Climate change and geopolitical risk. analyzing the relationship between Köppen-Geiger zone shifts and global stability

The complex relationship between climate change and geopolitical stability remains poorly quantified, with previous studies primarily focusing on indirect measures like composite indicators and expert opinion surveys. This contribution aims to investigate possible connection among climate zone shifts, global warming, geopolitical stability and income inequality at the global scale. To this purpose the analysis was conducted by evaluating locations world-wide with a spatial resolution of 0.1◦ x 0.1◦ using: the K¨oppen-Geiger (KG) system of climate data classification (1901-2020), Copernicus ERA5 temperature records (1961-2021), the Geopolitical Risk Index (1901-2021), and Gini coefficients (1961-2021). We categorized KG climate zone transitions into four types (‘warmer’, ‘cooler’, ‘dryer’, ‘wetter’) by comparing initial and subsequent KG classifications for each 0.1◦ area across the climatic 30-year periods spanning 1901-2021. Then we calculated coefficients of variance for both climatic and geopolitical indices, with statistical analyses including correlation coefficients, t-tests, and K-means clustering. Results reveal a borderline significant correlation between climate volatility and geopolitical risk (rPCC = 0.29, p ≈ 0.065), while demonstrating stronger correlation between income inequality and geopolitical risk (rPCC = 0.54, p < 0.001). Country-specific ERA5 surface temperature changes show significant correlation with income inequality volatility (rPCC = 0.18, p ≈ 0.034) for the years spanning 1961-2021. European countries, particularly in Eastern Europe, have experienced the highest rates of K¨oppen-Geiger climate zone shifts (20.08% warming shifts in 1991-2020 vs. 1961-1990). While changes in climate zones somewhat correlate with geopolitical risk, institutional capacity at country level could moderate this effect. This suggests that indirect metrics could be supplemented with direct climate change evaluations (temperature, and KG zone shifts) when assessing geopolitical stability risks. As climate change progresses and its geopolitical impacts become more pronounced, their correlation is expected to increase. Even a slight temperature increase can push an ecosystem beyond the climatic thresholds, resulting in severe consequences such as, crop failure, forced migration. If these events overwhelm local governments, the climate-conflict link may become more statistically evident.