The new Max Planck Institute Grand Ensemble with CMIP6 forcing and
high-frequency model output
Abstract
Single-model initial-condition large ensembles are powerful tools to
quantify the forced response, internal climate variability, and their
evolution under global warming. Here, we present the CMIP6 version of
the Max Planck Institute Grand Ensemble (MPI-GE CMIP6) with 30
realisations for the historical period and five emission scenarios. The
power of MPI-GE CMIP6 goes beyond its predecessor ensemble MPI-GE by
providing high-frequency output, the full range of emission scenarios
including the highly policy-relevant low emission scenarios SSP1-1.9 and
SSP1-2.6, and the opportunity to compare the ensemble to complementary
high-resolution simulations. First, we describe MPI-GE CMIP6, evaluate
it with observations and reanalyses and compare it to MPI-GE. Then, we
demonstrate with six novel application examples how to use the power of
the ensemble to better quantify and understand present and future
climate extremes, to inform about uncertainty in approaching Paris
Agreement global warming limits, and to combine large ensembles and
artificial intelligence. For instance, MPI-GE CMIP6 allows us to show
that the recently observed Siberian and Pacific North American heatwaves
would only avoid reaching 1-2 year return periods in 2071-2100 with low
emission scenarios, that recently observed European precipitation
extremes are captured only by complementary high-resolution simulations,
and that 3-hourly output projects a decreasing activity of storms in
mid-latitude oceans. Further, the ensemble is ideal for estimates of
probabilities of crossing global warming limits and the irreducible
uncertainty introduced by internal variability, and is sufficiently
large to be used for infilling surface temperature observations with
artificial intelligence.