Scientists warn climate change could reach the 'tipping point' sooner than predicted
The threat may be even graver than scientists have anticipated. In 2018, global carbon emissions hit the highest levels yet and researchers now warn Earths tipping point may be fast approaching. If emissions continue at the current rates, a new study found that the planets vegetation may not be able to keep up and, once plants and soil hit the maximum carbon uptake they can handle, warming could rapidly accelerate. The new study from Columbia Universitys School of Engineering and Applied Science investigates how the hydrological cycle ties into Earths ability to sequester carbon dioxide. As warming occurs, rainfall patterns around the world are expected change and with that, the ability of vegetation to uptake carbon. It is unclear, however, whether the land can continue to uptake anthropogenic emissions at the current rates, says lead researcher Pierre Gentine. 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. The researchers analyzed a factor known as net biome productivity (NBP) using data from the Global Land Atmosphere Coupling Experiment--Coupled Model Intercomparison Project (GLACE-CMIP5). This allowed them to define how much carbon is tored in vegetation and soil, and isolate the effects of changes in soil moisture. We saw that the value of NBP, in this instance a net gain of carbon on the land surface, would actually be almost twice as high if it werent for these changes (variability and trend) in soil moisture, said lead author PhD student Julia Green. This is a big deal. If soil moisture continues to reduce NBP at the current rate, and the rate of carbon uptake by the land starts to decrease by the middle of the 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,' Green said. According to the researchers, the soil-moisture variability reduces lands ability to soak up carbon. And, as climate change drives more extreme weather events including droughts and heat waves the problem could soon get much worse. Essentially, if there were no droughts and heat waves, if there were not going to be any long-term drying over the next century, then the continents would be able to store almost twice as much carbon as they do now, Gentine said. Because soil moisture plays such a large role in the carbon cycle, in the ability of the land to uptake carbon, its essential that processes related to its representation in models become a top research priority.