Robot to test health of ocean 'lungs'
In a pioneering move, a wave glider has been sent out to sea from Cape Town to measure pollution around Antarctica.
Table Mountain is wreathed in cloud, with a skirt of fog, and in the distance rolling clouds are moving in from the south. A team of scientists from the Council for Scientific and Industrial Research stands in a large patch of sunlight on the dock at the V&A Marina, hurrying to affix a robot to the side of a small vessel with a winch, hauling it from the dock so it hugs the side of the boat.
They are heading out past the breakwater to deploy this ocean glider, which will begin its monthlong journey to the Southern Ocean, and they are racing against the oncoming storm.
These storms are part of the reason that the Southern Ocean is one of the most under-researched in the world, even though it absorbs almost half of the world’s man-made carbon emissions.
A report from the United Nations’s Intergovernmental Panel on Climate Change, released earlier this year, says that the world is already experiencing climate change. “African ecosystems are already being impacted [on] by climate change, and the future impacts are expected to be substantial,” it said.
Dr Isabelle Ansorge of the University of Cape Town’s Marine Research Institute said in 2012 that Southern Ocean research is critical: “It is the only ocean that is not surrounded by land but by other oceans … It’s almost like the lungs of the world’s water.”
“Globally, there is a renewed interest in understanding what is going on in the Southern Ocean from a climate perspective and how it mediates global climate,” says Pedro Monteiro, principal oceanographer at the CSIR and head of the Southern Ocean Carbon-Climate Observatory programme. He stands on the dock with his hands in his pockets, shoulders hunched up to his beanie, braced against the chill wind.
Although anthropogenic carbon dioxide emissions – those created by humans – are well studied and account for about 10 gigatons, the natural carbon cycle is substantially larger at 100 gigatons and is less understood, he says.
“This is the first time we are deploying a wave glider directly from the coast to head to the Southern Ocean without the use of a ship,” says his colleague, Seb Swart, as he fastens the glider to the crane.
It looks like a thick, yellow-topped, black-bellied boogie board that has sprouted antennae. There are two parts: the surface board and a submerged subsystem that comprises thick-slatted “venetian blinds”. They that are connected by a 7m umbilical cord made of a rubber composite. When in the ocean, the vertical movement between the two parts makes the glider move forward.
The sun shines through clouds off Possession Island in the Crozet archipelago in the Southern Ocean near Antartica, where the glider is headed. (AFP)
“We’re sending it to 43 degrees south, the same location in the sub-Antarctic that we deployed gliders to last year,” Swart says, without taking his eyes off the winch that is now carrying more than R3-million worth of robotic equipment. “It’s an area in the Antarctic zone where there is phytoplankton growth [phytoplankton absorb carbon dioxide], and a key area for understanding the carbon cycle.”
The glider, fitted with a GPS and a communications system, will be driven by remote control from Cape Town, whereas the first and second gliders – which took ocean measurements in the summers of 2012-2013 and 2013-2014 – were deployed by ships travelling to Antarctica. “We are missing key data from the winter conditions and variability,” Swart says.
This is why ocean robots, Monteiro and Swart argue, are the next generation of climate observation. “Ships only measure [things such as the ocean’s oxygen and carbon content, temperature, salinity and acidity] where they are. They can cover large distances, but the time span [for measurements in each place] is limited,” Monteiro says.
Ships are also pricey. The SA Agulhas II, South Africa’s polar research vessel, costs about R300 000 a day to operate and can only take snapshots of ocean conditions along the way. Moorings with sensors are cheaper, but are at the mercy of ocean currents.
As the glider-carrying vessel lurches past the breakwater into the Cape’s choppy seas, a multilevel icebreaker giant such as the SA Agulhas II seems to be a safer transport option. The aluminium boat is pitched at a precarious angle: the ocean glider hangs from a small winch on the starboard. Four of the team are holding the glider away from the ship, which rolls in the heaving jade-coloured water as sprays of white foam fly over the boat.
