South Africa has task as global citizen to understand role of Southern Ocean in climate change

Dr Pedro Monteiro is a marine biogeochemistry and oceanography specialist at the CSIR in Stellenbosch.

There is already evidence that the oceans are starting to change - it is no longer a question if or when it is going to happen, but rather what we, as global citizens, are going to do to understand the process in order to mitigate the impact.

In the Southern Hemisphere the impact of climate change will be different to that in the Northern Hemisphere - but while many people in the north have already more or less figured out the role of the northern oceans in climate change and the global carbon cycle, understanding the impact of oceans on climate change in the south has been hampered by lack of data due to limited access and skilled manpower.

However, all is not doom and gloom, says CSIR principal researcher and unit fellow Dr Pedro Monteiro.

"While the Northern Hemisphere is dominated by land, the Southern Hemisphere is dominated by oceans. Scientists in our part of the world need to focus on and understand the kind of global changes we can expect here. Just look at this picture and see what the world looks like when you have South Africa in the centre," he explained at a lecture at the CSIR Knowledge Commons in November.

Monteiro heads up the Oceans Systems and Climate Research Group at CSIR Natural Resources and the Environment in Stellenbosch.

"We need to take advantage of our unique geographical position and start playing a much more active role in the international scientific community's carbon cycle and climate agenda," he says.

However, there is still much uncertainty in terms of fully understanding the global carbon cycle. Monteiro explains: "Over millions of years the earth has developed a natural cycle of producing and absorbing carbon - what scientists call the natural CO₂ flux. This natural CO₂ flux between the oceans and the atmosphere is much larger than the CO₂ produced by man, but, and this is a big but, the natural process has until now been more or less in balance.

"The carbon cycle is central to the Earth system, being inextricably coupled with climate, the water cycle, nutrient cycles and the production of biomass by photosynthesis on land and in the oceans. A proper understanding of the global carbon cycle is critical for understanding the environmental history of our planet and its human inhabitants, and for predicting and guiding their joint future." - Executive Summary, Global Carbon Project (2003)

"There is already evidence that the magnitude of the ocean sink is diminishing and that much of the origin of this reduction lies in the adjustments of the Southern Ocean to climate change. The moment the oceans lose their capacity to act as carbon sinks, we will be playing catch up on emissions reduction at a rate faster than we had anticipated," he warns.

According to Monteiro, the oceans account for the largest annual CO₂ exchanges with the atmosphere in the natural CO₂ cycle and approximately 25 to 30% of the CO₂ from industrial activity. However, while the year-to-year variability of ocean-atmosphere CO₂ exchanges in the North Atlantic and Pacific Oceans are already quantified at a low uncertainty of 10 - 15%, the level of uncertainty on the year-to-year magnitude of the ocean-atmosphere CO₂ exchange in the Southern Ocean remains too high to be taken into account in the global carbon debate.

The global uncertainty needs to be reduced and resolved because, for the foreseeable future, the terrestrial CO₂ sink can only be deduced by difference from emissions, the atmospheric reservoir and the ocean CO₂ uptake. A reliable annual assessment of the global CO₂ budget is essential to test the effectiveness of mitigation measures and understand how the natural carbon cycle may be responding to climate change.

Over the next five to ten years, the Southern Ocean Carbon and Climate Observatory Programme will focus on understanding the seasonal variability of the carbon cycle in the southern Atlantic and the south-western Indian Ocean. With improved equipment and funding from the Department of Science and Technology (DST), combined with advanced modelling capabilities, Monteiro hopes that this inter-institutional collaboration will make an important contribution to the global carbon debate in terms of quality observations and scientific understanding.

"At present the Southern Ocean carbon-climate system is not adequately understood because up to now global models have not resolved the scales at which climate and the ocean interact. These models are not able to capture subtle differences in, for example, how wind speed changes and ocean eddies - characteristic of the southern ocean - interact to drive the response of the carbon cycle. By including that kind of data into our models, we'll be able to see where we've been getting it wrong until now and thereby improve our capacity to predict climate change for this part of the world and globally."

However, the answer to achieving carbon and emission reduction does not only lie with observation and new equipment.

For Monteiro the country's best adaptation to the uncertainties of climate change and the simultaneous need for development will be to rapidly grow our capacity for innovative thinking through good science and technological skills. "Increasing numbers of students are taking up advanced training opportunities in this new programme through which we hope not only to grow South Africa's global citizenship, but also to strengthen the innovative capacity of both government and the private sector. We cannot only focus on reducing emissions.

"South Africa has the dual responsibility of playing a stronger role as a global citizen, as well as addressing the development challenges in the region. New solutions - some with major ethical implications - will be required and the Southern Ocean Carbon and Climate Observatory Programme hopes to make a strong contribution in coordination with the Applied Centre for Climate and Earth System Science (ACCESS)," he says.