The Environmental Measurements Tower in Harvard Forest

An experimental tower in Harvard Forest, Massachusetts. Data collected at the tower challenge a crucial numerical value used in carbon modelling. Credit: David Foster/Harvard Forest

Atmospheric science

A forest’s breath raises doubts about key carbon-cycle numbers

Data from a Massachusetts wood suggest that landmasses might capture more carbon than previously thought.

New measurements of the atmospheric gases wafting above a forest call into question basic estimates of how much carbon the Earth’s oceans and land masses absorb.

Researchers examine plant growth to estimate the amount of carbon dioxide plants take up during photosynthesis and the amount of oxygen they release during respiration. This information is incorporated into computer models that simulate carbon flow around the planet.

To improve estimates of the gases that vegetation inhales and exhales, Mark Battle at Bowdoin College in Brunswick, Maine, and his colleagues analysed 6 years of data on the amount of O2 and CO2 about 5 metres above the treetops in a New England forest.

The ratio of O2 to CO2 was different from that typically used to calculate the flow of carbon around the globe. The data could mean that the world’s landmasses are taking up 7% more carbon, and the ocean 7% less, than scientists had thought.