Significant Reduction of Unequal Population Exposure to Climate Extremes by Achieving the Carbon Neutrality

Abstract

Climate extremes, such as hot temperature and heavy precipitation events, have devastating effects on human societies. As the planet gets warmer, they have become more intense and more frequent. To avoid irreversible damages from climate extremes, many countries have committed to achieving net-zero anthropogenic carbon emissions, or carbon neutrality, by the 2050s. Here, we quantify the impact of carbon neutrality on population exposure to climate extremes using multi-model projections from the Coupled Model Intercomparison Project Phase 6 (CMIP6) Shared Socioeconomic Pathway (SSP)1-1.9 and SSP3-7.0 scenarios. It is found that the increasing population exposure to hot-temperature and heavy-precipitation extremes under SSP3-7.0 scenario can be substantially reduced by 87%-98% in the late 21st century by achieving the carbon neutrality based on SSP1-1.9 scenario. The benefits of carbon neutrality are particularly pronounced in Africa and Asia. The potential benefits of carbon neutrality are also significant in North America, Europe, and Oceania, where a reduction in climate extremes is more than twice as important as population decline in reducing population exposure to climate extremes. These results provide important scientific support for ongoing efforts to achieve net-zero carbon emissions by the 2050s to reduce potential climate risk and its inequity across continents. To avoid irreversible damages from climate extremes in a warming climate, net-zero anthropogenic carbon emissions, or carbon neutrality, has been proposed. However, how much damages from climate extremes can be mitigated by achieving the carbon neutrality has not been quantitatively assessed. Here, we show that achieving carbon neutrality could lead to a significant and widespread reduction in population exposure to hot-temperature and heavy-precipitation extremes by 87%-98% in the late 21st century. The benefits of carbon neutrality are particularly large in Africa and Asia. Even in North America, Europe, and Oceania, where the developed countries are concentrated, population exposure to climate extremes is projected to decrease significantly, primarily due to reduced climate extremes with a minor contribution of population decline. This finding underscores the critical importance of ongoing efforts to achieve net-zero carbon emissions by the 2050s to reduce potential climate risk and its inequity across continents. By the 2050s, carbon neutrality reduces population exposure to climate extremes by 87%-98% compared to current global warming rates Africa and Asia are projected to experience the most dramatic reductions in population exposure to climate extremes by carbon neutrality In North America, Europe, and Oceania, climate extreme change plays a more important role in population exposure to climate extremes