Possibilities of La Niña triple to 60%

Published: 10/09/2017, 4:38:26 PM

Most people don't fear little girls, but meteorologists know better when it comes to this one, and so do economists. In September, the risk of La Niña, (Spanish for "little girl"), a weather pattern that in its strongest manifestation has been blamed for flooded mines in Australia and failed crops in Brazil, was tripled to 60% by the US Climate Prediction Centre, according to the UK's Telegraph newspaper.

La Niña is part of what is known as the El Niño-Southern Oscillation cycle. While El Niño warms waters in the central Pacific Ocean, La Niña has an opposite effect. And the changes in sea temperature caused by these weather events can trigger large shifts in weather patterns.

Professor Adam Scaife, head of long-range prediction at the UK Meteorological Office, says that while the risk of a La Niña as extreme as that seen six years ago is low, it's important to consider the ramifications even a relatively weak event can have for next year's hurricane season.

"There are a couple of things that can take the wind out of a hurricane: one is landfall, which denies the storm access to the warm ocean surface and increases surface friction," Scaife explains.

The other, he notes, is when winds run counter to one another near the ocean surface and then at altitude. This difference is known as a shear.

"If that difference is strong enough it can shear out and kill a growing storm. As La Niña weakens the wind shear in the Atlantic, it tends to be associated with an active hurricane season," he says.

The increased risk of this weather event comes hot on the heels of a devastating hurricane season.

AccuWeather has estimated that hurricanes Harvey and Irma might cost a combined US$290 billion, nearly double that of the season that produced Hurricane Katrina.

But while it could pull down production levels in Brazil, it may be good for the harvest of Australian sugar cane, and stimulate a further rebound in South African crops, as wetter weather hits.

Sugar cane is a major crop for several southern African nations. And this bumper harvest could come exactly as UK farmers push ahead with increased production in sugar beet following the lifting of EU production and export caps on sugar.

La Niña might spell bad news for sugar prices, even as it supports the price that soybeans can command.