In a letter timed to kick policymakers in the pants before an upcoming United Nations climate summit, more than 130 investors holding more than $6 trillion in assets urged world leaders to rassle up a binding agreement to reduce global greenhouse-gas emissions 50 to 80 percent by 2050. “The climate crisis is a multi-generational challenge that requires strong national and international policies immediately,” says Mindy Lubber of investment group Ceres. “World leaders must shun the excuse that it is too expensive to act to curb global warming. It is too expensive not to act.”