It seems the UK Gov't have done the hard work in determining which scenarios are the most likely to happen and what impact they may have, no surprise there, however they have also seen fit to share it with the public, which was nice:

BBC News Article:
http://news.bbc.co.uk/1/hi/uk_politics/7548593.stm

The Risk Register Documents:
http://www.cabinetoffice.gov.uk/reports/national_risk_register.aspx

OIMO