“Solar dimming” and “solar brightening” & naturally occurring change in ocean circulation affect global temperatures

See Climate Alarmism: When Is This Bozo Going Down? by Patrick J. Michaels and Paul C. "Chip" Knappenberger of Cato. Excerpts:

"The aerosol paper describes research by a team of Israeli scientists led by Gerald Stanhill (from the ARO Volcani Center) who examined the causes of “solar dimming” and “solar brightening” that have taken place over the past half-century or so. Solar brightening (dimming) refers to multidecadal periods when more (less) solar radiation is reaching the surface of the earth. All else being equal (dangerous words in Science), the earth’s surface would warm during periods of brightening and cool during dimming. Solar dimming has been reported to have taken place from the 1950s through the 1980s and since then there has been a period of recovery (i.e., brightening).  These patterns have been linked by many to human aerosol emissions caused by pernicious economic activity, with heavy emissions leading to global cooling from the 1950s (witness the opaque air of Pittsburgh and London) through the late 1970s and then, as air quality was cleaned up and aerosol emissions declined, an unmasking of the warming impact from greenhouse gas emissions."

"Stanhill et al. have bad news for the feds. In their new paper, they examine the records of sunshine duration as recorded at five observation sites with long-term observations. When comparing these sunshine histories with fossil fuel use histories (a proxy for aerosol emissions) from nearby areas, they find very little correspondence. In other words, human aerosol emissions aren’t to blame for much of the solar dimming and brightening."

"What may be the cause? Variations in cloud cover. According to Stanhill and colleagues:

It is concluded that at the sites studied changes in cloud cover rather than anthropogenic aerosols emissions played the major role in determining solar dimming and brightening during the last half century and that there are reasons to suppose that these findings may have wider relevance.

Admittedly, there are only a small number of stations that were being analyzed, but Stanhill et al. have this to say:

This conclusion may be of wider significance than the very small number of sites examined in this study would suggest as the sites sampled Temperate - Maritime, Mediterranean, Continental and Tropical climates,… and covered a wide range of rates of anthropogenic aerosol emission.

The implications are that human aerosols have played a lot smaller role in the global temperature variability of the past 50 years than is generally taken to be the case. And if human aerosols are not responsible for muting the expected temperature rise from greenhouse gas emissions, then it seems that the expected rise is too much. That is, the earth’s temperature is less sensitive to rising greenhouse gas concentrations than forecasted by governmental climate models, and therefore we should expect less warming in the future."

"University of Washington’s Xianyao Chen and Ka-Kit Tung found that a naturally occurring change in ocean circulation features in the Atlantic Ocean can act to enhance or suppress the magnitude of heat that is transferred from the surface into the ocean depths. The authors find that this natural cycling was responsible for burying additional heat since the late 1990s while maintaining surface heating during the previous three decades. Coupled with earlier research (Tung and Zhou, 2013), they figure that a substantial portion (~40%) of the rise in the global surface temperatures that has occurred since the mid-20^th century was caused by natural variability in the circulation of the Atlantic Ocean. "