A new Nature Ecology & Evolution study shows that between 2010 and 2020, tropical regions like the Amazon, Congo, and Southeast Asia lost forest age through fire and logging, leading to a global net carbon loss of ~0.14 billion tonnes per year. While forests in Europe, China, and North America are ageing, their gains do not compensate for tropical losses, highlighting the critical need to protect old-growth forests while managing younger stands for climate benefits.