This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: There is no question that the current global temperature increase is human-caused. Global warming has long since emerged as the dominant signal amid natural climate fluctuations.
However, identifying how this warming manifests regionally remains a key challenge. Observations do not always align with climate model predictions. For example, the southeastern Pacific and parts of the Southern Ocean have cooled, and the subpolar North Atlantic has not warmed as much as expected.
This raises the question: Are expectations regarding the typical warming pattern associated with rising greenhouse gas levels equally accurate everywhere? Or, put differently, how reliable is the model-based 'fingerprint' of human activity in the climate system at the regional level? Researchers at the Max Planck Institute for Meteorology (MPI-M) have developed an empirical tool to answer these questions.
Aruhasi, Dirk Olonscheck, Jochem Marotzke and Chao Li identified the fingerprint in observational data by using global datasets of measured surface temperatures from 1850 to 2022 and linking regional observed temperatures with the globally averaged temperature increase—a value on which models and observations agree closely. Analyzing this 'observed fingerprint' allows scientists to detect climatic changes at a regional level and attribute them to human-induced climate change. The paper is published in the journal Science Advances.
Furthermore, by comparing the observed fingerprint with its model-based counterpart, the researchers can investigate the uncertainties of climate models in more detail. They focused on four regions where this uncertainty is particularly high: Aside from the southeastern Pacific, the Southern Ocean and the subpolar North Atlantic, where models and observations exhibit the aforementioned discrepancies, this includes the Arctic as an example of a region severely affected by climate change. Warming proceeded very rapidly there from the mid-20th century onward and temporarily slowed from the late 1990s to the early 2010s.
The study shows that this slowdown is due to natural variability, yet human influence is nevertheless evident. The same applies to the southeastern Pacific. However, in parts of the Southern Ocean and the subpolar North Atlantic, human-induced warming has not clearly emerged from the 'background noise' of natural climate fluctuations.
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