An early concept for the Anthropocene was the Noosphere by Vladimir Vernadsky, who in 1938 wrote of "scientific thought as a geological force."[10] Scientists in the Soviet Union appear to have used the term "anthropocene" as early as the 1960s to refer to the Quaternary, the most recent geological period.[11][full citation needed] Ecologist Eugene F. Stoermer subsequently used "anthropocene" with a different sense in the 1980s[12] and the term was widely popularized in 2000 by atmospheric chemist Paul J. Crutzen,[13] who regards the influence of human behavior on Earth's atmosphere in recent centuries as so significant as to constitute a new geological epoch.