Nav: Home

Improving climate models to account for plant behavior yields 'goodish' news

October 29, 2018

Climate scientists have not been properly accounting for what plants do at night, and that, it turns out, is a mistake. A new study from the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) has found that plant nutrient uptake in the absence of photosynthesis affects greenhouse gas emissions to the atmosphere.

In a study published today in Nature Climate Change, lead author William Riley demonstrates how to improve climate models to more accurately represent land biogeochemical dynamics. Using a new global land model they developed and integrated in DOE's Energy Exascale Earth System Model (E3SM), Riley and his team found that plants can uptake more carbon dioxide and soils lose less nitrous oxide than previously thought. Their global simulations imply weaker terrestrial ecosystem feedbacks with the atmosphere than current models predict.

"This is goodish news, with respect to what is currently in the climate models," said Riley, a scientist in Berkeley Lab's Earth & Environmental Sciences Area. "But it's not good news in general - it's not going to solve the problem. No matter what, plants will not keep up with anthropogenic carbon dioxide emissions; it's just that they might do better than current models suggest."

Humans have emitted a record-setting 34 gigatons of CO2 per year, averaged over the past decade. Roughly half of that remains in the atmosphere, while the rest is absorbed by oceans and land (through photosynthesis); the latter amount, called the terrestrial carbon sink, varies year to year depending on factors such as fires, drought, land use, and weather.

Scientists are trying to understand how increasing global carbon dioxide emissions will affect the terrestrial carbon sink, which is estimated to currently be between 0 and 11 gigatons of CO2 per year, including land-use change, with large inter-annual variability. A further complication involves terrestrial nitrous oxide, which is a powerful greenhouse gas naturally released from land and by agricultural and industrial activities. In other words, to what extent will plants be able to ameliorate increases in anthropogenic carbon dioxide emissions?

The new Berkeley Lab study found that by not properly accounting for what plants do at night and during the non-growing season, climate models may be underestimating the terrestrial carbon sink and overestimating nitrous oxide release, the latter by 2.4 gigatons of CO2-equivalent per year. "This number is substantial compared to the current terrestrial carbon sink," Riley said, anywhere from roughly one-quarter to more than 100 percent, depending on the year.

Plant-microbe competition for nutrients

Plants' ability to take in carbon dioxide is limited by the availability of soil nutrients, especially nitrogen and phosphorous. The more abundant nutrients are, the more plants can take advantage of increasing atmospheric carbon dioxide. Microbes in the soil are a factor too because they compete with plants for nutrients.

Microbes, in fact, play an important role in the carbon cycle, and interactions between plants, soil, and microbes are complex, presenting a challenge to climate scientists. Most climate models assume that plants compete for nutrients in the soil only when they're demanding it for photosynthesis, and not, for example, at night or in non-growing seasons.

"What most climate models have ignored is this pretty robust observational literature showing plants acquire nitrogen from soil even when they're not photosynthesizing," Riley said.

Berkeley Lab has been focused on the topic of plant-soil-microbe interactions through its Microbes to Biomes initiative, and it will be a core theme of the Biological and Environmental Program Integration Center, or BioEPIC, a proposed facility that would house one-of-a-kind experimental capabilities to advance DOE's mission objectives in energy and environmental science. One aim is to represent and study these processes at scale and in a controlled way.

"This study demonstrates progress in more mechanistically representing the terrestrial processes that are important for climate and will be important for BioEPIC," Riley said.

Lower nitrous oxide emissions

In this study, Berkeley Lab researcher Qing Zhu, a co-author of the paper, conducted a meta-analysis of 120 experiments of short-term nitrogen uptake by plants to test their new global land model, named ELMv1. "We also compared observations of nutrient uptake at nighttime versus daytime and across non-growing seasons," Riley said. "We're pretty confident that the basic mechanisms in the model are correct and this meta-analysis and individual site observations back that up."

