Caption: Cumbria's Stormy Sky
There is a stormy sky over Cumbria today, but on the other side of the world an “El Niño” weather system is building in the Pacific that has the potential to throw the weather into chaos all around the world later this year. The chances of flooding, drought and food price inflation worldwide will all increase if the system continues to build. First reported in March by the NOAA (National Oceanic and Atmospheric Administration), updates earlier this month show the system to be developing strongly.
What is El Niño? A band of warm air in the Pacific Ocean south of the equator is known as the “El Niño Southern Oscillation” or “ENSO”. This is a normal part of the world weather system. ENSO creates the trade winds in the Pacific Ocean – producing an easterly wind blowing from South America towards Asia and Australasia. This causes a movement of warm water to the west bringing nutrient rich cold water behind it that builds up on the pacific coastline of South America. This creates rich fishing conditions, particularly for anchovy harvesting.
The “El Niño” effect happens when there is prolonged warming of the surface sea temperature (SST) in this oceanic area. Normally, a cycle of warming and cooling happens every 2 to 7 years. Each El Niño can last between 9 months and 2 years and it changes the normal pattern of our global weather, sometimes with dramatic and damaging consequences.
In some instances, El Niño can actually reverse the flow of the trade wind turning it from an easterly into a westerly. The result being that the warm water block is pushed back to the South American coastline with far reaching impact.
How do we know El Niño is building? The NOAA monitors a network of buoys in the ocean, the information collected from these, along with temperature readings, wind patterns, satellite information and meteorological observations are used to create a computer model of how the El Niño effect is developing.
The latest observations reported earlier this month show that the warming of SSTs was above the threshold levels needed to create a strong El Niño. In fact, all 5 indices showed an increase of more than 1oC over average temperatures– exceeding the threshold level for El Niño formation. What is unusual is that the increase in temperature was seen across a very broad area of the tropical Pacific Ocean. This has not been seen since 1997 - 98.
What are the implications? 1997 – 98 saw the most severe El Niño on record, however it also occurred two years later and was partly blamed for the ‘Big Freeze’ of 2010 – the coldest winter for decades in Europe. The weather impacts of a strong El Niño effect are truly global in scale: the US gets cool, wet summers but consequently fewer hurricanes; South America is prone to flooding; the Far East has an increase in typhoons; the monsoon is weakened in India; in West Africa and Australia droughts are more prevalent and for us in Europe, colder winters are common.
A strong El Niño effect can have massive implications on the world’s food production chains. Rice, coffee and palm oil harvests can all be impacted in Asia. Increased rainfall in Brazil can play havoc with sugar production the reversal of the Pacific currents can have big implications on fishing. The warmer water around the South American coastline is less rich in nutrients and can reduce fishing yields. This has a knock on effect along our global food chain. One third of the fishmeal needed for animal food across the world comes from the eastern Pacific anchovy harvest – impacting animal food prices and ultimately the price of meat.
The effect on agricultural commodity markets can be huge – if the El Niño impact is large then clearly food prices can rise significantly due to shortages in supply, but even the uncertainly of a potential El Niño can make the markets skittish and prices volatile, way ahead of any weather events actually happening.
What happens now? A number of weather and climate agencies around the world publish regular updates on Pacific SST warming. The Australian government publishes fortnightly updates on bom.gov.au with detailed oceanic temperature maps, which make a very interesting read for map connoisseurs.
The NOAA’s latest update in early June suggests a 90% chance that the current El Niño conditions will last throughout autumn in the Northern Hemisphere and an 85% chance they will last for the whole of winter 2015/16. It will become clearer as the summer progresses how strongly the system is developing and therefore the potential impact this winter.
What role does climate change play? It’s important to consider that El Niño is not, in itself, a result of climate change. It is a normally occurring cyclical weather pattern in evidence for hundreds if not thousands of years. However, recent research published in the journal “Nature” suggests global warming will increase El Niño intensity – making for more extreme drought and flood events. This study is seen to be the most robust predictions yet.
We could well be in for some bumpy global weather as the year progresses.
For more information, and a visual description of how El Niño forms check out the following bbc video.