A student examines an ice core graph that tracks atmospheric carbon dioxide (CO₂) levels over the past 800,000 years.

A class is investigating the factors that influence global temperatures.

Scientists use models to understand how energy moves through the Earth system.

Researchers use advanced computer models to determine which variables best explain the observed rise in global temperatures over the past 140 years.

Climate scientists use models to predict how different variables change global temperatures.

A climate skeptic argues that the recent rise in Earth's temperature is just a random, natural cycle and has nothing to do with human activities.