Mary Gagen is a Professor of Geography at Swansea University, in the UK. Mary is a climate change scientist and her research focuses on the past climate records stored in the rings of ancient trees, and on exploring how environmental change is impacting forests. A keen outreach scientist, Mary co-runs Swansea University’s Science for Schools Scheme and is Deputy Director of Swansea’s Oriel Science centre project. 

Current research projects:

  • Exploring the paleoclimate potential of ancient rainforest trees in lowland tropical rainforest in Sabah, Malaysian Borneo.

  • Working to improve our understanding of Oak Decline Syndromes in UK ancient oak woodland.

  • Developing palaeocloudiness records from ancient sub-fossil pine trees in the northern Boreal forest areas of Fennoscandia

  • Research is funded by Research Council’s UK, National Geographic, the European Union, The Welsh Government, Forest Research UK, Woodland Heritage.

Science Communication


Mary is a keen science communicator running Swansea University’s Welsh Government-funded S4 project (Swansea University Science for Schools Scheme) and co-directing Swansea University’s Oriel Science exhibition centre.

Research Themes


Palaeoclimate studies. Studying changes in climate over the recent and distant past in order to contextualise the climate changes we observe today.
Dendroclimatology. Exploring past climate information in tree rings. Measurements of tree ring width, wood density and stable isotope variability are investigated as past climate archives.
Tree response to environmental change. Exploring the physical and chemical changes trees undergo as atmospheric carbon dioxide levels rise.
Forest health under climate change. Oak decline syndromes are becoming more widespread in the UK; we are exploring tree growth histories to improve our understanding of the tee growth response to these complex disease syndromes.
Cloudy records from ancient trees. Developing palaeocloud records from the annual rings of sub-fossil pine trees in high latitude lakes and bogs.
Tropical dendroclimatology. Exploring methods for accessing the palaeoclimate information stored in ancient tropical trees.
Water use efficiency of trees. Exploring how tree water use patterns are changing in response to rising CO2 and climate change.