CNN — Governments must prepare for more extreme weather events and record temperatures in the coming months, the World Meteorological Organization warned Tuesday, as it declared the onset of the warming phenomenon El Niño.

El Niño is a natural climate pattern in the tropical Pacific Ocean that brings warmer-than-average sea-surface temperatures and has a major influence on weather across the globe, affecting billions of people.

“The onset of El Niño will greatly increase the likelihood of breaking temperature records and triggering more extreme heat in many parts of the world and in the ocean,” said WMO Secretary-General Petteri Taalas.

The declaration “is the signal to governments around the world to mobilize preparations to limit the impacts on our health, our ecosystems and our economies.”

To save lives and livelihoods, governments must establish early warning systems and prepare for further disruptive weather events this year, he said.

The last three years have been some of the warmest on record, even with El Niño’s sister phase, La Niña – which is marked by cooler-than-average ocean temperatures.

A “double whammy” of a very strong El Niño and human-caused warming from the burning of fossil fuels led to 2016 becoming the hottest year on record, according to the WMO, the United Nations’ agency for weather, climate and water resources.

But the first El Niño to develop in seven years layered on top of human-caused global heating, could push 2023 or 2024 to break 2016’s heat record, the WMO said.

The WMO said there was a 90% probability of El Niño continuing during the second half of 2023 at moderate strength.

Along with increased ocean warming, El Niño events are usually associated with increased rainfall in parts of southern South America, the southern United States, the Horn of Africa and central Asia.

But it can also amplify severe droughts, heat waves and wildfires over Australia, Indonesia, parts of southern Asia, Central America and northern South America.

Other impacts include dangerous tropical cyclones in the Pacific and the mass bleaching of fragile coral reefs.

In India, a major rice producing nation, El Niño can weaken the monsoon that brings the rainfall the country relies on to fill aquifers and grow crops.

El Niño this year could also dent US economic growth, potentially impacting everything from food prices to winter clothing sales, a recent study found. The study attributed $5.7 trillion in global income losses to the 1997-98 El Niño and $4.1 trillion in losses to the 1982-83 El Niño.

The world could also be temporarily pushed past 1.5 degrees Celsius of warming above pre-industrial levels – a key tipping point beyond which the chances of extreme flooding, drought, wildfires and food shortages could increase dramatically.

Countries pledged in the Paris Climate Agreement to limit global warming to well below 2 degrees – and preferably to 1.5 degrees Celsius – compared to pre-industrial temperatures. But the world has already seen around 1.2 degrees Celsius of warming, as humans continue to burn fossil fuels and produce planet-heating pollution.

According to the WMO there is a 66% likelihood that the annual average near-surface global temperature between 2023 and 2027 will temporarily be more than 1.5 degrees Celsius above pre-industrial levels for at least one year.

“This is not to say that in the next five years we would exceed the 1.5 degrees Celsius level specified in the Paris Agreement because that agreement refers to long-term warming over many years,” said WMO director of climate services Chris Hewitt.

“However, it is yet another wake up call, or an early warning, that we are not yet going in the right direction to limit the warming to within the targets set in Paris in 2015 designed to substantially reduce the impacts of climate change.”

A multitude of climate records have already been broken in 2023, with soaring temperatures, unusually hot oceans and record high levels of carbon pollution in the atmosphere and record low levels of Antarctic ice.

Across Asia, Europe and the Americas, early and prolonged heat waves this year have killed people, animals and crops, sparked concerns about food security and water scarcity, and set the stage for unprecedented wildfires.