New research, to be published in the journal Science, suggests that plants could be playing a vital role in counteracting man-made climate change, by releasing chemicals into the atmosphere.
The science bit
For the first time, researchers have been able to detect short-lived and highly reactive types of chemical known as ‘Criegee intermediates’ or ‘Criegee biradicals’, which form when ozone and hydrocarbons (chemicals consisting of hydrogen and carbon) react together in the atmosphere.
Researchers have found that these chemicals react with sulfur dioxide in the atmosphere, and these reactions, which happen very quickly, play an important role in forming sulfate aerosols, which in turn help shape the Earth’s climate.
Scientists previously assumed a different chemical reaction was the most important in forming sulfate aerosols, but these early results suggest that this process – involving the Criegee intermediates – could be as important, or even more so. Sulfate aerosols affect the climate both by generating clouds and by directly reflecting energy. How sulfate aerosols effect the climate is a key area of uncertainty – and scientific research.
As Dr Carl Percival, Reader in Atmospheric Chemistry at The University of Manchester and one of the authors of the paper puts it:
“Our results will have a significant impact on our understanding of the oxidising capacity of the atmosphere and have wide ranging implications for pollution and climate change.”
What this means for the climate
Sulfate aerosols directly cool the atmosphere by reflecting some of the Sun’s energy out into space and stopping it from hitting the planet, Earlier this year scientists suggested that sulfate aerosols have slowed the temperature rise caused by man-made greenhouse gas emissions over the last decade. This new research suggests that Criegee intermediates may have played an important role in this process.
And this could indicate another reason why preserving the biosphere could be important to help keep man-made climate change in check. Professor Dudley Shallcross, Professor in Atmospheric Chemistry at The University of Bristol, points out:
“A significant ingredient required for the production of these Criegee biradicals comes from chemicals released quite naturally by plants, so natural ecosystems could be playing a significant role in off-setting warming.”
What it doesn’t mean
When breakthrough science like this is published it can be over-egged or even totally misinterpreted by the media and blogosphere. For example, the headline ” Global Warming may be Defeated by Molecule Discovery” which the International Business Times ran with is not helpful or accurate. In light of that, here’s what this paper does not show:
– It doesn’t mean that global warming has been ‘defeated’
No surprises there. The research does not suggest that we no longer need to mitigate climate change, nor that it will cease to be a problem.
– This isn’t a geoengineering ‘cure’ for global warming
The paper describes preliminary work identifying a natural process in the climate. An enormous amount of research would be needed and a huge number of technical and political issues overcome before we could work out how to harness this process for our own means.
– It doesn’t mean that global warming has stopped
Last year’s finding that sulfate aerosols have slowed man-made warming provoked a mass of misinformation, including the favourite claim of climate skeptics that global warming has stopped. It hasn’t, as we have explained many times, and this research says nothing to suggest that it has.
– This doesn’t mean clouds are a forcing and not a feedback
This paper doesn’t say anything about clouds causing climate change. Enough said.
The takeaway message from this research? Chemicals released to the atmosphere by plants could be playing an important role in limiting man-made global warming, through the production of sulfate aerosols.
We’ll update the post if the paper gets any interesting media coverage.