<prompt> unaweza kugeuza matini haya ya swahilikwa kiingereza?rais wa marekani barack obama atazindua leo kile anachokiita hatua kubwa kabisa na muhimu kuwahi kuchukuliwa katika kupambana na mabadiliko ya tabia nchi.  <response>: us president barack obama is expected to unveil today what he called the biggest, most important step weve ever taken to fight climate change, a sensitive issue central to his legacy. 