1. a Faculty of Environment and Technology, University of the West of England , Coldharbour Lane, Bristol , BS16 1QY , UK
2. b Institute of Earth Sciences , University of Iceland , Reykjavík , Iceland
3. c Bristol Futures Group, Bristol City Council, Create Centre , Smeaton Road, Bristol , UK
4. d Centre for Sustainable Energy , 3 St Peter's Court, Bedminster Parade, Bristol , BS3 4AQ , UK