Although air pollution levels have dropped since the coronavirus outbreak, the climate crisis will not go away. Scientists warn that in the near future, some areas of the United States may be on the verge of becoming a desert.
Based on analysis of rainfall levels since the turn of the century and comparing them to soil moisture levels over the past 1,200 years from tree rings, simulations indicated that a mega-drought could begin in the southwestern United States.
The researchers note that the conditions that have been observed in the region since 2000 coincide with times of severe drought in the past. It's possible that the desert transformation has already begun, although rainfall in 2019 did give some breathing room.
While the current drought could have happened anyway, the researchers estimate that global warming is causing the rate and intensity of the drought, producing hotter air that can hold more moisture from the ground.
“It doesn't matter if it's the worst drought in the world,” says environmental scientist Benjamin Cook of Columbia University. “The important thing is that it's because of climate change.”
Survey area. (Adapted from Williams et al., Science, 2020)
Earlier droughts were caused by natural factors such as ocean cooling, which prevented storms from reaching the US west coast. Add these factors to a human-induced rise in temperature of about 1.2 degrees Celsius, and it's a scary picture.
Rising temperatures could offset the natural variability in precipitation seen in past centuries, making droughts longer, more severe and more widespread. Signs of this shift are popping up everywhere, not just in North America.
The study also found that the 20th century was the wettest of all 1200-year periods, which may have led us to a false sense of security about how hard we need to work to protect the climate.
“The twentieth century gave us an overly optimistic view of how much water is potentially available,” Cook says. 'This suggests that such research is not only about ancient history. They are about problems that are already here. '
The research was published in the journal Science.
