11. Describe how the climate most likely changed between 220 million and 12 thousand years ago

The Earth was formed about 4.5 billion years ago—that's a very long time ago! It's hard to say exactly what the Earth's daily weather was like in any particular place on any particular day thousands or millions of years ago. But we know a lot about what the Earth's climate was like way back then because of clues that remain in rocks, ice, trees, corals, and fossils.

These clues tell us that the Earth's climate has changed many times before. There have been times when most of the planet was covered in ice, and there have also been much warmer periods. Over at least the last 650,000 years, temperatures and carbon dioxide levels in the atmosphere have increased and decreased in a cyclical pattern.

These two clue show how the amount of carbon dioxide and the Earth's temperature have changed over the last 650,000 years. Both clue show a similar up-and-down pattern.

People didn't cause the climate change that occurred thousands or millions of years ago, so it must have happened for other natural reasons.

nucleic acid molecules are incredibly complex, containing the code that guarantees the four different nucleotide units comprise dna, the nucleic acid of interest to the genealogist. and one of four nitrogen-containing molecules called nucleotides