The ocean is an important part of the global carbon cycle, taking up about a quarter of the anthropogenic CO₂ emitted by burning of fossil fuels and thus slowing down climate change. However, the CO₂ uptake by the ocean is, in turn, affected by variability and trends in climate. Here we use carbon measurements in the surface ocean to quantify the response of the oceanic CO₂ exchange to environmental conditions and discuss possible mechanisms underlying this response.