Truth on global warming

Do you believe that global warming is a real threat? If so, can you explain why? If not, can you explain why not? Most people have an opinion on the first question, but I've found that relatively few can answer the followups. In other words, most Americans have opinions of global warming based on what Stephen Colbert calls "truthiness" - which comes from the gut, rather than from facts - and can't even explain why they believe as they do.

So if you've landed on this post in hopes of learning the real facts behind the science of global warming, I think you'll find that you've come to the right place. I created the following video to explain the basic science that's necessary for developing an informed opinion:

I hope you'll watch the video, but I'll summarize the main point here. Despite all the debate you often hear about global warming, the basic scientific case is so simple that it can be reduced to a three-step deductive argument:

Fact 1: Carbon dioxide traps heat in the atmosphere. This fact was first measured in the laboratory more than 150 years ago and is necessary to explain why Earth is warm enough for life to begin with, as well as to explain the temperatures of all other planets in our solar system. Note that there is no scientific dispute about this fact whatsoever.

The actual calculation for Earth's temperature in the absence of greenhouse warming, from which we conclude that Earth is warm enough for life only because of the greenhouse effect caused by carbon dioxide and other greenhouse gases. (Image from The Wizard Who Saved the World.)

• https://goo.gl/maps/YJV3HW2xWCqaPkHh9

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