He said: “I certainly tend to be an optimistic person but if you do look at this year’s annual update, things are all moving in the wrong direction.”
“They’re not only moving in the wrong direction, we’re seeing some unprecedented changes.”
Reflecting on the IPCC reports, he said: “What we had hope to see by this time is these emissions beginning to turn a corner and unfortunately that hasn’t occurred.”
Instead emissions have increased year on year since the 2021 report, remaining at all-time highs, he said.
Breached
This year’s update covers key climate system indicators such as greenhouse gas emissions and concentrations, Earth energy imbalance, human-induced climate change, remaining carbon budgets and maximum land surface temperatures.
But for the first time, the annual update also included sea-level rise and global land precipitation.
In 2024, the best estimate of observed global surface temperature rise was 1.52C, of which 1.36C can be attributed to human activity, caused by global greenhouse gas emissions, the scientists said.
The report said last year’s high temperatures are “alarmingly unexceptional” as the combination of human-driven climate change and the El Nino weather phenomenon push global heat to record levels.
While global average temperatures exceeded 1.5C for the first time, this does not mean the world has breached landmark UN agreement, which would require average global temperatures to exceed the threshold over multiple decades.
Erosion
When analysing longer-term temperature change, the scientists’ best estimates show that between 2015 and 2024 average global temperatures were 1.24C higher than in pre-industrial times, with 1.22C caused by human activities.
Elsewhere, the report found that human activities were found to be affecting the Earth’s energy balance, with the oceans storing about 91 per cent of the excess heat, driving detrimental changes in every component of the climate system, including sea level rise, ocean warming, ice loss, and permafrost thawing.
Between 2019 and 2024, global mean sea level also increased by around 26mm, more than doubling the long-term rate of 1.8mm per year seen since the turn of the twentieth century.
Dr Aimee Slangen, research leader at the NIOZ Royal Netherlands Institute for Sea Research, said the rise is already having an “outsized impact” on low-lying coastal areas, causing more damaging storm surges and coastal erosion.
Extremes
“The concerning part is that we know that sea-level rise in response to climate change is relatively slow, which means that we have already locked in further increases in the coming years and decades,” she said.
IPCC’s last assessment of the climate system, published in 2021, highlighted how climate change was leading to widespread adverse impacts on nature and people.
Professor Rogelj said: “Every small increase in warming matters, leading to more frequent, more intense weather extremes.
“Emissions over the next decade will determine how soon and how fast 1.5C of warming is reached. They need to be swiftly reduced to meet the climate goals of the Paris Agreement.”
This Author
Rebecca Speare-Cole is the PA sustainability reporter.