“It is almost certain that 2023 to 2027 will be the warmest five-year period on record,” the UN warned on Wednesday.

The UN claims this “as greenhouse gases and El Niño together cause temperatures to skyrocket”.

Global temperatures are likely to exceed the “ambitious target” set in the Paris climate agreement.

“There is a two-thirds chance that one of the next five years will do it,” says the UN Meteorological Organization (WMO).

The eight warmest years on record were all between 2015 and 2022 – but temperatures are expected to rise further as climate change accelerates, the WMO believes.

There is a 98 percent probability that at least one of the next five years, and the five-year period as a whole, will be the warmest on record, says WMO.

In the Paris Agreement of 2015, the countries agreed to limit global warming to “well below” 2 degrees above the average measured between 1850 and 1900 – and if possible below 1.5 degrees.

The global average temperature in 2022 was 1.15 degrees above the average between 1850 and 1900.

The WMO said there was a 66 percent chance that annual global surface temperatures will exceed 1.5 degrees C above pre-industrial levels in at least one of the years from 2023 to 2027, with a range of 1.1 to 1.8 degrees C for each of those five years.

Uncharted territory

While this does not mean the world will permanently exceed the Paris reference, “the WMO is sounding the alarm that we will breach the 1.5 degrees C level on a temporary basis with increasing frequency,” according to the agency’s chief Petteri Taalas.

“A warming El Niño is expected to develop in the coming months, this, together with man-made climate change, will push global temperatures into unknown territory,” he said.

This will have far-reaching consequences for health, food safety, water management and the environment. We must be prepared, he added.

El Niño is the large-scale warming of surface temperatures in the central and eastern Pacific Ocean. The weather phenomenon normally occurs every two to seven years.

Conditions fluctuate between El Niño and the opposite La Niña.

The WMO said earlier in May that the chances of El Niño developing were 60 percent by the end of July and 80 percent by the end of September.

Typically, El Niño increases global temperatures the year after it develops – which in this cycle will be 2024.

Despite the cooling effect of La Niña for much of the past three years, the eight warmest years on record have all been from 2015 onwards, with 2016 being the warmest, the WMO claims.

They also claim that the global average temperature on land and in the ocean near the surface has increased since the 1960s.

The UK’s national weather service, the Met Office, is WMO’s leading centre for annual to decadal climate forecasts.

“While there is a 66 percent chance that one year between 2023 and 2027 will exceed the 1.5 degree threshold, there is now a 32 percent chance that the entire five-year average will do so,” according to the Met Office.

Global average temperatures are expected to continue to rise, taking us further and further away from the climate we are used to, says Met Office expert Leon Hermanson.

Temperatures in 2023 are “likely” to be higher than the 1991 to 2020 average in almost all regions except Alaska, South Africa, South Asia and parts of Australia, says the WMO, which also admits that parts of the South Pacific are likely to be cooler than average.