Leading climate change experts discuss one of the most complex scinetific puzzles ever to confront humankind. How do we know the earth is warming? How do we know the warming is caused by rising levels of carbon dioxide? How close are we to having all the answers?
How Do We Know? Introduction: Why study climate change? What are some of the climate change projections made by the Intergovernmental Panel on Climate Change? How do we know the earth is warming? How much has the earth warmed recently? Why is it important to reconstruct the long history of the earth's climate, and how can we do that? If the earth has warmed before, why be concerned now? What is unusual about the earth's warming during the past century or so? What does carbon dioxide have to do with global warming? What is the source of the increased greenhouse gases in the atmosphere? How do we know the rising carbon dioxide is not part of a natural cycle? How do we know the warming is caused by rising levels of carbon dioxide? How much warming do we face, and what are the uncertainties involved? How are climate models being improved? Would reducing greenhouse gas emissions avoid the impacts of climate change immediately? How close are we to having all the answers?