Will the $6 billion pledge to make transportation more sustainable be enough? Experts weigh in.

Billions of federal taxpayer dollars are being earmarked to help curb emissions, but is the latest promise of funds enough to propel the U.S. toward its ambitious goals?

The funds to help states make transportation more sustainable have been promised, but will they be enough to propel the U.S. toward its emissions goals?

While it's a step in the right direction, the $6.4 billion pledged by the Federal Highway Administration to help states fund projects to reduce greenhouse gas emissions will barely make a dent in the funds needed to help the U.S. meet its goal to be carbon neutral by 2050, experts said.

Transportation Secretary Pete Buttigieg announced last week that states would receive the money -- part of a $1 trillion infrastructure package passed by Congress in November -- over five years to create projects that support widespread use of electric vehicles and trail facilities for pedestrians and bicyclists.

"It's a good start," Tom Moerenhout, a research scholar at Columbia University's Center on Global Energy Policy, told ABC News. "But, it's not a lot of money."