Simulating High-Resolution Climate over East Asia for the Last Glacial
Maximum Utilising the Pseudo-Global Warming Approach
Abstract
To better understand the landscape dynamics and changes in habitat
connectivity influenced by glacial and interglacial oscillations over
the biodiversity-rich Hengduan Mountains (HM) region, high-resolution
climate data for past periods are essential. We apply the
non-hydrostatic limited-area model COSMO, with a resolution of 12 km
over East Asia, to simulate the Last Glacial Maximum (LGM), a period
characterized by a generally colder and drier climate compared to
present-day conditions. We perform the downscaling with a novel approach
for paleoclimate modelling, the Pseudo-Global Warming (PGW) method. The
COSMO PGW simulation for the LGM shows that COSMO generally replicates
the large-scale dynamics of the driving global climate model simulation
in the colder climate. Both models suggest weaker Asian summer monsoon
systems during this period. Consequently, regions such as the Bay of
Bengal, and the South China Sea, which typically receive substantial
monsoon rainfall, experience significantly reduced precipitation.
However, despite these model similarities, the high-resolution COSMO
simulation exhibits distinctive differences on a smaller
scale—particularly over land. For instance, COSMO suggests a more
pronounced southward shift of the jet stream during the LGM winter, with
cooler conditions in southern China. Moreover, the COSMO simulation,
despite the overall weaker summer monsoon circulation, features
increased precipitation amounts for much of the HM. Additionally, COSMO
suggests a more extensive increase in snowfall over the High Mountain
Asia region. Our study suggests that the resource-saving PGW approach is
a suitable method to bridge the gap between large-scale projections and
regional climate impacts—also for past periods like the LGM.