Rain Boosts Ocean Carbon Uptake by 13.6%
A Nature Geoscience study finds rainfall may be missing from current global carbon budgets.
Updated on Nov. 12, 2026 in Environmental
A new study published in Nature Geoscience estimates that rain increases global ocean carbon uptake by 13.6%. Researchers say global carbon budgets may underestimate ocean carbon absorption by roughly 5% to 15%.
Why it matters
Rain makes surface seawater less salty, changing its chemistry in ways that favor greater CO₂ uptake, and current estimates do not fully account for these surface effects. Accurate carbon budgets are central to tracking how much carbon the ocean absorbs from the atmosphere.
The estimate rests on a model simulation using 2000 rainfall and wind data for ocean regions between 60°S and 60°N, checked against satellite salinity observations. Nearly 95% of measurements in the SOCAT ocean carbon database are taken at 5 meters depth, leaving rain's surface effects largely unmeasured.
The details
Rain dilutes surface water, carries dissolved CO₂ into the ocean, and creates turbulence that enhances gas exchange. Early experiments at Biosphere 2 in Arizona in 2003 and 2004 provided evidence that rain-induced dilution increases ocean carbon uptake.
Timeline
2000: Rainfall and wind data used in the model analysis
2003: Biosphere 2 experiments on rain-induced dilution begin
2004: Biosphere 2 experiments continue
2024: Prior study estimates a 7.7% upper rain-related uptake
November 12, 2026: New study on rain and ocean carbon uptake is published
Seasonal Patterns
The finding extends the 2024 study's 7.7% upper estimate of rain-related ocean uptake, suggesting global carbon budgets may understate ocean absorption by roughly 5% to 15%. Its 8.4% estimate from a simpler method closely matches that earlier upper bound, while the new 13.6% figure points to a larger effect than prior accounting captured.
Future changes in rainfall, wind, ocean CO₂ levels, ocean temperature and salinity could increase or decrease rain's overall contribution to ocean carbon uptake. Because rain's effects shape how much carbon the ocean absorbs, these shifts could influence how climate estimates are revised over time.
The takeaway
Carbon budgets that leave out rainfall may understate how much carbon the ocean absorbs, so accounting for surface effects is key to more accurate climate tracking. Improved observations at the ocean surface, where most measurements are not taken, could help close that gap.
Further reading
For more on how oceans absorb carbon, explore Environmental coverage on Wisevoter.
