Quantifying generational and geographical inequality of climate change

Global warming caused by anthropogenic emissions of greenhouse gases (GHG) triggers a variety of related mechanisms including rising sea levels, heatwaves, and changes in weather regimes. The effects of global warming are not spatially homogenous; Low-income countries of the global south are more severely affected than the industrialized nations of the global north. In addition, large discrepancies between birth cohorts can be observed regarding their GHG emissions as well as exposure to the effects of climate change. Globally, calls for climate justice are emerging, and courts see an increase in so-called climate cases.

In a novel approach, we directly relate per-capita GHG emissions to the global temperature increase experienced by individual birth cohorts over their lifetime, in different world regions, and for different scenarios (Shared Socioeconomic Pathways; SSPs). Bridging the gap between emissions scenarios, temperature projections, and climate change impact, we quantify the geographical and generational inequality of climate change. This provides much-needed quantitative evidence to support the increasing number of climate cases and highlights the benefits, of staying within a low-emission scenario (1.5°C warming).

Our results suggest a grouping of world regions into high-, and low-emission regions, revealing clear geographic patterns between the global north and south when projected onto a world map. The geographic inequality regarding per-capita emissions intensifies under SSP3 and SSP5, whereas generational inequality is largest under SSP1.

We calculate an index of the ratio of GHG emissions to experienced global warming, to quantify inequality on a standardized scale, revealing the same geographic patterns and grouping of world regions observed above. Unexpectedly, the observed geographical inequality of the index is largest under SSP1 among the most recent birth cohorts, an observation that additionally pushes the debate about global justice of climate change and mitigation.