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Climate Change Evidence, Impacts, and Choices answers to common questions about the science of climate change
Contents Part I. Evidence for Human-Caused Climate Change 2 How do we know that Earth has warmed? 3 How do we know that greenhouse gases lead to warming? 4 How do we know that humans are causing greenhouse gases to increase? 6 How much are human activities heating Earth? 9 How do we know the current warming trend isn't caused by the Sun? 11 How do we know the current warming trend isn't caused by natural cycles? 12 What other climate changes and impacts have been observed? 15 The Ice Ages 18 Part II. Warming, Climate Changes, and Impacts in the 21st Century and Beyond 20 How do scientists project future climate change? 21 How will temperatures be affected? 22 How is precipitation expected to change? 23 How will sea ice and snow be affected? 26 How will coastlines be affected? 26 How will ecosystems be affected? 28 How will agriculture and food production be affected? 29 Part III. Making Climate Choices 30 How does science inform emissions choices? 31 What are the choices for reducing greenhouse gas emissions? 32 What are the choices for preparing for the impacts of climate change? 34 Why take action if there are still uncertainties about the risks of climate change? 35 Conclusion 36