Scientists
have to think like detectives. They look for clues to help them
understand how the world works. Then they investigate the clues
to find evidence real facts that can give them a better idea
of what is going on. Here are some of the ways that scientists gather
evidence about climate,
both past and present:
Weather
stations help us find out the temperature on the surface of the
Earth. Weather stations use special thermometers that tell us the
temperature. They can be set up almost anywhere on land. Weather
stations also can tell us how fast the wind is moving and how much
rain falls on the ground during a storm.
Almost
everyone likes balloons including scientists! Weather balloons
are released to float high up into the atmosphere.
They carry special instruments that send all kinds of information
about the weather back to people on the ground.
A
buoy is an object that floats on water, and is often used to warn
boats away from dangerous places in the ocean or on a river. But
some buoys have special instruments on them. These buoys can tell
us the temperature and other things about the conditions of the
atmosphere.
Humans
send satellites into space to travel around the Earth. The satellites
send back information to scientists on the ground. Some of the information
they give us is about the weather and the Earths temperature.
Some
scientists who want to find out more about climate study ice for
clues. Not just any ice they are studying the ice from glaciers
that have been around for a very long time. They cut pieces of ice
and look for air bubbles that were trapped in the ice hundreds or
even thousands of years ago. The air bubbles help them discover
what the climate used to be like on Earth. The evidence they uncover
is creating a historical record of regional temperatures and greenhouse
gas concentrations
dating back 160,000 years.
Sediment
is the earth and rock that has built up in layers over time. Scientists
are learning a great deal about past climate from studying these
layers. Sediment layering provides information about where glaciers
have been in the past. Ocean sediments provide a map of how ocean
currents have flowed in the past. And fossilized pollen found in
sediment layers tells us about where different plants have grown
in the past.
You
can tell how old a tree is by counting its rings because it grows
a new ring every year. Tree rings also can tell us how much precipitation
fell each year in the place where the tree lives. Precipitation
is rain or snow or any other moisture that falls to the Earth. Scientists
study the sizes of tree rings. The different sizes of the rings
tell us about changes in temperature and precipitation.
Weather
stations, balloons, ocean buoys, and satellites tell us the Earths
temperature today. Ice cores, sediment layers, and tree rings tell
us about what the Earths climate has been like in the past.
With this evidence, scientists are learning how climate changes
over time.
How
do clouds respond to changes in temperature and precipitation? How
do oceans transport heat? How do climate and intense weather events
like hurricanes affect each other? As scientists try to answer these
and other questions, they will discover many more clues about how
the Earths climate
system works.
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