"Will set a hard cap on all carbon emissions at a level that scientists say is necessary to curb global warming - an 80% reduction by 2050. To ensure this isn't just talk, I will also commit to interim targets toward this goal in 2020, 2030, and 2040. These reductions will start immediately, and we'll continue to follow the recommendations of top scientists to ensure that our targets are strong enough to meet the challenge we face."