Trying to showcase climate leadership at the U.N. Climate Summit in Glasgow, President Joe Biden is reaffirming his goal of creating “a carbon pollution-free power sector by 2035 and net-zero emissions economy by no later than 2050.” But that target will be prohibitively expensive. A new Nature study shows that a 95 percent reduction by 2050 — almost within reach of Biden’s net-zero — would cost 11.9 percent of GDP or more than $11,000 for each American every year.