“If the negative aerosol forcing is understated by as much as 0.7 W/m2, it means that aerosols have been counteracting half or more of the Green House Gas  forces. In that event, humanity has made itself a Faustian bargain more dangerous than commonly supposed.” Hansen has said this is a “Faustian aerosol bargain” because it can be maintained only through “continued exponential growth of the atmospheric aerosol load.”

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The world noted a decrease of surface solar radiation from the 1950's to the 1980's in the worldwide observational networks "global dimming" and a more recent recovery "brightening", (Wild et al. 2005, Wild 2009, 2012, 2016). These variations are often in accord with anthropogenic air pollution patterns. Anthropogenic air pollution has led to substantial changes in atmospheric aerosol levels over the past decades (Stern 2006; Ruckstuhl et al. 2008; Streets et al. 2009; Wang et al. 2009). Particularly, anthropogenic emissions, such as sulfur and black carbon, increased from the 1950s to 1980s but decreased thereafter in the Northern Hemisphere (Stern 2006). From 1950 to the mid-80's, the cooling effect from aerosols was masking the warming effect from CO2. When aerosol cooling ended, the current global warming trend began. "Clean air regulations passed in the 1970s, for example, have likely accelerated warming by diminishing the cooling effect of sulfates

"So without our pollution in the sixties global warming would have started much earlier."

Find more information: ipcc.ch/site/assets/uploads/2018/02/WG1AR5_Chapter08_FINAL.pdf