Enterprise Explains: The why and when of El Niño: One of the most closely studied weather phenomena around the world today, El Niño is a cyclical naturally occuring weather phenomenon affecting different regions around the world due to the unusual warming of the sea surface temperature in the eastern Pacific Ocean every two to seven years. Recent research has shown that its impacts are likely to hit harder and more frequently as the planet continues to heat up and global surface temperatures will rise by about 0.1 °C during the years the phenomenon occurs, with some scientists warning global average temperatures could tip off the 1.5 °C limit.

As the effects of El Niño become more severe and far reaching for mns of people and various ecosystems, interest in understanding how it affects food availability, fisheries, wildfires, coral bleaching, extreme rainfall, and other components of the climate system has grown. Countries are looking for ways to adapt and build resilience to mitigate the impacts on those occurrences. In part one of this two-part explainer, we discuss with experts what to expect in terms of weather-induced changes in our region.

We’re experiencing El Niño after a four-year absence: “Strong anomalies in the central and eastern Pacific regions have already been identified, and they are becoming stronger every day,” climate researcher at the International Centre for Theoretical Physics Muhammad Abid told Enterprise Climate, adding that its cascading effects usually peak in the winter months. Climate scientist and head of the Environmental and Geophysical Sciences Lab at Dubai’s Khalifa University Diana Francis told us this will be a strong El Niño year, pointing out that last month was already recognized as the warmest June on record, “even before the impacts of El Niño start to be felt worldwide.”

So how exactly does El Niño occur? In normal years, the permanent winds moving from east-to-west around the Earth’s equatorial region — called trade winds — push warm surface waters in the eastern Pacific westwards, away from Central and South America and towards South East Asia and Australia, Abid explains. This makes surface water temperatures in the west relatively warmer than in the east. However, when the trade winds become weaker than normal, warm waters accumulate in the east and “create a patch of warmth over the tropical Pacific,” Francis explains. This breaks the neutral cycle in the Pacific and triggers El Niño. With the cycle reversed, the warm air initially accumulating near Asia and Australia, shifts towards Central and South America, making the former wetter than usual, and the latter dryer than usual.

It’s part of a larger phenomenon: While El Niño often steals the spotlight given its role in exacerbating global warming, it is considered the “warm phase” of the bigger El Niño-Southern Oscillation (ENSO) atmospheric occurrence. The “cool phase” is represented by the La Niña phenomenon, when “strong trade winds are present which causes warm waters at the surface to be displaced westward and replaced by cooler waters from the bottom” causing the east “acific water temperatures to become cooler than the average. The world has been in the La Niña phase for the last three years, according to Abid.

Despite being largely understudied in MENA, it impacts our region: El Niño has affected 71% of drought years in the southern and southwestern parts of the Arabian Peninsula, and La Niña was linked to 38% of this area’s flood years, a study (pdf) by Abid and other researchers from King AbdulAziz University’s (KAU) Center of Excellence for Climate Change Research (CECCR) found. “Although it is not surprising that ENSO affects precipitation over the Arabian Peninsula, its apparently strong effect is,” co-author and climate and earth modeling expert Georgiy Stenchikov told Nature.

MENA and GCC will see shifting weather patterns soon: Intensifying El Niño conditions may bring heavy and more frequent rainfalls over the Gulf countries during the upcoming winter season, Abid told us. Nile Basin countries, including Egypt, will experience more droughts. “During El Niño years there is an increase in wind speed, coupled with dry and warm wind coming from the desert area of the Arabian Peninsula, blowing toward Egypt,” Canada-based climate researcher and water resources consultant Shereif Mahmoud tells Enterprise Climate. This wind moves the moist air away and replaces it with dry hot air, which increases the rate of evaporation over the Nile basin countries leading to a climate favorable for increasing drought, he added. The increase in air temperature and surface humidity in turn increases human thermal comfort indices, which poses a high health risk including difficulty breathing, he said.

Existing drought conditions will be exacerbated during El Niño years: One study (pdf) published in 2016 found that ENSO had some impacts on the 2015–2016 droughts in Morocco, which could increase in the coming years as Morocco faces tougher conditions that have led it and its neighboring countries to ration the nation’s water consumption. According to the researchers at World Weather Attribution, Morocco and Algeria are expected to hit record temperatures this summer.