LONDON, June 8 (Portal) – Countries are preparing intensely for extreme weather events later this year as the world slides into an El Niño – a natural climate phenomenon fueling tropical cyclones in the Pacific and risking rain and flooding in parts America’s elevated and elsewhere.
On Thursday, the US National Oceanic and Atmospheric Administration (NOAA) declared that an El Niño was now underway. The last three years have been shaped by the cooler La Nina pattern.
Scientists say this year is looking particularly worrying. The last time a strong El Nino was in full swing was 2016, when the world experienced its hottest year on record. Meteorologists predict that this El Nino, coupled with excessive warming from climate change, will mean the world struggles with record high temperatures.
Even experts are concerned about what’s going on in the ocean. An El Niño means the water in the eastern Pacific is warmer than usual. But even before that El Nino began in May, the average global sea surface temperature was about 0.1 °C (0.2 °F) higher than all other recorded temperatures. This could amplify extreme weather.
“We’re in unprecedented territory,” said Michelle L’Heureux, meteorologist at NOAA’s Climate Prediction Center.
Graphics explaining how El Nino works. Two charts showing climate patterns in the Pacific Ocean for neutral and El Niño conditions.
According to a study published last month in the journal Science, this year’s El Niño could result in $3 trillion in global economic losses and shrink GDP as extreme weather conditions affect agricultural production and manufacturing and spread disease contribute.
Governments in vulnerable countries are taking note. Peru has allocated $1.06 billion to deal with the effects of El Niño and climate change, while the Philippines – which is threatened by cyclones – has formed a special government team to deal with the predicted consequences.
Here you can find out how El Niño will develop and what weather we can expect:
WHAT DOES EL NINO CAUSE?
El Nino is a natural climate pattern that arises from unusually warm waters in the eastern Pacific.
It occurs when trade winds blowing east-west along the equatorial Pacific slow or reverse due to changes in barometric pressure, though scientists aren’t entirely sure what triggers the cycle.
As the trade winds affect the sun-warmed surface waters, weakening causes these warm western Pacific waters to slosh back into the colder central and eastern Pacific basins.
During the 2015-16 El Niño — the strongest such event on record — anchovy stocks off the coast of Peru collapsed due to this inrush of warm water. And nearly a third of the coral on Australia’s Great Barrier Reef has died. In waters that are too warm, corals expel living algae, causing them to calcify and turn white.
This pool of warm water in the eastern Pacific also transfers heat high into the atmosphere through convection, resulting in thunderstorms.
A farmer removes dried plants from his dried up paddy field on the outskirts of Ahmedabad, India September 8, 2015. Picture taken September 8, 2015. Portal/Amit Dave/
“When El Nino moves this warm water, it moves where thunderstorms happen,” said NOAA meteorologist Tom DiLiberto. “This is the first atmospheric domino to fall.”
How does El Niño affect the world’s weather?
This shift in storm activity is affecting the stream of fast-moving air that is moving weather around the world — known as the subtropical jet stream — by shifting its path southward and smoothing it into a flatter stream that delivers similar weather at the same latitudes.
“If you change where the storm highway goes … you change what kind of weather we would expect,” DiLiberto said.
During an El Niño, the southern United States experiences cooler, wetter weather while parts of the western United States and Canada experience warmer, drier weather.
Hurricane activity subsides as Atlantic storms fail to form due to wind changes and United States is spared. But tropical cyclones in the Pacific are on the rise, and the storms often turn toward vulnerable islands.
Some parts of Central and South America experience heavy rainfall, although the Amazon rainforest tends to suffer from drier conditions.
And Australia suffers from extreme heat, drought and bushfires.
El Nino could offer a reprieve for the Horn of Africa, which recently experienced five failed rainy seasons in a row. El Nino brings more rain to the Horn, in contrast to the triple La Nina that dried out the region.
Historically, both El Nino and La Nina have occurred on average about every two to seven years, with El Nino lasting 9 to 12 months. La Nina, which occurs when the waters in the eastern Pacific are cooler, can last for one to three years.
Does climate change affect El Niño?
How climate change might affect El Niño is “a very big research question,” DiLiberto said. While climate change is doubling the effects of El Niño—heat stacks on top of heat, or excess precipitation on excess precipitation—it’s less clear whether climate change is affecting the phenomenon itself.
Scientists aren’t sure if climate change will shift the balance between El Niños and La Nina, making a pattern more or less frequent. If sea temperatures rise across the board, the cycle is unlikely to change, scientists say, because the basic mechanics behind the phenomenon remain the same.
However, if some parts of the ocean warm up faster than others, it could affect the evolution of El Niño by amplifying temperature differences.
(This story was resubmitted to correct the spelling of a name in paragraph 14.)
Reporting by Gloria Dickie in London. Edited by Angus MacSwan
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Gloria Dickie