If we made our roads the color green instead of black, would that help global warming?

Question

Roads replace earth that absorbs most electromagnetic waves and converts them to chemical energy. The green wavelength is reflected, so my question is wouldn't we want to send only the wavelengths that are naturally reflected instead of all of them? Understand that blacktop road absorb all wavelength at first until they bleach; and reflect most by their whitish color. Can you think of any large natural surfaces that are entirely black? Snow is white - so how will that affect global warming when it's gone and plants arise that absorb?

Answer 1

It would help to an extent - the lighter the colour the more solar radiation is reflected back into space. It wouldn't necessarily have to be green, a light to mid grey colour would be as reflective as bright green.

Green surface dressing are already used in some places, as are red ones. A lot of roads here in the UK have anti-skid surfaces particularly on the appraches to bends, junctions, roundabouts etc and these are usually red but sometimes green. Cycle lanes are sometimes red or green. Not bright colours - more of a dull green or a dull red.

The difference it would make would be very small, I don't know how much of the earth is covered by road surfaces but it's not going to be much. In many places there are no roads just dirt tracks.

It may not be practical to surface entire roads with coloured dressings. The bitumastic compounds normally used to bind the chippings are naturally black so there would have to be an awful lot of colourant added or some alternative binder would be needed. I believe polyuratanes are used as the binder in coloured surface dressings and this is much more expensive than bitumen products.

The fractionation process for obtaining bitumastic compounds is relatively straightforward whereas the production of polyurathane is a much more complicated chemical process involving the use of toxic and volatile chemicals including isocyanate, chlorides and flourocarbons. The production of the polyurathane could more than offset the use of lighter coloured road surfaces. There's also the cost to consider - bitumens are cheap, polyurathanes aren't. The money may well be better spent elsewhere.

Answer 2

This idea would do nothing to change the amount of heat retained by the planet. The radiation already entered our atmosphere therefore has already contributed most of it's energy. Even if it were to be reflected from the surface it would still be exciting the air molecules and would most likely be reflected back down again by the atmosphere.

In order for the idea of reflecting some of the Sun's radiation to prevent it from warming the earth you would need to do it before it entered earth's atmosphere. This idea has been thought of before but the task would be Gigantic. It could serve two purposes though.

1. The reflector or shield would prevent some energy from reaching the planet.

2. If the material were photovoltaic ( like a solar panel ) the solar energy could be stored or transferred to be used for something else.

Answer 3

What you are depicting here is called the "albedo" component of global warming

http://en.wikipedia.org/wiki/Albedo

The color which reflects the most is white and this contributes to the very low temperatures of the earth poles since the few radiations hitting the ground are reflected.

Projects have actually been launched to have the building roofs in white to reflect the radiation instead of absorbing it.

Regarding the roads, it is more a safety matter as we can not allow a material which would have a lower grip with the rubber tires.

Problem: If you drive on a white road, isn´t the reflection of your headlights going to be more important and going to disturb your ability to drive ?

Answer 4

Global warming happens when the sun's rays hit that would usually be reflected back into space after reflecting off the earth are trapped because the greenhouse gasses reflect the rays back down to the earth. So reflecting rays back into the sky won't help because they will still get trapped. What you need to do is to reduce the amount of greenhouse gasses in the atmosphere. Then the rays could escape and global warming could be slowed down.

Answer 5

The effect is very small and you would burn more fossils fuels to rip it up or paint it green.

No real benefit, sorry.

Large natural surfaces that are black ... even been to the Hawaiian Islands? Lots of obsidian and basalts they're black.

Ever been to a flood plain? Lots of rich black soil.

Your idea is admirable, it actually has a name: "biomimicry", and has merit; but PV cells are much more efficient. They are developing "paint on" PV cells. IF the resulting surface isn't slippery, and they could stand up to the traffic, maybe one day you'll get you wish.

Answer 6

well i know what you mean but i don't think that it would help at all! Think about it... even if we did change the roads from black to green, what would we use to make it green? Certainly nothing natural! What we NEED to do is cut down on these man-made gases and start caring about our earth and not about paris hilton coming out of jail.

Answer 7

damned good question, I think it would have to be a light green though , dark green is like black.
Unfortunately that would take too much money to do.
AND we as humans have done, and are doing too much irreversible damage to the earth for that to make a big difference (if it were possible to do.)

Answer 8

Yeah but we will also crash more. Green grass and road next to each other is a bit confusing.

Answer 9

forget the scientific reasoning...it would just be pretty...so lets do it. i like the idea of painting all the cell phone and water towers legs brown and the tops green to make them look more like trees.

Answer 10

Its a possibility but I will have to admit it will take some getting used to.