They found that a significant portion of nutrient uptake takes place in the absence of photosynthesis as plants and microbes compete for nutrients. "The amounts vary a lot by latitude, but in the higher latitudes, such as the Arctic, roughly 20 percent of plants' annual nitrogen uptake occurs outside the growing season. That goes up to 55 percent for nighttime uptake in the tropics," he said. "That's a huge deal for plants and will facilitate atmospheric carbon uptake, and it's currently completely ignored in most climate models."

"This type of model improvement will help us better understand implications of future CO2 emissions," Riley said.
An additional co-author of the paper, "Weaker Land-Climate Feedbacks from Nutrient Uptake During Photosynthesis-Inactive Periods," was Berkeley Lab scientist Jinyun Tang. The study was funded by DOE's Office of Science.

Lawrence Berkeley National Laboratory addresses the world's most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab's scientific expertise has been recognized with 13 Nobel Prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy's Office of Science. For more, visit

DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit

DOE/Lawrence Berkeley National Laboratory

Related Photosynthesis Articles:

Photosynthesis olympics: can the best wheat varieties be even better?
Scientists have put elite wheat varieties through a sort of 'Photosynthesis Olympics' to find which varieties have the best performing photosynthesis.
Strange bacteria hint at ancient origin of photosynthesis
Structures inside rare bacteria are similar to those that power photosynthesis in plants today, suggesting the process is older than assumed.
Just how much does enhancing photosynthesis improve crop yield?
In the next two decades, crop yields need to increase dramatically to feed the growing global population.
Algal library lends insights into genes for photosynthesis
To identify genes involved in photosynthesis, researchers built a library containing thousands of single-celled algae, each with a different gene mutation.
New molecular blueprint advances our understanding of photosynthesis
Researchers at Lawrence Berkeley National Laboratory have used one of the most advanced microscopes in the world to reveal the structure of a large protein complex crucial to photosynthesis, the process by which plants convert sunlight into cellular energy.
How bacteria build hyper-efficient photosynthesis machines
Researchers facing a future with a larger population and more uncertain climate are looking for ways to improve crop yields, and they're looking to photosynthetic bacteria for engineering solutions.
Structure and function of photosynthesis protein explained in detail
An international team of researchers has solved the structure and elucidated the function of photosynthetic complex I.
Photosynthesis like a moss
Moss evolved after algae but before vascular land plants, such as ferns and trees, making them an interesting target for scientists studying photosynthesis, the process by which plants convert sunlight to fuel.
'Turbocharging' photosynthesis in corn hikes yield
Scientists from the Boyce Thompson Institute (BTI) and Cornell University have boosted a carbon-craving enzyme called RuBisCO to turbocharge photosynthesis in corn.
Eco-friendly nanoparticles for artificial photosynthesis
Researchers at the University of Zurich have developed a nanoparticle type for novel use in artificial photosynthesis by adding zinc sulfide on the surface of indium-based quantum dots.
More Photosynthesis News and Photosynthesis Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

Why do we revere risk-takers, even when their actions terrify us? Why are some better at taking risks than others? This hour, TED speakers explore the alluring, dangerous, and calculated sides of risk. Guests include professional rock climber Alex Honnold, economist Mariana Mazzucato, psychology researcher Kashfia Rahman, structural engineer and bridge designer Ian Firth, and risk intelligence expert Dylan Evans.
Now Playing: Science for the People

#540 Specialize? Or Generalize?
Ever been called a "jack of all trades, master of none"? The world loves to elevate specialists, people who drill deep into a single topic. Those people are great. But there's a place for generalists too, argues David Epstein. Jacks of all trades are often more successful than specialists. And he's got science to back it up. We talk with Epstein about his latest book, "Range: Why Generalists Triumph in a Specialized World".
Now Playing: Radiolab

Dolly Parton's America: Neon Moss
Today on Radiolab, we're bringing you the fourth episode of Jad's special series, Dolly Parton's America. In this episode, Jad goes back up the mountain to visit Dolly's actual Tennessee mountain home, where she tells stories about her first trips out of the holler. Back on the mountaintop, standing under the rain by the Little Pigeon River, the trip triggers memories of Jad's first visit to his father's childhood home, and opens the gateway to dizzying stories of music and migration. Support Radiolab today at