Worsening extreme heat is likely to significantly boost economic and public health costs in the United States without a major course correction on climate change, researchers said in a report published on Tuesday. The annual economic costs, which could spike as high as$ 500-billion by 2050, would disproportionately affect minority groups, according to the report from the Atlantic Council, a Washington-based think tank. The United States could also suffer 59, 000 heat deaths a year by 2050 under