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)