The White House is considering a pledge to cut US greenhouse-gas emissions by 50% or more by the end of the decade, according to people familiar with the deliberations, a target that would nearly double the country’s previous commitment and require dramatic changes in the power, transportation and other sectors. Al Jazeera reports that by comparison, under former President Barack Obama, the US promised to reduce planet-warming emissions from 26% to 28% below 2005 levels by 2025. Cutting US greenhouse gas emissions in half would however require broad action to clamp down on planet-warming pollution from power plants, automobiles, oil wells and agriculture. The US currently gets about 40% of its electricity from nuclear and renewables, but would have to double its carbon-free power to 80% by 2030 to put the country on track to curb emissions enough to meet that new target, according to Amanda Levin, a policy analyst for Natural Resources Defense Council.