proposed fixes make sense, some make nonsense. Here are a few:
Iron the sea
Large areas of ocean are nearly devoid of CO2-gobbling phytoplankton. Seeding these areas with a mixture of iron sulfate and a weak acid could cause a dramatic bloom of marine microorganisms that draw thousands of tons of CO2 out of the air and pull it to the bottom of the sea.
Objection: Tinkering with nature on such a massive scale could have unforeseen consequences.
Kill the cows
The tailpipe emissions of cattle, pigs and other livestock are a major source of methane, which may be a more potent greenhouse gas than CO2. Worldwide vegetarianism could make a major difference.
Objection: Politically unattainable.
Arrays of giant shiny panels could be put into orbit to reflect back enough sunlight to cool the earth.
Objection: That's a lot of mirrors.
Same idea as mirrors, but using millions of silvery mylar balloons instead.
Objection: That's a lot of balloons.
Reflect heat away by painting roofs white and using light-colored materials for highways,parking lots and even cars.
Objection: That's a lot of white paint.
Launch large quantities of soot into the stratosphere to increase cloud cover.
Objection: The soot would come from burning carbon-laden material, and that creates greenhouse gases.