According to the authors,
"Averaged series (using the nine locations) showed a statistically significant decrease in annual G [global solar shortwave] from 1950 to the mid 1980s (−1.7%dc−1) together with a significant increase from the mid 1980s to 2011 (1.6%dc−1)."
 |
| Figure from the paper showing solar dimming 1950-mid-1980's, followed by solar brightening |
 |
| Figure from another paper also finding similar solar dimming and brightening over Iberia |
The dimming of -1.7% of surface solar radiation from 1950 to mid-1980's [assuming average solar insolation in Iberia ~500W/m2] would equate to about 8.5 W/m2 change in surface solar forcing, which by way of comparison is ~5 times greater than all alleged forcing from increased CO2 since 1750 [1.68 W/m2].
The brightening of 1.6% of surface solar radiation from the mid-1980s to 2011 would likewise equate to about 8 W/m2, which by way of comparison is ~4.8 times greater than all alleged forcing from increased CO2 since 1750.
The paper joins many others documenting the well-known global solar dimming and brightening periods worldwide. IPCC climate models, on the other hand, do not include the global dimming/brightening in their simulations, instead falsely attributing the warming from the 1980's-present to greenhouse gases, even though the radiative effects of solar dimming/brightening are far greater than any alleged greenhouse gas changes during these periods.
Other papers find the the golbal brightening/dimming were due to natural changes in cloud cover, not man-made aerosols, possibly mediated by solar amplification mechanisms such as the Svensmark cosmic ray theory of climate.
The paper joins many others documenting the well-known global solar dimming and brightening periods worldwide. IPCC climate models, on the other hand, do not include the global dimming/brightening in their simulations, instead falsely attributing the warming from the 1980's-present to greenhouse gases, even though the radiative effects of solar dimming/brightening are far greater than any alleged greenhouse gas changes during these periods.
Other papers find the the golbal brightening/dimming were due to natural changes in cloud cover, not man-made aerosols, possibly mediated by solar amplification mechanisms such as the Svensmark cosmic ray theory of climate.
- •
- A method to reconstruct shortwave irradiation is developed.
- •
- Dimming and brightening periods are observed.
- •
- Uncertainty in series can affect temporal trends.
Abstract
Total global solar shortwave (G) irradiation and sunshine duration were recorded at nine Spanish stations located in the Iberian Peninsula. G irradiation under cloudless conditions was simulated by means of a radiative transfer model using satellite data as input. A method based on these cloudless simulations and sunshine duration records was developed to reconstruct G series. This model was validated against experimental data, providing a good agreement for cloudless skies (mean bias error of 0.4% and root mean square error of 5.8%). Monthly averages of modelled and measured G irradiation presented a mean bias error of 0.5% and a root mean square error of 3%. Differences between modelled and measured G irradiation were in agreement within the model uncertainties. The reconstruction model was applied to sunshine duration measurements, giving long-term G series at the nine locations. Monthly, seasonal, and annual G anomalies were calculated and analysed. Averaged series (using the nine locations) showed a statistically significant decrease in annual G [global solar shortwave] from 1950 to the mid 1980s (−1.7%dc−1) together with a significant increase from the mid 1980s to 2011 (1.6%dc−1). The effect of uncertainty in the reconstructed series on statistically significant trends was studied.
20th Century Global Dimming and Brightening: A Summary
ReplyDelete-----------------------------
ftp://bbso.njit.edu/pub/staff/pgoode/website/publications/Palle_etal_2005a_GRL.pdf
Traditionally the Earth’s reflectance has been assumed to be roughly constant, but large decadal variability, not reproduced by current climate models, has been reported lately from a variety of sources. There is a consistent picture among all data sets by which the Earth's albedo has decreased over the 1985-2000 interval. The amplitude of this decrease ranges from 2-3 W/m2 to 6-7 W/m2 but any value inside these ranges is highly climatologically significant and implies major changes in the Earth's radiation budget.
----------------------------
http://onlinelibrary.wiley.com/doi/10.1002/2014JD021877/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 [1893-2012]. Three-quarters of the increase in the long-wave flux was due to changes in the water content of the lower atmosphere; the remainder [25%] was attributed to increases in CO2 and other anthropogenic, radiatively active gases. Over the period radiative forcing in the short-wave flux [solar forcing] slightly exceeded [0.76 W/m2 per decade] that in the long wave [0.64 W/m2 per decade].
[The total long term radiative forcing for the Sun was 9.12 W/m2 for the 120-year period, and was 1.92 W/m2 for CO2.]
-----------------------------
http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00482.1?journalCode=clim
Data from this summation method suggest that surface incident solar radiation increased at a rate of 6.6 W m−2/decade−1 (3.6%/ decade) from 1992 to 2002 (brightening) at selected sites.
-----------------------------
http://onlinelibrary.wiley.com/doi/10.1029/2008JD011290/abstract
The decadal trend shown in the 5-year running mean indicates a period of rapid increase [brightening] starting in late 1930s and continuing to early 1950s with a change of 10 W m2. The dimming trend from the early 1950s to the late 1980s shows a decrease of -13 W m2. The subsequent increase starting in late 1980s is about 10 W m 2 by 2005. These changes are not confined to a small number of stations in western Europe, but shared by more than 400 other sites where global irradiance has been continuously observed for more than 40 years.
