Yacht race helps unlock secrets of distant seas

The Southern Ocean is the planet’s wildest ocean, circling the icy continent of Antarctica. Just to the north, Point Nemo in the South Pacific is the farthest location from land on Earth. It is 1,670 miles away from the closest shore and the nearest humans are generally those in the International Space Station as it passes overhead.

But this week, four sailing teams passed to the south of the point as part of a 12,750-nautical-mile (14,672-mile) race from Cape Town, South Africa to Itajaí, Brazil.

By the time these Imoca monohull sailing yachts neared Point Nemo, the five sailors on each boat had already been at sea for 23 days. This is leg three, the longest of the Ocean Race, a dash around the world that started in January and finishes in July.

Competition is fierce and racing is close. Boat speeds have been up to 40.5 knots – the equivalent of a gale force wind – and the vessels have, subject to ratification, broken the 24-hour distance record multiple times. The crews survive on freeze-dried food, and operate a four-hour alternating watch. Nobody gets much sleep. The toilet is a bucket.

The dangers are unpredictable. Winds in the Southern Ocean can reach up to 70 knots and hitting an iceberg at speed would be catastrophic, so the boats have to steer clear of an ice exclusion zone around Antarctica.

Despite the challenges, scientists have smelled an opportunity. The yachts visit the most remote part of the ocean, which even scientific vessels struggle to access, and this year crews are seeding scientific instruments all around Antarctica and measuring 15 different types of environmental data, including ocean temperature, atmospheric indicators and microplastic concentrations.

The Southern Ocean is one of the planet’s largest carbon dioxide sinks, but its inaccessibility has meant there is relatively little CO2 data available. Information from the devices will help with everything from weather forecasting to insights into the climate emergency.

“Data from the sailing races in the Southern Ocean is very important for us to understand the uptake of carbon dioxide by the ocean,” said Toste Tanhua, chemical oceanographer at Geomar Helmholtz Centre for Ocean Research in Kiel, Germany.

Each yacht is equipped with weather sensors that measure wind speed and direction, barometric pressure and air temperature. Each team will drop two surface drifter buoys provided by organisations such as Météo-France and the US National Oceanic and Atmospheric Administration, which capture data to help the World Meteorological Organization study ocean currents and forecast extreme weather.

The buoys are being dropped in areas where there are few other instruments. “The Southern Ocean is a very important driver of climate on a global scale. There is very little data,” Tanhua says.

A second type of buoy, the Argo profiler, deployed by Team Malizia in leg two, operates below the surface at depths of up to 2km, moving slowly with deep currents and transmitting information every 10 days. The data is used for climate analysis as well as for long-range weather forecasts.

Meanwhile, 11th Hour Racing Team and Team Malizia are using OceanPacks to take regular water samples to measure levels of carbon dioxide, oxygen, salinity and temperature. Tanhua said the fresh data revealed new patterns.

For example, it showed how carbon dioxide varies over a year – higher when the water warms up in summer, lower during a phytoplankton bloom, or growth spurt. It also shows how the ocean takes carbon from the surface and transports it into the depths.

The boats are also sampling trace elements such as iron, zinc, copper, cadmium, nickel and manganese, which are essential for the growth of plankton, the first part of the ocean food chain. Not only is it the base of the food chain, but phytoplankton are responsible for most of the transfer of CO2 from the atmosphere to the ocean.

“This data is extremely important,” said Dr Arne Bratkič, environmental biogeochemist at the University of Lleida, Spain. “It is important to know how much food is available for animals that will feed on phytoplankton eventually, and how much CO2 the phytoplankton is going to absorb from the atmosphere.”

Bratkič said sampling normally requires dedicated scientific voyages, on which places are limited and expensive. The Ocean Race is a way of testing to see whether investigations on nonscientific platforms at sea can be expanded. “We are paying attention to the design of the samplers – what works and what does not,” said Bratkič. “It’s really exciting.”

To add to the plankton study, Team Biotherm is working with the Tara Ocean Foundation to study ocean biodiversity, and the sailors have an automated onboard microscope to record images and provide insights into the diversity of phytoplankton species.

The 2017-18 race made news after samples taken near Point Nemo showed even these remote waters were polluted with microplastics. This year, two teams are taking water samples to test the source of the microplastics (for example, a bottle or plastic bag).

We still have a very poor understanding of the abundance and distribution of very small microplastics in the ocean, and it’s quite difficult to collect them, according to Dr Katsiaryna Pabortsava, a biogeochemist at the National Oceanography Centre

“The Ocean Race will be delivering samples from places that otherwise we’d have difficulty getting samples from,” she said. The hope is this type of sampling could eventually be employed on other non-scientific ships.

The sailors benefit, too: in such a close race, every piece of information is vital. Six hours after dropping the buoys, the sailors will download a new weather bulletin using data from the buoys.

‘The Southern Ocean is a driver of climate on a global scale’

Toste Tanhua Oceanographer