Anthony Watts has
uncovered some data from the NOAA website that appears to show water vapor levels have been decreasing for the last sixty years.
Strangely, a number of recent peer-reviewed publications claim that water vapor is increasing:
Elevated surface temperatures due to other greenhouse gases have enhanced water evaporation and contributed to a cycle that stimulates further surface temperature increases, according to a report in Geophysical Research Letters. The research could help to answer a long-debated Earth science question about whether the water cycle could strongly enhance greenhouse warming.
The following paper finds a positive trend but contradicts the findings over Europe.
The main region where positive trends are not very evident is over Europe, in spite of large and positive trends over the North Atlantic since 1988.
The following also finds positive feedback:
The moistening of the upper troposphere by deep convection leads to an enhanced positive water vapor feedback, about 3 times that implied solely by thermodynamics.
Is water vapor increasing or decreasing? Is feedback positive or negative? The graph below by Ken Gregory shows a clear decreasing trend at all atmospheric levels.
Water vapor levels are another worrisome variation between the ‘consensus’ view as represented by the IPCC reports and real world data.
The decline in water vapor with an increase in greenhouse gases is one clear prediction of Miskolczi’s theory of semi-transparent atmospheres. In contrast, decline in water vapor is not predicted by the theory of infinity thick atmosphere which maintains that temperatures increase for every incremental increase in greenhouse gases, and in fact the ‘consensus’ is that water vapor increases in a positive feedback loop.
Since the world oceans are virtually unlimited sources and sinks of the
atmospheric water vapor (optical depth), the system – depending on the time
constant of the different energy reservoirs – has many ways to restore the
equilibrium situation and maintain the steady state global climate. For
example, in case the increased CO2 is compensated by reduced H2O, then the
general circulation has to re-adjust itself to maintain the meridional energy
flow with less water vapor available. This could increase the global average
rain rate and speed up the global water cycle resulting in a more dynamical
climate, but still the energy balance equations do not allow the average surface
temperature to rise. The general circulation can not change the global radiative
balance although, changes in the meridional heat transfer may result in local or
zonal warming or cooling which again leads to a more dynamical climate.
Note that there are accumulating evidence of long term negative surface
pressure trends all over the southern hemisphere, (Hines et al., 2000), which
may be an indication of decreasing water vapor amount in the atmosphere.
On global scale, however, there can not be any direct water vapor feedback mechanism, working against the total energy balance requirement of the
system. Runaway greenhouse theories contradict to the energy balance
equations and therefore, can not work.
One should not be surprised. It has been proven mathematically that “Most Published Research Findings Are False”.
Update: Anthony Watts posts a followup post containing graphs showing rising specific humidity at the surface, and falling humidity at the higher (greenhouse relevant) altitudes. The obvious questions is why do the esteemed climate scientists above create the impression in their publications that increasing water vapor levels are proof of an increasing greenhouse effect? It’s very worrying.