SOURCE: Columbia University
DATE: January 23, 2019
SNIP: A Columbia Engineering study, published today in Nature, confirms the urgency to tackle climate change. While it’s known that extreme weather events can affect the year-to-year variability in carbon uptake, and some researchers have suggested that there may be longer-term effects, this new study is the first to actually quantify the effects through the 21st century and demonstrates that wetter-than-normal years do not compensate for losses in carbon uptake during dryer-than-normal years, caused by events such as droughts or heatwaves.
Currently, the ocean and terrestrial biosphere (forests, savannas, etc.) are absorbing about 50% of CO2 releases.
“It is unclear, however, whether the land can continue to uptake anthropogenic emissions at the current rates,” says Pierre Gentine, associate professor of earth and environmental engineering and affiliated with the Earth Institute, who led the study. “Should the land reach a maximum carbon uptake rate, global warming could accelerate, with important consequences for people and the environment. This means that we all really need to act now to avoid greater consequences of climate change.”
“If soil moisture continues to reduce net biome productivity (NBP) at the current rate, and the rate of carbon uptake by the land starts to decrease by the middle of this century—as we found in the models—we could potentially see a large increase in the concentration of atmospheric CO2 and a corresponding rise in the effects of global warming and climate change.”
Gentine and Green note that soil-moisture variability notably reduces the present land carbon sink, and their results show that both variability and drying trends reduce it in the future.