Event that occurred billions or millions of years ago | Event that occurred thousands of years ago | Event that occurred decades ago
put the right answers with the right categories.
answers: [the last Ice Age ended] , [oxygen builds up in Earth's atmosphere] , [carbon dioxide levels reach their highest levels on record]
Event that occurred billions or millions of years ago: [oxygen builds up in Earth's atmosphere]
Event that occurred thousands of years ago: [the last Ice Age ended]
Event that occurred decades ago: [carbon dioxide levels reach their highest levels on record]