To date, research on heat extremes has primarily focused on acute events such as heatwaves. However, many regions of the globe currently face a heat hazard that can persist for months at a time. We call this hazard ‘chronic heat’ and define it here as potentially dangerous heat that lasts for 90 days or more per year. Analyzing 30 years (1993–2023) of global weather station data using three complementary metrics, this study re...

Globally, increasing air moisture can limit not only the human body’s ability to cool down, but also that of the Earth’s surface. This interaction, however, remains understudied—especially across subtropical-to-tropical regions that experience high levels of humidity. Here, we examine how air moisture influences nighttime land surface temperatures (LSTs), as well as what this interaction means for thermal comfort overnight. Du...

The Ruki is a pristine blackwater tributary in the Congo Basin draining tropical lowland forest. Daily discharge and fortnightly concentrations, isotopic ratios, and molecular composition of carbon and organic matter were measured for 1 yr (2019–2020). Like the Congo River, discharge peaked from November–January, with a smaller secondary peak in June. Dissolved organic carbon (DOC), inorganic carbon (DIC), carbon dioxide ( p C...