Not exact matches
The relative contribution of each trace GHG to increased Eocene and Cretaceous land temperatures
at 4 × CO2, assessed with multiple separate coupled - ocean atmosphere HadCM3L model simulations, revealed methane and associated increases in
stratospheric water vapor dominate, with nitrous oxide and tropospheric ozone contributing approximately equally to the remainder.
(PS regarding Venus — as I have understood it, a runaway
water vapor feedback would have occured when solar heating increasing to become greater than a limiting OLR value (Simpson - Kombayashi - Ingersoll limit — see http://chriscolose.wordpress.com/2010/08/23/climate-feedbacks-part-1/ — although I should add that
at more «moderate» temperatures (warmer than today),
stratospheric H2O increases to a point where H escape to space becomes a significant H2O sink — if that stage worked fast enough relative to solar brightening, a runaway H2O case could be prevented, and it would be a dry (er) heat.
But then there's feedbacks within the stratosphere (
water vapor), which would increase the
stratospheric heating by upward radiation from below, as well as add some feedback to the downward flux
at TRPP that the upward flux
at TRPP would have to respond to via warming below TRPP.
Warming must occur below the tropopause to increase the net LW flux out of the tropopause to balance the tropopause - level forcing; there is some feedback
at that point as the stratosphere is «forced» by the fraction of that increase which it absorbs, and a fraction of that is transfered back to the tropopause level — for an optically thick stratosphere that could be significant, but I think it may be minor for the Earth as it is (while CO2 optical thickness of the stratosphere alone is large near the center of the band, most of the wavelengths in which the stratosphere is not transparent have a more moderate optical thickness on the order of 1 (mainly from
stratospheric water vapor;
stratospheric ozone makes a contribution over a narrow wavelength band, reaching somewhat larger optical thickness than
stratospheric water vapor)(in the limit of an optically thin stratosphere
at most wavelengths where the stratosphere is not transparent, changes in the net flux out of the stratosphere caused by
stratospheric warming or cooling will tend to be evenly split between upward
at TOA and downward
at the tropopause; with greater optically thickness over a larger fraction of optically - significant wavelengths, the distribution of warming or cooling within the stratosphere will affect how such a change is distributed, and it would even be possible for
stratospheric adjustment to have opposite effects on the downward flux
at the tropopause and the upward flux
at TOA).
First, for changing just CO2 forcing (or CH4, etc, or for a non-GHE forcing, such as a change in incident solar radiation, volcanic aerosols, etc.), there will be other GHE radiative «forcings» (feedbacks, though in the context of measuring their radiative effect, they can be described as having radiative forcings of x W / m2 per change in surface T), such as
water vapor feedback, LW cloud feedback, and also, because GHE depends on the vertical temperature distribution, the lapse rate feedback (this generally refers to the tropospheric lapse rate, though changes in the position of the tropopause and changes in the
stratospheric temperature could also be considered lapse - rate feedbacks for forcing
at TOA; forcing
at the tropopause with
stratospheric adjustment takes some of that into account; sensitivity to forcing
at the tropopause with
stratospheric adjustment will generally be different from sensitivity to forcing without
stratospheric adjustment and both will generally be different from forcing
at TOA before
stratospheric adjustment; forcing
at TOA after stratospehric adjustment is identical to forcing
at the tropopause after
stratospheric adjustment).
How is it that the AGW enthusiasts attribute such a
water vapor contribution to CH4 rather then the mixing of the Tropopause and
Stratospheric water vapor in a similar action as to the boundary layer temperature change
at the
Stratospheric and Mesospheric level?
By the same token if I look
at polar regions with the concentration of frontal changes there seems to be a rapid rise of tropospheric
water vapor invading the
stratospheric range.
In the antarctic polar band (60 and south) there is no ocean
at all, all
water vapor coming in from the
stratospheric conveyor belt (Hadley cell to temperate cell to polar cell), and in the north, there is an icy ocean mostly covered with floes and fast ice.
Everytime an author publishes something different from what the IPCC published in their last report — from Solomon et al. on
stratospheric water vapor trends to all the new hockey sticks post the so - called «iconic» Mann hockeystick, each of which is somewhat different, to all the GWP - replacement metrics proposed by Fuglesvedt et al., to practically any paper published in the scientific literature or any talk given
at AGU... scientists don't make their name by publishing papers that say, «yup, we're just saying exactly what the IPCC said.
Cointegration indicates that internal climate variability and / or the omission of some components of radiative forcing (e.g.,
stratospheric water vapor, black or organic carbon, nitrite aerosols, etc.) do not impart a stochastic or deterministic trend that would interfere with the interpretation of temperature changes
at the subdecadal scale (SI Appendix).
The high level of interest in scientific circles in upper tropospheric (and
stratospheric)
water vapor is because it is easy to demonstrate by theory and measurement that small amounts of
water vapor at high altitudes have disproportionate effects.