From site: Our planet is constantly changing. Natural cycles balance and regulate Earth and its atmosphere. Human activities can cause changes to these natural cycles.
Life on Earth is well adapted to our planets cycles. In our solar system, Earth is the only planet with air to breathe, liquid water to drink, and temperatures that are just right for life as we know it. Because our existence depends on our planet and its climate, we need to understand how what we do affects the Earth.
Scientists try to figure out how our planet works by studying Earths cycles. Changes to Earths cycles can cause changes in the climates of our planet. The more we know about these cycles, the more we will understand how humans are affecting them and how that might change the planet.
The cycles described include energy balance, carbon, rock, ocean, atmosphere, water and nitrogen.