Climate literacy: the essential principles of climate sciences: a guide for individuals and communities, a climate- oriented approach for learners of all ages

Throughout its history, Earth’s climate has varied, reflecting the complex interactions and dependencies of the solar, oceanic, terrestrial, atmospheric, and living components that make up planet Earth’s systems. For at least the last million years, our world has experienced cycles of warming and cooling that take approximately 100,000 years to complete. Over the course of each cycle, global average temperatures have fallen and then risen again by about 9°F (5°C), each time taking Earth into an ice age and then warming it again. This cycle is believed associated with regular changes in Earth’s orbit that alter the intensity of solar energy the planet receives. Earth’s climate has also been influenced on very long timescales by changes in ocean circulation that result from plate tectonic movements. Earth’s climate has changed abruptly at times, sometimes as a result of slower natural processes such as shifts in ocean circulation, sometimes due to sudden events such as massive volcanic eruptions. Species and ecosystems have either adapted to these past climate variations or perished.