High-resolution palaeoclimate simulation over China in the last millennium

The Earth's climate is currently undergoing significant transformations, marked by increasing temperatures, more frequent extreme events, and shifts in precipitation patterns. To comprehend these changes on decadal to centennial time scales and contextualize current climate change, it is essential to leverage paleoclimatic data spanning centuries to millennia. This analytical approach enhances our insight into natural climate variability, trends, and extremes, facilitating projections, planning, and preparation for the future. Paleoclimate reconstructions, utilizing physical, chemical, biological, or detailed documentary records, offer valuable insights into climate conditions and variability across different historical periods. In contrast, climate models provide comprehensive information and data describing the entire climate system. Paleoclimate models specifically simulate the climate of past centuries to millennia by reconstructing the forcings influencing Earth's energy and, consequently, its climate. However, global circulation models with low horizontal resolution fall short in fully elucidating atmospheric pattern interactions and linking potential climate impacts contributing to significant societal events in history. Recognizing these limitations, regional climate models emerge as promising tools for a more realistic representation of topography and regional climate information pertinent to paleoclimate studies. In our investigation, we employ the fully paleoclimate-adjusted regional climate model COSMO-CLM over China on a 0.22° resolution. This model incorporates external forcings such as solar, orbital, volcanic, greenhouse gas, and land-use changes, aiming to reduce reliance on input from coarse-resolution General Circulation Models (GCMs). The goal is to produce simulations that better capture climate changes over the past 2000 years at the regional scale. Focusing on specific periods during the Little Ice Age and major tropical volcanic eruptions, we compare our model results with climate reconstructions from various regions in China. The COSMO-CLM successfully reproduces the impact of volcanic eruptions on China's climate, particularly regarding temperature changes. However, the intricate topography introduces complexities that affect the regional model's performance, leading to notable differences compared to other reconstructions, along with inherent uncertainties in the results.