Temperature records: climate targets will soon be history

Temperature data in recent years have impressively shown how quickly the window for limiting global temperature rise to 1.5 degrees Celsius above pre-industrial levels can close. A team of researchers with participation from Austria has now revised the estimates of the remaining CO2 budget.

Their conclusion, published in the journal ‘Nature Climate Change’: if things continue as before for another six years, the goal will finally be history.

Developments surprise – in a negative sense
The latest developments in recent years have also surprised many experts in a negative way: the effects of the unprecedented increase in the concentrations of greenhouse gases in the atmosphere are occurring much faster than often expected.

This year’s heat anomalies with sea temperatures well above long-term average, the relatively very warm summer and hot autumn in many parts of the world and the highest daily average global temperatures recorded to date illustrate this.

2023 probably the warmest year ever recorded
The American climate agency NOAA expects with a probability of more than 99 percent that 2023 will be the warmest year worldwide since measurements began. Average temperatures so far this year are 1.4 degrees Celsius above pre-industrial levels, according to the EU climate change agency Copernicus.

Researchers in the studies are now wondering how much space is left until the 1.5 degree limit is more or less definitively exceeded, within which, according to experts, the negative effects of the climate crisis can at least be kept within reasonable limits – Lead authors Robin Lamboll from Imperial College London and Joeri Rogelj from the International Institute for Applied Systems Analysis (IIASA) in Laxenburg near Vienna.

This needs to happen now:
In their analysis, the scientists now conclude that there is still a 50 percent chance that the increase will be limited to the 1.5 degree threshold if humans emit only an additional 250 gigatons of CO2 from January 2023. This would mean that the room for maneuver for the CO2 budget would shrink by half compared to the last estimates of the Intergovernmental Panel on Climate Change (IPCC) in early 2020.

This is mainly because emissions have increased again after a brief decline due to the Covid-19 pandemic. The latest meteorological observations would also have a negative impact on budget estimates, according to a perspective article on the work of Benjamin Sanderson of the Center for International Climate and Environmental Research in Oslo.

Play against the clock
In other words: within this margin of 250 gigatons, according to the newspaper, there are only about six years in which CO2 can be emitted, such as this year. The scientists used the approximately 40 gigatons of CO2 emissions that humans caused worldwide last year as a reference value. For the 50 percent chance of staying below the two-degree plus limit, the team, which also includes IIASA researchers Zebedee Nicholls, Christopher Smith, Jarmo Kikstra and Edward Byers, calculated a remaining budget of about 1,200 gigatons of CO2.

However, the scientists emphasize in their work that this information is anything but certain: an uncertainty factor is the influence of the emissions of other greenhouse gases, the concentrations of which have also increased in recent decades.

“The budget is extremely tight”
It is also not clear how global warming will continue once net emissions reach zero, that is, if no more greenhouse gases enter the atmosphere than are removed by nature or technical efforts. Sanderson points out here that, given the new figures from Lamboll and colleagues, achieving net-zero emissions by mid-century, as politicians have often promised, would not be enough to prevent the 1.5-year limit from being hit. exceeded. limitation.

“The current research shows one thing above all: the target of 1.5 degrees will be very tight. It is virtually irrelevant whether the budget will be used up within six years – as in this study – or within ten years – as previously thought – with constant emissions. In any case, it is extremely tight. And this is not a new finding,” the head of the New Climate Institute in Cologne, Niklas Höhne, who was not involved in the study, explained to the German Science Media Center (SMC). But that doesn’t mean you have to give up. “Quite the opposite. It shows that every ton of CO2 saved is even more important because the budget is so extremely tight.”