-----------------------------
http://onlinelibrary.wiley.com/doi/10.1029/2010JD015396/abstract
We find distinct patterns of dimming and brightening in the aerosol optical depth and thus clear-sky downward surface shortwave radiation (SSR) in all analyzed subregions. The strongest brightening between 1973 and 1998 under clear-sky conditions is found in mid-Europe (+3.4 W m−2 per decade [8.5 W m−2 total], in line with observations).
-----------------------------
http://www.sciencemag.org/content/308/5723/850.abstract
Long-term variations in solar radiation at Earth's surface (S) can affect our climate... We observed an overall increase in S [solar radiation] from 1983 to 2001 at a rate of 0.16 watts per square meter (0.10%) per year [3.04 W/m-2 total]
-----------------------------
http://www.atmos-chem-phys.net/13/8505/2013/acp-13-8505-2013.html
[T]here has been a global net decrease [of 3.6%] in 340 nm cloud plus aerosol reflectivity [which has led to] an increase of 2.7 W m−2 of solar energy reaching the Earth's surface and an increase of 1.4% or 2.3 W m−2 absorbed by the surface.”[between 1979 and 2011]
-----------------------------
http://journals.ametsoc.org/doi/pdf/10.1175/BAMS-D-11-00074.1
Literature estimates for the overall SSR [surface solar radiation] decline during dimming [1950s-'80s] range from 3 to 9 W m−2, and from 1 to 4 W m−2 for the partial recovery during subsequent brightening [1980s-2000s]
-----------------------------
Graph illustrating the trends: https://www.metabunk.org/sk/skitched-20130810-101743.png
Thanks!
Deletehttp://www.scirp.org/journal/PaperInformation.aspx?PaperID=50837#.VFLoKPnF-Sq
ReplyDelete"The reduction in total cloud cover of 6.8% [between 1984 – 2009] means that 5.4 Wm−2 (6.8% of 79) is no longer being reflected but acts instead as an extra forcing into the atmosphere… To put this [5.4 Wm-2 of solar radiative forcing via cloud cover reduction between 1984-2009] into context, the IPCC Fifth Assessment Report…states that the total anthropogenic radiative forcing for 2011 relative to 1750 is 2.29 Wm−2 for all greenhouse gases and for carbon dioxide alone is 1.68 Wm−2. The increase in radiative forcing caused by the reduction in total cloud cover over 10 years is therefore more than double the IPCC’s estimated radiative forcing for all greenhouse gases and more than three times greater than the forcing by carbon dioxide alone [from 1750 to present]."
"Since 1950, global average temperature anomalies have been driven firstly, from 1950 to 1987, by a sustained shift in ENSO conditions, by reductions in total cloud cover (1987 to late 1990s) and then a shift from low cloud to mid and high-level cloud, with both changes in cloud cover being very widespread. According to the energy balance described by Trenberth et al. (2009), the reduction in total cloud cover accounts for the increase in temperature since 1987, leaving little, if any, of the temperature change to be attributed to other forcings [i.e., anthropogenic]."
Thanks for all the references, appreciate it!
Delete
ReplyDeletehttp://onlinelibrary.wiley.com/doi/10.1029/2008JD011290/abstract
http://ir.hfcas.ac.cn/bitstream/334002/5066/3/Observed%20decadal%20variations%20in%20surface%20solar%20radiation%20and%20their%20causes.pdf.txt
The decadal trend shown in the 5-year running mean indicates a period of rapid increase [solar radiation reaching the surface/brightening] starting in late 1930s and continuing to early 1950s with a change of 10 W m2. The dimming trend from the early 1950s to the late 1980s shows a decrease of 13 W m2. The subsequent increase starting in late 1980s is about 10 W m2 by 2005. These changes are not confined to a small number of stations in western Europe, but shared by more than 400 other sites where global irradiance has been continuously observed for more than 40 years.
For the period after January 1992 as BSRN data became available, the global brightening has been recognized at the majority of stations in the network ranging from Svalbard [Norway] to the South Pole. The BSRN radiation measurements are made simultaneously with other atmospheric observations, such as cloud observations. It was found that global radiation observed under cloudless conditions in BSRN also showed the same increasing tendency [Wild and Ohmura, 2004]. The observed variation in global radiation has been influenced both by the variations in cloud conditions and also by variable constituents of the cloudless atmosphere, that is aerosol.
The decadal trend is seen overlapped with El Chichon (1982) and Mount Pinatubo (1991) episodes that lasted for 3-4 years. By excluding the brief downward excursions caused by El Chichon and Mount Pinatubo, the mean transmittance decreased from the 1950s to sometime in the mid-1980s. The last 20 years or so have seen a rapid recovery of transmittance. The transmittance has never been so large during the last half a century as at present [~2005].
During the 15 years from 1990 to 2005 the sunshine duration hours over the five sites increased by 0.4 h/d which corresponds to the decrease in total cloud amount of 4%. The present analysis shows that the increase in 2.5 W m2 in global solar radiation was caused by the reduction of the total cloud amount by 4%.
Global solar irradiance showed a significant fluctuation during the last 90 years. It increased from 1920 to 1940s/1950s, thereafter it decreased toward late 1980s. In early 1990s 75% of the globe indicated the increasing trend of solar irradiance, while the remaining area continued to lose solar radiation. The magnitudes of the variation are estimated at +12 W m 2 [1920-1940s/1950s], - 8 W m 2 [1950s-1980s], and +8 Wm2 [early 1990s-2005], for the first brightening, for the dimming, and the recent brightening periods, respectively.