Abrupt change: High stakes at the climate casino

Scientists have warned that the global climate may be poised on a knife edge because gradual warming due to greenhouse gas emissions could trigger a collapse in ocean circulation. Although the Intergovernmental Panel on Climate Change (IPCC) believes such an event to be unlikely this century, there are few assurances as evidence mounts that the ocean circulation is weakening. A sudden and severe change in the climate could have catastrophic economic and social effects - prompting scientists to call for renewed efforts to stem greenhouse emissions.