I’m always excited to find new analogies that help explain climate change to more people – we all learn differently and with the complexity of a problem like global warming, it’s helpful to have a few ways to explain what’s happening with our atmosphere.  Here’s a great visual representation of the bathtub metaphor from National Geographic: "It’s simple, really: As long as we pour CO² into the atmosphere faster than nature drains it out, the planet warms. And that extra carbon takes a long time to drain out of the tub."  In this metaphor, 350ppm is where the water level ought to be – a delicate balance between what we are putting into the atmosphere, and what the Earth can absorb each year.  Right now, the tap is open way too far.  Click on the image to see it full size.