This has been a year of record temperatures and extreme weather – from floods to fires – due to a deadly cocktail of man-made climate change mixed with cyclical El Niño weather, scientists say.

A spate of recent heatwaves in West Africa, for example, would not have happened without climate change and was made still worse by the El Niño event, scientists from the World Weather Attribution (WWA) group found in a new report.

The scientists say extreme events such as these will become much more common – and more dangerous – without a rapid cut in planet-heating greenhouse gas emissions.

El Niño is what happens when unusually warm surface temperatures in the eastern Pacific Ocean unleash a domino effect on weather patterns right around the globe.

El Niño, which on average happens every 2 to 7 years as part of a natural cycle, lasts 9 to 12 months, a period that began last June and has now ended, according to Australia’s Bureau of Meteorology.

This warm spell is followed by a neutral period which could then shift to unusually cold ocean surface temperatures, called La Niña, later this year.

El Niño is a phenomenon distinct from our human-driven climate crisis, said Richard Allan, a climate scientist at the University of Reading, but its impacts will be all the more intense in a warmer atmosphere.

What impacts have El Niño and climate change had?

The effects of the El Niño depend on the region, with some parts of the world forgoing rain while others flood.

Weather conditions due to El Niño have been the key driver of deadly drought in Zambia, Zimbabwe and other parts of southern Africa, the WWA researchers said elsewhere.

But throw in climate change and scientists say the impact is exacerbated.

“Studies have shown that many extreme weather events have been driven by a combination of both climate change and El Niño,” said Joyce Kimutai, a researcher at the Grantham Institute at Imperial College London, who worked on the southern Africa report.

For example, the WWA said climate change was primarily responsible for last year’s exceptional Amazon rainforest drought, but El Niño was a contributor as it suppresses rainfall and often leads to droughts in the region.

Coral reefs have also suffered a fourth global bleaching – stretching from Australia to Mexico - as climate change and El Niño led to record high ocean temperatures, according to the US National Oceanic and Atmospheric Administration’s Coral Reef Watch.

Will 2024 be as hot as last year?

Climate change and El Niño drove average temperatures 1.5 degrees Celsius above pre-industrial times in the 12 months to February – a worrying world first that scientists fear could be a harbinger of worse to come.

Keeping warming below 1.5C in the coming decades is seen as crucial to avoiding dangerous tipping points and averting the worst impacts of climate change.

Although the current El Niño has ended, the impacts of the warm ocean on the atmosphere are expected to linger for most of 2024, mirroring the highs of 2023.

The World Meteorological Organization (WMO)’s head of climate monitoring, Omar Baddour, said in March that 2024 was highly likely to set new heat records, as the year after an El Niño event tends to be warmer still.