Mous Chahine: No area on Earth immune from effects of greenhouse gases

Mous Chahine is a senior research scientist at NASA’s Jet Propulsion Laboratory in California.

He told us about research using an instrument called the Atmospheric Infrared Sounder – AIRS – that works aboard NASA’s Aqua satellite. AIRS tracks carbon dioxide, a greenhouse gas known to cause global warming.

There is no area on Earth immune from the effects of carbon dioxide regardless of whether that area produces carbon dioxide or not. From AIRS, we have made one discovery. It is that carbon dioxide is not well mixed. It is lumpy. We can look at the carbon dioxide emitted from Asia moving across the Pacific to North America, where we add more carbon dioxide, and then to Europe. It goes round and around.

Dr. Chahine said AIRS also tracks water vapor in the atmosphere, which he called the planet’s most potent greenhouse gas. He said warming global temperatures mean more evaporation from the oceans. This water vapor gets stored in Earth’s upper atmosphere, heating up the Earth even more.

If the carbon dioxide is causing global warming of, say, one degree, the resulting water vapor in the atmosphere will multiply it so that the net is two and a half degrees, not just one.

He explained that AIRS tracks carbon dioxide using spectra, or colors.

We make the measurement in the infrared. This is the region in which we get heat emitted from the atmosphere. If we have more carbon dioxide, we have more energy emitted, and the satellite will measure more energy. What we do is take those measurements which we call spectra [infrared colors], and we unscramble it to see how much change from carbon dioxide, clouds, or water vapor.

Chahine said carbon dioxide is the most demanding gas to study.

Because we are asked to measure it one part per million. With AIRS we have shown we can do it between one and two. We have to be very careful, very attentive – this is a message to my colleagues. Treat your instrument with infinite care, it will pay off.

Chahine said AIRS has produced six years worth of global carbon dioxide data – the longest-running measurement. He said that a future project for AIRS is identifying Earth’s natural carbon dioxide ‘sinks’ – that is, CO2 storage spots like oceans and forests that might help keep Earth cool.

Our thanks today to NASA’s Aqua Mission, improving our knowledge of our home planet through satellite observations.