Why the heat wave that hit Argentina and Chile could be considered worse than that of Europe, the US and China

In recent days, temperatures in some areas of Chile and northern Argentina have been between 10°C and 20°C above average.

Cities in the Andes Mountains have reached 38°C or more, while Argentina’s capital, Buenos Aires, recorded temperatures above 30°C, surpassing the previous record set in August by more than 5°C. Maximum temperatures of 39 °C were reached in the city of Rivadavia.

Please note that we are in the middle of winter in this part of the world. And it’s far enough south that seasonal variations have a substantial impact on temperatures.

In terms of deviation from temperatures that would be expected at a given location and time of year, this heat wave is similar, if not greaterto the recent heat waves in southern Europe, the United States and China.

In Vicuña, one of the cities in the Chilean Andes that recently hit 38°C, a typical day in August can be around 18°C ​​– imagine it being 20°C warmer than usual wherever you are at this moment.

Not surprisingly, some climatologists have already suggested it could one of the most extreme heat waves ever recorded.

What causes the extreme heat?

A persistent high pressure area for the past six days, or anticyclone, has remained east of the Andes. Also known as “high block”seems to be the main cause of the intense heat.

Blocking anticyclones can cause heat waves in three ways. First of all, they draw in warmer air coming from near the equator.

The system too compresses and holds airwarming, as was the case with the 2021 heat wave in the Pacific Northwest, which broke the Canadian temperature record by almost 5°C.

Finally, the high pressures ensure that there is little rising air and thus little cloud cover. This allows the sun to continuously heat the land throughout the day, accumulating heat.

However, scientists need to take a closer look at the meteorology of this unprecedented event to gain a better understanding.

El Nino made it more likely

The heat wave between Chile and Argentina has been more likely due to the development of The boy in the Pacific Ocean. El Niño events, which typically occur about every four years, are characterized by warm sea surface temperatures in the central and eastern tropical Pacific.

Currently, temperatures in the Central Pacific are approx 1°C above average for the time of year.

These warmer ocean temperatures cause air to drift more over the central Pacific Ocean, causing the air to rise.

This causes changes in atmospheric circulation patterns past. El Niño-induced changes in atmospheric circulation typically result in higher pressure and warmer winter temperatures for this part of South America.

Climate change made it worse

The lockdown system that caused the extreme heat would likely have led to warm temperatures even if there was no anthropogenic climate change. However, the rapid warming caused by climate change allowed the heat wave to become truly unprecedented.

Climate scientists expect temperature records to be broken as our planet warms further. This is because the distribution of possible temperatures shifts higher and higher.

Chile has already experienced the effects of climate change recently with a severe heat wave in February – in late summer – that led to several deaths from wildfires, as well as a decade-long mega-drought.

The country recently rejected a new draft constitution that would have forced its government to take action on the nature and climate crises.

The long-term impact of a winter heat wave

The higher temperatures appear to have largely abated in the Andes. However, temperatures remain well above average in the Northern Argentina, Bolivia and Paraguayand will remain so for the next few days.

The effects of heat waves in winter are less well known than those of heat waves in summer. For Chile, the most likely impact is the snow cover in the mountains, which provides water for drinking water, agriculture and power generation.

He melting of the snowpack it is also likely to affect the diverse flora and fauna of the Andes.

Overall, this heat wave is a striking reminder of how humans are changing the Earth’s climate. We will continue to see these extremes unprecedented until we stop burning fossil fuels and emitting greenhouse gases into the atmosphere.

*Matthew Patterson Postdoctoral Research Assistant in Atmospheric Sciences, University of Oxford, UK.

*This article was published on The Conversation and reproduced here under the Creative Commons license. Click here to read the original version.