Scientists predict new El Niño and – temporarily – additional warming

Global warming will most likely skyrocket next year. It may even temporarily reach 1.5 degrees, the limit the United Nations wants to stay below. The cause is the expected arrival of the El Niño climate phenomenon, which will cause higher average temperatures on Earth.

The World Meteorological Organization (WMO), the meteorological agency of the United Nations, warned on May 3 that the world must prepare for an El Niño. That warning follows reports from, among others, the US agency for oceanography and meteorology, NOAA. That wrote on April 13 already about a possible imminent El Niño. The NOAA estimated the chance that it would have already manifested itself in the period May-July at 62 percent. And that chance increases as the year goes on. By autumn it will be 80 percent.

“The odds of no El Niño happening this year have become very slim,” said Adam Scaife, head of long-term forecasting at the Met Office Hadley Center, Britain’s meteorological institute. “With us, at least all models predict that we are entering an El Niño.”

El Niño is a natural phenomenon in the Pacific Ocean that occurs every two to seven years. He alternates with his counterpart, a La Niña. An El Niño brings extra heat into the air from the ocean. This causes a temporary additional warming of the earth, on top of the structural warming as a result of the increasing emission of greenhouse gases by humans. An El Niño also affects weather patterns. Areas such as Australia, Indonesia, the Middle East and South Africa will experience extra drought. In the Horn of Africa, the south of the US, Mexico and parts of South America, among others, there is usually much more rainfall. In Europe the effects are small.

A severe El Niño will temporarily cause an additional 0.2 to 0.3 degrees of warming

Trade winds

The origin of an El Niño has to do with the interaction between winds and ocean currents in the Pacific Ocean. Trade winds around the equator normally blow from east to west. They push the warmer, superficial ocean water from Central America towards Australia and Indonesia. This has an effect on deep ocean currents. Cold, nutrient-rich water wells up from the depths off the coast of South America, which attracts fish (and anglers), for example. During an El Niño, the trade winds weaken, or they come to a standstill (in a La Niña, the normal situation is strengthened). As a result, the area with warm water, cloud formation and heavy precipitation is moving eastward. Cold water no longer wells up off the coast of South America – bad news for fishermen. On average, the surface temperature of the water rises around the equator. This temperature is continuously monitored in four large measuring sections.

Last March, NOAA researchers saw the situation in the Pacific Ocean suddenly reverse. A La Niña had persisted for no less than three years. But suddenly she was gone. In the upper 300 meters of the ocean, in the central and eastern part, the researchers saw the temperature increase. The increase was strongest off the coast of Peru. The April average there was about 3 degrees above normal.

Measurement section 3.4

There is no official El Niño yet. For this, the deviation from the average must be more than half a degree in measurement section 3.4, in the middle of the ocean. And the deviation must last for at least three months. It’s not that far yet. That is why the state is now called “neutral”.

In its press release, the WMO emphasizes that global warming has been partly suppressed by La Niña over the past three years. Nevertheless, we have had “the eight warmest years on record”. Should an El Niño indeed develop, it is expected to lead to another spike in global warming next year, as happened in 2016, after a strong El Niño in 2015-2016.

According to Scaife, in the event of an El Niño you can use the following rule: every degree that the ocean water warms above average causes the earth to temporarily become 0.1 degrees warmer. “If we get a severe El Niño, like in 1997/1998, or in 2015/2016, it will temporarily add 0.2 to 0.3 degrees of warming,” says Scaife. The Earth has already warmed 1.2 to 1.25 degrees in the past century and a half, says Scaife. With a strong El Niño added, you quickly get close to 1.5 degrees, says Scaife. In the 2015 Paris climate treaty, the United Nations committed itself to staying below that limit.

But according to Scaife, it doesn’t matter much whether or not we touch that 1.5 degree warming. “It’s not like we’re falling off a cliff.” Any additional warming from an El Niño is worrying anyway, according to Scaife. “We are entering new territory. Every new record in heat, drought, rainfall, will have a major impact.”

On average, an El Niño lasts six months. But the persistent La Niña of the last three years shows that it can also last longer. El Niño usually peaks in December – hence its name after the Christmas child.

Scaife emphasizes that countries must prepare for an El Niño. Areas that are expected to be hit by additional drought should try to store more water – for agriculture, for drinking water supply, for fighting fires. “And aid organizations must be ready.”