Countries around the world, from China to the United States, are battling heatwaves, with the onset of climate phenomenon El Niño helping to drive temperatures higher.
Climate change and El Nino are key drivers of extreme heat, scientists told Reuters, causing temperature records in Beijing and Rome to be broken, while some 80 million Americans have been warned of extreme heat.
El Niño is a natural phenomenon that, in addition to contributing to higher temperatures in many parts of the world, also drives tropical cyclones in the Pacific and increases the risk of rainfall and flooding in the Americas, Asia and elsewhere.
In June, the US National Oceanic and Atmospheric Administration (NOAA) announced that El Niño is now underway. A cold La Nina pattern has dominated the past three years.
Scientists have warned that this year looks particularly worrying. The last time a strong El Niño was in full swing in 2016, the world saw its warmest year on record. Meteorologists expect the world to grapple with record-high temperatures this El Niño as well as extreme heat from climate change.
Experts are also worried about what is happening in the sea. El Nino means that the waters in the eastern Pacific are warmer than normal. Globally, ocean temperatures set new records in the months of May and June, according to the European Union’s Copernicus Climate Change service. It can supercharge extreme weather.
“We are in unprecedented territory,” said Michel L’Heureux, a meteorologist at NOAA’s Climate Prediction Center.
According to a study published last month in the journal Science, this year’s El Niño could cause $3 trillion in global economic losses, with extreme weather slashing GDP, destroying agricultural production, manufacturing and helping spread disease.
Governments of weak countries are paying attention to this. Peru has set aside $1.06 billion to deal with the effects of El Niño and climate change, while the Philippines – at risk of cyclones – has set up a special government team to deal with the predicted fallout.
Here’s how El Nino will unfold and the kind of weather we can expect:
What is the cause of El Nino?
El Niño is a natural climate pattern resulting from unusually warm waters in the eastern Pacific.
It forms when the trade winds blowing from east to west along the equatorial Pacific Ocean slow or reverse due to changes in air pressure, although scientists are not entirely sure what initiates the cycle.
As the trade winds affect sun-warmed surface waters, the weakening forces these warm western Pacific waters back into the cooler central and eastern Pacific basins.
During the 2015-16 El Niño – the strongest such event on record – anchovy stocks off the coast of Peru crashed amid the onslaught of this warm water. And about a third of the corals on Australia’s Great Barrier Reef died. Corals in very warm water will expel live algae, causing them to calcify and turn white.
This buildup of warm water in the eastern Pacific transfers heat to the atmosphere through convection, causing hurricanes.
“When El Niño pushes that warm water forward, that’s where the storms come from,” said NOAA meteorologist Tom Diliberto. “This is the first atmospheric domino to fall.”
How does El Nino affect the world’s weather?
This change in storm activity causes the stream of fast-moving air that changes weather around the world – called the subtropical jet stream – to push its path south and straighten it into a flat stream. which gives similar climates with similar latitudes.
Diliberto said, “If you’re changing where the hurricane highway goes … you’re changing what kind of weather we would expect to see.”
During El Niño, the southern United States experiences cooler and wetter weather, while the US West and parts of Canada are hotter and drier.
Hurricane activity faltered as wind changes caused hurricanes to fail to form in the Atlantic, leaving the United States unscathed. But tropical cyclones are boosted in the Pacific, with storms often swerving toward vulnerable islands.
Parts of Central and South America receive heavy rainfall, although the Amazon rainforest is prone to dry conditions.
And Australia tolerates extreme heat, drought and bush fires.
El Niño could bring relief to the Horn of Africa, which has recently suffered five consecutive failed rainy seasons. Unlike the triple-dip La Niña, El Niño brings more rain to the Horn, which has left the region dry.
Historically, both El Niño and La Niña occur on average every two to seven years, with El Niño lasting 9 to 12 months. La Niña, which takes effect when water cools in the eastern Pacific, can last from one to three years.
Is Climate Change Affecting El Niño?
How climate change might affect El Niño is “a huge research question,” Diliberto said. While climate change is doubling the effects of El Niño – putting heat on top of heat, or more rain on top of more rain – it is less clear whether climate change itself is influencing the phenomenon.
Scientists are not certain whether climate change will alter the balance between El Niño and La Niña, making one pattern more or less frequent. If ocean temperatures are rising across the board, it is unlikely that the cycle will change, the scientists said, because the basic mechanics behind the phenomenon remain the same.
However, if some parts of the ocean are warming faster than others, it can influence El Niño by exaggerating the temperature difference.
(Except for the headline, this story has not been edited by NDTV Staff and is published from a syndicated feed.)