How Peruvian coastal deserts respond to rains will aid future disaster response

Barbara Fraser in Nature:

Torrential rains pummelled Peru’s northern coastal desert in February and March, triggering floods that killed at least 113 people and destroyed some 40,000 homes. As families grapple with their losses and government officials tally the cost of repair and reconstruction, scientists are gearing up for an unusual opportunity to study ecosystems that go decades without much rain. The rains were spurred by an unusual ‘coastal’ El Niño climate pattern, in which warm water pooled off the coast of southern Ecuador and northern Peru — more so than during the much larger 2015–16 El Niño. Rains fell in both countries, but the human toll was highest in Peru’s normally parched northern desert.

In the now-greening land, plants are growing, bird populations are shifting and rivers are moving sediments and pollution in ways they haven’t done for two decades. What scientists learn as they descend on the region could aid conservation efforts and help people and government officials to prepare for severe weather events. “Except for the impacts on the people,” says biologist Juan Torres of La Molina National Agrarian University in Lima, “this is a meteoro­logically enchanting moment.” Once roads are passable, Torres will visit field sites that he studied after the powerful 1997–98 El Niño, which also soaked the region. At that time, Torres found wild relatives of domesticated crops — including tomatoes, peppers, potatoes and squash — that had sprouted from dormant seeds. This year, he will again catalogue wild plants, along with the crops that farmers choose to grow on lands made fertile by the flooding. Part of the northern desert is irrigated farmland, but there are also patches of a dry forest that has been devastated in recent years by industrial agriculture, urban sprawl and the charcoal trade. Oliver Whaley at the Royal Botanic Gardens, Kew, in London, has studied Peru’s dry forests for 25 years, and hopes that the rain will bring respite to the ecosystem.

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