Pacific ‘hot spot’ causes massive drought in Chile
(CNN) – In the southwest Pacific, there is a huge area of unusually warm water covering an area the size of Australia, known as the “South Point”.
Several thousand kilometers away in South America, Chile has been experiencing a severe drought for more than a decade, with reduced rainfall and water supplies.
On the surface, these two events have nothing to do with each other, but a new study has found that they are related to invisible forces from global atmospheric pressure and circulation.
The southern spot, located east of Australia and New Zealand, emerged about four decades ago, possibly due to the natural decrease in precipitation in the central tropical Pacific.
The falling rain affected atmospheric circulation in the area, creating wind patterns that changed the way warm and cold currents flow to the ocean, directing more warm water into the patch while pushing colder waters down.
said Kyle Clem, co-author of the study and professor of climate sciences at Victoria University of Wellington.
This mountain range, which stretches across the South Pacific, alters the path storms often take as they move across the oceans, known as “storm tracks.” Because of the ridges, storm systems have 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 their fresh water 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 was published Thursday in the journal Climate Magazine, is the first time researchers have established a direct relationship between the hot spot and the megadrought.
This is the longest drought in Chile in the meteorological record, according to NASA. The last major drought of this scale likely occurred in the region more than 1,000 years ago, according to Rene de Garrod, a scientist at the University of Chile and one of the study’s co-authors.
South America previously experienced an overall decrease in precipitation decades ago, coinciding with the appearance of the southern point. But it was intermittent: sometimes there were years of drought and other times there were torrential rains.
But as climate change intensifies, global warming has caused the area to get much warmer in the past decade, and droughts are quickly becoming an unending extension. During winter in the Southern Hemisphere, the spot warms three times faster than the global average in other parts of the ocean, Clem said.
“This started in the middle of the tropical Pacific, got a little hotter, and the pattern lasted for 40 years, then added heat to it because of the increase in greenhouse gases,” Clem said. “This is what has allowed the region to reach extreme rates of warming… and that’s why we are experiencing an unprecedented drought.”
A prolonged drought has decimated farms across Chile, with crops weakening and livestock dying dramatically. Reservoirs are at very low levels and residents of some rural areas are now dependent on water supplies from tanker trucks.
Hot spot side effects have been felt elsewhere, too. As the change causes warmer air to move toward Antarctica, it has caused a reduction in Antarctic sea ice, which in turn threatens the region’s sensitive ecosystems and could have far-reaching consequences in changing global weather patterns.
It’s unclear when or whether the stain will dissipate, which Clem and the team plan to study next. The decrease in precipitation is expected to subside at some point, but researchers don’t know if that will be enough to break up the spot, or if it will only persist due to human-caused heat.
“One of the most fascinating things about this is that we have this human (man-made) signal in the climate system, which is the point in the middle of nowhere,” Clem said. “But because of the way ocean circulation is shaped, it has the potential to affect 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.”