Winter heatwave in Andes is sign of things to come, scientists warn

Human-caused climate disruption and El Niño push temperature in mountains to 37C

Exceptional winter heat in the Andean mountains of South America has surged to 37C, prompting local scientists to warn the worst may be yet to come as human-caused climate disruption and El Niño cause havoc across the region.

The heatwave in the central Chilean Andes is melting the snow below 3,000 metres (9,840ft), which will have knock-on effects for people living in downstream valleys who depend on meltwater during the spring and summer.

Tuesday was probably the warmest winter day in northern Chile in 72 years, according to Raul Cordero, a climate scientist at the University of Groningen, who said the 37C recorded at the Vicuña Los Pimientos station in the Coquimbo region was caused by a combination of global heating, El Niño and easterly gusts, known by locals as Terral winds that bring hot, dry weather.

Dozens of meteorological monitoring stations at more than 1,000 metres altitude recorded temperatures above 35C in winter, according to the Extreme Temperatures Around The World blog.

Cordero said the unusual heat at this altitude was a worry. “The main problem is how the high temperatures exacerbate droughts (in eastern Argentina and Uruguay and accelerate snow melting.”

Water shortages are already a dire problem in and around Uruguay’s capital, Montevideo, where reservoirs are running dry and tap water is no longer drinkable.

South America has suffered one of the warmest January-to-July periods on record. Chile has been among the worst affected countries with fires at the beginning of the year and now extended droughts. Cordero said Santiago was sweltering in its ninth heatwave since January and was expected to break the annual record of 10 heatwaves, set in 2020.

Marcos Andrade, the director of atmospheric physics at the Universidad Mayor de San Andrés in La Paz, said the Andean plateau in Bolivia and Peru had also experienced “unusual” weather since the start of the year.

“At Puno, on the other side of Titicaca Lake, they had their driest January since records began 59 years ago. In May, we had a storm with 20% of the usual annual rainfall,” he said. “The winter has also been unusually warm. We broke temperature records in some parts of the country.”

He expressed concern that worse may follow as the southern hemisphere approaches its summer. “El Niño usually peaks at the end of the year. I don’t think we have seen the full effects yet.”

Heat records have been broken in several cities in Brazil, Argentina and Uruguay. Karla Beltrán, an environmental consultant, said that this year Buenos Aires had also recorded its highest ever temperature of 38.6C on 11 March, while the city of Mercedes in Uruguay hit a new peak of 40.5C.

She said the heatwave was in line with the latest report of the Intergovernmental Panel on Climate Change, which noted that the southern part of South America was particularly vulnerable to episodes of high temperatures. Studies have shown that northern South America, including the Amazon region and the Pacific coast up to the Atacama desert, will experience more frequent and intense heatwaves. “With the arrival of the El Niño phenomenon, it is expected that in the coming years this region will suffer an increase in the already high temperatures, making it necessary to take adaptation measures to avoid deaths and greater disasters,” she said.

Chico Geleira, a professor of climatology and oceanography at the Universidade Federal do Rio Grande do Sul and deputy director of Brazil’s Polar and Climatic Center, said the trends were concerning. “Without a doubt, the maximum temperature records in winter in Chile and, to a certain extent, in South America are atypical,” he said.

“High pressure systems are more intense and persistent anomalies in the southern hemisphere, inducing hot air advection and/or directly generating temperature extremes. This high pressure will tend to remain and intensify in the coming decades with climate change.”

Snow in the Chilean Andes Photograph: Francisco Arias/Zuma Wire/Rex/Shutterstock