Tony Blair included a forward to a UK Met Office report on climate change [LINK]. It sounds like the report is the UK's own personal IPCC-style assessment, and it sounds like they aren't holding back, even invoking the holy of holies, the west Antarctic ice sheet. If that ice starts melting, which according to scenarios dreamed up by people like Jim Hansen could happen quickly once it starts, the southern ocean will be flooded with fresh water, heat uptake by the ocean would be shut down in a climatically important region, and sea-levels would immediately rise. It would be bad news.
The report is available: [LINK]