I read in today's newspaper that Richard Branson is offering $ 25 millions for ideas to reduce greenhouse gases from the earth's atmosphere. Hereby I stake first claim for the prize money with a simple but very effective idea. My idea depends on the fact that carbon dioxide freezes directly to solid dry ice at around minus 40 degrees celsius while oxygen and nitrogen stay as gases till about minus 180 degrees celsius. I propose that a geostationary capsule be sent up to a spot at the margin of earth's gravity. It will dangle two pipes into the earth's atmosphere and a pump will suck air up one pipe and pump down the other back into the atmosphere. Carbon dioxide will freeze to dry ice and stay in the capsule while essential oxygen and nitrogen will be returned clean. This dry ice can then be thrown out into space where it will just dissipate. Solar power will keep the pumps working 24 hours a day and hundreds of such capsule may be deployed to reduce greenhouse gases to low levels. Countries will pay according to the amounts of pollution they generate but cost should not be a problem. This is not to replace measures to reduce greenhouse gas production such as using clean fuels and switching to renewable sources of energy such as wind power. There are two dangers to this idea. One, people will become complacent and stop spending on reducing greenhouse gas emissions and two, we might overdo the reduction of carbon dioxide and tip the world into an ice age which would not be very clever. Now my problem will be how to spend so much money.