- [Narrator] Humans have gotten really good
at predicting the weather, but we've had a hard time
figuring out how to control it.
Now, with the threat of rising global temperatures
and severe droughts, scientists are racing to develop
technologies that will actually change the weather.
Scientists are literally making it rain.
Cloud seeding is the process of adding particles
to clouds to force them to rain or snow.
It has already been tested around the globe.
The goal is to increase precipitation
in places with water shortages.
Cloud seeding is a form of geo-engineering
or manipulating of weather systems
to reduce the negative effects of climate change.
Here's how it works.
Silver iodide gets sprinkled into clouds
by airplanes or blasted up into clouds on rockets.
Another possible technique that China is exploring
is using winds to naturally transport
the silver iodide into the clouds.
Silver iodide has a very similar structure to ice,
so the ice crystals in clouds will bond to it,
making the cloud increasingly heavy
until it releases its moisture as rain or snow.
And so far, preliminary tests look promising.
For example, cloud seeding tests in Wyoming,
where snowpack is a primary source of water,
reportedly increased snowfall in the area by 5 to 15%.
But cloud seeding can be used
for more than just curing droughts.
The European company called Oliver's Travels
offers cloudbursting services
to prevent rain on your wedding day.
And China used cloud seeding during
the Beijing Olympics to make sure clouds
released precipitation before reaching the capital.
Some of these tests seem to be working,
but there's no telling what the consequences
could be if we start toying
with Mother Nature on such a level.
One clear down side is that if we force it to rain
in one region, those clouds won't have water left
to drop in other areas that may also need it.
Scientist aren't just adding substances
to clouds, they're also creating clouds.
The process is called stratospheric aerosol injection.
The goal is to prevent too much sunlight from entering
the atmosphere by reflecting it back into space.
With less sunlight reaching the Earth,
the temperature would theoretically drop
and hopefully reduce global warming and its effects.
This already happens naturally.
When volcanoes erupt, they shoot thick,
sulfurous clouds into the air that block
the Sun's rays and cool the planet.
Scientists at Harvard University
are researching the possibility of creating
a similar effect without the volcano.
First, they plan to use balloons to create
normal clouds out of ice particles.
Then, once they've perfected that method,
they hope to move on to chemicals
that can block even more light.
The chemicals released in a volcanic explosion,
called sulfate aerosols, would probably
work the best, but they can damage the ozone layer.
So Harvard Scientists are looking into
other chemicals that might do the job
without risking ozone damage.
But it will be a while before we know
how this would work on a large scale
and if there are any side effects.
So until more research is done,
it's hard to tell if the benefits outweigh the risks.
Needless to say, controlling the weather
is complicated, but there are other technologies
in development that could help battle
the extreme effects of climate change.
Several companies have come up with ways
to convert fog to drinking water in areas
with severe droughts, and it's already
being used in places like California, Morocco, and Chile.
But the best way for us to control
the weather is to cut emissions now.
For decades, researchers have explored ways to remove
carbon dioxide from the atmosphere and store it
somewhere else, like deep in the ocean or inside bedrock.
Some researchers are even trying to turn it into
building materials like concrete and bricks.
But if we continue to fill the air with greenhouse gases
at the rate we are now, ultimately there will be
too much for us to bury or sink.
Reducing emissions would help eliminate
the need for all of these technologies in the first place,
and then we wouldn't need to worry
about controlling the weather.
But let's face it, there are some days
where it would be really convenient.
(thunder rolling)