Climate change, with all its ecological and economic implications, is one of society's greatest challenges. It is imperative that we develop efficient strategies and derive measures to protect our sensitive climate system on a global scale. In order to do this, we must gain a profound understanding of the complex environmental processes that contribute to climate change. Atmospheric researchers from the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) have recently made an important contribution to this.
The EMAC (ECHAM/MESSy Atmospheric Chemistry) simulation system was used to reconstruct respectively forecast the chemical composition of our atmosphere from 1950 to 2100. Exact knowledge of this development is important, as there is a connection between atmospheric chemistry and the climate. Among other things, the data obtained from the model allow scientists to draw conclusions on the influences of individual atmospheric variations on climate change. A detailed description of atmospheric composition is a particular feature of the climate-chemistry model. Moreover, the modular EMAC system was linked to an ocean model to also enable comprehensive consideration of oceanic influences.
Scientists were able to obtain over two petabytes of climate data from model calculations, which are now available to climate researchers worldwide. The elaborate simulations required over six million processor hours from the supercomputer at the German Climate Computing Center (Deutsches Klimarechenzentrums; DKRZ). The project was implemented within the framework of the national ESCiMo (Earth System Chemistry integrated Modelling), in collaboration with eight research institutions and universities under the aegis of the DLR Institute of Atmospheric Physics in Oberpfaffenhofen. The ESCiMo data will contribute to future reports by the Intergovernmental Panel on Climate Change (IPCC - Intergovernmental Panel on Climate Change) and the World Meteorological Organization (WMO) on developments in the ozone layer. The project group has already presented initial findings based on this data in a series of scientific publications.
Confirmations and surprises
Using the long-term simulation, DLR scientists were able to demonstrate, among other things, that the prohibition of ozone-depleting chlorofluorocarbons (CFCs) was an effective measure. After its rapid depletion during the 1980s, it seems that the ozone will recover again after 2035. The simulation results were compared with measurements taken by satellite instruments over the last three decades.
Atmospheric researchers also used the new climate data to understand the seemingly anomalous measurements obtained by the research aircraft HALO Project Website (High Altitude and Long Range Research Aircraft) in 2012. At the time, measurement flights across the southern peripheral regions of the so-called Asian summer monsoon anticyclones revealed ozone-rich air masses at an altitude of roughly 13 kilometres. This contradicted previous studies that had reported ozone-depleted air masses, produced by a precipitous rise in warm air during the monsoon period. The ESCiMo simulations enabled reclassification of the results, clarifying that the ozone-rich air masses did not originate from layers close to the ground, but had indeed come from the stratosphere.
The new climate data also assists in detecting water vapour in its function as a greenhouse gas. Scientists were able to identify a significantly increased, or significantly reduced amount of water vapour in the middle atmosphere following volcanic eruptions or the El-Niño climate phenomenon, both infamous causes of extreme weather conditions. This change in water vapour content impacts temperatures in the various atmospheric layers, and hence the climate system as a whole. It is now possible to conduct additional research on individual factors and interactions.
This unique treasure trove of data obtained in the ESCiMo project is by no means fully analysed as such. The data will lay the foundation to finding answers to a broad variety of scientific issues. In future, the simulation results will be made available in the CERA database (Climate and Environmental Retrieval and Archive), allowing scientists in current and future studies to work with ESCiMo data. Parts of the simulation results will also be transferred to the BADC database(British Atmospheric Data Centre) in the Chemistry–Climate Model Initiative (CCMI) for further analysis and comparison with results from other models.
About the project
In addition to the German Aerospace Center (DLR), the partners in the project ESCiMo (Earth System Chemistry integrated Modelling) include the Max Planck Institute for Chemistry (MPIC), the Karlsruhe Institute of Technology (KIT), Forschungszentrum Jülich (FZJ), Freie Universität Berlin (FUB), Johannes Gutenberg University Mainz (UMZ) and the Cyprus Institute (CYI), with support from the German Climate Computing Center (DKRZ).