For his contributions to the physical modeling of the Earth's climate, the quantification of natural variability, and the reliable prediction of global warming, Prof. Klaus Hasselmann, founding director of the Max Planck Institute for Meteorology and scientific director of DKRZ from 1987-1999, received the Nobel Prize in Physics 2021 together with Syukuro Manabe (USA, native of Japan) and Giorgio Parisi (Italy).

The Nobel Committee's recognition of excellent scientific advances often occurs - if at all - much later than the scientific work itself, since their importance and impact usually only become clear in retrospect.

In order to present some of the work for which Prof. Hasselmann is being honored with the prize in an appropriate way, we would like to take you on a short journey back in time to the early 1990s, when the Max Planck Institute for Meteorology headed by Prof. Hasselmann carried out the first climate change scenarios with coupled atmosphere-ocean models using the new high-performance computer CRAY 2S at DKRZ.
These model calculations only became technically possible with the founding of the German Climate Computing Center, which was able to acquire an internationally competitive supercomputer, the CRAY 2S, in 1988 as a national subject-specific research infrastructure and thus provide climate research in Germany with the urgently needed computing power.

At that time, society was still quite far from recognizing the scientific findings obtained at that time on climate change that had already occurred and that were projected for the future as sufficiently substantiated scientific facts and from reacting to them accordingly. Therefore, we prepared the new results in a manner suitable for the media and actively communicated them to the public. DKRZ, headed by Prof. Hasselmann as scientific director, started very early to present the simulated temporal-spatial climate changes in the form of animated visualizations - on the one hand for gaining scientific knowledge, and on the other hand for communicating to experts as well as to the public, for example by using them within TV reports about the achieved results.

In view of the 1992 UN Conference on Environment and Development ("Rio Conference"), Joachim Biercamp and Michael Böttinger of DKRZ, together with Prof. Hasselmann, developed a concept for a film presenting the latest scenario calculations performed with a three-dimensional coupled atmosphere-ocean model. Surprisingly, this almost 30-year-old film is still highly topical.

The Climate of the next Century (1992)

Shortly thereafter - in the run-up to the UN Climate Conference in Berlin in 1995, Joachim Biercamp and Michael Böttinger, together with Klaus Hasselmann, produced another film presenting three works of the Hamburg Max Planck Institute at that time, including the new fingerprint method developed by Hasselmann for the statistical detection of human influence on climate change observed so far [Hasselmann, K. (1993). Optimal Fingerprints for the Detection of Time-dependent Climate Change, Journal of Climate, 6(10), 1957-1971.].

The film first explains the basics of the climate system and shows examples of its modeling using simulations of the atmosphere, ocean, sea ice, biosphere, chemical processes, and even volcanic eruptions. The example of the El Nino phenomenon is used to demonstrate the usefulness of climate models for society, as this phenomenon, which occurs about every 4-7 years and brings global climate anomalies, becomes predictable with coupled models. Furthermore, new scenario calculations, which now also take into account the effect of aerosols, are presented and explained, before finally the fingerprint method is explained, on the basis of which it could be statistically proven that already the warming observed until 1993 can be explained with a 95% probability only by human influences.

Climate Simulations - Predictions of Global Change (1995)

The film was awarded the 1995 German Business Film Prize, perhaps because of the social significance of the subject matter presented.