Accelerated global warming: The 1.5-degree target is dangerously close

The debate about whether the blue planet is heating up faster than previously assumed has received a new, scientifically sound answer. In a current study published in the journal Geophysical Research Letters, researchers Grant Foster and Stefan Rahmstorf from the Potsdam Institute for Climate Impact Research (PIK) demonstrate that global warming has significantly accelerated in the past decade. While the temperature increased by an average of 0.2 degrees Celsius per decade between 1970 and 2015, this value climbed to around 0.35 degrees Celsius in the last decade.

This nearly doubled warming rate marks a turning point in climate statistics, according to the study, which goes far beyond normal natural fluctuations. To arrive at this result, the scientists performed a complex statistical correction of five leading global temperature datasets. The goal was to minimize atmospheric “noise” caused by short-term phenomena.

Foster and Rahmstorf factored out the influence of the El Niño weather phenomenon, volcanic activities, and cyclical fluctuations in solar radiation from the raw data. The result is clear: after correction, the underlying signal of man-made warming is more evident than ever before. According to Foster, a strong and statistically significant acceleration of global warming can now be proven for the period after 2015 for the first time.

The 1.5-degree limit is wavering

Particularly concerning is the outlook for 2024, which has already gone down in history as the warmest year since weather records began in 1850. Even when the amplifying effects of natural factors are excluded, 2024 remains a solitary leader in global heat.

The study also highlights how narrow the window for political countermeasures has become. Rahmstorf urgently warns that if the current warming trend continues, the 1.5-degree limit set in the Paris Agreement could be permanently exceeded before 2030. The goal of keeping warming well below two degrees thus threatens to become utopian.

The purely data-based PIK analysis does not make direct statements about the exact causes of this sudden jump. However, it refers to ongoing scientific debates. One widely discussed explanation is, paradoxically, the improvement of air quality. Tiny particles in the atmosphere, so-called aerosols, produced by burning fossil fuels, reflect sunlight and indirectly cool the Earth.

Due to stricter environmental regulations, for example in shipping, the concentration of these pollutant particles is decreasing. This causes the cooling “veil” to dissipate, and temperatures rise faster. Even though further research is needed to precisely weigh this effect, the main cause remains the emission of greenhouse gases from coal, oil, and gas.

Tipping points and political responsibility

The consequences of every further tenth of a degree of warming are already being felt worldwide. Extreme weather events such as devastating storms, floods, prolonged droughts, and heatwaves increasingly threaten human livelihoods, experts warn. The irreversible tipping of important elements in the global climate system is thus threatened.

The researchers emphasize that an immediate and accelerated phase-out of fossil fuels remains the only option to break this trend. At the same time, however, they view the current political world situation with skepticism. It is entirely possible that the warming trend will continue or even intensify.

(nie)