Rather than delivering prepared remarks, 16-year-old Swedish climate activist Greta Thunberg submitted a landmark United Nations report on global warming as testimony at a U.S. House hearing Wednesday and urged federal lawmakers to heed experts' warnings about the necessity of ambitious, urgent efforts to address the planetary emergency.

"I am submitting this report as my testimony because I don't want you to listen to me," said the Fridays for Future founder. "I want you to listen to the scientists. And I want you to unite behind the science. And then I want you to take real action."

"I don't want you to listen to me. I want you to listen to the scientists. And I want you to unite behind science. I want you to take real action. Thank you."

— @GretaThunberg No, thank YOU, Greta and everyone taking climate action.

We're #UniteBehindTheScience! pic.twitter.com/FQt4PsWnLg — NRDC (@NRDC) September 18, 2019

Thunberg appeared at a joint hearing of the U.S. House Committee on Foreign Affairs Subcommittee on Europe, Eurasia, Energy, and the Environment and the Select Committee on the Climate Crisis.

The Special Report on Global Warming of 1.5°C (pdf) that Thunberg submitted was released last October by the U.N.'s Intergovernmental Panel on Climate Change (IPCC). Warning that "climate change represents an urgent and potentially irreversible threat to human societies and the planet," the report called for "rapid, far-reaching, and unprecedented" reforms on a global scale to avert climate catastrophe.

Thunberg's decision to submit the report as her testimony was widely praised by other climate advocates.

"Yes!" tweeted the Natural Resources Defense Council. "Greta Thunberg is telling us exactly what the scientists have been saying for years—we have to rapidly reduce emissions to protect all humanity together. Starting now. No more excuses."

Bill McKibben, co-founder of the environmental advocacy group 350.org, praised Thunberg as "one great politician" and "a master of the gesture."

.@GretaThunberg is one great politician. Instead of testifying she simply hands the Foreign Relations committee a copy of the IPCC report on 1.5 degrees. A master of the gesture — Bill McKibben (@billmckibben) September 18, 2019

Linking to Thunberg's short remarks explaining the move, 350.org co-founder Jaime Henn tweeted, "This is so badass."

The joint hearing Wednesday also featured testimonies from Jamie Margolin, co-founder of This Is Zero Hour and a plaintiff in Piper v. State of Washington; Vic Barrett, fellow at the Alliance for Climate Education and a plaintiff in Juliana v. United States; and Benji Backer, president of the American Conservation Coalition.

Youth climate activist Jamie Margolin tells lawmakers: "It doesn't matter how many dreams we have. The reality is my generation is committed to a planet that is collapsing ... Youth climate activism should not have to exist." pic.twitter.com/SMOtvWuDOe — AJ+ (@ajplus) September 18, 2019

The hearing preceded a global week of action that will kick off with climate strikes worldwide on Friday. The demonstrations will coincide with the U.N. Climate Action Summit in New York City.

Thunberg traveled on a zero-carbon sailboat across the Atlantic to New York last month to participate in the strikes, summit, and other related events—including to deliver an another address to members of Congress Wednesday at 5 pm ET.