Abstract
The increase in record-breaking extreme events caused by climate change
poses a threat to human health and well-being; understanding the future
impacts of such events on global populations can provide decision-making
support for policies aiming to mitigate climate change. Here, we
investigated the population exposure to eight climate extreme indices
and drivers of exposure trajectories based on NASA Earth Exchange Global
Daily Downscaled Projections Coupled Model Intercomparison Project 6
(CMIP6) and population projection data under four shared socioeconomic
pathway (SSP) scenarios at a spatial resolution of 0.25°×0.25°. The
results show that by the mid-21st century, most regions around the
world, especially Africa and South America, will continue to experience
record-breaking temperatures and compound drought and heatwaves (CDHWs).
Regarding population exposure, under the worst-case scenario of SSP3-7.0
in the late 21st century, the mean value of the multimodel median
expected annual exposure (EAE) of all extreme temperature indices and
CDHW reaches 8.79 billion persons per year; population exposure hotspots
will be concentrated in Central Africa, South Asia, Southeast Asia, and
East Asia, mostly in developing countries, where 62.77%-87.42% of the
EAE is found. The drivers of exposure trajectories are spatially
heterogeneous; the increase in record-breaking probability contributes
more than population growth to EAE growth in most regions of the world
except Central Asia, the Middle East, and most of Africa. These findings
highlight the necessity of using various climate extreme indices to
reveal spatiotemporal patterns of population exposure, which can provide
references for future adaptation decisions and risk management.