4B/H6 ( Grades: 9-12 ): The earth's climates have changed in the past, are currently changing, and are expected to change in the future, primarily due to changes in the amount of light reaching places on the earth and the composition of the atmosphere. The burning of fossil fuels in the last century has increased the amount of greenhouse gases in the atmosphere, which has contributed to Earth's warming.
4B/M14 ( Grades: 6-8 ): The earth has a variety of climates, defined by average temperature, precipitation, humidity, air pressure, and wind, over time in a particular place.
4B/M6 ( Grades: 6-8 ): Climates have sometimes changed abruptly in the past as a result of volcanic eruptions or impacts of huge rocks from space.
5D/H2 ( Grades: 9-12 ): If a disturbance such as flood, fire, or the addition or loss of species occurs, the affected ecosystem may return to a system similar to the original one, or it may take a new direction, leading to a very different type of ecosystem. Changes in climate can produce very large changes in ecosystems.