“The fog has a smooth surface on the top, which distinguishes it from mid- and high-level clouds that are more textured and have distinct shadows on their edge,” explained Rudolf Husar, director of the Center for Air Pollution Impact and Trend Analysis at Washington University. “If there is a significant haze layer on top of the fog, it appears brownish. In this case, most of the fog over eastern China is free of elevated haze, and most of the pollution is trapped in the shallow winter boundary layer of a few hundred meters.”
#1 "From a climate change perspective, individually, PFTBA's atmospheric concentration does not significantly alert the phenomenon of climate change," Hong said. "Still the biggest culprit is CO2 from fossil fuel emissions."
But PFTBA is long-lived. The Toronot researchers estimated PFTBA remains in the atmosphere for about 500 years, and unlike carbon dioxide, that is taken up by forests and oceans, there are no known natural "sinks" on Earth to absorb it.
"If the concentration in Toronto is representative of the change in global background concentration since the preindustrial period, then the radiative forcing of PFTBA is 1.5 × 10−4 W m−2. We calculate the global warming potential of PFTBA over a 100 year time horizon to be 7100. Detection of PFTBA demonstrates that perfluoroalkyl amines are a class of LLGHGs worthy of future study."