Imagine a white picket fence
around a white house,
with a white driveway and a white car.
And it’s not just your house that's white.
It's also the road,
sidewalks,
and every single building.
"Everything's white.
This is mad."
It looks boring and sterile
but it could be the future.
And it could help save our world.
The human race is facing a huge threat.
A mass extinction of plants and animals,
dwindling food,
and extreme weather awaits us
if we don’t stop the increasing heat
from climate change.
And if we let the global temperature
rise by just 6 °C (10.8 °F),
we’re toast.
There are tons of ideas out there
about how to stop the rising temperatures.
One idea
is painting roofs, roads, and other surfaces
with white paint.
Sunlight contains three different types of light.
Visible,
infrared,
and UV light.
When visible lights hits a surface,
that energy is either absorbed or reflected.
The fraction of light that is reflected
by a surface is called albedo.
A high albedo means that a surface reflects a lot of light,
while a low albedo means that a surface absorbs more light.
Dark asphalt roads have a low albedo,
so they absorb a lot of light.
That’s why they get so hot in the summertime.
Snow has a high albedo
and reflects 95% of solar radiation.
Currently, the Earth has an albedo of 30%.
So the surface of the Earth
absorbs plenty of sunlight,
which contributes to rising temperatures.
And climate change lowers Earth’s albedo.
It’s a vicious cycle that goes like this.
The Earth gets hotter,
which melts ice caps.
Because there's less snow,
less light is reflected back into space,
and the Earth’s albedo becomes lower.
So Earth absorbs even more sunlight,
and heat,
which increases Earth’s temperature
and melts more ice caps.
But we can slow this warming cycle.
Painting the Earth white
would significantly increase its albedo.
And if the Earth’s albedo increases,
it would reflect more
visible light back into space,
which would cool surface temperatures.
If you've lived through a heat wave,
you'd likely appreciate cooler temps.
And we’re not talking about using just any white paint.
We’d need to use a special paint
that was recently developed.
This paint reflects 95.5% of incoming light.
And it could cool surface temperatures up to 1.7 °C (3 °F)
lower than the surrounding air temperature.
We'd need about 60,000 swimming pools
worth of this stuff to cover all the urban areas on Earth.
We’d coat roofs,
roads, and pavement in this paint.
raising the albedo of urban areas by 10%.
If we painted everything tomorrow,
That might not sound like a lot.
But it would be like offsetting the emissions
of all the cars in the world
for the next 20 to 30 years.
It would take a couple of hundred years
for this temperature decrease to happen,
but there are some immediate effects.
The white paint would decrease
the urban heat island effect,
so you wouldn’t have to run your air conditioner as much
during the summer.
The downside of the white paint
is all that glare.
You’d want to buy a good pair of sunglasses
to protect your eyes from the blinding light.
But just painting the Earth white
won't solve our climate crisis.
We'd still have to grapple with the greenhouse gas effect.
As the amounts of carbon dioxide and methane
in our atmosphere increase,
they create a blanket of gases that trap infrared radiation.
This will continue to warm our planet,
even with our new paint job.
So, although painting the Earth white,
or at least our roads and roofs,
could help mitigate rising temperatures,
it would have to be one small part of a larger plan
to geo-engineer the Earth.
But that’s a story for another What If.