The ‘southern hot spot’ in the Pacific Ocean is causing a mega-drought thousands of kilometers in Chile

(CNN) – In the southwestern Pacific Ocean, there is a huge region of unusually warm water that covers an area the size of Australia, known as the “Southern Spot”.

Several thousand kilometers away in South America, Chile has been experiencing a mega-drought for more than a decade, with decreased rainfall and water supplies.

On the surface, these two events have nothing to do with each other, but, a new study found, they are linked by invisible forces of global atmospheric pressure and circulation.

The southern spot, located east of Australia and New Zealand, emerged about four decades ago, probably caused by a natural decrease in rainfall in the central tropical Pacific.

Falling rain affected atmospheric circulation in the region, creating wind patterns that changed the way warm and cold currents flow into the ocean, guiding more warm water into the patch while pushing cold water downward.

The warm surface water that forms the stain heats the air above it, and as the atmosphere warms, it expands into a “large, wide area of ​​high pressure,” known as a high-pressure ridge, said Kyle Clem, co-author of the study and professor of climate science at Victoria University of Wellington.

This mountain range, which stretches across the South Pacific, changes the path that storms often take as they move through the oceans, known as “storm tracks.” Due to the ridge, the storm systems drifted south towards Antarctica and away from the west coast of South America.

The coastal region of South America, including central Chile, Argentina, and parts of the Andes Mountains, depends on those winter storms to replenish freshwater supplies before the dry summer season. With storms now redirected to Antarctica, Chile has been plunged into severe drought conditions since 2010, with widespread damage to the environment and people’s livelihoods.

The study, published Thursday in the journal Journal of Climate, marks the first time that researchers have established a direct connection between the hot spot and the mega-drought.

This is the longest drought in Chile in the meteorological record, according to the POT. The last mega-drought of this scale probably took place in the region more than 1,000 years ago, according to René D. Garreaud, a scientist at the University of Chile and one of the study’s co-authors.

The El Colorado ski resort with mostly melted snow, in the middle of the 2021 winter season, in Santiago de Chile.

South America had previously experienced a general decrease in rainfall dating back decades, coinciding with the appearance of the Southern Spot. But it was sporadic: sometimes there were years of drought and other times heavy rains.

But as climate change intensified, global warming caused the patch to expand and get much warmer in the last decade, and the drought soon became a continuous and never-ending stretch. During the winter season in the southern hemisphere, the patch heats up about three times faster than the global average in other parts of the ocean, Clem said.

“So this started in the central tropical Pacific, warmed up a bit, the pattern continues for 40 years, then just added heat to it because of increased greenhouse gases,” Clem said. “That is what has allowed the spot to reach such extreme warming rates … which is why we are seeing an unprecedented drought.”

The prolonged drought has devastated farms across Chile, with poor harvests and massive livestock deaths. Reservoirs are at critically low levels and residents of some rural areas are now dependent on water supplies from tanker trucks.

The side effects of the hot spot have been felt elsewhere as well. As the change causes warmer air to move towards Antarctica, it has caused a reduction in Antarctic sea ice, which in turn threatens the region’s delicate ecosystems and could have far-reaching consequences in altering the global weather patterns.

It’s unclear when or if the stain will dissipate, which is what Clem and the team plan to study next. The decline in rainfall is expected to subside at some point, but the researchers don’t know if that will be enough to break up the stain, or if it will be sustained only by human-caused heat.

“One of the most fascinating things about this is that we have this anthropogenic (man-made) signal in the climate system, which is the blob, in the middle of nowhere,” Clem said. “But because of the way ocean circulations are shaped, it has the ability to influence regional climates where large numbers of people live, tens of thousands of miles away.”

“What our study shows is that, with human-induced climate change, what happens in one place doesn’t necessarily stay there.”