Working Papers

Ecosystem restoration is increasingly promoted as a global strategy to combat biodiversity loss, climate change, and environmental degradation. Yet robust empirical evidence for long-term, cost-effective recovery at national scales remains limited. Critics also emphasize that restoration outcomes are often context-dependent and that trade-offs and costs are poorly quantified. Here we show that China’s ecological reforestation programs (ERPs), which have restored over 100 million hectares of land, generated substantial ecological and public health benefits, including reductions in climate extremes, improvements in air and water quality, and biodiversity recovery, all without compromising agricultural productivity. Over two decades, the monetized health gains from the ERPs exceeded program costs ten times over. Using China as an empirical benchmark, we construct a global return-on-investment (ROI) map for forest restoration. This projection identifies regions, such as parts of South and Southeast Asia, West Africa, Central Europe, and the eastern United States, where reforestation could yield comparably high returns.

Hospitals in many countries operate close to capacity, so short-run surges in demand can generate congestion and threaten care quality. Yet there is limited evidence on how hospitals adjust physician staffing in response to such shocks and whether these adjustments protect patients. Using daily data from 1,113 public hospitals in China from 2013–2022 linked to hospital-centered weather fluctuations, we study how temperature-driven demand shocks affect emergency department (ED) inpatient workload, staffing, and outcomes. Relative to 12–15°C days, ED inpatient admissions fall by 11.6% below −6°C and rise by 8.0% above 30°C, implying a nearly linear temperature-utilization relationship. On very hot days, physicians treating new ED inpatients increase by 2.3%, driven almost entirely by junior doctors, while senior staffing does not change systematically. Admissions per physician rise only about one quarter as much as total admissions, indicating that staffing adjustments substantially attenuate workload shocks. Despite large swings in demand, we find no statistically significant effects on in-hospital mortality, length of stay, or waiting time to first surgery, and total healthcare expenditure on hot days rises mainly through higher out-of-pocket payments. These results show that hospitals buffer acute demand shocks by reallocating work toward junior physicians, maintaining short-run quality and throughput even when demand fluctuates sharply.