Evolution of high latitude climate hazards with global warming in large climate model ensembles

The Arctic has warmed at more than twice the global mean rate in recent decades, resulting in rapid changes to the northern high latitude Earth system. This includes changes to essential climate variables and associated physical hazards, such as temperature, precipitation, storminess, and cryosphere conditions - in turn posing emerging impacts/risks for society and ecosystems. Here we use data from four large ensembles and perform a detailed and systematic characterization of the distribution and variability of key physical climate hazards across the high latitude and polar regions.

Climate change is known to manifest as shifts in the means and extremes of the variables but can also affect the shapes of their distributions. As highlighted in existing literature, comprehensive understanding of climate risk therefore involves quantification of the full, regional Probability Density Functions (PDFs), as these contain information on expected weather not apparent from the distribution mean or tails. Large initial condition ensembles of coupled climate model simulations have opened new opportunities for studying climate variability and how it evolves with warming, as well as diversity across models, in more detail. Building on methodology from Samset et al. (2019), we consistently quantify regionally (focusing on the northern hemisphere) and seasonally resolved PDFs of daily data for different scenarios and levels of global warming. The analysis also includes a reality check of model performance against reanalysis data for the recent past. Chosen hazards include core ETCCDI climate change indices, as well as specific indices identified of relevance to high latitude impacts through work in the EU Horizon 2020 project CRiceS.

Rapid warming and associated environmental changes are having increasingly significant socioeconomic consequences for high latitude settlements and populations. Our results provide a comprehensive picture of the projected evolution of high latitude climate impact drivers, providing knowledge of high relevance for further assessment of climate risk.