A bloggers novel Global Warming Theory

[Egalitarian]

I've been following these threads since the OP posted them. I find his theory intriguing.

What do you think? (the second link is the briefest introduction, but intersting comments abound in both threads which are now quite long).

http://www.gnn.tv/threads/23878/Aricultural_and_Agricultural_Irrigation_is_the_Cause_of_Anthropogenic_Warming_of_Earth_s_Climate_System

http://www.gnn.tv/threads/23905/Global_Warming_Think_Again_or_For_the_First_Time_Think


Edit to add some snippets:

Water vapor is the most critical and important “green house gas.”

Show me the models that factor in the impact of 20th century agricultural practices regarding the countless billions of tons of water that formerly found their way to the oceans via rivers and streams or into underground aquifers that are now diverted to vast tracts of what used to be desert and prairie?

How many gigatons of additional water vapor are added to the atmosphere on a continuous basis throughout the growing seasons and even while fields lay fallow?

What impact is this additional water vapor having on both the weather and the overall climate.

snip

Agricultural irrigation on average adds nearly 12 cubic kilometers of water, in the form of water vapor to the atmosphere each and every day.

snip

Imagine every nuclear power plant, barrel of oil produced, all the natural gas and propane and the coal mined all burned to create just steam that would be released directly to the atmosphere.

Now multiply that X21

snip

[StClone]

1. I'll take a look.

:-)

[Dead_Parrot]

2. The idea's been floated before...

And it's not without some merit, although as a percentage of the total water cycle it's still a fairly low number.

I suspect, however, it's more than offset by the reduction caused by deforestation - acre for acre, a typical deciduous forest gets through 3 or 4 times as much water as a grain crop (even more for a rainforest). And we've got rid of a lot of acres of forest in the last few centuries.

What would be useful would be the total area we've irrigated, and the total area deforested, and see how they compare. Anyone fancy a go?

But bear in mind the water cycle (left to it's own devices) is fairly self-regulating: more evaporation = more cloud = higher albedo = lower temperature = less evaporation (and vice versa :)) I'm not sure we could directly throw it out of balance enough to make a difference, even with our ability to screw things up.

[StClone]

5. Seasonality and more

Irrigation not only is a fraction of natural evaporation it is seasonal. There isn't much need for it in winter over most of U.S. or for that matter Northern Hemisphere. However, increased water evaporation due to warmer winters is significant to ground water levels. Lake Superior has been hovering at near record lowest for the last 5 years and may go for the record by late summer of '07.

Carbon (as carbon dioxide), methane and water vapor (natural and irrigation-based) all increase in summer.

One rain storm will take out most water vapor from irrigation, though some will re-vapor within hours, most is runoff or ground water.

Increased salt content dispersed into air by irrigation may also created increased nuclei for rain drops which may increase rain fall.

Irrigation may contribute but I think the mega input climate models predictions seem to be "on" (maybe even on the low side) when compared with observed weather statistics. I doubt Science has overlooked or underestimated this water vapor source.

One more factor is relative humidity. As temperatures increase it can hold more water and as it increases more water stays in gases until equilibrium (or disturbance, change of albedo).

[dbonds]

3. Water Vapor?

When did that become the most critical component? Water Vapor is taken care of by rain. CO2 is the gas that is getting out of balance and holding in heat. I'm not throwing away the water vapor as a short term factor, but is it really the most critical component?

[greenman3610]

4. we know how much vapor was in the atmosphere before

and we know how much is there now.

There has been no significant buildup.


When water is added to the atmosphere, it
tends to simply rain out within a week or so.
The relative humidity tends to remain within
a range.

[NNadir]

6. Sigh...

I don't know where the hell this spin is coming from, but it's been showing up over the last few days. The greenhouse potential of a gas is related to its lifetime, not just its absorption spectrum.

We have to contemplate a lot of pathetic silliness these days, but are we so scientifically illiterate in these times that we don't know whence rain comes?

[Javaman]

7. You mean it's not god crying?

:sarcasm: