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Global warming continues to get worse.
It's destroying our land
and killing our people.
But what if there was a way to stop it
almost instantly?
We might not even need to sacrifice our cars,
or change what we eat.
Instead, we could build a shield
to block out the Sun.
A Sun shield would be like
a massive umbrella in space.
It would divert rays from the Sun,
reducing heat and solar radiation on Earth.
It's been proposed for decades by scientists,
and could one day become a reality.
But there's a couple of conditions.
It would cost trillions of dollars,
and every country on Earth
would need to be on board.
Easy, right?
Let's assume this happens,
and we'll just skip to the good stuff.
The Sun shield would be created
by sending small flyers up into space.
They would have incredibly thin mirrors,
and would connect to make one massive umbrella.
It would be half the size of Earth,
and located 1.5 million km away from the planet.
At this location, it would be the
same distance from Earth all year round. 
The shield would block out just 2% of the Sun's rays,
which would reduce the
Earth's temperature by about 1°C (1.8°F).
That was Earth's temperature
just before the Industrial Revolution.
As more flyers are added,
the Sun shield would change
Earth's temperature gradually.
This is so we don't shock every living species on Earth
with a sudden temperature change. 
As this happens,
tropical climates will get colder,
and the Arctic will be able to stay
frozen for the first time in decades.
Decreasing the Earth's temperature
will also affect the water cycle.
We would have fewer heavy rainstorms,
hurricanes, and flooding.
But if we got rid of climate change,
would humans continue to act as they do today?
People and big industries might
still release lots of C02 and methane.
Since we'd have conquered global warming,
humans might go ahead and create
even more greenhouse gases.
And then they'll all get trapped in our atmosphere.
But at least we wouldn't have
to worry about climate change, right?
Well, not quite.
It is possible that something
could go wrong with the Sun shield.
Like getting hit by an asteroid,
or drifting out of position.
We'd have to adjust the shield every few years.
And if we forgot to do that,
the consequences would be devastating.
If we didn't replace the shield
at the end of its 50-year life cycle,
we'd be hit by a global temperature change
faster than ever before.
Instead of the Earth's temperature
increasing over years or decades,
it would happen within a couple of months,
by up to 3°C (5.4°F)
This increase in temperature
would be a huge shock to everything on Earth,
including the planet itself.
Certain areas would become more prone to droughts,
while others would have massive floods.
This would destroy our infrastructure and cities.
Crops would also die,
and water would be harder to obtain.
Antarctica would be melting again,
while drier areas would be burning with wildfires.
And with this happening so quickly,
species wouldn't be able to adapt.
And that includes us.
Millions of people could die, and
hundreds of species could go extinct.
And since people didn't decrease
the amount of CO2 and methane 
we released into our atmosphere
when we had the Sun shield,
it would be too late at this point.
The Earth would continue to heat up,
until our planet becomes an unliveable desert.
So having a Sun shield
shouldn't be seen as a bandage for climate change.
Instead, it should be looked at
as a possible second chance for
humanity to make up for its mistakes.
But due to the astronomical cost,
it's unlikely a Sun shield would even be built.
If we had all this money,
shouldn't we go to Mars first?
Well, that's a story for another WHAT IF.
