Greta Thunberg unfazed by stormy seas

On day 12, the waves picked up.

Climate activist Greta Thunberg's wind-powered journey across the Atlantic Ocean hit a particularly stormy stretch on Sunday. Thunberg and her sailing team, en route to a U.N. Climate Action Summit in New York City, hit rough seas some 300 miles from Canada's Nova Scotia. She noted this in a brief Twitter video update, soon after a wave crashed over the boat.

"It's very rough with very high waves," Thunberg said.

Amid a long seafaring journey surrounded by boundless waters and the formation of a tropical storm in the north Atlantic, Thunberg and her team have consistently reported undaunted spirits.

"So far they’re really enjoying the trip," Axel Hackbarth, an onshore member of the Boris Herrmann Racing team who is supporting the mission, told Mashable on Wednesday.

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When Tropical Storm Chantal developed and began charging eastward across the North Atlantic on Wednesday -- though not posing an immediate danger to their boat the Malizia II -- the team expressed little concern. Rather, they exploited and rode the resulting winds.

"It's working to our advantage," explained Hackbarth.

Hackbarth estimates that Thunberg and company will arrive in New York City between Aug. 27 and 29, depending on wind conditions. As of Sunday, the Malizia II bumped along at speeds between 23 and 28 mph (20 to 25 knots).

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Thunberg has chosen a rough, adventurous trip to New York City to avoid contributing unnecessary carbon dioxide emissions into Earth's atmosphere. It's an unmistakable statement made by a now prominent climate activist.

Airplanes have an outsized role in emitting carbon, as airliners contribute over 2 percent of total global carbon emissions — more than most nations in the world. "Someone flying from London to New York and back generates roughly the same level of emissions as the average person in the EU does by heating their home for a whole year," the European Commission notes. 

Earth's carbon dioxide levels -- the planet's most important greenhouse gas -- are skyrocketing. The heat-trapping greenhouse gas is now at its highest atmospheric levels in at least 800,000 years, though more likely millions of years .

But that's not all. The current atmospheric CO2 increase is now happening at rates that are unprecedented in both the historic and geologic record.