WASHINGTON (REUTERS) - Teenage activist Greta Thunberg, who has inspired a global movement for climate change, delivered a pointed message before a Congressional hearing on Wednesday (Sept 18): "I don't want you to listen to me. I want you to listen to the scientists."

The 16-year old founder of the Fridays For Future weekly school walkouts to demand government climate-change action submitted a 2018 report by the Intergovernmental Panel on Climate Change at the hearing in lieu of testimony.

It urged rapid, unprecedented changes to the way people live in order to keep temperatures from rising 1.5 deg C by 2030.

"People in general don't seem to be aware of how severe the crisis" is, Thunberg said, urging lawmakers to "unite behind the science" and take action, pleading that people treat climate change "like the existential crisis it is."

Thunberg was one of four students invited to a joint hearing of the House Foreign Affairs Subcommittee on Europe, Eurasia, Energy, and the Environment and the Select Committee on the Climate Crisis, to provide the next generation's views on climate change.

She has been in Washington since last week to join US and indigenous activists to build up support for a global climate strike on Friday and pressure lawmakers to take action on climate change.

At the hearing on Wednesday was also 21-year-old conservative climate-change advocate Benji Backer. He told lawmakers that young conservatives also favour climate change action, but through an approach focused on technology and allowing the continued use of fossil fuels.

"As a proud American, as a life-long conservative and as a young person, I urge you to accept climate change for the reality it is and respond accordingly. We need your leadership,"he said.

While he praised Thunberg and other climate activists for putting the issue at the forefront of politics, he said there was time to take more measured action.

In addition to meetings on Capitol Hill, Thunberg met former President Barack Obama on Tuesday. Obama described the teenager on Twitter as "already one of the planet's greatest advocates."

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Later on Wednesday, she will join seven young Americans who have sued the US government for failing to take action on climate change on the steps of the Supreme Court. They will urge political leaders and lawmakers to support their legal fight and take action to phase out the use of fossil fuels.

At the panel, Republican representatives praised the students for raising awareness about climate change but disagreed over what action the U.S. should take.

Representative Garret Graves from Louisiana, said his state was affected by rising sea levels and that he supported the US emission reduction target enshrined in the Paris Climate Agreement, but he criticised the pact for allowing emerging economies like China to continue to emit greenhouse gases.

"I think that signing on to an agreement... that allows for China to have a 50 per cent increase in greenhouse gas emissions annually by 2030 is inappropriate," he said.

Thunberg responded that in her home country, Sweden, people similarly criticise the United States for not taking enough action.

Another activist on the panel, 17-year-old Jamie Margolin from Seattle, called out lawmakers for taking too long to enact climate change policies.

"The fact that you are staring at a panel of young people testifying before you today pleading for a livable earth should not fill you with pride; it should fill you with shame," she said.