The world is now likely to breach a key climate threshold for the first time within the next five years, according to the World Meteorological Organization, due to a combination of heat-trapping pollution and a looming El Niño.
Global temperatures have soared in recent years as the world continues to burn planet-warming fossil fuels like coal, oil and gas. And that trend shows no sign of slowing. In its annual climate update, the WMO said that between 2023 and 2027, there is now a 66 percent chance that the planet’s temperature will climb above 1.5 degrees Celsius of warming above pre-industrial levels for at least one year.
As temperatures surge, there is also a 98 percent likelihood that at least one of the next five years – and the five-year period as a whole – will be the warmest on record for the planet, the WMO reported.
Breaching the 1.5-degree threshold may only be temporary, the WMO said, but it would be the clearest signal yet of how quickly climate change is accelerating – hastening sea level rise, more extreme weather and the demise of vital ecosystems.
Countries pledged in the Paris Climate Agreement to limit global warming to well below 2 degrees – and preferably to 1.5 degrees – compared to pre-industrial temperatures. Scientists consider 1.5 degrees of warming as a key tipping point, beyond which the chances of extreme flooding, drought, wildfires and food shortages could increase dramatically.
"This report does not mean that we will permanently exceed the 1.5 degrees Celsius 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 degrees Celsius level on a temporary basis with increasing frequency," said WMO Secretary-General Professor Petteri Taalas, in a statement.
The temperature increases are fueled by the rise of planet-heating pollution from burning fossil fuels, as well as the predicted arrival of El Niño, a natural climate phenomenon with a global heating effect.
"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," Taalas said. "This will have far-reaching repercussions for health, food security, water management and the environment. We need to be prepared."
The current hottest year on record is 2016, which followed a very strong El Niño event. El Niño tends to ramp up the temperatures the year after it develops, which could put 2024 on track to be the hottest year on record.
The world has already seen around 1.2 degrees of warming, as humans continue to burn fossil fuels and produce planet-heating pollution. And despite three years of cooling La Niña, temperatures have soared to dangerous levels. The last eight years were the warmest on record.
The report stated that the chance of temporarily exceeding 1.5 degrees Celsius has risen steadily since 2015, when the WMO put the chance of breaching this threshold at close to zero.
The annual mean global near-surface temperature for each year between 2023 and 2027 is predicted to be between 1.1 degrees Celsius and 1.8 degree Celsius higher than the 1850-1900 average, said the WMO. That refers to the period before the sharp increase of planet-heating pollution from burning fossil fuels.
"Global mean temperatures are predicted to continue increasing, moving us away further and further away from the climate we are used to," said Leon Hermanson, a Met Office expert scientist who led the report, in a statement.
Why does 1.5 degrees matter?
Scientists have long warned that the world needs to stay within 1.5 degrees of warming to avoid catastrophic and potentially irreversible changes.
Warming above this point increases the risk of triggering major tipping points, including the death of coral reefs and the melting of polar ice sheets, which will add to sea level rise, devastating coastal communities.
In the US alone, 13 million people could be forced to relocate because of sea level rise by the end of the century. For many low-lying Pacific Island nations, warming over 1.5 degrees is a threat to their survival.
Temperature rises also increase the frequency and intensity of extreme weather events including droughts, storms, wildfires and heatwaves.
Already this year a slew of temperature records have been broken – and in some cases smashed – across the world.
In March, parts of Argentina grappled with temperatures up to 10 degrees Celsius (18 degrees Fahrenheit) above normal. High temperature records were smashed across large parts of Asia in April, while record-breaking temperatures scorched locations in the Pacific Northwest in May.
Limiting warming to 1.5 degrees could reduce the number of people exposed to extreme heatwaves by around 420 million, according to NASA.
The window to act is closing
The 1.5 threshold may be important, but it's not a tipping point in itself.
With every fraction of a degree the world warms, the worse the effects will be. But, that also means every fraction of a degree by which warming can be reduced, will help.
Scientists say that, while the window to act is fact closing, there is still time to reduce global warming by moving away from burning oil, coal and gas and toward clean energy.
Many have also called for adaptation measures to prepare for the climate impacts that are already baked in, such as vast coastal walls to protect communities from sea level rise.
Countries will meet at the UN COP28 climate summit in Dubai at the end of the year, where they will undertake a "global stocktake" – an assessment of their progress toward targets agreed in the Paris Climate Agreement.
They are expected to be a long way off track on meeting goals to keep within 1.5 degrees of warming by cutting planet-heating pollution by more than 40 percent by 2030.
