If we accept the idea that AGW (Climate Change if you must) is a problem and that greenhouse gases are the main culprit, what can we do about it?

• Reduce emissions of carbon dioxide
• Increase absorbsion of CO₂ from the atmosphere
• Reduce the amount of energy absorbed from the sun

Set off some nuclear weapons to put particles high in the atmosphere to reflect more sunlight. A controlled version of "nuclear winter" could save the day. Was nuclear testing why the Earth experienced unexpected cooling in the 60's and 70's?

Put some giant reflectors in space between the Earth and the sun to reduce the amount of energy striking the Earth. 342 watts per square meter, 1,700 watts per square meter when the sun is directly overhead. 510 million square km. energy striking only 1/2 at a time. 255 million square km. 8.7 *10¹⁶ watts overall. What would be the impact of a 100 square kilometer (10*10) shield? 1,700*100*10⁶ = 1.7 * 10¹¹ watts or 2*10^-5 or 0.002% of the energy reflected away. Is that enough? What would hold it in place?

Invent giant machines to filter carbon out of the air. Of course they would operate by burning fossil fuels.

Seed the oceans with genetically engineered super CO₂ absorbing organisms. Of course if they got out of control we could end up with a bigger problem than we started with. Is this an idea for another Michael Crichton novel?

Convert to nuclear and other non-CO₂ emitting power generation and a hydrogen / electric economy. Promote efficiency. Carbon emission credits are a good first move in this direction. Spread nuclear power generation worldwide so developing countries have energy without going the fossil fuel route.