The increased warmth causes the atmosphere to evaporate and condense
more water vapour so that total energy flow through the system increases.
Warmer air holds
more water vapour so that warmer air will extract more vapour from the ocean surface thereby cooling the ocean surface..
The increased warmth allows the atmosphere to hold
more water vapour so that total atmospheric density increases and the atmospheric greenhouse effect strengthens.
Not exact matches
Or increased
water content (
so that energy is
more efficiently transported by ferrying
vapour up to condense, release the energy and rain out).
I've been discussing climate change with lots of people at campaign stalls recently, and it has opened my eyes as to how far this «balanced» climate sceptic reporting is shaping the thinking of even those people who are concerned and want to see some action («I am aware that flying might make climate change worse, but I'll still do it because the warming may just be part of a natural cycle — I would stop if I was
more certain»; «I am worried, but I have also heard that it is just
water vapour which makes us warmer,
so we just don't kow if this CO2 thing is true, everybody seems to have a different agenda» etc.).
Water vapour partial pressure is an exponential function of temperature: it just amplifies the CO2 effect —
more or less independent of where you are (It requires careful spectral analysis to say
so — part of all model codes).
(c) The level of
water vapour depends on the global temperature,
so it is roughly fixed until something else warms the atmosphere when it increases in amount producing
more warming.
Re # 36 Lawrence, your cousin is correct that the greenhouse effect of
water vapour, and even
more so clouds are much larger (x 2 — x 4) than that from CO2.
To do
so, you'd need a study such as mine which shows
water vapour cools and
more moist regions have lower mean daily maximum and minimum temperatures than drier regions at similar latitudes and altitudes.
Although the surface is now cooler again, the skies are also clear which again allows
more sun through to warm the seas which produces
more water vapour which rises to form clouds, and
so on and
so on.
This temp increase will eventually cause
more water vapour to be released and
so you have a runaway effect (assuming of course that the
water vapour can cause a larger increase in temp then the original forcing).
These effects are relatively well understood in the lowest level of the atmosphere, the troposphere, where increased warming leads to greater evaporation, causing
more water vapour and
so further warming, although this is offset to some extent through the formation of clouds that reflect incoming sunlight back into space.
BH: Some of them are talking about climate sensitivity at 1.2 C, at 1.5 C. I think this is completely implausible because the basic energetics of the climate system responding to the additional greenhouse gas emissions almost from simple physics, has to be at least 1.2 C and possibly
more before you begin to take into account any of the feedbacks in the system from
water vapour in clouds and
so on.
Air containing
water in
vapour form will rise higher than dry air because it is lighter
so when the
vapour is removed it must fall back to its «correct» height but because of the air around it becoming warmer as it descends it will remain too dense for its height until it reaches the ground and receives
more energy from the irradiated surface.
This is because
more warmth in Antarctica would allow the air to hold
more water vapour, leading to increased precipitation and
so a thickening of the snow cover.
The theory is that heating from increased CO2 will warm the earth, sea and atmosphere and
so produce
more water vapour, the foremost greenhouse gas in total effect, which in turn warms the system further and releases both
more vapour and CO2 from the seas.
Methane only has an effect at the 7.7 micron range and this is a very low energy portion of the Earth's radiative spectrum which is already saturated by
water vapour so even a hundred fold increase in methane would be incapable of any
more than a tenth of a degree C of further warming.
1) CO2 is not rising significantly compared to earlier in the 20th century (Beck, Segalstad, Jaworowski) 2) OK,
so CO2 is rising, but human sources are but a minor player (Howard Hayden, Spencer on WUWT) 3) OK,
so human CO2 is significant, but its temperature effect is nonexistant (Heinz Hug) 4) OK,
so CO2 has a temperature effect, but it is dwarfed by
water vapour (Lindzen, Reid Bryson, Tim Ball 5) OK,
so the CO2 temperature effect is not completely dwarfed by
water vapour, but the sun is much
more important (Svensmark, Shaviv, many others) 6) OK,
so the solar output has been flat since the 50ies, but there are no net positive feedback (Lindzen again, Spencer again) 7) Actually, there has been no significant global warming (Watts, Singer +
more), 8) Hey, all this warming is a) unstoppable anyway (Singer again) b) good for humanity (Michaels).