Wildfires that began smouldering in Indonesia’s rainforests and peat soils at the start of the year had burned about 1000 square kilometres by June. Then in July, the blazes started to accelerate, doubling that area in just a month, and then doubling it again. Hundreds of thousands of people have faced respiratory illness, and carbon emissions are on track to equal Indonesia’s catastrophic 2015 fires.
The acceleration came as the strongest El Niño on record started developing in the tropical Pacific. A blob of warm water began moving from Indonesia toward Peru, shifting atmospheric circulation eastward. Warm air that typically rises above the warm blob, raining out its moisture over Indonesia’s rainforests, was instead rising above the central Pacific.
And rather than descending over East Africa, the resulting warm, dry air descended over Indonesia, encouraging slash-and-burn agricultural fires to spread out of control. The super El Niño is still gaining strength and will persist for months, unleashing a panoply of extreme weather across the world. A stronger El Niño will likely mean stronger impacts – especially when it comes on top of 1.4°C of global warming.
What might the next year hold? Past events suggest what extreme weather is likely and where it will hit. As of the start of October, not a single full hurricane has formed in the Atlantic Ocean this year, the first time that has happened in more than a century.
The El Niño circulation changes tend to amplify high-level winds and weaken low-level winds over the Atlantic, creating wind shear that breaks up hurricanes. The flip side is that over the Pacific, the weakened winds reduce shear and encourage the air heated by the blob of warm water there to spin up into typhoons. And because the centre of rising air has shifted eastward, when these storms head toward Asia, they cover more distance and suck up more heat energy and moisture before landfall.
Nearly two dozen typhoons hit east Asia in the autumn during the three previous super El Niños. In October 2015, “super typhoon” Koppu destroyed thousands of buildings and killed at least 47 people in the Philippines. This came about two weeks after typhoon Mujigae set off tornadoes and landslides in China, killing at least 20, and super typhoon Dujuan killed at least two in Taiwan.
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