Here’s How Weather Balloons Can Harm Marine Animals

This article is from Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this at hakaimagazine.com.

On a fall day in 2023, a juvenile Atlantic yellow-nosed albatross was lying listless in southeastern Brazil’s Santos Basin. Beach monitors found the young bird in the sand, weak and hypothermic. The cause of the albatross’s misery was evident: it was caught in a weather balloon. The balloon’s string, still attached to a radio transmitter, had gouged into the bird’s flesh—fracturing bones, killing tissues and cutting off circulation to the bird’s feet. The albatross, too entangled to spread oil from its tail gland to its feathers for waterproofing, was soaked to the skin.

Staff from the nonprofit Albatross Project took the desperate bird to the organization’s rehabilitation center nearby, where veterinarian Daphne Goldberg and her colleagues examined the albatross and decided euthanasia was the only option. Albatrosses need their feet to paddle and fly—it would not have survived as an amputee. “It was a tragedy. It was awful,” Goldberg recalls.

Goldberg is the coauthor of a recent study about the impact weather-balloon debris is having on seabirds and marine animals. Globally, hundreds of thousands of weather balloons are launched into the sky every year, and the majority are never recovered. Instead, their waste—a mix of latex, cotton and plastics—remains in marine ecosystems for years. And because only a small percentage of dead animals wash ashore, the impact is likely worse than the numbers suggest. “Probably there are a lot more [balloon entanglements],” Goldberg says.

Many countries use weather balloons to gather high-altitude data on air temperature, pressure and humidity. Before the invention of modern weather balloons in the 1930s, scientists flew kites—and later, hot air balloons—equipped with thermometers to get such measurements.

Today, there are about 1,300 stations globally that release balloons—each one more than three times the size of a standard beach ball—to inform weather reports as well as warnings for storms such as Hurricanes Helene and Milton. Attached to the balloon’s cotton string is a radiosonde, a polystyrene or hard plastic box containing sensors and a battery-operated radio transmitter that sends weather data to a ground receiver every second.

The United States launches some 76,600 balloons annually, while Canada sends up around 22,000. As each balloon ascends, it expands. Once it has traveled up about 21 miles and its volume has grown 100-fold, it explodes, shooting latex in all directions and releasing a small parachute that floats the radiosonde back to Earth. These balloons are used just once.

Australian researchers at the Tangaroa Blue Foundation first flagged the problem of weather-balloon garbage a decade ago. Over 21 months, they collected 2,460 pieces of weather-balloon litter around the Great Barrier Reef. The researchers estimated that up to 70 percent of Australia’s weather balloons end up in the ocean. (The country has 38 sites from which it releases up to 300 balloons every week.)

Goldberg’s group witnessed the impact of weather balloons firsthand when they examined seven albatrosses found in Brazil’s Santos Basin, including the one with the broken feet. Of the other six birds, two more were Atlantic yellow-nosed albatrosses. The remaining four were black-browed albatrosses. The birds were found with debris tangled around their feet, wings and legs. Postmortem examinations concluded that these animals likely became caught while alive. The researchers traced one balloon to the Brazilian city of Guarulhos, 55 miles inland; another came from Florianópolis, 310 miles south.

In 2023, a different group of researchers published the details of two dead juvenile Kemp’s ridley turtles that were found twisted in weather-balloon debris in Virginia. One animal had string wrapped around its flipper. The second had string binding all four flippers along with its neck and plastron (underside).

The study notes that while some of the materials used in weather balloons—like latex and cotton string—are considered biodegradable, much of it, including the string, is not breaking down quickly. The string from weather balloons launched annually in the United States alone could stretch to the peak of Mount Everest 185 times.

Jennifer Provencher, an adjunct research professor at Carleton University in Ottawa who wasn’t involved in either study, points out that the larger impact of weather-balloon debris is unknown because it’s mostly invisible. “We have essentially no clue about what it does at the population level,” she says.

The birds in the Brazilian paper were caught in equipment manufactured by the Finnish company Vaisala, a major manufacturer of weather equipment. In an email, Niina Ala-Luopa, Vaisala’s head of communications, said, “We deeply value the welfare of animals and the environment.” She added that the string is now made from cellulose-based fiber designed to weaken much faster than previous cotton versions and that the company also offers radiosonde containers made of natural materials and starch in addition to conventional ones. These new models are 20 to 30 percent more expensive.

Despite the higher cost, weather bureaus are also starting to reduce the impact of their instruments. Australia’s Bureau of Meteorology has tried out Vaisala’s more sustainable balloon prototypes and has switched from white to blue balloons, which marine animals may be less likely to mistake for food. The United Kingdom’s Met Office also plans to test out Vaisala’s new balloons; it will launch them from two British Antarctic Survey stations in 2025.

The National Oceanic and Atmospheric Administration in the United States has been experimenting with various new weather balloons and data-gathering devices as well, including a balloon that can stay aloft for up to 16 days instead of just a couple of hours. In 2024, the agency announced it would be testing two different drones to collect weather data, both of which are recoverable.

Weather agencies aren’t trialing these new devices solely because they’re more sustainable; they also want better data. For now, though, balloons still soar much higher than drones, so they remain an important data-collecting tool. Lower-impact versions would at least be a small improvement for the ocean’s animals.

This article is from Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this at hakaimagazine.com.

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