Information Spaghetti Junction

The web can be a tangled labyrinth. The other day I saw an item scrolling arcos the bottom of the screen on a news channel that suggested water vapour was a more harmful greenhouse gas than carbon dioxide. I only caught half the tape on the ticker, and so I looked up the details on the web.

Sure enough water vapour is a greenhouse gas,. I got a number of hits from 'concerned individuals' who worried that the focus on CO₂ was wrong, and that the lack of discussions about water vapour emissions at climate conferences showed that the whole thing was a farce. One even pointed out that carbon dioxide was a plant food, so what were we all worried about. That got me thinking ... isn't water also something that plants like? What was going on here?

I dug deeper. I came across a recent press release from GM about their new eco-car, a hydrogen fuel cell vehicle that emits only "harmless water vapour". Hang on I thought ... if water vapour is a greenhouse gas is the emission of it harmless? I began to wonder if there really was something odd going on here. Were so-called 'zero emission' cars merely swapping one greenhouse gas for another? If water vapour contributed to greenhouse effects, as wiki informed me, five times more than carbon dioxide then would a zero emission car actually make things worse.

I struggled to find answers, I did find lots of hyperbole. Lots of sites that cheerfully told me of the conspiracy to promote the myth of 'man-made' global warming. Some of the sites were even written with good grammar and references. Maybe banning Dihydrogen Monoxide isn't that stupid after all? At least when it's in vapour form.

It took a bit of searching, and some refinement of my search terms, but I did find an answer. Water vapour is indeed the most important variable in terms of the greenhouse gas at any given moment. It has a greater effect than any pollutant. But water vapour is a natural component of the atmosphere and it goes through a cycle (remember those posters of the water cycle kids) that last days. Water does not remain in the atmosphere for any time, and the human contribution is too small to be important. Way too small. Also the contribution from water vapour to warming is very complex, as while clouds trap heat in the atmosphere, they also reflect sunlight away from the Earth.

Cardon dioxide, on the other hand, hangs around. It builds up. Sure, it is a plant food, but we are pumping more CO₂ into the air than the plants can gobble up. Much more. Carbon dioxide, and a number of other pollutants, build up in the atmosphere, making it their permanent residence, while the water merely comes and goes in its natural cycle. That's why the focus is on human emissions, but not water vapour. That's why eco-cars are technically correct when they call water vapour harmless.

But that hasn't stopped people using the notion of water vapour to justify their claims of climate conspiracies ... or why they should continue to pump 'plant food' carbon dioxide into the air ... or even how the US government is creating global warming with cloud-creating airplanes. That's right ... vapour trails are a conspiracy to heat up the earth.

My point though is that it took me some time to find answers to the initial query generated by that news ticker. I consider myself to be moderately intelligent, yet I'm embarrassed to say that for a while there I was seriously wondering if the water vapour emissions from 'eco-cars' might not be making things worse. It took effort, thought, time and patience as well as a critical ability to weed the nutcase sites from the more reputable to get an answer. The web is a confusing and tricky place to navigate and find what you want. Unless you're looking for porn.