Global temperatures have been rising. That is beyond doubt. The warmest eight years have all been since 2015, with 2016, 2019 and 2020 constituting the top three. This is generally attributed to be caused by rising levels of greenhouse gases in the atmosphere which is undoubtedly a key contributing factor to global warming.
If you thought these years were hot, be prepared for things to get even warmer. Forecasters at the National Oceanic and Atmospheric Administration in Washington, D.C are already over 60 per cent sure that 2023 will rank among the top two hottest years on record, and over 50 per cent sure that the year will rank as the hottest ever.
The reason for these predictions is the forecast of an exceptionally strong El Niño event which is expected to develop in the coming months. Every few years the El Niño phenomenon kicks into life in the Pacific Ocean around the Equator and can affect weather around the world creating floods, drought, heatwaves and cold seasons for different regions.
The last El Niño occurred in 2016 and contributed to the record global temperatures that followed. When this complex climatic cycle returns this year, it will change weather and climate patterns worldwide, bringing with it heat and uncertainty.
El Niño Chaos
To understand how El Niño works, one needs to understand what normally happens in the tropical Pacific. East to West trade winds push warm water near the surface to the western side of the ocean around Asia and Australasia. As the warm water moves west it is replaced around south and central America by cold water which is pulled up from deeper down in the ocean in a process called ‘up-welling’.
The effect is an oceanic, global conveyor belt. Warmer water in the west causes warm, energy-packed air to rise, creating unsettled weather with more clouds and rainfall. This sets up atmospheric circulation across the ocean with warm moist air rising on one and cooler drier air descending on the other. This reinforces the easterly winds and becomes a self-perpetuating loop; a planetary climate engine. This system is sensitive to rising temperatures but keeps the climate in statis until El Niño begins.
Periodically, tropical pacific weather systems or slow changes in the water around the Equator can set off a chain of events that weaken or reverse the trade winds. This in turn affects the volume of warm water pushed westward which reduces upwelling.
The cyclical climate engine slows allowing the usually colder parts of the ocean to warm. Normal rainfall patterns over the equatorial ocean change and the extra heat in the ocean releases vast amounts of energy in the atmosphere. This pushes up global temperatures and has knock-on effects around the world.
El Niño (which means ‘the boy’ in Spanish) peaks around Christmas and lasts several months but the climatic effects can last years. Sometimes it reverses into a cooling event called La Niña (‘the girl’) as has happened since 2020.
Most concerning is that although the world has been hit with an exceptionally long La Niña, the event’s cooling properties appear not to have had any effect on temperatures in certain parts of the world. In 2022, for example, Europe experienced the hottest summer on record. Indeed, last year was ranked the sixth-warmest since 1880.
According to the UN World Meteorological Organization chief, Professor Petteri Taalas, La Niña has merely ‘acted as a temporary brake on global temperature increase’. When El Niño arrives, it is feared the brakes will come off.
Prof Taalas warns: ‘A warming El Niño is expected to develop in the coming months and this will combine with human-induced climate change to push global temperatures into uncharted territory. This will have far-reaching repercussions for health, food security, water management and the environment. We need to be prepared.’
The predictions are that heat-trapping greenhouse gases and a naturally occurring El Niño will create a double-whammy heating event in which global temperatures are likely to surge to record levels in the next five years.
The forecast was contained in a report issued by the WMO last month which stated there is a 66 per cent likelihood that the annual average near-surface global temperature between 2023 and 2027 will be more than 1.5°C above pre-industrial levels for at least one year. There is a 98 per cent likelihood that at least one of the next five years, and the five-year period as a whole, will be the warmest on record.
Prof Taalas continued: ‘This report does not mean that we will permanently exceed the 1.5°C level specified in the Paris Agreement which refers to long-term warming over many years. However, WMO is sounding the alarm that we will breach the 1.5°C level on a temporary basis with increasing frequency.’
The experts fear that extreme heat events will become the norm. ‘Global mean temperatures are predicted to continue increasing, moving us further and further away from the climate we are used to,’ said Dr Leon Hermanson, a Met Office expert scientist who led the report.
The higher predicted temperatures will mean more extreme weather, sea level rise, flooding, polar and glacial ice melt, increased acidification of the oceans and warmer seas.
While it’s too late to mitigate the effects of the impending El Niño, a drastic reduction in greenhouse gas emissions will help stabilise rising temperatures, which is why the WMO calls for climate action now.
There remains uncertainty as to how El Niño will affect weather patterns in the UAE, which continues to face the challenges of climate change. A 2016 study, The Impact of El Niño and La Niña on the United Arab Emirates (UAE) Rainfall by a team led by Mohamed Alebri, of the National Centre of Meteorology and Seismology in Abu Dhabi, used analysis of more than 30 years of rainfall data from almost 100 weather stations and may provide some clues.
The researchers compared rainfall during El Niño and La Niña years with other years respectively to identify patterns. The amount of rainfall varied significantly across the years.
The authors wrote: ‘As evidence of a related impact, the years that were considered to have been impacted by La Niña showed low rainfall; an instance 1981, 1984, 1989, 1999, 2005, and 2011. On the other hand, some years showed remarkable amounts of rainfall in the UAE on the events of El Niño, for instance 1982, 1987, 1997, 2007 and 2009 which showed rainfall that went above the average total annual rainfall.’
The results were published in the journal General Scientific Researches and are a reversal of previous patterns whereby El Niño events led to drought in the Arabian Peninsula.
Speaking in 2015 ahead of the last El Niño, Omar Baddour, WMO scientist said: ‘In the Middle East, recent studies have shown that in pre-1980s, El Niño used to be associated with reducing rainfall in the Arabian Peninsula. However, in recent years, it seems El Niño is associated with more rainfall over the same domain. There is evidence the Indian Ocean relationship with climate in the region has shifted in the past three to four decades.’
He said it was likely that in future the Middle East will experience erratic climate events during El Niño including dust storms, warm spells, cold spells and excess rain.
What data there is suggests that when El Niño arrives later this year, the world will get hotter and Dubai will get wetter. Beyond that, the effects are hard to predict, but all the forecasts suggest that the El Niño effect, when combined with climate change, will not be good.
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