Sunday, July 20, 2014

New paper finds significantly more solar & less greenhouse gas climate forcing than IPCC claims over past 120 years

A new paper published in the Journal of Geophysical Research Atmospheres finds the change in shortwave forcing from the Sun [0.76 W/m2 per decade] exceeded that of longwave forcing from greenhouse gases [0.64 W/m2 per decade] over the past 120 years in Potsdam, Germany, one of the few worldwide sites with sufficient long-term observations. The authors find water vapor alone was responsible for 3/4 of this change in longwave forcing, with only 25% of the longwave forcing [0.16W/m2 per decade, total 1.92 W/m2 over 120 years] attributable to all man-made greenhouse gases including CO2. 

In contrast, the IPCC claims CO2, methane, nitrous oxide, and other man-made greenhouse gases have produced a total ~2.7 W/m2 in longwave forcing since pre-industrial times, i.e. about 29% more radiative forcing than found by the long-term observations in this new paper. The shortwave forcing from the Sun after albedo/aerosols was +9.12 W/m2 over the 120 years, 9.7 times more than the IPCC claim of negative 1.05 W/m2 forcing from the Sun + aerosols since pre-industrial times. 


According to the authors,
"Three-quarters of the increase in the long-wave flux was due to changes in the water content of the lower atmosphere; the remainder was attributed to increases in CO2 and other anthropogenic, radiatively active gases. Over the period radiative forcing in the short-wave flux slightly exceeded that in the long-wave but its effect on air temperature was much less as the climate sensitivity to atmospheric radiation, 0.187 °C per Wm−2, was three times greater than to short-wave global radiation. This anomalous finding, similar to that previously reported at two coastal sites, awaits explanation..."
This "anomalous finding" is quite a paradox, since "for [climate sensitivity] to be useful, the measure must be independent of the nature of the forcing (e.g. from greenhouse gases or solar variation)." Potential reasons for this anomaly include assumptions made to calculate longwave forcing [which was not directly measured] on the basis of pressure & humidity, and questionable blackbody assumptions. 
In addition, the authors find no indication of a trend in precipitation amount or variability over the past 120 years, in contrast to alarmist claims.

The authors attribute the significant increase in specific humidity to a reduction in cloud cover and/or pollution [black carbon]:
"The significant increase in specific humidity measured at Potsdam in the early 1980's (Fig. 3) which amplified the down-welling long-wave flux, indicates an increased frequency of warmer, moister air masses reaching the region. The significant increase in global radiation measured at the same time (Fig. 3) indicates a reduction in cloud cover and/or pollution." 
And find, "low levels of solar activity promote frequent and persistent atmospheric blocking events in the eastern North Atlantic which modify the flow of Westerly winds leading to an increased frequency of cold winters in Europe" [and the US], i.e. ascribing jet stream dips and the polar vortex to solar activity, not global warming as alarmists have claimed. 
"Changes in circulation patterns over Europe have been shown to occur on both decadal and centennial time periods. Over the 1958 to 1998 period an increase in the frequency of anti-cyclonic circulation patterns in winter took place between the late 1960's and the early 1990's followed by a decline and a sharp increase in persistence (mean residence time) of allcirculation types in winter around 1990 and of anti-cyclonic types in summer during the 1990's (Kysely and Huth, 2006). On a millennial time scale proxy measures were used toreconstruct the temperature and salinity conditions in the North Atlantic with a sub decadal resolution over the 818 to 1780 period. The variations found were highly correlated with those in climate simulated over the past millennium and in total solar irradiance. Simulations of the changes in atmospheric circulation over this period indicated that low levels of solar activity promote frequent and persistent atmospheric blocking events in the eastern North Atlantic which modify the flow of Westerly winds leading to an increased frequency of cold winters in Europe (Moffa-Sanchez et al, 2014)."

Radiative forcing and temperature change at Potsdam between 1893 and 2012 


Gerald Stanhill and Ori Ahiman

Abstract

Radiative forcing in both the short and long-wave lengths reaching the Earth's surface accounted for more than 80% of the inter-annual variations in the mean yearly temperatures measured at Potsdam, Germany during the last 120 years. Three-quarters of the increase in the long-wave flux was due to changes in the water content of the lower atmosphere; the remainder was attributed to increases in CO2 and other anthropogenic, radiatively active gases. Over the period radiative forcing in the short-wave flux slightly exceeded that in the long-wave but its effect on air temperature was much less as the climate sensitivity to atmospheric radiation, 0.187 °C per Wm−2, was three times greater than to short-wave global radiation. This anomalous finding, similar to that previously reported at two coastal sites, awaits explanation as does the complex interaction existing between radiative forcing and advection [horizontal movement of air] in determining temperature change.

1 comment:

  1. see also

    http://star.arm.ac.uk/preprints/2011/590.pdf

    ReplyDelete

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