A NASA airborne campaign called ATom, which flew a DC-8 aircraft across the Pacific and Atlantic from 2016 to 2018, measured carbon dioxide levels at various altitudes. The data showed higher CO2 concentrations over tropical forests than Earth system models expected, suggesting these forests are taking up less carbon than assumed. Meanwhile, lower CO2 levels were found in northern and southern regions, indicating some forests there may be absorbing more or fossil fuel emissions were overestimated. If tropical forests are weaker carbon sinks than models project, more human-caused CO2 stays in the atmosphere, which could worsen warming and affect climate forecasts for disaster planning, food systems, and public health. The study also showed that just four years of airborne data cut model uncertainty by up to half, highlighting the value of long-term atmospheric monitoring for improving climate science.
