Nav: Home

Research shows global photosynthesis on the rise

April 05, 2017

Plant photosynthesis was stable for hundreds of years before the industrial revolution, but grew rapidly in the 20th century, according to new research published today in Nature.

"Virtually all life on our planet depends on photosynthesis," said UC Merced Professor Elliott Campbell, who led the research. "Keeping tabs on global plant growth should be a central goal for the human race."

Photosynthesis is the process through which plants use sunlight to convert carbon dioxide (CO2) into carbohydrates to fuel their growth and other activities.

Yet, researchers lack a clear picture of global trends in photosynthesis over the past few centuries. Some human activities might have stimulated plant growth, while others might have hampered photosynthesis. Conflicting results from different experiments have stoked scientific debate for years.

But maybe not for long. Campbell and an interdisciplinary, international team of scientists discovered a chemical record of global photosynthesis spanning hundreds of years.

"Previous studies covered small physical areas or short periods of time," Campbell said. "We set out to find a long-term record for the whole planet."

The researchers estimate that the sum of all plant photosynthesis on Earth grew by 30 percent over the 200-year record they captured.

"Studies have already demonstrated unprecedented changes in climate and greenhouse gases during the industrial era," Campbell said. "Now we have evidence that there is also a fundamental shift in the Earth's plants."

The Net Effect

The research did not identify the cause of the increased photosynthesis, but computer models have shown several processes that could, together, create such a large change in global plant growth.

The leading candidates are rising atmospheric CO2 levels, a result of emissions from human activities; longer growing seasons, a result of climate change caused by CO2 emissions; and nitrogen pollution, another result of fossil fuel combustion and agriculture.

The human activities that underlie the growth in photosynthesis have both positive and negative consequences.

"The rising CO2 level stimulates crops yields," said Campbell, who's with the School of Engineering and the Sierra Nevada Research Institute. "But it also benefits weeds and invasive species. Most importantly, CO2 emissions cause climate change, which will increase flooding of coastal cities, extreme weather and ocean acidification."

Another effect of the rise in photosynthesis is that it can cause plants to remove CO2 from the air and store it in ecosystems. Unfortunately, CO2 emissions from fossil fuel burning overwhelm any uptake by plants.

"The increase in photosynthesis has not been large enough to compensate for the burning of fossil fuels," said paper co-author Joe Berry, from the Carnegie Institution for Science. "Nature's brakes have already been overwhelmed. So now it's up to us to figure out how to reduce the CO2 concentration in the atmosphere."

Secrets in the Snow

The researchers discovered the record of global photosynthesis by analyzing Antarctic snow data captured by the National Oceanic and Atmospheric Administration (NOAA).

Gases trapped in different layers of Antarctic snow allow scientists to study global atmospheres of the past. The key was finding a gas stored in the ice that provides a record of the Earth's plant growth.

Previous studies have found that carbonyl sulfide (COS) serves this function. COS is a cousin of CO2, and plants remove COS from the air through a process that is related to the way they uptake CO2.

While photosynthesis is closely related to the atmospheric COS level, other processes in oceans, ecosystems and industry can change COS level also.

To account for all these processes, Campbell coordinated analysis between members of the research team, including Ulli Seibt from UCLA; Steve Smith of the Pacific Northwest National Laboratory; Steve Montzka of NOAA; Thomas Launois of Institut National de la Recherche Agronomique; Sauveur Belviso of Laboratoire des Sciences du Climat et de l'Environnement; Laurent Bopp of Laboratoire de Météorologie Dynamique; and Marko Laine of the Finnish Meteorological Institute. Their work was funded by the U.S. Department of Energy, NOAA, the Academy of Finland, H2020 and the European Research Council.

Future research, the researchers said, will include studying current changes in photosynthesis using the ongoing COS measurements made by NOAA.

"Part of predicting the future state of our atmosphere depends on understanding natural mechanisms and how they are changing over time," said Montzka, a research chemist with NOAA. "We are making measurements and observations, and if we don't continue to do that, we won't have the fundamental information needed to answer important questions related to future atmospheric changes."

Chris Field, a climate scientist at Stanford University who was not involved in the study, said the new results "provide another line of evidence confirming the dynamic nature of Earth's ecosystems and the large magnitude of the changes caused by human actions."
-end-


University of California - Merced

Related Climate Change Articles:

Mapping the path of climate change
Predicting a major transition, such as climate change, is extremely difficult, but the probabilistic framework developed by the authors is the first step in identifying the path between a shift in two environmental states.
Small change for climate change: Time to increase research funding to save the world
A new study shows that there is a huge disproportion in the level of funding for social science research into the greatest challenge in combating global warming -- how to get individuals and societies to overcome ingrained human habits to make the changes necessary to mitigate climate change.
Sub-national 'climate clubs' could offer key to combating climate change
'Climate clubs' offering membership for sub-national states, in addition to just countries, could speed up progress towards a globally harmonized climate change policy, which in turn offers a way to achieve stronger climate policies in all countries.
Review of Chinese atmospheric science research over the past 70 years: Climate and climate change
Over the past 70 years since the foundation of the People's Republic of China, Chinese scientists have made great contributions to various fields in the research of atmospheric sciences, which attracted worldwide attention.
A CERN for climate change
In a Perspective article appearing in this week's Proceedings of the National Academy of Sciences, Tim Palmer (Oxford University), and Bjorn Stevens (Max Planck Society), critically reflect on the present state of Earth system modelling.
Fairy-wrens change breeding habits to cope with climate change
Warmer temperatures linked to climate change are having a big impact on the breeding habits of one of Australia's most recognisable bird species, according to researchers at The Australian National University (ANU).
Believing in climate change doesn't mean you are preparing for climate change, study finds
Notre Dame researchers found that although coastal homeowners may perceive a worsening of climate change-related hazards, these attitudes are largely unrelated to a homeowner's expectations of actual home damage.
Older forests resist change -- climate change, that is
Older forests in eastern North America are less vulnerable to climate change than younger forests, particularly for carbon storage, timber production, and biodiversity, new research finds.
Could climate change cause infertility?
A number of plant and animal species could find it increasingly difficult to reproduce if climate change worsens and global temperatures become more extreme -- a stark warning highlighted by new scientific research.
Predicting climate change
Thomas Crowther, ETH Zurich identifies long-disappeared forests available for restoration across the world.
More Climate Change News and Climate Change Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at Radiolab.org/donate.