Atmospheric water vapour is a feedback (not forcing) - on Watts and Eschenbach #AGU16 poster

Willis Eschenbach has a poster at AGU16, to which Anthony Watts added his name. Anthony's now written a blog article about it (archived here). Actually, Anthony put his name first although I strongly suspect he doesn't have a clue what the poster is all about.

They haven't made the poster available on the AGU16 website, or not at the time of this article. It is downloadable on Anthony's blog at WUWT, here.  He's also made available what he calls "data and code". The file is 500 MB or so, therefore I won't be downloading it till I get home in 20 hours or so.

There are a few points I'll make:

• The poster is based on a couple of blog articles by Willis Eschenbach at WUWT, including the one I wrote about here.
• Willis Eschenbach still doesn't know the difference between a forcing and a feedback (more below). Nor does Anthony Watts.
• Their poster supports what real scientists tell us, that there's more water vapour in the air because of global warming.
• Most of the data they use is ocean only, not land.
• They seem happy to rely on RSS data, while disparaging it elsewhere.
• They seem happy with lots of data carefully collected and analysed by climate scientists, despite calling it fraudulent elsewhere, and despite WUWT-ers wanting to stop all research.

The water vapour penny precipitates, almost, for Willis Eschenbach at WUWT

There's a new article at WUWT by Willis Eschenbach (archived here, latest here). It took him almost twenty years, but he's finally found the RSS total precipitable water (TPW) record. For years Willis has been arguing that Earth's climate can't change much because of thunderstorms. It seems that he may have finally woken up to the fact that there is more water vapour in a warmer atmosphere than in a cooler one and that this is contributing to the greenhouse effect. He wrote (about the dataset that was reported 20 years ago in 1996): "One of my great pleasures is to come across a new dataset."

I've been meaning to write about global warming, water vapour and precipitation for some time. There have been several papers on the subject (see below). What's happening is:

• the amount of water in the air is increasing as the world warms,
• the water cycle is intensifying,
• therefore there is more rain (and snow), and
• more greenhouse warming because water vapour is a strong greenhouse gas.

Warning: This is a rather long article, with no apologies :)

Activating water vapour

I'm a bit bored.  WUWT is struggling at the moment so I'll comment on a comment on WUWT.

JPeden says, referring to the silly video that science deniers paid far too much for (archived here):

September 2, 2013 at 7:45 am

Great presentation so far – I’m about half way through. Money well spent!

But on feedbacks, according to the mechanism presumed by “mainstream” Climate Science, I still have no idea why water vapor didn’t already do completely by itself what the “mainstream” Climate Scientists say it will do to assist CO2. It makes absolutely no sense to me that water vapor would need any CO2 at all to do the same thing Climate Scientists say it will do when ‘activated ‘by CO2. Or at the least, why would water vapor not become already activated by a much smaller CO2 concentration? It sounds like Climate Science says both that water vapor is and is not a ghg……………

JPeden thinks that scientists say that water is "activated" by CO2.  It's an interesting way of looking at it I suppose.

In simple terms, what JPeden is missing is that CO2, being a greenhouse gas, slows the amount radiation leaving earth.  When it's constant that's fine.  As long as CO2 and other greenhouse gases stay fairly constant they keep the earth nice and warm so life can thrive.  When CO2 increases the temperature goes up.  That means that more water evaporates.  The properties of water don't change.  It's just that there's more of it in the atmosphere.  The extra CO2 plus the extra water vapour means the amount of radiation leaving earth is even less.  As long as we're adding more CO2, earth will keep heating up and more water will evaporate so earth will heat up more and so on it goes - until we stop adding more CO2 to the atmosphere than leaves it.

Goodness knows when that will be.  I hope it's before earth gets too hot to handle.

Fortunately, water also leaves the atmosphere fairly readily.  It falls as rain, snow and ice.  Otherwise earth would get really, really hot very quickly.  As it is it's getting hot much too quickly for our good.

The Bureau of Meteorology has a booklet about the greenhouse effect and climate change.

PS I know my readers know all this and many of you know a heck of a lot more than I do about climate.  Occasionally there are strays who land here by accident or design, who might be just starting to learn about climate change.  This post is for them.