Corralling the carbon cycle

November 13, 2008
Corralling the carbon cycle
NASA’s Atmospheric Infrared Sounder (AIRS) instrument on the Aqua spacecraft is used to observe carbon dioxide in the atmospheric. This image shows CO2 over the United States in July 2003. High concentrations of the greenhouse gas are red, while low concentrations are blue. Image courtesy NASA

(PhysOrg.com) -- Scientists may have overcome a major hurdle to calculating how much carbon dioxide (CO2) is absorbed and released by plants, vital information for understanding how the biosphere responds to stress and for determining the amount of carbon that can be safely emitted by human activities. The problem is that ecosystems simultaneously take up and release CO2. The key finding is that the compound carbonyl sulfide, which plants consume in tandem with CO2, can be used to quantify gas flow into the plants during photosynthesis. The research is published in the November 14, issue of Science.

“In photosynthesis, plants ‘breath’ in carbon dioxide from the atmosphere and, with sunlight energy, convert it and water into food and oxygen, which they then ‘exhale,’” explained co-author Joe Berry from the Carnegie Institution’s Department of Global Ecology. “In ecosystems, plants and other organisms respire producing carbon dioxide. We can measure the net change in CO2, but we do not have an accurate way to measure how much is going in or out and how this is affected by climate. Understanding this photosynthesis-climate feedback riddle is key to understanding how climate change may affect the natural processes that are a sink for human-made carbon emissions.”

Previous laboratory research showed that carbonyl sulfide is taken up in step with photosynthesis. But unlike CO2, there is no emission of carbonyl sulfide from plants.

The researchers compared atmospheric measurements of carbonyl sulfide over North American during the growing season with two simulations of an atmospheric transport model. The airborne observations, from the Intercontinental Chemical Transport Experiment-North America, also measured CO2. They combined that data with results from laboratory experiments that looked at gas exchange at the leaf level.

“We’ve always looked at the total change in CO2, but now we can look for the influence of photosynthesis on this total change,” remarked lead author Elliott Campbell a former Carnegie postdoctoral researcher, currently at UC Merced. “Our approach, based on the relation of carbonyl sulfide to photosynthesis, gives us this unique ability.”

With the new inputs, the researchers ran their simulations, which consider plant uptake, soil and ocean absorption, human-made emissions and how the gases flow through these systems. The simulations showed that the magnitude of the plant uptake was much larger than other sources and sinks at a continental scale during the growing season, which is important for using the compound to trace photosynthesis.

“The intriguing outcome of this study is that an inverse analysis of the atmospheric carbonyl sulfide measurements may be used to quantify the carbon released during plant respiration,” remarked Berry. “That key missing piece has been a thorn in the side of carbon-cycle research for years.”

Provided by Carnegie Institution

Explore further: Where is solar power headed?

Related Stories

Where is solar power headed?

July 22, 2015

Most experts agree that to have a shot at curbing the worst impacts of climate change, we need to extricate our society from fossil fuels and ramp up our use of renewable energy.

Scientists create low-methane rice

July 22, 2015

Scientists said Wednesday they had created a rice variety with starchier grains that emits less methane, a step towards the twin goals of feeding more people and curbing global warming.

First report on greenhouse gas emissions from African rivers

July 21, 2015

Twelve scientists from the University of Liege, the KU Leuven and the Research Institute for Development (France), have just completed a large-scale research project conducted over a five-year period on the African continent. ...

Study reveals how rivers regulate global carbon cycle

May 13, 2015

Humans concerned about climate change are working to find ways of capturing excess carbon dioxide (CO2) from the atmosphere and sequestering it in the Earth. But Nature has its own methods for the removal and long-term storage ...

Recommended for you

Playing 'tag' with pollution lets scientists see who's 'it'

July 29, 2015

Using a climate model that can tag sources of soot from different global regions and can track where it lands on the Tibetan Plateau, researchers have determined which areas around the plateau contribute the most soot—and ...

A cataclysmic event of a certain age

July 27, 2015

At the end of the Pleistocene period, approximately 12,800 years ago—give or take a few centuries—a cosmic impact triggered an abrupt cooling episode that earth scientists refer to as the Younger Dryas.

4 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

GrayMouser
5 / 5 (2) Nov 13, 2008
The picture is useless without a scale to go with the colors. What are the concentrations? At what altitudes?
Velanarris
3.7 / 5 (3) Nov 14, 2008
The article is rather useless as well as there's either a typo, or the quoted gentleman was trying to talk about two different processes as one here:

%u201CIn photosynthesis, plants %u2018breath%u2019 in carbon dioxide from the atmosphere and, with sunlight energy, convert it and water into food and oxygen, which they then %u2018exhale,%u2019%u201D explained co-author Joe Berry from the Carnegie Institution%u2019s Department of Global Ecology. %u201CIn ecosystems, plants and other organisms respire producing carbon dioxide. We can measure the net change in CO2, but we do not have an accurate way to measure how much is going in or out and how this is affected by climate. Understanding this photosynthesis-climate feedback riddle is key to understanding how climate change may affect the natural processes that are a sink for human-made carbon emissions.%u201D


CWFlink
5 / 5 (1) Jul 02, 2009
Consider the phrase "plants and other organisms respire producing carbon dioxide"; change 'respire' to 'expire' (i.e. die).

Then the quote makes some sense.

Also, consider:
http://www.physor...929.html

Which implies that "weathering of stones", enhanced by the activity of plant life, is a significant natural way to reduce CO2 levels. And goes on to imply that when CO2 levels fall below 250 ppm, "starvation" of plant life slows the weathering process significantly.

Taken together, these two articles suggest that plant life reduces CO2 levels through TWO processes... photosynthesis and "weathering", which work to multiply the impact of plants on reducing CO2 levels.

We may well find that rising CO2 levels will level off as plants catch up and balance our emissions with photosynthesis and "weathering".
Velanarris
3 / 5 (1) Jul 02, 2009
Well the "weathering" is actually the uptake of vital nutrients for plant growth (mainly Iron and nitrous photosynthetic intermediates). In plants you can increase fertilizer as much as you want, but if you're lacking a single nutrient (like carbon) the growth is slowed.

Conversely, if you increase the carbon, when the plants are already in a carbon rich environment, growth will not be affected, begin fertilizing, and excess carbon (if lacking) will assist plant growth.

As with all things in nature, it's a balancing act.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.