Global temperatures are likely to surge to record levels in the next five years, fuelled by heat-trapping greenhouse gases and a naturally-occurring El Niño event, according to an update by the World Meteorological Organisation (WMO).
The critical Paris Agreement target of containing global average world temperature rise to within 1.5 degrees above pre-industrial levels will be temporarily exceeded, its analysis published on Wednesday concludes.
There is a 66 per cent likelihood that the annual average near-surface global temperature between 2023 and 2027 will be more than 1.5 degrees above pre-industrial levels for at least one year. There is a 98 per cent likelihood that at least one of the next five years, and the five-year period as a whole, will be the warmest on record.
“This report does not mean that we will permanently exceed the 1.5-degree level specified in the Paris Agreement which refers to long-term warming over many years. However, WMO is sounding the alarm that we will breach the 1.5-degree level on a temporary basis with increasing frequency,” said WMO secretary general Prof Petteri Taalas.
“A warming El Niño is expected to develop in the coming months and this will combine with human-induced climate change to push global temperatures into uncharted territory,” he said. “This will have far-reaching repercussions for health, food security, water management and the environment. We need to be prepared.”
There is only a 32 per cent chance that the five-year mean will exceed the 1.5-degree threshold, according to the Global Annual to Decadal Climate Update produced by the UK Met Office – the WMO’s lead centre for such predictions.
Issued annually by the UN body, it provides a synthesis of the global annual to decadal predictions produced by the Met Office and other designated centres around the world.
The Paris Agreement sets long-term goals to substantially reduce emissions to limit global temperature increase this century to 2 degrees while pursuing efforts to limit the increase even further to 1.5 degrees to avoid or reduce adverse impacts.
The chance of temporarily exceeding 1.5 degrees has risen steadily since 2015, when it was close to zero. For the years between 2017 and 2021, there was a 10 per cent chance of exceedance.
“Global mean temperatures are predicted to continue increasing, moving us away further and further away from the climate we are used to,” said Dr Leon Hermanson of the Met Office, who led compilation of the report.
The average global temperature in 2022 was about 1.15 degrees above the 1850-1900 average. The cooling influence of La Niña conditions over much of the past three years temporarily reined in the longer-term warming trend.
But La Niña ended in March 2023 and an El Niño is forecast to develop in coming months. Typically, El Niño - climate pattern describing unusual warming of surface waters in the eastern equatorial Pacific Ocean - increases global temperatures in the year after it develops, meaning that in this case, this would be 2024.
The annual mean global near-surface temperature for each year between 2023 and 2027 is predicted to be between 1.1 and 1.8 degrees higher than the 1850-1900 average. This is used as a baseline because it was before the emission of greenhouse gases from human and industrial activities.
Arctic warming is disproportionately high, the WMO concludes. Compared to the 1991-2020 average, “the temperature anomaly is predicted to be more than three times as large as the global mean anomaly when averaged over the next five northern hemisphere extended winters”.
UCC palaeontologist Dr Chris Mays said faster warming at the poles was precisely what is seen in the rock and fossil records from Earth’s deep past. “When the world warms, the extra heat is smeared across the globe, with the coldest parts becoming warmer quicker,” he added.
“For most of Earth’s history, the planet has been without polar ice caps. But the transitions from an icy world (like today) and an ice-free world is usually much slower. We’re heading towards an ice-free globe, but the rate at which things are changing is reminiscent of the most extreme and most devastating warming events in Earth’s past.”
A small glimmer of hope was that Antarctica was not warming as fast as the Arctic, he noted. “If this was the case, we would see a dramatic and rapid rise in sea levels, as the landlocked Antarctic ice sheets melted. Instead, we still have (limited) time to avert the worst outcomes of climate change.”
The global Paris Agreement target of 1.5 degrees was admittedly ambitious, “but very few of the relevant scientists think this is realistic anymore. A safer bet would be to prepare for a world that is at least 2 degrees warmer”, Dr Mays said.
Predicted precipitation patterns for the May to September 2023-2027 average, compared to the 1991-2020 average, suggest increased rainfall in the Northern Europe, the Sahel, Alaska and northern Siberia – with reduced rainfall for this season over the Amazon and parts of Australia, the WMO says.
“In addition to increasing global temperatures, human-induced greenhouse gases are leading to more ocean heating and acidification, sea ice and glacier melt, sea level rise and more extreme weather,” its report notes.
