I am now retired but am still interested in all aspects of radiocarbon dating and calibrations including applications in archaeology, forensics, carbon cycling, ecology and palaeoenvironment.

My research interests are primarily focused on carbon, in both modern and past environments, as a tracer of geochemical processes, as a key component in climate variability and  as a chronological tool. Much of my work focuses on extending and refining the internationally ratified radiocarbon calibration curves which are used by geoscientists and archaeologists to correct radiocarbon ages for the variability of atmospheric or marine ¹⁴C in the past. These datasets also provide information on solar variability, ocean circulation changes and geomagnetic field changes over the past 50,000 years. I chair the IntCal Working Group which has been responsible for producing the calibration curves from independently dated material such as tree-rings and corals since 2002 although I have been closely involved with the work from 1986.

As a corollary to radiocarbon calibration, I am interested in both marine and freshwater radiocarbon reservoir offsets which effect radiocarbon ages and calibration of samples from these environments or from humans or animals with a marine dietary component.My investigations also inform about the nature of ocean upwelling and circulation changes over time. I am also interested in the use of carbon and nitrogen stable isotopes in past dietary studies as a tool to answer questions about human and animal diet in the past and as a way of understanding radiocarbon reservoir effects on the accuracy dating humans and animals subsisting on marine or freshwater resources.

I am also involved in research combining radiocarbon and stable isotopes in understanding the source and fate of carbon in the environment whether terrestrial carbon storage in sediment, efflux to the atmosphere or utilisation in the foodweb of lakes and streams.

 I am no longer teaching and cannot accept research students.

In 2013 I was awarded the Lyell Medal by the Geological Society of London for contributions towards the development of radiocarbon dating and calibration and carbon cycling in the environment.  I was elected as a member of the Royal Irish Academy in 2014 and asked to participate as a convener for selection of members for the Geosciences and Geographical Sciences committee and become a member. I was voted the 2021 'Archaeologist of the Year' in the annual Current Archaeology awards and was the recipient of the Pomerance Award for Scientific Contributions to Archaeology from the Archaeological Institute of America.  I received the James Croll Medal from the Quaternary Research Association in January 2022 and in July 2022 was appointed as Honorary Officer of the Order of the British Empire (OBE), for "services to Radiocarbon Dating, Calibration and Chronology".