Tectonic Scale
		q Tectonic Scale: the longest time scale of climate change on Earth, which encompasses most of Earth’s 4.55-billion years of history. q Tectonic processes driven by Earth’s internal heat alter Earth’s geography and affect climate over intervals of millions of years. q On this time scale, Earth’s climate has oscillated between times when ice sheets were presented somewhere on Earth (such as today) and times when no ice sheets were presented.