HAPPI

The international HAPPI (Half a degree Additional Heating, Prognosis and Projected Impacts) initiative is the response of climate scientists to the announcement of the 1.5°C special report (SR1.5) of the IPCC (Intergovernmental Panel on Climate Change). This special report is intended to summarize the current scientific state of knowledge on the effects of 1.5°C warming against pre-industrial conditions and on the greenhouse gas emission pathways consistent with such a warming. The initiative aims to analyze global and regional climate model simulations, estimates of model uncertainties for extreme precipitation and climate impact model simulations for the water and agricultural sector in scientific publications. The differences between the risks and climate impacts of global warming by 1.5 and of 2.0°C compared to the preindustrial level should be assessed.

DKRZ participates in this initiative with several AMIP-like experiments. The processed model data are publicly provided, like all HAPPI data, and can be used in climate impact models. The scientific publications, which are based on the analyzes of these data and the results of climate impact models, are to be included in the SR1.5. In addition, data are used on the one hand by MPI-M (Max Planck Institute for Meteorology, Hamburg) in the HAPPI-LAND initiative at the Swiss Federal Institute of Technology, Zurich for sensitivity studies and on the other hand by GERICS (Climate Service Center Germany) in the HAPPI-DE initiative as forcing data for the regional model REMO (REgional Model) of MPI-M.