President Barack Obama said his administration has made the "largest-ever" American investment in renewable energy, at the U.N. Climate Change Summit in New York, Tuesday.
Obama expressed urgency on the global warming issue, stating that the U.S. has to catch up with the rest of the world.
"The journey is hard. And we don't have much time left to make it," he said.
Click here to read the full text of President Obama's speech at the U.N. Climate Change Summit.
The president's speech came after pressure from environmentalists to pass a clean-energy law in the U.S. to control environmentally dangerous emissions.
Environmentalists have warned of catastrophic changes that could result from global warming, such as rising sea levels and drought.
"We understand the gravity of the climate threat. We are determined to act," Obama said. "And we will meet our responsibility to future generations."
Obama also called for other countries to get involved in environmental clean up.
"All of us will face doubts and difficulties in our own capitals as we try to reach a lasting solution to the climate challenge," Obama said. "But difficulty is no excuse for complacency."
The U.N. Climate Change Summit and the G-20 summit in Pittsburgh, Pa., later this week aims to persuade wealthier nations to cut greenhouse gases and in turn pay for less wealthy nations to burn less coal and preserve their forest land.