We’ve had 12 months of record-breaking global heat. How close are we to passing the 1.5C limit?

While the last 12 months have seen global temperatures reach 1.64 degrees Celsius above pre-industrial levels, latest data According to the Copernicus climate research programme, this is not quite the same as exceeding the 1.5 degree Celsius limit set in the 2015 Paris Climate Agreement.

But it is very worrying that we are almost there and that global warming has been accelerating in recent years.

According to the European programme, every month from July 2023 to June 2024 was the warmest on record, with each month being 1.5 degrees Celsius above the pre-industrial average for that month.

The warming is partly caused by the natural El Niño weather pattern, which usually causes temperatures to rise. But the underlying trend of global warming is clear, and experts point to factors beyond greenhouse gas emissions that may have pushed temperatures to their current record levels.

Is there more going on than just greenhouse gases?

Zeke Hausfather, a scientist with Berkeley Eartha nonprofit organization that analyzes data for climate science, says the temperature rise is in line with what its climate models predict and with the acceleration of global warming observed over the past 15 years.

“It is a pretty serious sign that the world will soon exceed the 1.5 degrees Celsius target and that we have in fact waited too late to reduce emissions to prevent this,” he wrote in an email.

“The recent 12-month period of temperatures above 1.5°C also corresponds to a clear recent acceleration in warming, consistent with what our climate models expect in a world where emissions of planet-cooling aerosols (e.g. sulphur dioxide) are rapidly reduced, while emissions of CO2 and other greenhouse gases remain at record highs.”

These aerosol emissions refer to air pollutants from things like burning coal and marine fuel. New regulations have reduced emissions of these pollutants — which are harmful to human health but also reflect heat and have a cooling effect on the atmosphere.

Some models suggest that reducing their emissions could have a warming effect.

The magnitude of the heat in 2023 is causing scientists to take a more serious look at the impact of removing these aerosols from the atmosphere – and the long-term consequences for climate change, said Bill Merryfield, a climate scientist with Environment and Climate Change Canada.

“2023 has been so exceptional that there has been a lot of speculation that there are other effects besides greenhouse gases that are contributing to global warming,” Merryfield said, referring to the impact of the new fuel regulations.

“The size of the effect is still being studied and debated. Some scientists think it’s very small, others think it could be significant,” Merryfield said.

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How is this different from the Paris threshold?

The alarming statistics also indicate that the climate system is teetering on the brink of collapse. According to experts, global warming will have consequences for countries around the world, such as storms, floods and extreme heat.

But those implications don’t reflect what it actually means to exceed the 1.5 degree Celsius limit set by the Paris Agreement, which refers to a shift in long-term average temperatures.

“Beating 1.5 C for 12 months is not the same as exceeding the threshold year after year in a global average sense,” said Stanford University climate scientist Rob Jackson. “It’s different for ice melt, it’s different for all sorts of processes.”

Jackson’s upcoming book, In the clear blue skyis about climate solutions and the urgent need to repair the damage to the atmosphere.

“It’s surprising and disheartening to be so close to the 1.5C mark,” he said. “We’ve sprinted quickly and quite recklessly towards the edge of that mark.”

In addition to extreme weather, a rise in global average temperature above 1.5°C would have serious implications for sea level rise and could lead to climate tipping points, such as the irreversible melting of Arctic permafrost or a change in the major ocean currents that shape global weather.

These major consequences would not be noticeable if temperatures only temporarily exceeded the 1.5°C limit for a few years.

According to the World Meteorological Organization2023 was the warmest year on record and there is an 80 percent chance that at least one of the years between 2024 and 2028 will see temperatures exceed 1.5 degrees Celsius.

According to the WMO, the chance of this happening was virtually zero in 2015.

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