Director for the School for Climate Studies, Interim Director at the Centre for Invasion Biology, and Distinguished Professor, Stellenbosch University, he has worked on climate change risks to biodiversity since the 1980s. Previously A-rated in Plant Sciences, he has recently achieved a further NRF A rating in Earth Sciences. 

A recipient of the South African NFTS and Ecologic Awards, Royal Society of South Africa’s Marloth Medal, and German Humboldt Research Award for lifetime scientific contributions, he is ranked by Thomson-Reuters as highly cited, and in the top 200 most influential climate change scientists globally (2022). He has contributed to multiple international environmental assessments under the UN Framework Convention on Climate Change, Convention on Biological Diversity and Intergovernmental Platform for Biodiversity and Ecosystem. He chaired SA’s Global Change Science Committee in the 1990s and 2000s, and has graduated many students now occupying senior government, consulting, and academic positions.

Research interests include: Global change; Climate change and its biological impacts; Integrated climate change studies; Austral and specifically disturbance driven ecosystems; animal plant interactions; Paleoecological aspects of phylogeography, Elevated CO2 impacts on plant physiology and the ecological implications, species distribution modelling, Dynamic global vegetation modelling, Social ecological systems and the human niche from Pleistocene to Anthropocene.