Changes in Northern Hemisphere temperature variability shaped by regional warming patterns

Regional warming patterns control temperature variance and skewness changes in the Northern Hemisphere, suggests analysis of tracked temperature anomalies. Global warming involves changes not only in the mean atmospheric temperature, but also in its variability and extremes. Here, we use a feature-tracking technique to investigate the dynamical contribution to temperature anomalies in the Northern Hemisphere in climate-change simulations from the Coupled Model Intercomparison Project - Phase 5 (CMIP5). We develop a simple theory to explain how temperature variance and skewness changes are generated dynamically from mean temperature gradient changes, and demonstrate the crucial role of regional warming patterns in shaping the distinct response of cold and warm anomalies. We also show that skewness changes must be taken into account, in addition to variance changes, to correctly capture the projected temperature variability response. Our findings suggest that the world may experience not only a warmer mean climate in the coming decades, but also changes in the likelihood of temperature anomalies within that climate.