The case against climate regulation via oceanic phytoplankton sulphur emissions

The CLAW hypothesis advanced the idea of biological regulation of Earth's climate. In the proposed feedback loop, cloud condensation nuclei and cloud albedo are regulated up or down by oceanic phytoplankton through the medium of dimethyl sulphide emissions, such that climate remains moderate. CLAW, named after the authors of the Nature article that introduced it in 1987 (Charlson, Lovelock, Andreae and Warren, see go.nature.com/alfv2n), proved influential and spawned two decades of intensive research investigating the required mechanisms. Patricia Quinn and Timothy Bates have now synthesized this sprawling field and argue that there is no strong evidence to support any of the critical steps required by CLAW. Instead, contributions by organic and non-organic compounds suggest a far more complex reality.