[9] During a 1970-72 break between his MS and PhD studies at Berkeley, he performed alternative service as a conscientious objector to the Vietnam War as a research assistant at the Kansas University Medical Center.

Birks began his academic career in 1974 when he joined the University of Illinois at Urbana-Champaign as an assistant professor in the Department of Chemistry.

Birks co-founded 2B Technologies, a company specializing in the development of instruments for environmental and atmospheric measurements, with Dr. Mark Bollinger in 1998.

[12] In 2003, Birks received the ACS Award for Creative Advances in Environmental Science and Technology from the American Chemical Society "for his measurements of the rate coefficients of chemical reactions key to understanding stratospheric ozone depletion, co-development of the nuclear winter theory, and invention of new analytical instruments for environmental analysis.

[10] The AQTreks educational outreach program, an outgrowth of the GO3 Project that allows students to perform mobile monitoring of air pollutants along treks of their own design, was founded by Birks and his colleagues in 2017.

[24] Their calculations showed that fires in cities, forests and oil production and storage facilities resulting from a major nuclear war would produce enough smoke to block as much as 99 percent of sunlight from reaching the Earth's surface throughout the northern hemisphere.

[25] This work, published in 1982 in a special issue of the Swedish journal Ambio as part of a larger study of the environmental effects of nuclear warfare commissioned by the Swedish Academy of Sciences, was followed by a paper by Richard Turco, Brian Toon, Thomas Ackerman,[26] James Pollack and Carl Sagan (TTAPS) in the journal Science in 1983.

[32][33][34][35][36][37][38][39] Seven of the instruments, including the pocket-sized Personal Ozone Monitor (POM),[33] have been designated as EPA Federal Equivalent Methods (FEM).