Plants' ability to absorb increased levels of carbon dioxide in the air may have been overestimated, according to the findings of a study by researchers at the University of Minnesota.

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The study, published this week in the journal Nature Climate Change, shows that even though plants absorb large amounts of carbon dioxide and actually can benefit from higher levels of it, they may not get enough of the nutrients they need from typical soils to absorb as much CO2 as scientists had previously estimated.

The scientists have warned that this finding has extremely serious implications for mitigating fossil fuel emissions and climate change predictions, as Carbon dioxide absorption is an important function, factored into modelling and projections made in both these areas.

The study, based on long-term experiments, was compiled over 13 years of research at the Cedar Creek Ecosystem Science Reserve in Minnesota. University scientists Peter Reich and Sarah Hobbie, who said their study is one of only three such experiments ever conducted,  monitored nearly 300 open-air plots planted with perennial grasses with varying levels of atmospheric carbon dioxide and soil nitrogen.

Professor Reich explained the methodology, "Rather than building a time machine and comparing how ecosystems behave in 2070 – which is hard to do – we basically create the atmosphere of 2070 above our plots."

Worryingly, the researchers' results suggest that the limited levels of fertility in most soils will effectively reduce the capacity of many plants to remove CO2 from the atmosphere as levels increase.

Reich said the Minnesota experiment should be repeated across other global regions to enable a clearer understanding of the effects and build up a better picture of plants' ability to absorb atmospheric carbon dioxide. He said, "It would be better if there were experiments like ours in tropical rain forest, temperate forest, and tundra, to see how well responses there match with what we have found. But as such experiments do not exist, our results play an important role in addressing this issue for ecosystems everywhere."

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