Let's math it up kk how big kk so 8.5 million square kilometers. 8.5e6 km^2 is 8.5e12 m^2 x 1.5g/m^2 is 1.275e^10 kg to L1. That's 12,750,000,000 kg to L1, is 12,750,000 metric tons. Is Mars Transfer Orbit similar enough to L1 to fudge? Kind of.. Delta-V budget from LEO to Mars Injection Orbit is 4.3 km/s, from LEO to Sun-Earth Lagrange 1 is 7.4 km/s. Things get chewy there though and I've looked up enough stuff so we'll just pretend they're the same. A Falcon Heavy can loft 16.8 metric tons to Mars Injection Orbit. 12,750,000 metric tons / 16.8 metric tons per launch = 759,000 launches of a Falcon Heavy. Each launch burns 400 tons of kerosene. there are 3.09 kg per gallon of kerosene, and each gallon of kerosene burned creates 9.88 kg of C02. 400 tons x 3.09 = 1,236,000 gallons of kerosene per launch = 12,212 tons of CO2 per launch, = 9,270,000,000 tons of CO2 to get the raw material of our shield to L1 = 9,270,000 kilotons = 9,270 megatons = 9.2 gigatons = one third of annual global CO2 emissions, more or less. Cheaper to nuke PakistanOur initial calculations , considering liquid-based spherical bubbles, suggest that the resulting raft’s expected mass density wouldbe<1.5g/m2,onparwiththelightestshield proposedbyAngel[3-5].
Once expanded in space it would be around the same size as Brazil
In general, I would say that any geoengineering approach to "solving" CC is a really, really bad idea. Threading the needle of halting temperature rise or even rolling it back without overshooting is impossible. And that's on a global scale, so it doesn't take into account the unevenness of say, cooling region X by 1ºC and warming region Y by 0.5ºC. Only bad things can happen. I think the government should start a program where they just pay for captured carbon on a per kg basis. Someone will crack that nut if the financial incentive is there.
I say go for it Your increment is 1/42,000th of an effort. That increment can be further reduced below the ability to measure. Not gonna lie. If I were competing with Jeff Bezos or Elon Musk I'd go "you know what? I like this planet plenty."