Event that occurred billions or millions of years ago Event that occurred thousands of years ago Event that occurred decades ago

Question

carbon dioxide levels reach their highest levels on record
oxygen builds up in Earth's atmosphere
the last Ice Age ended

Answer 1

- Carbon dioxide levels reach their highest levels on record (billions or millions of years ago)
- Oxygen builds up in Earth's atmosphere (billions or millions of years ago)
- The last Ice Age ended (thousands of years ago)