Air Date: Week of October 13, 2017

As carbon emissions rise, plants are responding by performing more photosynthesis and using water more efficiently. (Photo: Bill Dickinson, Flickr CC BY-NC-ND 2.0)

As carbon dioxide levels climb in the atmosphere, plants step up photosynthesis. Living on Earth’s Savannah Christiansen reports in this week’s Note on Emerging Science that the increased carbon in the air also allows vegetation to use water more efficiently.

Transcript

CURWOOD: It’s Living on Earth, and I’m Steve Curwood. Just ahead, how tropical forests have become a net source of carbon emissions. But first this note on emerging science from Savannah Christiansen.

[MUSIC: SCIENCE NOTE THEME]

CHRISTIANSEN: As carbon dioxide builds up in the atmosphere, plants and their energy generation process, photosynthesis, are bound to be impacted. Scientists suspected that more carbon in the air would provide more fuel for photosynthesis so plants could grow more and store more carbon. Now a study led by Scripps CO2 program head, Ralph Keeling, has confirmed this suspicion, and helped explain a mystery about atmospheric carbon.

Atmospheric carbon has two different forms, or isotopes, carbon-12 and carbon-13. Carbon-13 is less common, yet the researchers found that it’s building up in the atmosphere more quickly than expected. Something is taking out extra carbon-12.

To find out why, the team measured ratios of these carbon isotopes from different areas and from archived samples. Plants find carbon-12 easier to use for photosynthesis, so they prefer it. And the sample measurements suggest that they are becoming increasingly picky, using even more carbon-12 and leading to the imbalance.

The researchers note that the current plentiful level of carbon-12 also allows plants to adjust their stomata, the holes in their leaves that control carbon intake, so that they can actually minimize water loss. And while many implications of this are still unclear, it’s possible that, as carbon dioxide levels rise, plants will have a tool to allow for more growth, even when water is scarce.

That’s this week’s note on emerging science. I’m Savannah Christiansen.

[MUSIC: SCIENCE NOTE THEME]

 

Links

Link to the study in Proceedings of the National Academy of Sciences: “Atmospheric evidence for a global secular increase in carbon isotopic discrimination of land photosynthesis”

Washington Post: “Some good news about global warming for once -- plants are speeding up their use of carbon”