**The Planet in the Machine**

By Diane K. Fisher and Tony Phillips

The story goes that a butterfly flapping its wings in Brazil can, over
time, cause a tornado in Kansas. The "butterfly effect" is a common term
to evoke the complexity of interdependent variables affecting weather
around the globe.  It alludes to the notion that small changes in
initial conditions can cause wildly varying outcomes. \
 \
Now imagine millions of butterflies flapping their wings.  And flies and
crickets and birds.  Now you understand why weather is so complex.\
\
All kidding aside, insects are not in control.  The real "butterfly
effect" is driven by, for example, global winds and ocean currents,
polar ice (melting *and* freezing), clouds and rain, and blowing desert
dust.  All these things interact with one another in bewilderingly
complicated ways.\
 \
And then there's the human race. If a butterfly can cause a tornado,
what can humans cause with their boundlessly reckless disturbances of
initial conditions?\
 \
Understanding how it all fits together is a relatively new field called
Earth system science. Earth system scientists work on building and
fine-tuning mathematical models (computer programs) that describe the
complex inter-relationships of Earth's carbon, water, energy, and trace
gases as they are exchanged between the terrestrial biosphere and the
atmosphere.  Ultimately, they hope to understand Earth as an integrated
system, and model changes in climate over the next 50-100 years.  The
better the models, the more accurate and detailed will be the image in
the crystal ball.\
 \
NASA's Earth System Science program provides real-world data for these
models via a swarm of Earth-observing satellites.  The satellites, which
go by names like Terra and Aqua, keep an eye on Earth's land, biosphere,
atmosphere, clouds, ice, and oceans.  The data they collect are crucial
to the modeling efforts.\
 \
Some models aim to predict short-term effects---in other words,
weather.  They may become part of severe weather warning systems and
actually save lives. Other models aim to predict long-term effects---or
climate.  But, long-term predictions are much more difficult and much
less likely to be believed by the general population, since only time
can actually prove or disprove their validity.  After all, small errors
become large errors as the model is left to run into the future. 
However, as the models are further validated with near- and longer-term
data, and as different models converge on a common scenario, they become
more and more trustworthy to show us the future while we can still do
something about it---we hope.

For a listing and more information on each of NASA's (and their
partners') Earth data-gathering missions, visit
[science.hq.nasa.gov/missions/earth.html](http://science.hq.nasa.gov/missions/earth.html).
Kids can get an easy introduction to Earth system science and play
Earthy word games at
[spaceplace.nasa.gov/en/kids/earth/wordfind](http://spaceplace.nasa.gov/en/kids/earth/wordfind)
.

*This article was provided by the Jet Propulsion Laboratory, California
Institute of Technology, under a contract with the National Aeronautics
and Space Administration.*

![](media/image1.jpeg){width="6.0in" height="4.047916666666667in"}

Caption:

*CloudSat is one of the Earth observing satellites collecting data that
will help develop and refine atmospheric circulation models and other
types of weather and climate models. CloudSat's unique radar system
reads the vertical structure of clouds, including liquid water and ice
content, and how clouds affect the distribution of the Sun's energy in
the atmosphere. See animation of this data simulation at
www.nasa.gov/mission_pages/calipso/multimedia/cloud_calip_mm.html.*

Note to editors:

This image may be downloaded at

<http://spaceplace.nasa.gov/news_images/cloudsat_3D_clouds.jpg>