WASHINGTON (AP) — Top Democratic presidential contenders talked tough Wednesday on cutting climate-damaging emissions from oil, gas and coal, turning their focus to global warming in a marathon evening of town halls that gave the candidates a chance to distinguish themselves on a topic of growing importance to their party's liberal base.

The unique and lengthy climate conversations promised to hand Republicans ammunition for next year's general election fight by emphasizing one common element in the Democrats' climate change plans: their overwhelming — and overwhelmingly costly — scope. But th...