Strongest El Nino on record comes to an end

Finally, we can breathe a sigh of relief. One of the strongest El Ninos on record has come to an end. It has had a dramatic effect on the weather around the world, bringing a whole host of floods and drought. Now that it has subsided, hopefully the weather across the globe will return to normal as well.
There’s always a fair amount of uncertainty about exactly when El Nino starts and ends. This might seem strange at first, after all we are told that El Nino is simply the warming of the waters of the Pacific Ocean. We can use satellites to measure the temperature of the water, so surely it should be fairly straight forward to detect when it starts and when it ends.
Unfortunately, it’s not quite that simple. The different meteorological agencies have slightly different criteria for the onset and decline of El Nino. The Australian Bureau of Meteorology require the temperatures of a certain part of the Pacific to be 0.8C above normal and they also take the winds and atmospheric pressure into consideration; the US agency NOAA say the temperature needs to be over 0.5C above normal for 3 months in a row; and the Japan Meteorology Agency require an average of 0.5C above normal for 5 months.
Given that the US and the Japanese meteorologists need to wait for several months before they can confirm that El Nino has ended, it is not a surprise that it is the Australian Bureau of Meteorology which has been the first to announce its demise. It has to be said, however, most people who have suffered in the El Nino-induced droughts or floods won’t care who it is that’s declaring the end of El Nino, the important thing is that it has ended.
At its peak in December 2015, El Nino was the strongest on record, tied with the super El Nino of 1997-98. Its strength ensured it had an impact that was felt in many corners of the globe. It was during its peak that more than 160,000 people were displaced by the worst floods to hit South America in 50 years. Paraguay, Argentina, Brazil and Uruguay were all hit by the flooding, with Paraguay suffering the worst.
The following month, the World Food Programme announced that about 14 million people in Africa were facing hunger thanks to the poor harvest caused by El Nino. The worst affected countries were Malawi, Madagascar and Zimbabwe, and the UN organisation warned that the number of people without enough food was likely to rise further in 2016 as the drought worsened across the region.
In March, the drought in Thailand began to hit the headlines. It was the worst drought for more than 20 years, with water levels in some of the country’s biggest dams below ten percent of capacity. In a desperate attempt to alleviate the water shortage, Thailand started pumping water from the Mekong River into its own waterways. This caused major concern to those living in countries downstream, especially Vietnam which itself was suffering its worst drought in almost a century.
A drought was also affecting Venezuela. This caused major problems in a country where hydroelectric dams supply more than 60 percent of the country’s electricity. In April, as the drought worsened and the electricity supply dwindled, the government took the drastic step of reducing the working week and implement power rationing in the ten most populous states.
In May 2016, Ethiopia suffered flooding. Approximately 100 people were killed by flooding and landslides, with another 20,000 families made homeless.
Clearly not all extreme weather events which took place in the last year can be blamed on El Niño, but those mentioned have all happened in parts of the world that are known to suffer during the phenomenon. For the residents of these countries, it is a relief that El Niño has ended, but that relief may be short lived.
Scientists believe there is a strong chance that the opposite phenomenon, La Nina, will emerge by the end of the year. Whereas El Nino is the warming of the surface waters of the Pacific, La Nina is the cooling and it’s fairly common for it to follow hot on the heels of El Nino. Generally it brings the opposite weather that you would expect to see in an El Nino event; for example Paraguay and Kenya often experience droughts and Thailand and Southern Africa expect flooding.
The good news is that La Nina events are typically weaker than El Nino ones, but the bad news is that they usually last longer. The La Nina event that followed the powerful 1997-98 El Nino lasted for thirty-three months, almost three years! That is a long time for a region to experience a drought or flood. Currently there are no indications that the emerging La Nina event will last this long, but equally there is no guarantee that it won’t. We will simply have to wait and see.