Stuart Penkett obituary | Environment

Stuart Penkett’s discovery of the chemical processes that cause acid rain transformed our understanding of atmospheric pollution and what was required to deal with it.

Penkett, who has died aged 87, and his colleagues at the Atomic Energy Research Establishment (AERE) in Harwell, Berkshire, published a landmark paper in 1979 in the journal Atmospheric Environment, identifying how sulphur dioxide, primarily emitted from industrial sources, is converted into sulphuric acid in clouds that subsequently falls as rain.

Acid rain had been causing significant environmental harm throughout the 20th century, devastating aquatic ecosystems and forests, as well as damaging infrastructure throughout Europe and North America, where chemicals concentrated in the atmosphere above industrialised areas.

Later, while based at the University of East Anglia (UEA) in Norwich in the 1980s, Penkett worked on understanding the processes that produce and destroy ozone in the Earth’s atmosphere. His measurements helped identify the role being played by chlorofluorocarbons and other ozone-depleting substances (ODSs) and would contribute significantly to the successful implementation of the 1987 Montreal Protocol, the international treaty designed to protect the Earth’s ozone layer by phasing out the production and emission of ODSs.

The protocol was signed by all United Nations member states, the first treaty in UN history to achieve universal ratification. For many years afterwards, Penkett would contribute to the UN’s Scientific Assessments of Ozone Depletion reports, which underpinned the protocol. The former UN secretary general Kofi Annan described Montreal as “perhaps the single most successful international agreement to date”. What Penkett described in New Scientist magazine as the “creeping horror of ozone hole-induced damage” has since been reversed.

Born in Eccles, Lancashire, Stuart was the only child of Arthur, a fitter at Gardner and Sons, an engine building company in Eccles, and Ilene (nee Henshaw), who had been a secretary before marriage. Penkett passed the 11-plus exam and attended Eccles grammar school before, in 1960, graduating with a degree in chemistry at Leeds University.

He stayed at Leeds to gain his PhD, specialising in chemical kinetics – the branch of physical chemistry focused on understanding the rate of chemical reactions and the factors that influence them. He then spent two years carrying out postdoctoral research in the US at the University of Southern California before returning to the UK to work in the labs at the multinational consumer-goods company Unilever.

In 1968 Penkett was appointed senior (later principal) scientific officer at the AERE, initially focusing on how atmospheric pollutants oxidise and damage materials with which they come into contact. In addition to his discovery of the processes causing acid rain, his other work at the AERE and subsequently at UEA showed how our atmosphere breaks down pollutants, effectively cleaning the air we breathe, and how badly adjusted domestic gas stoves can cause serious health risks to those using them.

He left the AERE in 1985 to join UEA, initially as a Natural Environment Research Council (NERC) reader, before becoming professor of environmental sciences in 1990. He would remain at UEA until retirement in 2004, following which he became emeritus professor.

Penkett established the Weybourne Atmospheric Observatory (WAO) on the Norfolk coast to the north of Norwich, to monitor pollutants and record other atmospheric phenomena. It is now one of the stations in the World Meteorological Organisation’s Global Atmosphere Watch network.

He also led the development of the UK Met Office’s C-130 aircraft, which became the Facility for Airborne Atmospheric Measurements, an airborne laboratory capable of measuring the chemistry of the atmosphere. In addition, by bringing together scientists from different universities and NERC research centres, he created the first co-ordinated national programme for atmospheric chemistry, offering a blueprint for future global research projects.

Among numerous appointments, Penkett was a member of the Intergovernmental Panel on Climate Change, an affiliate scientist at the National Center for Atmospheric Research in Boulder, Colorado, and a member of the Max Planck Society, a non-governmental, non-profit association of German research institutes. He also worked for the World Meteorological Organization and the European Research Council, advised the British and US governments on climate and atmospheric science, and was awarded the Gaskell Memorial Medal by the Royal Meteorological Society in 1987.

In 2003 he received the Haagen-Smit award, considered the “Nobel prize” in air quality research, from the academic publisher Elsevier, for his original, seminal paper on acid rain formation.

Penkett’s made the UEA’s school of environmental sciences the UK’s leading research group looking into atmospheric chemistry measurements. He trained a large cohort of young scientists now working in important research positions, and was generous with his time, notably with visitors from abroad, who would always be treated to a fish-and-chip supper after visiting the WAO.

In 1962 Penkett married Marigold Gibbens, whom he had met during his PhD course while seconded to the Akers research laboratory in Welwyn, Hertfordshire. For many years she worked as his personal assistant.

She survives him, along with three of their four children, Fiona, Clive and Rebecca, and five grandchildren. Another son, Christopher, died in 2021.