New Study Reveals Shorter Carbon Storage Period in Plants

A recent study has unveiled that the carbon sequestered by plants globally is stored for shorter periods and is more susceptible to climate change impacts than previously understood. Conducted by an international team led by Dr. Heather Graven from Imperial College London and published in Science, this research holds significant implications for climate change mitigation strategies, particularly nature-based carbon removal initiatives such as large-scale tree planting.

Revised Understanding of Carbon Storage

The study’s findings suggest that current climate models have underestimated the annual uptake of carbon dioxide (CO2) by vegetation while overestimating the duration of time this carbon remains sequestered. Dr. Heather Graven, a Reader in Climate Physics at Imperial College, highlighted that plants are more productive than previously thought, absorbing CO2 at a higher rate. However, this increased uptake is coupled with a faster release of carbon back into the atmosphere, challenging the assumption that carbon remains locked in plants for extended periods.

This revelation calls into question the effectiveness of relying on forests and other plant-based solutions to draw down and store planet-warming CO2. Dr. Graven emphasized that while plants are crucial in mitigating climate change, their capacity to store carbon long-term is limited, underscoring the urgent need to reduce fossil fuel emissions to minimize climate change impacts.

Enhanced Plant Productivity and Carbon Cycling

Traditionally, the rate at which plants utilize CO2 to produce new tissues—Net Primary Productivity—has been estimated by extrapolating data from specific sites. However, the scarcity of comprehensive measurement sites has hindered accurate global calculations. The study employed radiocarbon (14C) data, a radioactive isotope of carbon, to provide new insights into global plant productivity and carbon cycling.

Since the early 1900s, plant productivity has been on the rise, with plants currently absorbing more CO2 than they release. Approximately 30% of human-induced CO2 emissions are stored annually in plants and soils, playing a crucial role in reducing climate change impacts. Despite this, the mechanisms and stability of this carbon storage remain poorly understood. Using radiocarbon data from the post-atomic bomb testing era in the 1960s allowed researchers to better track how quickly carbon moves from the atmosphere into vegetation and its subsequent fate.

Implications for Climate Models

The study’s results demonstrate that widely used models overestimate the storage duration of carbon in plants while underestimating their productivity. Dr. Charles Koven from Lawrence Berkeley National Laboratory noted that the historical observations from the 1960s, a unique period following peak atmospheric nuclear testing, revealed faster plant growth than current models suggest. This indicates a more rapid cycling of carbon between the atmosphere and biosphere than previously believed, necessitating adjustments in climate models to accurately reflect this dynamic.

Co-author Dr. Will Wieder from the National Center for Atmospheric Research stressed the importance of refining our understanding of historical land carbon uptake to improve future climate projections. The study highlights the value of radiocarbon measurements in decoding the complexities of the biosphere’s role in climate regulation.

The findings of this study underline the necessity of re-evaluating the potential of nature-based carbon removal projects and enhancing our theoretical models to better predict and mitigate climate change. As global efforts to combat climate change intensify, this research provides critical insights that can inform more effective strategies and policies.