Billionaire philanthropist and businessman Michael Bloomberg is defying President Trump's decision to exit the Paris climate change agreement, saying he is rallying a bipartisan coalition of states, cities and business leaders to meet the climate pact's targets even as the president rescinds the nation's commitment to it.

"Americans are not walking away from the Paris Climate Agreement," Bloomberg said on Thursday. "Just the opposite — we are forging ahead. Mayors, governors, and business leaders from both political parties are signing on to to a statement of support that we will submit to the U.N. — and together, we will reach the emission reduction goals the United States made in Paris in 2015."

Bloomberg is a special U.N. envoy for mayors and local leaders in meeting the goals of the climate change deal signed by former President Barack Obama.

Bloomberg's philanthropic groups, in partnership with others, is also making a $15 million contribution to fund the U.N.'s climate secretariat, which will lose money under Trump. "Americans will honor and fulfill the Paris Agreement by leading from the bottom up — and there isn't anything Washington can do to stop us," Bloomberg said.

Bloomberg made the announcement as California, New York and Washington are forming a pact to enact policies to help meet the emission reduction targets called for under the Paris Agreement.

The Democratic governors' new agreement would seek to meet the same goal of reducing emissions 26 to 28 percent from 2005 levels as the U.S. committed to under the Paris deal. Details on individual state contributions are still to be worked out.

Together, the three states account for almost 10 percent of the nation's greenhouse gas emissions.