It hadn't rained here in centuries – now it's raining and everything's dying

atacama dessert
© Carlos González Silva

Recent rains attributed to a changing climate are leading to mass extinction in the Atacama Desert.

Upon first consideration, one might think "desert gets surprise rain, everything springs to life." But in the case of the Atacama Desert in northern Chile, this is decidedly not how things went down.

The Atacama Desert is an extreme place. As the driest and oldest desert on the planet, there has been little to no recorded rain there in the past 500 years. Well, until 2015 that is. Since March of that year, the hyper-arid expanse has been getting some rain ... and with the rain, death.

"When the rains came to the Atacama, we were hoping for majestic blooms and deserts springing to life," says Dr. Alberto G. Fairén, an astrobiologist from Cornell. "Instead, we learned the contrary, as we found that rain in the hyperarid core of the Atacama Desert caused a massive extinction of most of the indigenous microbial species there."

Oh dear.

"The hyperdry soils before the rains were inhabited by up to 16 different, ancient microbe species," he adds. "After it rained, there were only two to four microbe species found in the lagoons. The extinction event was massive."

In an international study exploring the devastation, the authors explain how the area's indigenous microorganisms have evolved to thrive under the harsh conditions of their super-arid habitat. But then climate changes over the Pacific brought on the rains. From the study:

"These rain events of 2015 and 2017 originated because extensive mass of clouds entered the Atacama from the Pacific Ocean (from the west) during the last days of autumn, an unprecedented phenomenon that took place twice in a period of only three years. Including other minor rain events in-between, during the 2015–2017 period mean annual precipitation reached values one order of magnitude higher than the usual for the region, up to 40 mm/m2. Climate models suggest that similar rain events could take place once about every century, however there are no records of similar rain events for at least the past 500 years."

The authors add:

This significant alteration in weather patterns has been attributed to global climate change, with important shifts in rain patterns that have randomly affected different areas of the core Atacama...

"Our group has discovered that, contrary to what could be expected intuitively, the never-before-seen rainfall has not triggered a flowering of life in Atacama, but instead the rains have caused enormous devastation in the microbial species that inhabited the region before the heavy precipitations," says Fairén.

While desert microbes may not have quite the same heartstrings tug of climate change poster children like polar bears and penguins, this is a sobering reminder that the effects of global warming reach far and wide. That 85 percent of the area's species – species that have been doing their microbial things there for the past 150 million years – have gone extinct feels like something worthy of attention. We were all told that climate change would look like sci-fi scenes of cities under water, and it might. But in the meantime, some puddles in the Atacama Desert feel like an eerie warning of things to come.

You can read the study here: Unprecedented rains decimate surface microbial communities in the hyperarid core of the Atacama Desert

It hadn't rained here in centuries – now it's raining and everything's dying
Recent rains attributed to a changing climate are leading to mass extinction in the Atacama Desert.

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