Last month, NOAA researchers announced that CO2 and CH4 (carbon dioxide and methane, two greenhouse gases) concentrations continued to grow in 2008, despite the slowing global economy. CO2 concentrations continue to grow exponentially, as 2008’s increase of 2.1ppm to 386ppm, fell well within the range of rates seen in recent years (individual years always vary somewhat due to natural processes; exponential rates of growth aren’t explained by natural phenomena). Methane concentrations grew by 4.4ppb.
There is an obvious large difference between the two, but don’t let the individual magnitudes fool you. Methane is 25 times as effective a greenhouse gas as CO2. The fact that methane concentrations increased for the second year in a row is the real worry here: they occurred after nearly 10 years of not increasing, as this Nature graphic shows. With increasing amounts of a more potent GHG in the atmosphere, combined with increasing amounts of CO2, the climate system is being forced more than ever before to a different state.
Increasing methane concentrations in the atmosphere is additional evidence that methane beds are likely thawing out near the poles. Scientists noted increased methane out-gassing starting a few years ago. Global concentrations have since increased. That could mean a positive feedback cycle is also being forced. With warmer near-surface temperatures, especially in polar regions, more permafrost can thaw, which has been shown to increase methane out-gassing, which results in warmer near-surface temperatures. Here’s a very important detail: the total size of methane deposits rival that of fossil fuels. Except we’re not drilling for methane to fuel our vehicles. It’s being released at rates that exceed natural sinks in part due to the burning of fossil fuels.
While we have a choice whether to drill for fossil fuels or not, methane out-gassing in a positive feedback cycle is something that we might not have a choice about. The decision to do something about it could have been made already – and we might have chosen incorrectly. Every abrupt period of climate change in Earth’s history for millions of years has included methane as one of the factors involved. After global ice sheets have melted in the past, geologic eras were defined by temperatures tens of degrees warmer than those we experience today. They were also defined by sea levels dozens of feet higher than those we experience today.
If the recent economic downturn hasn’t slowed down or stopped these greenhouse gas concentrations’ rise, continuing along a business-as-usual path looks more idiotic by the day.