Observational Evidence
of Water Vapor Feedback
¥Increasing water vapor concentrations shift the altitude of
water IR emission upward which DECREASES
its emission (because of colder temperatures)
¥Atmospheric temperatures
have also been increasing over time (at least in theory) which should INCREASE the IR
emission from water vapor
¥To isolate the water vapor concentration change, Subtract
the IR measured from water (=ÔT12Õ
from HIRS) from emission measured from O2 (whose concentrations have not changed) (=ÔT2Õ from MSU)
¥If IR from water is becoming
less than emission from O2, the atmospheric water concentrations have
increased
=> THIS IS WHAT IS
OBSERVED
Soden et al. 2005