Reuters: U.S. states have taken the lead in setting greenhouse gas reduction targets in the absence of federal leadership on mandatory limits on the emissions scientists link to global warming. In stark contrast to the previous U.S. administration, President Barack Obama has said he favors cutting national emissions to 1990 levels by 2020 and by 80 percent below 1990 levels by 2050. Some of the state targets were passed through state legislatures and penalize the state if they are not …