Sarah Janzen.

Climate change threatens to increase the likelihood of extreme weather events, with impacts projected to disproportionately affect vulnerable low-income populations. This paper examines how local deviations in temperature and precipitation affect early-childhood growth outcomes in the first 1,000 days of development — from conception to 24 months old — when children are most developmentally vulnerable. We exploit Demographic and Health Surveys data linked to high-resolution ERA5 weather data to reconstruct the full daily weather exposure history of over 1.2 million children from 57 low- and middle-income countries. Identification compares children surveyed in the same province-climate zone and month, while accounting for time-varying country-level factors, who experienced different weather realizations in the first 1,000 days. We further exploit differences in the timing of shocks within those 1,000 days to estimate persistent effects of shocks experienced at different points across a child's early-life exposure history. We observe limited evidence of persistent effects of early life extreme heat exposure. Drought exposure and extreme cold exposure in utero both persistently lower the average height-for-age z-scores (i.e. increase stunting) of children ages 3-5 years.