An adventurous team of South African scientists is preparing for a journey to an ocean at the bottom of the Earth. Their expedition will delve deeper into how the climate will change in Africa, and how South Africa can better protect its food supplies.
In July 2019, researchers led by Dr Pedro Monteiro at the Southern Ocean Carbon & Climate Observatory (SOCCO) in Cape Town, will sail to the Southern Ocean, which swirls around Antarctica.
Known as the stormiest place on the planet, conditions here are incredibly miserable all year around, and only a few research teams visit regularly. But scientists say the Southern Ocean is one of the most important bodies of water when it comes to understanding the future of climate change.
The Southern Ocean is so critical because it absorbs half of the carbon dioxide (CO2) released into the atmosphere by the burning of fossil fuels. Its temperature is also rising: it has absorbed more than two-thirds of the extra heat that has blanketed the Earth due to global warming.
The ocean sucks up differing amounts of CO2 and heat each year, which has a knock-on effect on climate elsewhere on Earth. But it also has a little-understood seasonal cycle, something which Dr Monteiro and his team are hoping to shed light on
“The processes that we now understand to be driving the sensitivity of the climate to the [Southern] Ocean are actually happening on the timescale of minutes to one year,” says Monteiro.
For years, international teams of scientists have mounted expeditions to measure how much CO2 is absorbed and released from different parts of the ocean, using ships, and also robotic buoys. As part of the Centre for Scientific and Industrial Research (CSIR), this expedition is its biggest project since it was founded five years ago, which marks South Africa’s entry into this effort.
On a three-week winter journey from Cape Town to Antarctica, a multidisciplinary team of oceanographers, climate scientists, and marine ecologists will drop water-gliding robots into the ocean.
The robots will continuously measure the presence of carbon dioxide in the ocean’s top 1000 metres, while the team’s research vessel, SA Agulhas II, will take measurements of the deeper ocean as it passes through. On a second journey, six months later, the team will collect the robotic data and integrate that with the ship’s measurements.
The results should help other researchers understand in more detail the rates at which the Southern Ocean takes up and releases CO2, says Professor Francois Engelbrecht.
Engelbrecht leads a team in Pretoria that is developing a model of the Earth’s changing climate using the Lengau Cluster, Africa’s most powerful supercomputer housed at the Centre for High Performance Computing in Cape Town, also part of the CSIR. “Of the current global climate models that exist, not one of them can realistically simulate the seasonal cycle of carbon above the Southern Ocean,” he says.
Monteiro’s team is betting that their method of collecting data in the ocean will significantly improve these models, especially the Variable Resolution Earth Systems Model (VRESM) Engelbrecht is developing. The model is being developed especially for Africa as other global models have focused on better predicting the climates of the global north.
Africa, in particular, would benefit from models that more accurately predict CO2 exchange in the Southern Ocean, because global circulation patterns mean the changing ocean has a greater influence on the continent’s than anywhere else.
At the moment, climate models are better at predicting changes in the northern hemisphere than they are in Africa, but researchers like Engelbrecht and Monteiro are changing that.
“The ocean-atmosphere dynamics of CO2 and heat exchange in the Southern Ocean drive weather in South Africa,“ says Monteiro.
Scientists expect that the next 30 years in South Africa will see hotter and drier conditions with more extreme weather, droughts, and floods which pose a threat to the country’s food security.
But precise predictions are hampered by blurry climate models, says Ndoni Mcunu, a PhD candidate at Wits University who studies the effects of climate change on food production in South Africa.
Better models would be unlikely to help South Africa reduce the impacts of climate change, but they would help inform what actions should be taken to cope with those impacts, like droughts and floods, says Professor Bob Scholes, an ecologist at Wits University.
Better climate models would thus also help South Africa adapt in terms of ensuring food security. Mcunu makes the example of the 2015 drought that hit farmers in the hardest in South Africa as a possible future that better climate models can help farmers and researchers prepare for.
“Currently, the biggest limitation we have in climate research is data —we need data,” Mcunu says.
And this data is exactly what Monteiro’s team will go in search of in the depths below Antartica next year.
- This article was made possible through funding from the Africa Science Desk, and assistance from science journalist Richard Van Noorden through the initiative of the African Academy of Science and partners.