Source: New model predicts El Nino one year ahead | The Herald 11 NOV, 2019

Jeffrey Gogo

An international team of researchers has developed a model that can predict El Nino a year in advance, and their latest forecast points to an 80 percent chance of the disruptive weather pattern occurring late 2020.

“Conventional methods are unable to make a reliable ‘El Nino’ forecast more than six months in advance,” physicist Armin Bunde of Germany’s Justus Liebig University Giessen, was quoted by the Thomson Reuters Foundation (TRF) as saying.

“With our method, we have roughly doubled the previous warning time,” said Bunde, who co-developed the model.

“The method “uses an algorithm that draws on analysis of links between changing air temperatures at a network of grid points across the Pacific region.”

El Nino is a naturally occurring weather cycle caused by warming waters in the Pacific Ocean.

Striking every two to seven years, and lasting for upto 12 months, the phenomenon alters rainfall patterns worldwide, leaving some areas soaked.

But in Zimbabwe, it is predominantly linked with a severe shortage of rain.

For example, the 2015/16 El Nino resulted in Zimbabwe’s worst drought in 25 years, killing more than 19 000 cattle and left 4 million people hungry. The one that hit between 1982 and 1983 resulted in a severe drought, leaving families mired in poverty and hunger.

Effects of the 2018/19 El Nino are still evident, with a drought that’s left seven million people in need of food aid.

The team of researchers, whose new method has been tested since 2013, was, however, unsure of the impact of the predicted El Nino on seasonal climates – meaning they are still uncertain whether it will be a weak, moderate, or strong.

TRF reported that “the team is now adapting the algorithm to be able to predict the timing and strength of El Nino.” It added, “in the future, a similar method could be used to improve forecasts of Asia’s monsoon.”

First published in the journal Proceedings of the National Academy of Sciences six years ago, the new prediction model is expected to help Government authorities prepare better for the impacts of El Nino.

Scientists have been checking its accuracy since then. They say the model correctly forecast the onset of the El Nino that started in 2014 and ended in 2016 and the most recent event in 2018, as well as absences in other years.

“The next expected El Nino, due to peak in late 2020, could push global average annual temperature rise to a new record in 2021,” said the researchers. 2016 became the warmest year on record thanks to the devastating El Nino of 2015/16, according to the World Meteorological Organisation.

Now, it is not yet clear what sort of impact the predicted 2020 El Nino could have on Zimbabwe.  But based on events in recent decades, the periodic weather pattern is slowly becoming the norm, rather than the exception, evoking painful memories of shattered lives and livelihoods. It’s biggest impact locally is on how it influences precipitation and temperatures, often resulting in drought and heatwaves.

Not only does it define seasons, but about two thirds of the 13 million Zimbabweans are dependent on it, through agriculture, according to the national statistics agency, ZimStats.

In good times, precipitation averages between 400mm and 1 000mm, with regions in the south-west of the country receiving the least amount of rain, and those in the east along the border with Mozambique, the highest.

However, changes in climates have seen rainfall decline by between 5 and 15 percent countrywide since the 1960s, experts say.

Emerging research point towards a spike in deadly El Nino events in the future. They are likely to increase in frequency and strength, possibly occurring once every decade, due to climate change. Historically, the most extreme El Nino happens once in 20 years.

These change – and other – could see Zimbabwe’s production of the maize staple fall by between 30 and 50 percent through 2030, as temperatures soar two degrees Celsius by 2080, according to the UN’s expert panel on climate change.

Probability of years in which growing season is likely to fail in future due to drought is projected to be as high as 100 percent in some parts in the south, the panel says.

But the immediate concern is how a drought induced by El Nino will be expected to hit agriculture — a sector that accounts for up to a fifth of GDP, and 60 percent of the manufacturing industry raw materials need – again. And with it the rest of the economy, an economy reliant on rain-fed agriculture.

This is what happened during the 2015 /16 summer cropping season, precisely. El Nino left much of Zimbabwe dry, forcing a series of heat waves that saw daytime temperatures breaking 60-year records. Crops failed and Government had to appeal for $1,6 billion in aid to undo the damage.

God is faithful.

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