Warming, thermal variability, and the 96% decline in childhood respiratory-infection mortality in China: a national time-series analysis of the Global Burden of Disease Study 2021 and the C-LSAT high-resolution climate dataset
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Background
Childhood respiratory mortality in China has fallen by over 90% in three decades alongside sustained national warming, yet national long-run evidence on temperature and child respiratory mortality is lacking.
Methods
We linked Global Burden of Disease (GBD) 2021 mortality estimates for China — lower respiratory infections (LRI), ages 0–19, and asthma, ages 0–24, 1990–2021 — with C-LSAT 0.5° gridded temperature data (1990–2019), aggregated nationally and to five climate zones. Four annual indicators (mean temperature, diurnal temperature range, seasonal amplitude, interannual variability) entered regressions of log mortality rates with Newey–West standard errors. A bootstrapped (500 resamples) quadratic model probed the minimum mortality temperature (MMT), with PM2.5-adjusted analyses and future-exposure, permutation, and detrended falsification tests.
Results
LRI deaths fell by 96.3% (330,194 in 1990 to 12,098 in 2021; 95% uncertainty interval 9,669–14,891) and asthma deaths by 94.9% (3,287 to 167), while mean temperature rose 0.364 °C per decade and diurnal temperature range narrowed 0.092 °C per decade. Baseline coefficients were large (mean temperature −1.696, SE 0.174; diurnal temperature range +2.408, SE 0.336; seasonal amplitude −0.162, SE 0.082; interannual variability +2.924, SE 1.514, per 1 °C in log rate), but the future-exposure test failed and detrending nullified every coefficient: the associations are trend-level, and short-cycle causal effects are not identifiable. Nor was the national MMT identifiable — observed temperature support spans only 6.66–8.13 °C, and the nominal turning point of 35.84 °C is an extrapolation artifact (quadratic term p = 0.963). Within the observed range, warming and declining mortality moved in the same direction.
Conclusions
The 96% decline in childhood respiratory mortality cannot be attributed to warming. China sits on the low-temperature side of the optimum, and the marginal direction of future warming requires stronger designs to establish. The falsification framework offers a discipline for climate–health inference in China.
