Plants are not holding onto carbon for as long as we previously thought, according to a new study analyzing radioactive carbon-14 from 20th-century bomb tests. The analysis reveals that plants store more carbon in short-lived tissues like leaves than previously estimated, making this carbon more susceptible to re-release into the atmosphere. This finding could have significant implications for our understanding of the biosphere’s capacity to sequester carbon and its impact on climate change.
The bomb tests conducted in the mid-20th century released pulses of radioactive carbon-14 into the atmosphere, which became part of Earth’s carbon cycle. Scientists have been able to use this radiocarbon as a tracer to study how carbon is stored and released by plants and soil. This information is crucial as we seek to understand the role of the biosphere in mitigating climate change by absorbing carbon dioxide emissions.
Current climate models estimate that plants and soil absorb about 30 percent of human-caused carbon dioxide emissions. However, the new study suggests that these models may be underestimating the amount of carbon stored by plants. Researchers found that plants are growing faster and absorbing more carbon than previously thought, potentially doubling the amount of carbon they take up each year. This is promising for carbon sequestration efforts, but there is a downside.
The study also found that more carbon is being stored in short-lived plant tissues, such as leaves and fine roots, which are more prone to degradation and releasing carbon back into the atmosphere. This means that the carbon absorbed by plants may not stay sequestered for as long as we had assumed. It underscores the importance of reducing fossil fuel emissions to limit the amount of carbon that needs to be stored in vegetation.
The implications of these findings for future climate projections are still unclear, according to experts. While it may challenge our confidence in current climate models, it also highlights the need to better understand how vegetation interacts with the carbon cycle. By reevaluating our assumptions about carbon storage in plants, we can improve our efforts to address climate change and protect the environment for future generations.