code below.

For more information view our media page and republishing guidelines.

The full article is available here as HTML.

Press Ctrl-C to copy

<div class="article-wrap">
<div id="article-introduction">
<h1>Rising CO2 levels not as good for crops as thought</h1>
<h4>By: Kimani Chege</h4>
</div>
<br />
<br />

<div id="article-body">
<p><P>Scientists’ predictions that rising levels of atmospheric carbon dioxide will boost crop yields have been too optimistic, according to a study published today (30 June) in Science.</P><br />
<P>It says the effect is likely to be only about half as strong as previously thought.</P><br />
<P>Researchers have long reported that most major crops grow faster and need less water when more carbon dioxide (CO2) is available. </P><br />
<P>It was thought that this ‘fertilisation effect’ might offset the negative effects on crops — such as increased temperature and reduced soil moisture — that climate change is expected to bring.</P><br />
<P>But the new study, led by Stephen Long of the University of Illinois at Urbana-Champaign, United States, points out that these conclusions are mostly based on research done in greenhouses or controlled-environment chambers in labs and fields.</P><br />
<P>Long’s team surveyed results from a more realistic approach known as Free-Air Concentration Enrichment (FACE), which involves releasing CO2 just above the crops in open fields without interfering with other environmental conditions.</P><br />
<P>They concluded that the CO2 level expected by 2050 would only increase crop yields by about half what was predicted.</P><br />
<P>Long told SciDev.Net that the new results suggest that “the damaging effects of rising temperature and decreased soil moisture will not be offset by the fertilisation effect of rising CO2”.</P><br />
<P>The researchers note that for some tropical crops such as maize and sorghum the fertilisation effect might not even apply because they do not use CO2 for growth in the same way that most other plants do.</P><br />
<P>Commenting on the research in the same issue of Science, David Schimel of the US National Center for Atmospheric Research says the findings “may move impacts on agriculture higher up on the list of pressing concerns about climate change”.</P><br />
<P>Atmospheric CO2 concentrations have risen from 260 parts per million (ppm) 150 years ago to 380 ppm today, and are expected to rise to 550 ppm by 2050 because of human activities.<BR><BR></P><br />
<P><a  href="/ /sci.cfm?redir=http://www.sciencemag.org/cgi/content/full/312/5782/1918?ijkey=43k5M8ZBHPjuU&keytype=ref&siteid=sci" target="_blank" onclick="pageTracker._trackPageview('/tracking/external/'+this.href);" rel="noopener noreferrer">Link to full paper in Science</A></P><br />
<P>Reference: Science 312, 1918 (2006)</P><br />
<P><a  href="/sci.cfm?redir=http://www.sciencemag.org/cgi/content/full/312/5782/1889?ijkey=8/9t9HvCidaAY&keytype=ref&siteid=sci" target="_blank" onclick="pageTracker._trackPageview('/tracking/external/'+this.href);" rel="noopener noreferrer">Link to full commentary by David Schimel</A><BR></P></p>

</div>
<div class="quick-links-wrapper">
<h3>You might also like</h3>
[related-articles]
</div>
<p>This article was originally published on <a href="https://www.scidev.net" target="_blank">SciDev.Net</a>. Read the <a href="https://www.scidev.net/sub-saharan-africa/news/rising-co2-levels-not-as-good-for-crops-as-thought-ssa/" target="_blank">original article</a>.</p>
<script type="text/javascript">
(function(e,t,n,r,i,s,o){e["GoogleAnalyticsObject"]=i;e[i]=e[i]||function(){(e[i].q=e[i].q||[]).push(arguments)},e[i].l=1*new Date;s=t.createElement(n),o=t.getElementsByTagName(n)[0];s.async=1;s.src=r;o.parentNode.insertBefore(s,o)})(window,document,"script","//www.google-analytics.com/ga.js","ga");var _gaq=_gaq||[];var _gaq=_gaq||[];_gaq.push(["_setAccount","UA-3223906-8"],["_trackEvent","article interaction","republished","https://www.scidev.net/sub-saharan-africa/news/rising-co2-levels-not-as-good-for-crops-as-thought-ssa/",null,true])
</script>
</div>

Scientists’ predictions that rising levels of atmospheric carbon dioxide will boost crop yields have been too optimistic, according to a study published today (30 June) in Science.

It says the effect is likely to be only about half as strong as previously thought.

Researchers have long reported that most major crops grow faster and need less water when more carbon dioxide (CO2) is available.

It was thought that this ‘fertilisation effect’ might offset the negative effects on crops — such as increased temperature and reduced soil moisture — that climate change is expected to bring.

But the new study, led by Stephen Long of the University of Illinois at Urbana-Champaign, United States, points out that these conclusions are mostly based on research done in greenhouses or controlled-environment chambers in labs and fields.

Long’s team surveyed results from a more realistic approach known as Free-Air Concentration Enrichment (FACE), which involves releasing CO2 just above the crops in open fields without interfering with other environmental conditions.

They concluded that the CO2 level expected by 2050 would only increase crop yields by about half what was predicted.

Long told SciDev.Net that the new results suggest that “the damaging effects of rising temperature and decreased soil moisture will not be offset by the fertilisation effect of rising CO2”.

The researchers note that for some tropical crops such as maize and sorghum the fertilisation effect might not even apply because they do not use CO2 for growth in the same way that most other plants do.

Commenting on the research in the same issue of Science, David Schimel of the US National Center for Atmospheric Research says the findings “may move impacts on agriculture higher up on the list of pressing concerns about climate change”.

Atmospheric CO2 concentrations have risen from 260 parts per million (ppm) 150 years ago to 380 ppm today, and are expected to rise to 550 ppm by 2050 because of human activities.

Link to full paper in Science

Reference: Science 312, 1918 (2006)

Link to full commentary by David Schimel