climate change does not cause the perennial drought Those are devastating parts of Argentina, Uruguay, Brazil and Bolivia, but warming is exacerbating some of the effects of the drought, a new study says.
The natural three-year climatic condition of La Nina — A central Pacific cooling that is temporarily altering weather around the world but this time lasting much longer than normal — is the main culprit in a drought that has ravaged central South America and is still ongoing, according to a lightning study released Thursday by international scientists at World Weather Attribution. The study has not yet been reviewed.
Drought hit the region since 2019, with last year being the driest year in central Argentina since 1960, widespread crop failures and Uruguay declaring an agricultural emergency in October. Water supply and transportation were also hampered.
“There is no signal for climate change in the rain,” said study co-author Friederike Otto, of the Grantham Institute at Imperial College London. “Of course, that doesn’t mean that climate change doesn’t play an important role in connection with these droughts. Due to the extreme increase in heat that we are seeing, the soils are drying faster and the effects are more severe than they otherwise would have been.”
The heat has increased evaporation of what little water there is, exacerbating a natural water shortage and contributing to the destruction of crops, scientists said. The same group of scientists found that climate change made last December’s heatwave 60 times more likely.
And tree felling in the southern Amazon in 2020 hit the highest rate in a decade, and that means there’s less moisture available farther south in Argentina, said the study’s lead author Paola Arias, a climate scientist and professor at the university’s environmental school from Antioquia in Colombia.
World Weather Attribution’s team of scientists use observations and climate models to see if they can find a climate change factor in how often or how severely extreme weather occurs. They compare what happened, how often it happened in the past, and they run computer simulations that compare reality to what would have happened in a world without human-caused climate change from burning fossil fuels.
In the case of this drought, the models do show a slight, non-significant increase in humidity from climate change, but a clear link to La Nina, which scientists say is decreasing. It will be months, if not longer, for the region to emerge from the drought — and that depends on whether the downside of La Nina — El Nino — occurs, said study co-author Juan Rivera, a scientist at the Argentine Institute for Snow Research, Glaciology and Environmental Sciences.
In the past, the team of scientists has found no obvious link to climate change for some droughts and floods, but they note that global warming is a factor in most of the severe weather events they study.
“One of the reasons we are doing these attribution studies is to show what the realistic effects of climate change are. And it’s not like climate change is making things worse,” Otto said. “Not everything bad that’s happening now is due to climate change.”
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