How does a “hot spot” near New Zealand contribute to the drought in Chile and Argentina? Ecology | Magazine

According to a new study, a warmer zone in the western South Pacific is causing a mega drought that has partially affected Chile and western Argentina.

Scientists have given a dialect name to this sea area near New Zealand and it is similar to the size of Australia: they call it “Warm place“Oh”Southern location”.

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The study, conducted by scientists from Chile and New Zealand, was published in the journal Climate Magazine From the American Meteorological Association.

Four times the heat

“All parts of the ocean are warming, but the southern hemisphere is warming, at least in the southern hemisphere,” said Ren சில Carrot, a Chilean climate researcher.

Professor of Geophysics at the University of Chile and Assistant Director of the Center for Climate and Recession, CR2.

The southern part is not the hottest part of the ocean because the tropics are so hot. But that’s the basic thing for researchers Heat rate.

“We focus on long-term trends, 40 years.”

“To give you an idea, on average one tenth of the ocean warms a decade, but this area warms about 0.4 degrees a decade, which means in 40 years it has warmed 1, 5 or 1.6 degrees.”

“This is four times the warming rate of your environment In the same latitudes as in the Pacific, Atlantic, or Indian Ocean.

Southern location and climate change

Hot sea spots are called in English BubblesOh Ocean heat waves (Ocean heat waves), a natural phenomenon already known to scientists.

But those places are usually temporary and can last a year or two.

“A sea heat wave was recorded in California a few years ago,” Garrett said.

“Suddenly there are a lot of those places on the Atlantic coast of South America that last for a few months and then you see scattered hot spots.”

“This is an unstable phenomenon associated with ocean currents.”

However, the location is close to New Zealand This is very unusual because it has been around for 40 years.. And the big question is whether this climate is due to climate change.

We know in terms of simulations that the southern part of the natural world can occur without the anthropological effect (of human action) of climate change. But it has a much higher rate of warming than we have seen in prehistoric times. “

“This leads to the end of two things. One is that staining can occur naturally. Second, climate change is pushing it forward, causing the Pacific region to heat up faster.

La Manza, “responsible for the Great Drought”

Garrett confirmed that “the stain now appears to be more directly responsible for the great drought in South America.”

“The test one can do on a sample is: ‘Let’s remove the stain and let the sea be normal in that area.’ When you do this test on a numerical model, you find that the drought is reduced by more than 70%.

“I will say it Drought is the cause of stains on at least three-quarters of the baseIn other words, stain plays a very, very important role.

In Chile, the mega-drought affected the central part of the country, covering an area of ​​1,000 kilometers. It stretches about 500 km north and 500 km south of Santiago.

In the western part of Argentina, the drought affects the region of Mendoza and Cuo.

From stains to dryness: gradually

If so, what is the sequence of events that link the location near New Zealand to the drought in South America?

“It starts with the stain, the warming surface in the ocean. That heat is transferred to the atmosphere, So the whole area above the stain is hot, it’s like you put a little flame on the bottom, in this case there is stain, “Karate began.

“Heat also goes hand in hand with atmospheric pressureAlso, as the wind blows from Australia to South America, higher temperatures are eventually translated into higher pressures Expanding across the PacificHe continued.

“What it’s doing when it expands is always the Pacific anticyclone.

The Pacific Anticyclone This explains why Santiago’s climate on the coasts of South America is generally drier than Montevideo, although both cities are at the same latitude.

But the effect of the stain is that it becomes more intense due to the anticyclone Prevents the arrival of storm front or front systems Central Chile, Cordillera and western Argentina.

In very simple terms, Carrot explained that the anticyclone is an air descent zone.

“An anticyclone is a component of high pressure and is formed by the descent of air, while it does the opposite when it rains: it condenses and eventually rises when it rains.”

“If you have these conditions that crush the atmosphere – I say it very colloquially – of course you have no chance of developing cloud and rain systems.”

In central Chile, unlike western Argentina, there is no summer rain.

“So our only chance is coming to the systems in front of the window, in the storm front, in the winter,” he continued.

“But with the increase in stains and pressure that has heated the atmosphere, the anticyclone has become more intense and closed the door to front systems that can reach central Chile.”

Hurricanes not reaching central Chile Moving further south.

Increased rainfall in the Magallanes and Deora del Fuego area.

“Even part of the Antarctic Peninsula has received more westerly winds and eventually more rain. The stain may have played a part there.”

Impact of major drought

The current drought in Chile for more than a decade is very different from what it was in the past.

“Our country has always had droughts and they are as severe as the Mediterranean climates like California, South Africa, Australia.”

“But Drought lasts from one to two years“Garrett explained.

The central region, which has been hit hard by the Great Drought, is home to “70 or 80% of Chileans, and agriculture, industry, commerce and some mines will be good areas.”

On the other hand, water consumption is increasing. “So you need less supply and more at the same time, which is a bad recipe.”

“To give you an idea, the average deficit is consistently 30%, ie We live one-third less than the average from 1980 to 2010”.

In Santiago, for example, we have an average of 330 mm.

Natural variation + climate change

James Renwick, a scientist not involved in the study, is the head of the Department of Geography, Environment and Geology at Victoria University in Wellington, New Zealand.

Renwick, who studied in the south, told BBC Mundo that the study’s best contribution would show “the combination of natural variation with continuous warming and climate change caused by greenhouse gas emissions.”

“Its effects on the hot spot and South American climate can occur naturally without any human assistance,” Renwick said.

“But the study clearly shows that climate change has increased global warming Its effects in Chile have increased due to climate change”.

“The biggest peaks we experience from climate change occur when natural variation in climate adds background warming.”

New Zealand meteorologist Kyle Clem, another author of the study, told BBC Mundo, “Growth in the south appears to be a natural phenomenon to reduce rainfall in the tropical central Pacific, but warming in the oceans is exacerbated by increased emissions of greenhouse gases.”

“Therefore, Natural climate change and anthropological climate change have come together It has caused such intense sea warming in the last 40 years, ”Clem added.

“This has created a high pressure zone that explains the unprecedented nature of the drought in central Chile.”

“Anticipation for the Future”

Garrett and his colleagues still have many questions to answer about Southern stains.

“So far we have only seen the surface of the stain … we know that part of the Pacific is accumulating more heat in the first few hundred meters.”

“With that, Million dollar question How (and how) the stain has a ‘natural’ appearance (and eventually reversible) and the contribution of climate change tends to maintain the stain.

“This sharing is not only of scientific interest. Your response can tell us the duration of this event and its fate in the decade we started.

The big question for many in Chile is how long the Great Drought will last.

“One can reasonably expect more or less the next few decades, Now and between 2030 and 2040, we will definitely be a little inverted Towards slightly more humid conditions. Because part of the stain has a natural appearance and that part eventually disappears, natural things have cycles and they go back and forth, “Garrett explained.

However, the scientist later said, “In the middle of the century, In 2050, 2060, this state of what we call mega-drought today will not be news because it will be a permanent regime”.

“Climate change is already on the tail, so I’m not expecting things to go back to the 80s or 90s in terms of rainfall. Unlike other places like Uruguay or central Argentina, the future in central Chile will be dry and hot, with rain and heat.”

“So to Central Chile The Great Drought is a foretaste of the future. As the future lay ahead of us, the signal of climate change mingled with the signal of natural variation. (I)