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Key Idea 6
Greenhouse Gases and Climate Change
Concept Question: How are greenhouse gases changing Earth’s climate?

Atmospheric greenhouse gas concentrations are a key factor in our changing climate. However, you have now learned that greenhouse gases are required to keep the Earth warm enough for humans and other living things to survive. Why are people concerned about greenhouse gases?

 Sunrise over the ocean with clouds overhead


Question for Thought

Greenhouse gases have warmed the Earth for billions of years, making our planet suitable for life. Why are we now concerned about greenhouse gases?