David is an oil exploration geologist who branched out to work in mineral exploration, cancer research, the steel industry, defence, fighter aircraft design and climate science. He has lectured on climate science in US Senate and House hearing rooms and has been a visiting fellow at the Institute of World Politics in Washington, a graduate school for the CIA, Department of Defense, State Department and other agencies. He has authored books on climate science, geopolitics, defence, fighter aircraft design and cancer.