Some supercomputers can do more than 12 trillion calculations a second! Click on image for full size (55 Kb) Courtesy of UCAR Digital Image Library

Global climate models use hundreds of different mathematical equations to describe processes and interactions in the Earth system. The mathematical equations for a large climate model require quick supercomputers that perform many calculations rapidly, often more than 80 million calculations an hour.

The most sophisticated climate models take into account five important components:

• The biosphere: the amounts and types of animals and plants
• The hydrosphere: the oceans and other bodies of water
• The cryosphere: including sea ice, glaciers and ice sheets
• The atmosphere: its chemical composition and behavior
• The geosphere: tectonic variations such as volcanic eruptions and moving continents

For more information about climate models, visit the following pages:

• What Is a Climate Model?
• How Climate Models Work
• Accuracy and Uncertainty in Climate Models

What will the next century bring? According to scientists Tom Wigley (NCAR) and Sarah Raper (Climate Research Unit, England) there is 90% probability that temperatures will rise 1.8 to 4.0°C (3.1 to 7.2°F) in the next 100 years as a result of human influences, assuming continued greenhouse gas emissions. To put this amount of warming into perspective, remember that in the past century, a smaller temperatures rise of only about 0.6°C (1.0 °F) has been able to disrupt many aspects of the Earth system.

Some supercomputers can do more than 12 trillion calculations a second! Click on image for full size (55 Kb) Courtesy of UCAR Digital Image Library

To figure out the future of climate change, scientists need tools to measure how Earth responds to change. Some of these tools are global climate models. Using models, scientists can better understand how the Earth works and how it will react to change in the future.

Global climate models (GCMs) use math to describe how the Earth works. Supercomputers are needed to run large global climate models. These speedy computers can sometimes do more than 80 million math problems in an hour.

Climate models usually try to take into account all the parts of the Earth system including:

• The animals and plants (the biosphere)
• The oceans, lakes, and rivers (the hydrosphere)
• Icebergs, glaciers and ice sheets (the cryosphere)
• Air (the atmosphere)
• Volcanoes and moving continents (the geosphere)

• What Is a Climate Model?
• How Climate Models Work
• Accuracy and Uncertainty in Climate Models

What will the next century bring? According to scientists, it is likely that temperatures will rise 1.8 to 4.0°C (3.1 to 7.2°F) in the next 100 years if we continue to let more greenhouse gases loose in the atmosphere. A smaller amount of warming (0.6°C or 1.0 °F) over the past century has caused disruptions to the planet. So, more warming over the next century would likely cause many more changes to Earth.

Some supercomputers can do more than 12 trillion calculations a second! Click on image for full size (55 Kb) Courtesy of UCAR Digital Image Library

To figure out what the Earth might be like in the future, scientists need to know how Earth reacts to changes. Models help scientists to better understand how the Earth works and how it will react to climate change.

A model can help you understand how a something works. For instance, a model airplane is a small version of a real airplane. You can look at a model airplane from all sides to quickly understand what it is like. But it would be more difficult to look at a real airplane quickly from all sides. In the same way, a model of the Earth helps scientists understand more about the planet.

Unlike a model airplane, the models that scientists use to study the Earth system don’t look much like a small version of the planet. Global climate models use math to describe how the Earth works. Tons of math equations describe everything from the oceans to plants and animals. Supercomputers are needed to do all the calculations. These speedy computers can sometimes do more than 80 million math problems in an hour!

What will the next century bring? According to scientists, it is likely that temperatures will rise 1.8 to 4.0 degrees C (3.1 to 7.2°F) in the next 100 years if we continue to let more greenhouse gases loose in the atmosphere. More warming over the next century would likely cause many more changes to Earth.