Predicting Earth’s climate with precision is impossible. Historically, even when CO₂ levels were hundreds of times higher than today in the geological past, it did not dictate climate outcomes. Between 1.0 and 2.7 million years ago, Earth’s climate oscillated every 41,000 years. ♦ CO₂ dissolves more in cooler water—cold oceans absorb more CO₂, warm oceans release it. ♦ Historically, CO₂ levels have been much higher than today without driving climate change.