The congresswoman delivered a scathing rebuke to a Republican representative who depicted the environmental proposals as elitist during a financial services committee hearing on Tuesday.
Ms Ocasio-Cortez said: “This is not an elitist issue, this is a quality of life issue. You want to tell people that their concern and their desire for clean air and clean water is elitist?
“Tell that to the kids of the South Bronx who are suffering from the highest rates of childhood asthma in the country.
“Tell that to the families in Flint, whose kids have their blood ascending in lead levels; their brains are damaged for the rest of their lives. Call them elitist.
“People are dying … This is serious. This should not be a partisan issue.”
Footage of Ms Ocasio-Cortez's speech has been watched more than 3.5 million times after being posted on social media.
The New York Democrat was responding to Wisconsin Republican Sean Duffy, who had claimed the Green New Deal championed by Ms Ocasio-Cortez would make housing more expensive.
“If you’re a rich liberal from maybe New York or California, it sounds great because you can afford to retrofit your home or build a new home that has zero emissions, that’s energy efficient,” he said.
The Green New Deal calls for the virtual elimination by 2030 of greenhouse gas emissions responsible for global warming, which scientists warn is on course to have a catastrophic impact around the world.
The plan calls for the US to shift away from fossil fuels such as oil and coal and replace them with renewable sources such as wind and solar power. It has broad support among Democratic activists, and all six of the 2020 presidential contenders currently serving in the Senate have signed on as co-sponsors, putting it at the forefront of the party’s sprawling primary race.
But Republicans claim the Green New Deal would devastate the economy and lead to a huge tax increase.
Addressing that criticism before the committee, Ms Ocasio-Cortez: “We talk about cost – we’re going to pay for this whether we pass a Green New Deal or not. Because as towns and cities go underwater, as wildfires ravage our communities, we are going to pay. And we’re either going to decide if we’re going to pay to react, or pay to be proactive.
“We have the choice to lower the cost now, because I can tell you the cost of pursuing a Green New Deal will be far less than the cost of not passing it.”
Senate Republicans forced a vote on the Green New Deal on Tuesday as they sought to divide Democrats by pushing them to take a stand on the issue. The GOP-majority Senate voted 57-0 against a procedural motion to take up the nonbinding resolution, with 43 Democrats abstaining in protest over a vote they condemned as as "sham".
Ahead of the vote, Republican Mike Lee mocked the the Green New Deal as “ridiculous” and displayed pictures of dinosaurs, cartoon characters and babies on the Senate floor. He said he was treating the plan “with the seriousness it deserves”.
His remarks enraged Democrats, who called climate change deadly serious, citing recent floods in the US Midwest, wildfires in the west, and hurricanes in the south.