The interaction between the atmosphere and ocean plays a key role in our climate and weather. For example the world’s oceans absorb approximately 30–40% of the carbon dioxide produced by man. Without this buffer climate change would be much more rapid and severe. This is particularly important in the vast expanses of the Southern Ocean where gas exchange is efficient because the ocean surface is roughened by the strong winds and large waves, and temperatures are low.

SOLAS (Surface Ocean–Lower Atmosphere Study) is a new international research programme. In this SOLAS Air–Sea Gas Exchange (SAGE) experiment, we aim to study the exchange of gases that are important to our climate, in a semi-controlled situation. We will stimulate the growth of plankton by fertilizing the ocean with iron sulphate over 50 square kilometres of ocean. This should provide an enhancement of gas fluxes that should last several weeks.

To get the full picture, we also need to consider biology and simple plankton in the ocean that drive the biological pumping of CO2 through photosynthesis. And it is not just carbon dioxide that needs to be considered. The plankton in the ocean could also play a role in climate change by emitting the gas dimethyl sulphide (DMS). This potentially affects the properties of aerosols that govern the extent and reflectivity of marine cloud cover. Even modest changes of DMS emission could have significant effects on global temperature.

Only by understanding the physical, biological and chemical processes governing the interchange of gases, can we confidently predict timing and magnitude of future changes in climate. To mount this multidisciplinary SOLAS study we have brought together researchers from around 20 organisations to work in the logistically challenging environment of the Southern Ocean.

The New Zealand component of this work is sponsored by the Foundation for Research, Science and Technology.