Stephen Hadley said climate change will be one of the top national security issues for the next administration. | Rodney Lamkey Jr. for POLITICO PLAYBOOK LIVE Former Bush adviser: Climate change threatens national security

Climate change will be one of the top national security issues for the next administration, a former national security adviser to President George W. Bush said Thursday.

Stephen Hadley, who served both as deputy and top adviser through Bush’s administration from 2001 to 2009, said climate change has resulted in massive refugee flows that have threatened European unity.

“I have not been particularly sensitive to the climate change issue,” he said at a POLITICO Playbook event in Washington. “Climate change and a lot of other economic dislocations have put a lot of people out of work, they are on the move and they have no place to go and it means they are recruiting grounds for terrorists and extremists and potential refugee flows that will tax Europe even more.”

Hadley also mentioned North Korea and other authoritarian governments as major national security threats for the next administration, noting the need to engage with China.