The consensus on how human activity is changing our climate is now so comprehensive that it is easy to forget that crucial to building the scientific understanding has been the acquisition over decades of many careful environmental measurements. John Harries, who has died aged 76, was involved in designing, developing and deploying instruments that were placed on aeroplanes, balloons and satellites to measure the heat radiation emitted by the Earth. His work resulted in the first direct observational evidence of an increase in the carbon dioxide greenhouse effect.
Visible light is radiation with a spectrum of colours from blue at short wavelengths to red at long wavelengths. Radiation at even longer wavelengths is invisible, but the spectrum continues with heat radiation in the infrared and far-infrared. Each gas in the atmosphere absorbs and emits radiation uniquely, having its own characteristic spectrum, and, knowing this, we can interpret measurements of radiation to reveal the concentration of that gas.
John was a leading expert in how to take advantage of measurements made at infrared to longer wavelengths. This started while he was working in the 1970s at the National Physical Laboratory (NPL) in Teddington, south-west London, using a spectrometer in the lab to look at the far infrared properties of various gases.
Motivated in part by the Met Office, which was interested in measuring atmospheric water vapour high in the atmosphere, where it is important in determining both temperature and composition, John then, with his colleague Nigel Swann, developed a version of the lab instrument to fly on aeroplanes and balloons. They would sleep in vans in order to be prepared for their 4am balloon launches. The two young scientists even managed to secure a place on Concorde for a sales tour across the middle and far east and Australia in June 1972, allowing them to make some of the early observations of gases important at higher levels in the Earth’s atmosphere.
In 1980 John was appointed associate director of the Rutherford Appleton Laboratory near Didcot, Oxfordshire. During the years following the 1984 discovery of the Antarctic “ozone hole”, John’s team, together with American colleagues, used data from Nasa satellites to shed light on the factors determining the relationship between stratospheric water vapour and ozone, to what extent the existence and depth of the hole depended on wind strength and on how air transported gases up and down in the atmosphere. John excelled in stimulating teamwork, bringing people together and getting the best out of them.
I worked with John after he was enticed to Imperial College London in 1994 to establish a new research group in Earth Observation. This was a hugely productive period of his career. One important element was the development of the Geostationary Earth Radiation Budget (GERB) instrument. The Earth’s surface temperature depends on the balance between the radiative energy it receives from the Sun and that which it loses back to space, with global heating taking place when more energy is absorbed than emitted. Collaborating with colleagues in the UK, Belgium and Italy, John led this project from concept to deployment on Meteosat, a European meteorological satellite, which retains a position high above a fixed point on the equator. Launched on four satellites since 2004, GERB has provided a continuous stream of invaluable data for the study of the climate.
Another of John’s innovations was the only instrument in the world capable of measuring far-infrared spectrums from aircraft. The resulting data has provided new understanding of the behaviour of water vapour and ice cloud high in the atmosphere, helping to determine the Earth’s radiation budget.
In the 1990s, with colleagues in Italy, John began to develop ideas around the possibility of mounting a far-infrared spectrometer on a satellite. That the European Space Agency (ESA) is now committed to launching such an instrument on a satellite in 2027 is testament to their vision and efforts. Measurements from this exciting new mission will improve confidence in the accuracy of climate change assessments that form the basis for future policy decisions.
As well as creating instruments, John was keen to make sure that the data they produced was exploited to the full for the advancement of climate science. He helped to pioneer the direct use of satellite infrared observations to detect spectral signatures of global heating, and in 2001, with Imperial colleagues, he published a groundbreaking paper in the journal Nature that provided the first direct observational evidence of an increase over decades of the carbon dioxide greenhouse effect.
From 2010 until his retirement in 2013 John was the first chief scientific adviser for Wales, advising the first minister and the Welsh government on science and technology and providing the first national science strategy, Science for Wales.
Among his many other roles, he served as president of the Royal Meteorological Society and chair of the ESA’s Earth observation programme board. He was awarded Nasa’s distinguished public service medal in 2011 and the Mason gold medal of the Royal Meteorological Society in 2014.
John was born in Sedgefield, Durham. His parents, Marion (nee Price) and Brynmor Harries, were from south Wales, and he was very proud of his Welsh roots. Indeed, a good way to distract him, should this ever be deemed necessary, was to ask him about the state of Welsh rugby. His father’s army job meant frequent relocation, so John and his two younger siblings went to a variety of schools.
John attended Bishop Wordsworth’s grammar school in Salisbury, Bournemouth school, and for the sixth form Burford school, in Oxfordshire. He studied physics at the University of Birmingham, graduating in 1967, and immediately took the post of scientific officer at the NPL. While employed there, in 1971 he obtained his doctorate at King’s College London. He met his future wife Sheila Basford at Birmingham, and they married in 1968.
In 2018 John was diagnosed with dementia and he and Sheila moved to Aberystwyth in 2020 to be near to family.
He is survived by Sheila, their children, Paul, James and Rebecca, and seven grandchildren, and his siblings, Jean and David.
• John Edward Harries, atmospheric physicist, born 26 March 1946; died 21 December 2022
