Human climate fingerprint detected regionally and across Europe

45 years of satellite data are now available. According to the team led by Chao Li, they are sufficient to make human-caused warming empirically detectable in most regions. The data thus provide a regional view of a signal that has long been known globally — including for Europe, which is suffering from an unprecedented heatwave.

To do this, the researchers analyzed surface temperature data from 1850 to 2022 and compared regional trends with the global average. The decisive pattern consists of several elements: The troposphere is warming while the stratosphere is cooling; landmasses are heating up more than oceans; and the Arctic is warming particularly quickly. Together, these produce a statistical fingerprint that differs from natural variability.

The method is called “detection and attribution”: It statistically establishes that a climate change is occurring and assigns it a cause. Its origins lie in the work of Klaus Hasselmann, the founding director of the Max Planck Institute for Meteorology. Hasselmann showed as early as the 1970s how human influences could be extracted from the climate’s natural ups and downs; in 2021, he received the Nobel Prize in Physics for this work. The Intergovernmental Panel on Climate Change IPCC also builds on his method.

The new analysis is likewise limited by the data. According to scientist Josie Aruhasi, climate models often estimate the time until a statistically robust regional signal emerges — the so-called “emergence timescale” — too optimistically. In the Arctic, natural variability noticeably slowed warming between the late 1990s and early 2010s. In the Southern Ocean and subpolar North Atlantic, the human signal is still disappearing into natural noise.

So what does this change in concrete terms? Researchers can no longer describe human influence only as a global average; they can now identify it directly from observational data for most regions. This strengthens the link between measured changes on the ground — such as the warming pattern in Europe — and their human cause. At the same time, the study shows where attribution remains uncertain and further observations are needed.