@pintohoo , rather than isolate the years of WW2, which admittedly stick out like the proverbials in that graphic, it may be more useful to view about 1940 as a point of change in longer trends.
Climate scientists seem mostly to talk about the few warming decades before 1940 and then a slight cooling over a few decades to the 1970s.
Jim Hansen is a bete noire of many climate change deniers because was one of the first to call the current anthropogenic global warming.
Briefly, From 1981 to 2013, he was the director of the NASA Goddard Institute for Space Studies in New York City, a part of the Goddard Space Flight Center. Since As 2014, Hansen directs the Program on Climate Science, Awareness and Solutions at Columbia University's Earth Institute.
On a page earthobservatory.nasa.gov, Hansen suspected the relatively sudden, massive output of aerosols from industries and power plants contributed to the global cooling trend from 1940-1970.
“That’s my suggestion, though it’s still not proven,” he said. “There is a nice record of sulfates in Greenland ice cores that shows this type of particle was peaking in the atmosphere around 1970. And then the ice core record shows a rapid decline in sulfates, right about the time nations began regulating their emission.” (Sulfates cause acid rain and other health and environmental problems.)
Over the course of the twentieth century, Hansen and other climate scientists estimate aerosols may have offset global warming by as much as 50 percent by reducing the amount of sunlight reaching the surface.
in passing, and looking at the several decades of warming until 1940, John Cook of Skepticalscience.com said that to understand climate change, you need to factor in all the various forcings that influence global temperature.
“In the early 20th century, while CO2 levels were much smaller, solar activity was on the rise. Also, after a burst of volcanic activity in the late 19th century, there was a relative quiet volcanic period in the early 20th century, Cook wrote.
” These were two dominant factors in the warming from 1900 to 1940.
”.However, both factors have played little to no part in the warming since 1975. Solar activity has been steady since the 50's. Volcanoes have been relatively frequent in the last few decades and if anything, have exerted a cooling effect that has somewhat masked the CO2 warming effect.”.
