The El Niño weather pattern, which originates in the Pacific Ocean is now well underway and is growing in strength according to British scientists. This is likely to have widespread regional impacts and to continue to contribute to raised global average temperatures this year and next - after a 15-year “cool” phase, during which the Pacific Ocean has dragged down the world’s average surface temperature, the signs are it has entered a “warm” phase, according to Prof Adam Scaife of the UK Met Office.

With input from seasonal forecasting centres worldwide, including the Met Office, the World Meteorological Organization issues updates on the state of the El Niño-Southern Oscillation (ENSO) and an outlook for the coming months. In the September issue it is stated that “temperatures in the east-central tropical Pacific Ocean are likely to exceed 2° Celsius above average, potentially placing this El Niño event among the four strongest events since 1950.”

 

Last year was the warmest on record according to the World Meteorological Organization and a UN-sponsored climate change summit in Paris in December has the goal to reach an agreement on limiting global greenhouse gas emissions.

Regional temperature and rainfall worldwide will be affected by the big changes that are underway in key global climate system.

New research from the UK Met Office shows regional temperature and rainfall worldwide will be affected by big changes that are underway in key patterns in the global climate system.

It says that in May and June 2015 there has been reduced rainfall in Southeast Asia, Central America and northeastern South America, which are typical effects of El Niño. Global mean temperatures are also very high in 2015. "The near-El Niño conditions earlier this year were also consistent with the below-normal rains in North East Brazil and north-eastern Australia in early 2015."

The latest climate predictions and global observations suggest that shifts in key global climate patterns, the Pacific Decadal Oscillation (PDO), an El Niño in the tropical Pacific and the Atlantic Multi-decadal Oscillation (AMO) are underway. They are implicated in the weak Indian monsoon and relatively inactive Atlantic hurricane season this year and will affect regional temperature and rainfall worldwide in coming years. They also affect global temperature; with a warming influence from El Niño and positive PDO, and a cooling from a negative AMO.

Prof Scaife said: "Although we can't say for sure that the slowdown in global warming is over, global temperatures are now rising again."

These changes suggest both 2015 and 2016 are likely to be very warm globally. Earth's average surface temperature is running at or near record levels so far in 2015 at 0.38±0.14°C above the 1981-2010 average (0.68±0.14 °C above the 1961-1990 average). The observations of exceptional global temperature this year agree well with the Met Office forecast issued in 2014.

Prof Stephen Belcher, head of the Met Office Hadley Centre, said: "We know natural patterns contribute to global temperature in any given year, but the very warm temperatures so far this year indicate the continued impact of increasing greenhouse gases. With the potential that next year could be similarly warm, it's clear that our climate continues to change."

These changes are consistent with a return of rapid warming in the near term. Prof Scaife continued: "We can't be sure this is the end of the slowdown but decadal warming rates are likely to reach late 20th century levels within two years."

The scientists said: "Further long-term warming is expected over the coming decades, but the patterns described in this report will continue to vary the pace of that warming."

David Herring of NASA wrote in 1999 on El Niño:

"Fishermen who ply the waters of the Pacific off the coast of Peru and Ecuador have known for centuries about the El Niño. Every three to seven years during the months of December and January, fish in the coastal waters off of these countries virtually vanish, causing the fishing business to come to a standstill. South American fishermen have given this phenomenon the name El Niño, which is Spanish for "the Boy Child," because it comes about the time of the celebration of the birth of the Christ Child. During an El Niño, the physical relationships between wind, ocean currents, oceanic and atmospheric temperature, and biosphere break down into destructive patterns that are second only to the march of the seasons in their impacts to weather conditions around the world."

David Carlson, director of the World Meteorological Organization (WMO) co-sponsored World Climate Research Programme (WCRP), said earlier this month that the 2015 El Niño is the first to take place since the rapid melting of Arctic sea ice and snow cover.

"The last big El Niño was 1997-1998. The planet has changed a lot in 15 years,” he said. “We have had years of record Arctic sea ice minimum. We have lost a massive area of northern hemisphere snow cover, probably by more than 1 million square kilometers in the past 15 years. We are working on a different planet and we fully do not understand the new patterns emerging."

Dr Carlson said the 2015 El Niño is unique because of the unprecedented combination of the Equatorial influence of El Niño, and the Arctic influence of low sea ice and snow cover in place at the same time.

"This is a new planet. Will the two patterns reinforce each other or cancel each other? We have no precedent. Climate change is increasingly going to put us in this situation. We don’t have a previous event like this," he said.

Typically, because of the warm air is over the eastern Pacific, there are drier conditions over Australia, Indonesia and Southeast and South Asia. Many countries in the region are actively preparing for drought.

This year’s El Niño has also impacted the South Asian monsoon. The India Meteorological Department, for the first time in its history, gave a public drought forecast predicting monsoon rainfall 12 percent below normal, in which the early predictions of El Niño played a crucial role.

“We are seeing that Indian monsoon right now is almost 12% below normal. There is only a month left of the summer monsoon season making it difficult to recover,” said Rupa Kumar Kolli, WMO’s El Niño expert .

“That was the kind of early warning information we can extract from the El Niño signal and it helps policy makers to prepare,” he said.

Very often during an El Niño, the Horn of Africa gets increased precipitation and sometimes flooding, whereas in southern Africa there are often get drier conditions.

From Central America to the northeastern parts of South America it is often dry. The western coast of South America is more likely to be wetter than normal. Countries in the region are making contingency plans and mobilising disaster preparedness teams.

Typically, strong El Niño events bring winter rains to California. However, Dr Carlson said it was unclear whether this year’s event would actually break the persistent ridge that has brought drought to California.

Pic: Sea surface temperature in the equatorial Pacific Ocean (above). El Niño is characterized by unusually warm temperatures and La Niña by unusually cool temperatures in the equatorial Pacific. See more here.

This video demonstrates how warm water in the central Pacific can influence prevailing pressure and precipitation patterns across the ocean basin. These atmospheric disturbances influence the average position of the Jet Stream. In turn, the jet alters temperature and precipitation patterns in the United States.