Photosynthesis 'faster than thought'
Washington: Scientists have estimated that the global rate of photosynthesis - the chemical process governing how ocean and land plants absorb and release carbon dioxide - is occurring 25 percent faster than earlier thought.
By analysing more than 30 years of data collected by Scripps Institution of Oceanography, an international team has deduced the mean rate of photosynthesis over several decades and identified the El Nino-Southern Oscillation phenomenon as a regulator of the type of oxygen atoms found in CO2 from the far north to the south pole.
The findings, published in the latest edition of the 'Nature' journal, will assist researchers to more accurately assess future climate change, says the team.
"Our analysis suggests that current estimates of global primary production are too low and the refinements we propose represent a new benchmark for models to simulate carbon cycling through plants," Dr Colin Allison of CSIRO's Aspendale laboratories, a team member, said.
The study, led by Dr Lisa Welp at the Scripps Institution of Oceanography, California, traced the path of oxygen atoms in CO2 molecules, which tells how long the CO2 has been in the atmosphere and how fast it had passed through plants.
From this, the scientists estimated that the global rate of photosynthesis is about 25 per cent faster than previously thought.
Dr Welp said: "It's difficult to measure the rate of photosynthesis for forests, let alone the entire globe. For a single leaf it's straightforward, you just put it in an instrument chamber and measure CO2 decreasing in chamber air.
"But you cannot do that for an entire forest. What we have done is to use a naturally occurring marker, an oxygen isotope, in atmospheric CO2 that allows us to track how often it ended up inside a plant leaf, and from oxygen isotopic CO2 data collected around the world we can estimate the mean global rate of photosynthesis over the last few decades."
"These results can be used to validate the biospheric components included in carbon cycle models and, although still tentative, may be useful in predicting future climate change, say the scientists.