J. Geophys. Res. http://doi.org/bcd7 (2016)

Credit: © MISCELLANEOUSTOCK / ALAMY STOCK PHOTO

Solar radiation management schemes can contribute to reducing climate change by decreasing the amount of light reaching the Earth's surface. One such scheme proposes to brighten the ocean surface by increasing the number of microbubbles in ship wakes, resulting in more light being reflected back to the atmosphere. But the extent to which current shipping lanes could contribute to this effect is unclear.

Julie A. Crook from the University of Leeds, UK, and colleagues examine how existing shipping wakes would need to be modified in order to have a significant impact on surface temperatures. They use a global climate model to simulate brightening wakes and find that global-mean surface temperature could potentially be reduced by 0.5 °C by 2070 (0.9 °C in the Northern Hemisphere). But this requires increasing the bubble lifetime from minutes to days, which can only be achieved by the addition of an as-yet undetermined amount of surfactant — a substance that helps stabilize microbubbles.

Using only the current shipping lanes for wake brightening could potentially reduce climate change, but with an effect mainly in the Northern Hemisphere. The wider implications of adding surfactant to the ocean are also not fully understood and should be considered before such geoengineering proposals are adopted.