A new study led by researchers at Penn State University in State College, Pennsylvania, reveals that trees in warmer, drier climates are struggling to sequester carbon dioxide effectively. The study, published in the Proceedings of the National Academy of Sciences, highlights the challenges trees face in absorbing CO2 as the planet continues to warm.
According to the lead author of the study, Max Lloyd, trees in warmer and drier environments are experiencing increased rates of photorespiration—a process where stressed trees release CO2 back into the atmosphere. This phenomenon compromises the ability of trees to act as natural carbon sinks, raising concerns about their role in mitigating climate change.
Through an analysis of a global dataset of tree tissue, researchers found that trees in warmer climates exhibit photorespiration rates up to two times higher, especially when water is scarce. This trend becomes more pronounced as temperatures rise, particularly in subtropical regions where daytime temperatures exceed 68 degrees Fahrenheit.
The findings challenge the conventional belief that plants assist in drawing down carbon from the atmosphere, shedding light on the complexities of plant adaptation to climate change. As the climate warms, plants may struggle to absorb CO2 effectively, hindering their capacity to help cool the planet.
Lloyd emphasized the crucial link between plants and climate, noting that small changes in plant behavior can have significant impacts on atmospheric composition. While plants currently absorb about 25% of human-generated CO2 emissions each year, this percentage is expected to decline as temperatures rise, especially in water-scarce environments.
The study introduced a novel method to measure photorespiration rates in trees by examining isotopic variations in wood samples. By analyzing these isotopes, researchers can track how trees have responded to changing environmental conditions over time, offering insights into future climate scenarios.
Looking ahead, the research team plans to investigate photorespiration rates in ancient plant species using fossilized wood samples. This approach will provide valuable information on how plant behavior has evolved over millions of years, guiding predictions of future climate dynamics.
The study was funded by the Agouron Institute, the Heising-Simons Foundation, and the U.S. National Science Foundation, underscoring the collaborative effort to advance understanding of plant responses to climate change. Further research in this area promises to deepen our knowledge of the intricate relationship between plants, carbon cycling, and climate dynamics.