- DEng (Doctorate of Engineering).
- ASTC Dip.
- FRS NZ.
Geoffrey Duffy is a emeritus professor of chemical engineering at the University of Auckland.
He is also the owner and operator of Fibre Dynamics Ltd, a consulting and marketing company specializing in infrared drying and fluid mechanics problems.
Duffy has written numerous articles for Climate Realists, a website that promotes the views of New Zealand climate change skeptics.
Stance on Climate Change
“It is also interesting to note that NASA’s Aqua satellite system has shown that the earth has been cooling since 1998. This corresponds with measurements from the Argos sub-ocean probes that the ocean is cooling. This is in stark contrast with the proposals from many 'climate alarmists'…
“So what are the key players in 'Climate Change'? The major driver is the sun. Warming depends on the sun. Cooling is due to the lack of sun’s energy.” 
“Even doubling our tripling the amount of carbon dioxide will virtually have little impact, as water vapor and water condensed on particles as clouds dominate the worldwide scene and always will.” 
“Climate and local weather is forever changing. Sure we must minimize pollution of our air and water systems with obnoxious chemical and particulates, and not treat them as 'sewers'. But even doubling or trebling the amount of carbon dioxide will virtually have little impact, as water vapour and water condensed on particles as clouds dominate the worldwide scene and always will.” 
“Climate has forever been changing and will continue to do so. The major driver is the sun and the radiation from it. The main atmospheric 'intermediary' between the sun and earth is water, and thus it dictates the behaviour of the earth's climate.” 
Geoffrey Duffy is listed as a “Founding Member” of group named Climate Exit (Clexit) led by climate change denier Christopher Monckton. According to Clexit's founding statement (PDF), “The world must abandon this suicidal Global Warming crusade. Man does not and cannot control the climate.” , 
Desmog reports on how the group grew in the wake of the UK's decision to leave the EU. A key member of Clexit's “60 well-informed science, business and economic leaders” is Hugh Morgan, a former board member of the Reserve Bank of Australia and former CEO of Western Mining Corporation with close ties to Australia's Liberal party. , 
According to Clexit's founding statement:
“If the Paris climate accord is ratified, or enforced locally by compliant governments, it will strangle the leading economies of the world with pointless carbon taxes and costly climate and energy policies, all with no sound basis in evidence or science […]” 
Duffy is one of a list of “climate experts” who signed the Manhattan Declaration of Climate Change. The declaration was put forward by the International Climate Science Coalition (ICSC) at the Heartland Institute's 2008 International Conference on Climate Change.
He is also listed as a “registered endorser” of the ICSC's “Climate Scientists' Register” which describes its mission to have “the vast majority of the public come to regard human caused climate catastrophe concerns as unfounded.”
- Climate Realists' Network — Contributor.
- International Climate Science Coalition (ICSC) — Signatory to Manhattan Declaration and Climate Scientists' register.
- Climate Exit (Clexit) — ”Founding Member.” 
- Geoffrey G Duffy, “Climate Change - The real cause,” Climate Realists.
- Geoffrey G Duffy, “Climate Change - A Deeper Look at the Evidence” (PDF), Climate Realists.
- “Some insights into Carbon Dioxide by Geoff Duffy,” Climate Realists.
- “Climate Change Facts,” Climate Realists.
“Did you know - Professor Emeritus Geoff Duffy DEng, PhD, BSc, ASTC Dip, FRS NZ, FIChemE, CEng,” Climate Realists, November, 2009.
“UN Climate Scientists Speak Out on Global Warming” (PDF), Edited by Senator Orrin G. Hatch from the Minority Report October 5, 2009.
Larry Bell, Climate of Corruption: Politics and Power Behind the Global Warming Hoax. Greenleaf Book Group (January 2011).
Geoffrey G Duffy, “Climate Change - The real cause,” Climate Realists.
Geoffrey G Duffy, “Climate Change - A Deeper Look at the Evidence” (PDF), Climate Realists.
“The Clexit Committee comprises” (PDF), Clexit.net. Archived.pdf on file at Desmog.
“After Brexit, Clexit” (PDF), Clexit.net. Archived .pdf on file at Desmog.
Graham Readfearn. “After Brexit, Climate Science Denialists Form New Group to Call for a Clexit,” Desmog, August 3, 2016.
“GEOFFREY G. DUFFY,” CV at the University of Auckland. Archived Oct 14, 2008.
“International Climate Science Coalition,” Sourcewatch.