How to explain Milankovitch cycles to a hostile Congressman in 30 seconds

Over the last few weeks, I've been publicly put on the spot on two occasions, asked to give very short answers to complex climate questions. On a climate communication panel, Naomi Oreskes asked how I'd answer the CO2 lag question in 30 seconds (and no iPhone app to fall back on). On the Climate Show podcast, Glenn and Gareth asked how I'd answer the global cooling argument in 30 seconds. What's with this 30 second limit?!

Meanwhile, Professor Richard Alley was being grilled by a hostile Republican Congressman who asked him to explain in 15 seconds why climate has changed in the past and how we know humans are causing it now when they didn't back then. I've long been a fan of Richard Alley. Not just because of his rendition of Geoman, possibly the nerdiest song in the history of science. I consider his lecture, The Biggest Control Knob: Carbon Dioxide in Earth's Climate System, must-watch viewing for anyone interested in climate and wishing to understand past climate change at a much deeper and richer level.

But seeing his answer in a Congressional hearing under those conditions, my admiration went up another notch. In 35 seconds, he manages to explain Milankovitch cycles (aka changes in the Earth's orbit) quicker, funnier and with more clarity than I've heard before. Check out the first 60 seconds then continue on for plenty more Alley goodness...

Another video worth watching features Alley and Ben Santer explaining why we know CO2 is causing global warming. They invoke a subject SkS readers will be well familiar with - the stratosphere is cooling while the troposphere is warming.

So next time I'm in a conversation where someone invokes past climate change, I'll be sure to begin by saying "imagine my bald spot is the North Pole". As my parents informed me last weekend, I'm thinning on top so the metaphor should work well.

H/T to Peter Sinclair from Climate Denial Crock of the Week who posted these videos.

Posted by John Cook on Monday, 6 December, 2010

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