ABOUT CO2 LEVELS
CO2 levels reported in the videos were accurate at the time of filming, when they were around 385 parts per million (ppm) (38% over the pre-industrial level of 280 ppm). However they have now (May 2012) risen to 392 ppm (seasonally corrected). Check for yourself at www.esrl.noaa.gov/gmd/ccgg/trends/global.html. CO2 is considered a bigger problem than most greenhouse gases because naturally it stays in the atmosphere for thousands of years. See, for example, this 2008 review by David Archer.
Katja and Martin talk about how the levels of CO2 and oxygen in the atmosphere are routinely measured at the Baring Head clean air monitoring station in New Zealand. In New Zealand, CO2 is rising and O2 is falling.
Myles explains how the absorption of infrared radiation by the Earth and its atmosphere warms the Earth, and hence how rising CO2 levels increase average global temperature.
Neil and Hugh explain how the absorption of heat by greenhouse gases such as CO2 and water can be measured with a spectrometer.
Ray explains how higher levels of gases like CO2 warm the Earth's surface by creating a thicker atmospheric blanket.
It is measured daily around the world, but as Myles notes it's the long term temperature trends that are important. Phil discusses the historical record from weather stations world-wide, and proxy records going back thousands of years.
Myles and Wally explain how the response of Earth's climate to rising levels of greenhouse gases can be modified by other factors. For example, atmospheric dust particles, water vapour and clouds, will either decrease or increase the expected warming caused by CO2 emissions alone. One consequence of this is that cleaning up the dirty emissions from coal-fired power stations removed their cooling effect and unmasks the full greenhouse warming effect.
Lonny describes his life's mission to retrieve the climate record in tropical glaciers from the world's highest mountains before they melt.