Monteiro shouts over the sounds of the vessel’s two engines: “It’s been a learning curve [using ocean gliders], but these guys are some of the world’s best in ocean robotics.”
He points to the four people clustered around the ocean glider while Sinekhaya Bilana, a Cape Peninsula University of Technology graduate whose studies are now funded by the CSIR, attaches one of the antennae to the glider in preparation for deployment.
A stomach-churning journey past the breakwater ends as they lower it into the water after Bilana has reattached the antenna, releasing the winch and pushing the glider away from the boat. They will hopefully see the glider again in three months, and the return to the waterfront is coloured with relief and big smiles.
These smiles evaporate when we reach the boat docks, and Monteiro gets a phone call: the ground-based team observing the deployment has not received a signal from the glider in the past 30 minutes. At the last communication, it was headed for a major shipping line, and as the glider does not emit a radar signal, a huge freight ship could sail right over it. The laugh lines disappear from Monteiro’s face, and he walks quickly to wait for a car to take him back to the command centre at the environmental affairs office on the east pier.
Cape Point hosts South Africa’s only Global Atmosphere Watch monitoring station, which measures greenhouse gases.
Meanwhile, at the air monitoring station next to the lighthouse at Cape Point, Ernst Brunke is measuring the quality of the ocean air. He has been at the Cape Point station for more than two decades; he was here when it was under the control of the CSIR, before the South African Weather Service took over management of the facility. It is home to one of the World Meteorological Organisation’s Global Atmosphere Watch (GAW) outposts.
“[We] monitor the chemistry of the ‘clean’ background atmosphere – not in cities, but in remote places, so we can paint a picture of how polluted the globe is,” Brunke says.
Cape Point is the only GAW station in South Africa, measuring the greenhouse gases carbon dioxide, methane, ozone and nitrous oxide.
Chemistry of air
The station comprises a little stone cottage and a large metal tower on the rocky outcrop against which the cottage was built. The tower used to be a beacon for ships, says Brunke. It now has dishes and piping running down its legs. Air is sucked out of the atmosphere by the pipes and siphoned into the stone cottage, which has even more pipes running along the ceiling into the racks of equipment that fill the room. Here the chemistry of the fresh ocean air is analysed.
Brunke is the only person in the station today; usually weather service employees come in twice a week. Many of the station’s projects – such as the GAW work – are collaborative, an important thing considering the station’s isolation, which is reinforced by the howl of the sea wind and the long climb up the hill to the station.
“We cannot work in isolation,” Brunke says, listing the station’s collaborators, which include local universities and science councils such as the CSIR, as well as international partners such as the Max Planck Institute. One of its partnerships with the CSIR is Monteiro’s carbon programme, in which “we make long-term carbon dioxide measurements and provide calibration facilities”.
Monteiro and Brunke are also collaborating with CSIR systems ecologist Dr Bob Scholes, whose research team is collecting environmental data in the Kruger National Park.
“It is important to put all the pieces together,” Brunke says. “Each one supplies a scientific block of information that should be gelled together ... Pollution knows no boundaries. To understand the planet system, we must work with the big picture.”
For Monteiro, a picture on a computer screen has his undivided attention. “Put the glider on to a circle route and hold it in that position, or maybe we should [drive] it to the harbour entrance,” he says, and starts to pace. In the past 50 minutes, they have heard from the glider just once, 10 minutes earlier.
The storm on the horizon means that, if they do not hear from the glider and it has to hold its position, they will have to wait a week to retrieve it, and it might be too late to get it down to the Antarctic for winter.
Long minutes pass as the team stares at the screen. It is still in the shipping lane, but it is safe for the moment. Two minutes later: “Ping.” Another long two minutes, then: “Ping.” Engineer André Hook turns to Monteiro and says: “We’re getting hits every two minutes.” They set the glider’s course west, out of the shipping lane, and wait.