Thunberg said she was inspired by other young activists.
"During the past year, millions of young people have raised their voice to make world leaders wake up to the climate and ecological emergency," she said in a statement. "Over the next months, the events in New York and Santiago de Chile will show if they listened."
Thunberg is best known for inspiring "Fridays for Future," weekly global student protests that began in August 2018 after her own protest in front of the Swedish parliament went viral. She is now part of an increasingly vocal youth movement on climate change issues that include such activist groups as Sunrise Movement and Zero Hour.
The boat Thunberg will take, the Malizia II, is equipped with solar panels and electricity-producing underwater turbines. The boat was chosen as a zero-carbon alternative to flying, which produces a large amount of emissions. The trip from Britain to the United States will take about two weeks, the length and date of departure depending on weather conditions.
The months of August and September are peak Atlantic hurricane season. Because sailors avoid Atlantic waters during this period, finding a boat and captain was challenging, Thunberg said in an interview with the Associated Press. But Pierre Casiraghi, Malizia team founder and one of the boat's captains, said he and the team are proud to be able to host her trip and "respect Greta's courage to take on this adventure."
Thunberg said she will limit transportation emissions throughout her tour and has chosen low-carbon and public options, such as trains and buses, to make her way across the continents.
But pursuing her latest activist campaign means putting a pause on school. In order to make the trip, Thunberg said she would take a sabbatical year, pointing to what she says is the urgency of the climate crisis.
"We still have a window of time when things are in our own hands," she said in a statement. "But that window is closing fast."
Thunberg says she hopes to instill the same kind of commitment to change in world leaders through her trip.
"We will make our voices heard," she said. "It is our future on the line, and we must at least have a say in it."