The super El Niño climate phase that has begun in the Pacific Ocean is already the strongest on record on some measures. When it peaks at the end of this year, sea surface temperatures in the east-central Pacific Ocean are projected to reach 4°C above normal, a 60 per cent increase over the old record. As well as raising global temperatures, El Niño also shifts atmospheric circulation patterns, causing extreme weather around the world.
This brings drought to some regions and flooding to others, damaging property and disrupting food supplies. While the exact impacts vary from El Niño to El Niño, what’s clear is they will, on the whole, be stronger than in previous events. This huge blob of warm water heats the atmosphere.
When El Niño isn’t occurring, the heat of the warm pool causes moist air to rise into the atmosphere above it, with the moisture condensing and falling as rain over South-East Asia. At the same time, air sinks over the cooler eastern Pacific. The warm air aloft, now mostly free of moisture, flows in to replace it, creating a giant loop.
This loop is joined up with similar loops that circle the global tropics in what is known as the Walker circulation. But when the warm pool sloshes eastward across the Pacific during El Niño, the centre of rising moist air moves with it, shifting the entire Walker circulation eastward. As a result, the warm, dry air now sinks over South America rather than the eastern Pacific.
Another loop of warm, dry air has also shifted and begun descending over South-East Asia and Australia. The Met Office is forecasting dry conditions in these areas over the next few months. Now, thousands of square kilometres of Borneo are burning again, with peatlands releasing huge amounts of carbon dioxide.
Warm weather and drought can also wilt crops. The Met Office is forecasting dry conditions in Central America, home to several major coffee producers, and India, the world’s largest rice exporter. As a result of El Niño, India is experiencing its weakest monsoon since 2009, a major blow to the rice crop.
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