Our History - 50 Years of Climate Research

Against the background of the environmental policy debates of the 1970s, both in Germany and worldwide, an institute dedicated to climate science is to be established within the Max Planck Society (MPG). The MPI for Chemistry in Mainz and the MPI for Aeronomy in Katlenburg-Lindau are already institutes within the MPG dealing with certain aspects of the Earth’s atmosphere. However, the establishment of a new institute is intended to ensure that Germany catches up with international Earth system research, which it lags behind by about a decade. It is also clear that computer modeling will play an important role in the new institute.

On February 1, 1975, Klaus Hasselmann takes up his position as director of the MPI for Meteorology. Two months later, the employees start their work. For the first five years, they are based in the newly built Geomatikum, a high-rise building of the University. The Hamburg Senate approves the establishment of the MPI for Meteorology on May 20, 1975. The vote of the Hamburg Parliament takes longer: First, the Budget Committee is consulted because it is unclear where the MPI for Meteorology is going to move to after the five years and whether there would be any follow-up costs for the Hanseatic city if the MPI remained in the Geomatikum. It is not until November 27 of the same year that the Hamburg Parliament clears the way for the establishment of the MPI for Meteorology.

In contrast to Klaus Hasselmann’s original proposal, the MPI for Meteorology initially has only two departments. While Hasselmann establishes his new department “Physics of the Ocean and Climate Dynamics”, the second department “Physics of the Atmosphere” consists of the “Maritime Meteorology” group of the former Fraunhofer Institute. Hans Hinzpeter, full professor of general meteorology at the University of Hamburg, is appointed head of this department and part-time director in March 1976. His team uses observations and experiments to study ocean-atmosphere processes and the interactions between clouds, aerosols, water vapor, and radiation. Among other things, Hasselmann’s department develops stochastic climate models to explain observed natural climate variability.

In the mid-1980s, the Max Planck Society and the University of Hamburg jointly search for a successor to Hans Hinzpeter. The choice falls on his former student and research assistant Hartmut Grassl, who has been heading the Institute of Physics at the GKSS Research Centre Geesthacht since 1984. Hinzpeter and Grassl initially work together at the MPI for Meteorology from April 1, 1988, until Hinzpeter, who has already retired from the university, also resigns as MPI director on January 31, 1989. Grassl expands the department, now called “Climate Processes”, and increasingly uses remote sensing methods with satellites.

On August 9, 1989, the Hamburg Senate decides to establish a “Center for Marine and Atmospheric Sciences” (ZMAW). In addition to the university’s greatly expanded Institute of Physical Oceanography, the planned building would also house the Max Planck Institute for Meteorology. On March 15, 1990, the Senate of the Max Planck Society appoint the Swedish meteorologist and Director of the European Centre for Medium-Range Weather Forecasts (ECMWF), Lennart Bengtsson, as director and head of the third department at the MPI for Meteorology. Bengtsson officially takes up his post on January 1, 1991. His department develops the ECMWF numerical weather prediction model into a general circulation model and improves the representation of relevant processes. The name of the model, ECHAM, is a combination of its origin (ECMWF) and its location in Hamburg.

In 1996, the successful development of coupled atmosphere-ocean models allows a group led by researcher Gabi Hegerl to apply the method developed by Hasselmann in 1979 to prove the influence of humans on the Earth’s climate. The scientists compare calculations that include the human influence with those that do not, and show that the probability that the observed temperature increase is due to natural factors alone is less than five percent. Today, that number is even lower.

The Max Planck Society is able to recruit Guy Brasseur from the American National Center for Atmospheric Research (NCAR) as Klaus Hasselmann’s successor under two conditions: First, with the promise to expand its computing capacities, and second, by promising the institute its own building. Brasseur is an atmospheric chemist and brings a new focus to the institute: The transition from physical atmosphere-ocean modeling to a comprehensive Earth system approach. Brasseur is also adapting the Institute’s structures and processes, thereby making a significant contribution to its modernization.

In April 2002, the MPI for Meteorology and the University of Hamburg set up the International Max Planck Research School on Earth System Modeling (IMPRS-ESM) as part of the establishment of graduate schools within the Max Planck Society. Guy Brasseur becomes the first spokesperson for the graduate program. When Jochem Marotzke joins the institute in 2003, he and Brasseur develop the school together based on practices in the US and UK. The internationally oriented school offers doctoral students a structured program and monitors their progress through regular meetings. Almost at the same time, the IMPRS for Maritime Affairs is founded, a cooperation between the University of Hamburg and the Hamburg Max Planck Institutes for Meteorology and for Comparative and International Private Law as well as the Heidelberg MPI for Comparative Public Law and International Law. It will only exist until 2014, while the IMPRS-ESM remains an integral part of the doctoral training at the MPI for Meteorology today.

Guy Brasseur’s request that the MPI for Meteorology should have its own building is fulfilled thanks to cooperation with the City of Hamburg. With a grant from the Federal Government, a building for the Centre for Marine and Atmospheric Sciences (ZMAW), which was approved in 1989, is erected. The Max Planck Society contributes indirectly to the financing by signing a 99-year lease with the city and paying a substantial part of the rent in advance. The foundation stone is laid in 2001, parts of the institute move in in February 2004, and the building is officially opened in June 2004. However, the temporary pavilion building has to remain in place as there is not enough space in the new building for all of the departments.

