Extreme proposals to stop global warming

Here is a chart of multiple Geo-engineering projects that have been suggested.

Project	What’s to be done?	Why do it?	Which areas would it help	How much will it actually help?	What are potential risks?	Cost?	Is it worth pursuing…
White roofs	All houses have their roofs either painted white or built so they are white.	To create more reflective surfaces to reflect sunlight back into space.	globally	Not much	There aren’t any high risks	Relatively cheap	No- because recent studies show that it could actually end up warming the earth by black carbon in the atmosphere taking in the light.
Copycat volcanoes	Attach a garden hose to a helium balloon to pump sulfur into the atmosphere	Sulfur dioxide blocks sunlight	globally	Not sure	-It could have dangerous unintended environmental changes like weather change - cause ozone depletion	$8-10 billion per year	No – more experiments should be done to see side effects of the project. Also we don’t have the technology to do this yet.
High flying airplanes	Use high flying airplanes to constantly refill a layer of particles in the stratosphere	It would deflect away about 2% of sunlight and its actually beneficial to crops	globally	It would be pretty effective	Same as copycat volcano	~$8 billion per year	Side effects still need to be further evaluated and we don’t have the technology.
Sun Shield	Launch trillions of small mirrors into space to form a large mirror between the sun and earth	Reduce sunlight by 2%	globally	Very effective	Don’t see any large risks but is untested so there still could potentially be risks.	about $4 trillion	No- don’t have the technology yet the mirrors are too heavy to be launched into space and it’s also very expensive
More clouds	Use specially made ships to sending sea water into the sky	Increase the reflective power of the clouds by 3%	globally	Pretty  effective	It’s still untested so risks are hard to determine	$7 billion	No- more testing and experimenting need to be done
Fake trees	Towers that suck CO2  from the air and store it underground	Take in about 1 ton of CO2 each day	globally	Effective	Being tested right now – doesn’t seem to have any large risks	$150 per ton	Maybe after more testing
							made by me