The rapid rate at which human-caused climate change is altering terrestrial carbon stores threatens to undermine current mitigation efforts unless behavioral changes are implemented quickly. Using a dozen long-term global GPP Gross Primary Production datasets, scientists from Nanjing Agricultural University quantified the evolution of global GPP trends.
Anthropogenic climate change has been a prominent issue for decades and remains a critical concern. As with any complex problem, analyzing historical data is crucial for understanding trends and informing solutions. Gross primary productivity (GPP), a key indicator of ecosystem health, measures the amount of CO2 fixed by plants per unit of time and area. To better understand future trends and inform efforts to meet the Paris Agreement’s goal of limiting global temperature increases to at least 2℃, researchers have investigated the drivers of GPP change.
Researchers published their results in Ecosystem Health and Sustainability in December 2024.
By utilizing a dozen long-term datasets on global GPP from the years 1982-2016, researchers observed a decrease of GPP across over 68% of the terrestrial surface of Earth. This finding alone points to a carbon sink saturation point, establishing a deeper sense of urgency to find ways to mitigate global climate change by altering our carbon-emitting activities.
Carbon sinks are natural features, such as forests, oceans and even the soil that absorb atmospheric carbon dioxide. Unlike humans, which exhale carbon dioxide, plants intake carbon dioxide to produce energy for photosynthesis to occur. If these carbon sinks reach a saturation point, atmospheric carbon dioxide is not being taken up as quickly or effectively. This leads to further warming of the atmosphere as this greenhouse gas is trapped, in addition to the overall lower productivity of plants.
“The decline in the CO2 fertilization effect is suggested to be the main driver accounting for the slowing-down of global GPP trends. Although it still has positive effects, the impact of rising CO2 on GPP on a global scale fell by about one-half from 2000 onwards compared to its impact in 1982–1999,” said Songhan Wang, researcher at Nanjing Agricultural University and author of the study.
The CO2 fertilization effect describes the potential for increased plant growth due to rising atmospheric carbon dioxide levels. However, despite increased CO2 availability, this effect is not being widely observed, likely due to nutrient limitations in soil and foliage.
If these research trends continue, current mitigation strategies that rely on terrestrial carbon sinks will become inadequate once those sinks reach saturation. Future efforts must focus on mitigating human-caused global temperature increases to at least 2℃ to achieve the Paris Agreement’s climate neutrality target.
