Good news about global warming, at last!

I normally try to write about drinking water, but I stumbled across some good news about global warming. It's a bit bizarre, but the take home message is that we could be so much worse off, apparently.

Global warming by production of greenhouse gases, especially carbon dioxide and methane, has lead to concerns over the survival of the planet. Actually, it's the survival of humans on this planet that is the real issue - the Earth will muddle along without us very well, and even probably do better without our polluting ways!

We have just completed a string of ten relatively stable years, 2000-2009, with respect to Earth's temperatures, that has been partly attributed to a reduction in water vapour in parts of the middle atmosphere, the Stratosphere, according to an article published online at the journal Science this week. Water vapour absorbs solar energy and then re-emits it as heat down into the lower Troposphere and the Earth below, thus acting as a heat-trap or 'greenhouse'. This fall in concentration of water vapour in the Stratosphere (for reason(s) unknown) has slowed the rate of Earth's warming by a staggering 25%. So that's 25% slow-down from a 10% change in water vapour, 10 miles over our heads, over the past 10 years. Not bad.

Compare this to 1980-2000, when an increase in water vapour in the Stratosphere sped up the rate of warming. This was due to higher rates of methane emission; methane oxidises into water vapour and carbon dioxide, which trap heat:


NB: not all carbon dioxide comes from methane, the majority of it comes directly from our activities.

It has long been known that water vapour in the lower Troposphere, the layer nearest the Earth, amplifies the effect of greenhouse gas emission, but this finding of its effects when present in the Stratosphere is novel.

Good news as far as it goes, but it doesn't let us off the hook there is no doubt that the Earth is still warming, its just not doing it as fast as we used to see.