What impact will climate change have on the United States' national security? Will the security issue gain traction as the Senate takes up climate legislation? During today's OnPoint, former Sen. John Warner (R-Va.) explains how the United States' security will be affected by climate change. Warner, who recently joined the Pew Project on National Security, Energy and Climate, discusses how Congress can address this issue in the legislation making its way through the Senate. He also gives his take on this year's climate debate.