Models help us to work through complicated problems and understand complex systems. They also allow us to test theories and solutions. From models as simple as toy cars and kitchens to complex representations such as flight simulators and virtual globes, we use models throughout our lives to explore and understand how things work.

Global climate is changing. Our future climate will certainly be different than our present climate. Where, when, and how rapidly these changes will take place is still a matter of scientific study.

Some natural processes record the passage of time: for instance, layers of sediments accumulate over many years, and some of them preserve information about weather conditions during the time they were deposited. Throughout Earth's history, global and regional climate has changed on very long time scales, and many of the past conditions can be discovered by studying natural records.

You can use a number of software packages and Web sites to to access or generate image maps or graphs of historical climate data or future climate projections.

Putting your cursor on the data you want isn't always easy. For instance, when you want a data table of temperatures, you may only find a map or graph. Similarly, you might want climate data for a specific state, but you can only find global or country-based data. Still other times, you might feel like you've found what you want, but the data access interface is more complex than you anticipated, or the file formats are unfamiliar.

This section presents information on how climate scientists develop scientific predictions about future climate.

Climate classifications help people know what types of conditions a region usually experiences through the year. Rather than having to describe the full range of conditions observed in a region over each month or season of a year, a classification scheme can communicate expected conditions using just two or three terms.

Learn more about how weather data, collected by volunteer observers and automated instruments, is processed into weather and climate data products such as maps, graphics, and models.

Are you new to climate data? Ready to learn or review some of the basics?

From daily temperature readings to tracking of hurricanes across the ocean, monitoring weather gives us a way to check the pulse of the planet. Combining local data from weather stations on the ground with remotely sensed data from instruments on satellites helps build a clear picture of the state of the atmosphere around the world.