Some climate experts are now willing to consider schemes for partly shielding the planet from the sun’s rays, such as putting sulfer dioxide in the stratosphere to scatter sunlight; using 1,500 ships, each spraying eight gallons of sea water a second to whiten existing marine clouds (and reflect more light); and a space-based sunshade at L1, the inner Lagrangian point, using solar sails with tiny mirrors to deflect light.