Climate models overestimate CO2 retention by plants

June 21. () –

According to a new study, the carbon stored by plants globally has a shorter life and is more vulnerable to climate change than previously believed.

The findings have implications for our understanding of nature’s role in climate change mitigation, including the potential for nature-based carbon removal projects, like massive tree planting.

The research, carried out by an international team led by Dr Heather Graven at Imperial College London and published in Sciencereveals that existing climate models underestimate the amount of carbon dioxide (CO2) that vegetation absorbs globally each year, while overestimating the time that carbon remains there.

Dr Graven, Associate Professor of Climate Physics in Imperial’s Department of Physics, said: “Plants around the world are actually more productive than we thought.”

The findings also mean that while plants absorb carbon faster than previously thought, the carbon is also trapped for a shorter time, meaning carbon from human activities will be released back into the atmosphere sooner. than previously anticipated.

Dr. Graven added it’s a statement: “Many of the strategies that governments and corporations are developing to address climate change depend on plants and forests absorbing the CO2 that warms the planet and storing it in the ecosystem.

“But our study suggests that the carbon stored in living plants does not stay there as long as we thought. The study highlights that the potential of these nature-based carbon removal projects is limited and that fossil fuel emissions must be reduced rapidly to minimize the impact of climate change.”

Until now, the rate at which plants use CO2 to produce new tissues and other parts globally (a measure known as Net Primary Productivity) has been approximated by expanding data from individual sites. But the paucity of sites with comprehensive measurements means it has not been possible to accurately calculate Net Primary Productivity globally.

Plant productivity has increased since the beginning of the 20th century and currently plants absorb more CO2 than they release into the air. Researchers know that approximately 30% of CO2 emissions from human activities are stored in plants and soils each year, reducing climate change and its impacts.

However, The details of how this storage occurs and its stability in the future are not well understood.

In this study, radiocarbon (14C), a radioactive isotope of carbon, was combined with model simulations to understand how plants use CO2. CO2 on a global scale, which has allowed us to obtain valuable information on the interaction between the atmosphere and the biosphere.

Radiocarbon occurs naturally, but nuclear bomb testing in the 1950s and 1960s increased the level of 14C in the atmosphere. This extra 14C was available to plants around the world, giving researchers a good tool to measure the speed at which they could absorb it.

By examining the accumulation of 14C in plants between 1963 and 1967 (a period in which there were no significant nuclear detonations and total 14C in the Earth system was relatively constant), the authors were able to assess the rate at which carbon moves from the atmosphere to the vegetation and what happens to it once it is there.

The results show that current, widely used models that simulate how land and vegetation interact with the atmosphere underestimate the net primary productivity of plants globally. The results also show that the models overestimate the carbon storage time in plants.

Co-author Dr Charles Koven, of Lawrence Berkeley National Laboratory, said: “These observations correspond to a unique time in history, just after the peak of atmospheric atomic weapons testing in the 1960s.

“The observations show that plant growth at that time was faster than current climate models estimate. The importance is that it implies that carbon circulates more quickly between the atmosphere and the biosphere than we thought, and that we need to better understand and account for this faster cycle in climate models.”

The authors say the research demonstrates the need to improve theories about how plants grow and interact with their ecosystems, and adjust global climate models accordingly, to better understand how the biosphere is mitigating climate change.