El Niño – what is this phenomenon? The most important risks it brings

For three consecutive years, the La Nina weather anomaly prevailed in the Pacific Ocean. The surface water temperature of the Pacific was lower than average, affecting atmospheric circulation and shaping the weather in many regions of the world. In 2023, the phenomenon began to weaken until meteorologists announced its end.

Everything indicates, however, that the next few months will bring its opposite – El Nino will prevail in the ocean and the temperature of surface waters will increase. This is not good news, because this anomaly can bring with it many disturbing weather phenomena. They may intensify the effects of climate change, and thus exacerbate the extreme conditions that are increasingly prevalent in various parts of the world.

Oceans play an important role in regulating the global air temperature – cool water effectively absorbs excess heat from the atmosphere. When La Nina dominated the Pacific, the cool ocean waves acted as a thermal buffer with particular efficiency, and yet the sea temperature rose. Scientists fear that El Niño will only exacerbate this effect – for the first time in history, average air temperature may rise more than 1.5 degrees Celsius above pre-industrial levels.

Scientists consider 1.5 degrees of warming to be a tipping point beyond which the risk of extreme floods, droughts, fires and food shortages will dramatically increase. It is also one of the values ​​included in the Paris Agreement, which assumes attempts to limit global warming to 1.5 degrees Celsius.

“2024 will probably be the warmest year on record,” Josef Ludescher of the Potsdam Institute for Climate Impact Research told CNN. So far, the hottest year on a global scale was 2016, which followed a very strong El Nino. This means that the following years may bring us extreme, even unprecedented temperatures, even higher than in 2022, which turned out to be a record warm for Europe.

As Adam Scaife of the British Met Office Met Office added, it doesn’t really matter if the 1.5C threshold is breached – what matters is that, for the first time in human history, we are at a point where the occurrence of this value is possible, which in itself should worry us.

Changing the circulation of the atmosphere will translate into atmospheric conditions in different parts of the world. Under the influence of El Niño, places that have struggled with severe droughts for years – including the west coast of the United States – are expected to become wetter month by month. Meteorologists, however, warn that the weather may go from extreme to extreme.

“In the continental United States, La Nina is the ‘creator of drought’ and El Nino is its ‘destroyer’,” Brad Rippey of the U.S. Department of Agriculture told CNN. – However, the exact location of drought or flood varies depending on the anomaly.

As El Niño begins to take over the Pacific, increasing amounts of rain and snow are likely to hit the country’s west coast, with increased risk of flooding, landslides and landslides. In addition, the changed circulation over the ocean may contribute to the more frequent occurrence of atmospheric rivers – dangerous weather phenomena, bringing with them violent storms and strong gusts of wind.

Places that experienced higher-than-average rainfall as a result of La Nina will be in a completely different situation. South Africa and India are threatened by droughts and extreme heat. Dry weather will also affect the inhabitants of Australia, where entire regions were devastated by heavy rains in the summer.

Australian meteorologists predict that El Niño is likely to bring extremely dry and hot weather, especially in the eastern parts of the country. The onset of drought after a period of heavy rainfall is especially dangerous as it can fuel dangerous bushfires. Rain causes faster growth of vegetation, which in times of drought becomes an excellent fuel for fire.

In India, an El Niño could bring temperatures up and the summer monsoons to weaken – warm, humid wind systems that transport huge amounts of water inland. As Raghu Murtugudde of the University of Maryland explained to CNN, the phenomenon is most limited when there is a change from winter La Nina to summer El Niño. “General Deficit [opadów monsunowych – red.] may be as high as 15 percent.

The warmer surface of the Pacific Ocean will create favorable conditions for the formation of typhoons. Although there may be fewer hurricanes in the Atlantic, Pacific phenomena will form further and further west from the coast of the Americas. This will give violent gales, driven by the warm waters of the Pacific, an opportunity to build up even more force before hitting Hawaii or the Latin American coast.

Daniel Swain of the University of California, Los Angeles, explained that warm ocean waters gather off the coast of Peru, bringing unusually heavy rainfall. Their first effects are already painfully felt by the inhabitants of Peru, Chile and Ecuador – the region has been struggling with floods for weeks. This is one of the factors indicating that the upcoming El Niño may be very strong.

The increased ocean temperature is also bad news for many of its inhabitants. El Niño blocks the rise of cold, nutrient-rich water from the ocean floor, leaving its inhabitants starved for food. Fish and crustaceans living near the surface migrate to other places, which forces oceanic birds and mammals to migrate. Those that fail to find a new habitat will die.

El Niño is also bad news for coral reefs. When it gets too hot, corals get rid of the colorful algae living inside their tissues that provide them with energy. This causes coral bleaching – a condition in which organisms can survive but are weakened and vulnerable to disease. A particularly catastrophic period of coral bleaching took place between 2014 and 2017, affecting all the world’s coral reefs. In 2016, a marine heatwave that followed a strong El Niño contributed to the death of nearly 30 percent of the corals of Australia’s Great Barrier Reef

“What we’re predicting is terrifying,” Peter Houk of the University of Guam told CNN. “Each time it happens, the phenomenon becomes a little more intense,” he added.

Earlier this year, Antarctic ice levels dropped to a record low for the second time in two years. El Niño may further exacerbate the situation – as research shows, there is a connection between the strength and frequency of this anomaly and the rate at which the Antarctic ice melts.

“Models that predict a stronger El Niño show faster ice sheet melt than models that predict a weaker anomaly,” Wenju Cai of the Australian Center for Scientific and Industrial Research (CSIRO) told CNN.

While the Antarctic ice sheet is unlikely to melt completely, it holds enough water to raise global sea levels by 70 meters. Cai added that while El Niño events may have varying impacts on the extent of the ice sheet, the current trend is certain – we are facing a “general decline in sea ice.”