At the turn of the millennium, the MPI for Meteorology’s ECHAM atmospheric model is being used with great success. However, it also reaches its limits, particularly in terms of its suitability for emerging computing technologies, and its ability to represent conservation laws important for the evolution of the climate system. Under Guy Brasseur, scientists including Marco Giorgetta and Luis Kornblueh therefore suggest a reorientation of modeling. Brasseur initiates the creation of the Community Earth System Models (COSMOS) network in May 2003. He also invites the mathematician Luca Bonaventura to the MPI for Meteorology. Bonaventura investigates whether a Platonic solid, the icosahedron, can be used as the basis for a new model grid consisting of triangles instead of rectangles. The results, published in 2005, are positive. Together with the German meteorological service DWD, which has also been using a weather forecast model with a triangular grid since 1999, a standardized model for weather forecasts and climate simulations is to be developed on this basis. Years of intensive development work follow, resulting in the ICON model, which is still the most important tool at the MPI for Meteorology today.

In 2007, the German Research Foundation approves the Cluster of Excellence “Integrated Climate System Analysis and Prediction” (CliSAP) at the University of Hamburg, applied for by the university institutes of the Center for Marine and Atmospheric Sciences, the MPI for Meteorology, the Institute for Coastal Research of the Helmholtz Center Hereon and the German Climate Computing Center. Martin Claußen is the first CliSAP spokesperson. As part of the Cluster of Excellence and its successor "Climate, Climate Change and Society" (CLICCS), scientists are researching global change through interdisciplinary collaboration: alongside meteorology, oceanography and ecology, social sciences and economics are also involved, for example.

After years of development work, the MPI for Meteorology has a comprehensive tool for studying the climate system: the coupled Earth system model MPI-ESM. The model includes not only the atmosphere, land, and ocean, but also an interactive carbon cycle in all components. The results are incorporated into the reports of the Intergovernmental Panel on Climate Change. In addition, as part of the Millennium Project, researchers are studying past climate variability over a period of 1,200 years. It is a collaborative effort that involves the entire institute and uses a comprehensive Earth system model on a millennium time scale for the first time. In addition to solar activity and volcanic eruptions, the model takes into account land use changes and anthropogenic carbon dioxide emissions as external drivers of the climate system. The results published in 2010 demonstrate the validity of the MPI-ESM: the evolution of temperature and atmospheric carbon dioxide during the last millennium simulated by the model is consistent with observations — including the anthropogenic warming of the 20th century.

In January 2001, the Max Planck Society and the German Aerospace Center (DLR) jointly submit an application to the German Federal Ministry of Education and Research for a research aircraft called HALO (High Altitude and Long Range Research Aircraft). It is to have outstanding characteristics such as a particularly large payload, high ceiling, and an exceptionally long range. In September 2004, the Ministry decides to finance the project. After the necessary modifications, approvals and test flights, HALO makes its first scientific flight in September 2010. Since 2013, the MPI for Meteorology has been using HALO regularly for measurement flights. For this purpose, it carries the HAMP (HALO Microwave Package) instrument package, which has been specially developed for cloud observation in collaboration with the University of Hamburg and the Institute of Atmospheric Physics at DLR – in anticipation of a new satellite, called EarthCARE, which is simultaneously being built.

In 2007, Jochem Marotzke initiates the establishment of a national program for decadal climate prediction — MiKlip — and manages it from 2011 to 2019. The aim is to develop and operationalize a prediction system. This means that the forecasting tool is transferred to the German meteorological service (DWD) to close the gap between short-term weather forecasts and seasonal forecasts on the one hand and long-term climate projections on the other. The DWD has been carrying out these decadal forecasts since 2020, providing important information for policymakers.

In 2021, the Royal Swedish Academy of Sciences awards the Nobel Prize in Physics “for pioneering contributions to our understanding of complex physical systems”. Half of the prize goes to Klaus Hasselmann and Syukuro Manabe “for the physical modeling of the Earth’s climate, the quantification of its variability and the reliable prediction of global warming”, the other half to Giorgio Parisi. With this award, the Nobel Committee honors, among other things, Hasselmann’s work on stochastic climate models and the evidence that humans are changing the Earth’s climate. After the announcement of the Nobel Prize winners in October 2021, in the midst of the Covid-19 pandemic, the staff of the MPI for Meteorology welcomes the former director with a standing ovation in the ZMAW building. Hasselmann accepts the award on December 7, 2021 at the Harnack House in Berlin.

The MPI for Meteorology is delighted to win the South Korean-American atmospheric scientist Sarah M. Kang as the successor to Martin Claussen, who retired in 2021. Kang has made a name for herself in the field of climate research with theoretical and modeling studies on the response of the climate system to global warming. She becomes the new director of the MPI for Meteorology on August 15, 2023, and is the first woman to hold this position. The institute is also being restructured in terms of content: instead of the Land-Ocean-Atmosphere division, there are now the departments of Climate Dynamics (Sarah Kang), Climate Physics (Bjorn Stevens) and Climate Variability (Jochem Marotzke). The aim is to study the climate system as a whole from different perspectives.

Under the leadership of Bjorn Stevens, the MPI for Meteorology is planning another campaign to measure thunderclouds and air mass movements in the tropical Atlantic. Initially, the focus is on measurements with the research aircraft HALO and a ship-based campaign. However, the plans are drawing ever wider circles: The start of the campaign is delayed due to the pandemic and now coincides with the launch of the EarthCARE satellite, which means that more project partners are added. Finally, in August and September 2024, eight coordinated sub-campaigns take place as part of the ORCESTRA expedition. More than 200 scientists and technicians from over 40 institutions are involved.