# Improved air-sea CO2 flux estimates from sailboat measurements

## TL;DR

Sailboat measurements from citizen science help improve estimates of how much CO2 the ocean absorbs, especially in remote areas.

## Contribution

The study shows that sailboat data can enhance ocean CO2 sink estimates, though more data is needed to correct overestimations.

## Key findings

- Adding sailboat data improves ocean carbon sink estimates, especially between 40°S and 60°S.
- Two additional circumnavigations improve the mean sink estimate, but not enough to correct overestimated CO2 trends.

## Abstract

Despite their importance in the climate system, remote ocean regions and their ability to absorb anthropogenic carbon dioxide (CO2) remain highly uncertain. To address this issue, citizen science initiatives, including sailboats, expand the observational network. Using observing system simulations and novel sailboat tracks, we demonstrate how integrating sailboat data improves estimates of ocean carbon uptake. While we underestimate the ocean carbon sink when mimicking real-world sampling, adding available sailboat data does not substantially improve reconstructions. Nevertheless, increased sampling reveals a stronger carbon sink, particularly between 40°S and 60°S. The improvement persists with hypothetical measurement uncertainties, but substantial differences arise depending on whether positive or negative biases are applied to the race track data. While we show that two additional circumnavigations already improve the ocean mean sink estimate, we further highlight the finding that the additional data remain insufficient to correct the overestimated CO2 sink trend, calling for continuation of the ongoing data collection.

Citizen science enables continuous sailboat sampling during global races, improving carbon uptake estimates in remote oceans.