The risks of global disasters because of climate change may be much greater than previously believed, says a report issued by the U.K. Meteorological Office. It expresses concern that the world may be nearing temperature-change thresholds that could trigger irreversible effects. The document, "Avoiding Dangerous Climate Change," presents evidence that the Greenland ice cap may already be melting and that a local increase of 2.7 °C over today's average temperature in Greenland "may be a threshold that triggers" irreversible melting of the ice cap. Such a temperature increase is well within the range of climate-change projections for the century. A global increase of 1 °C is likely to lead to extensive coral bleaching, vastly disrupting marine ecosystems, the report says. It noted recent studies showing that the ocean is already more acidic because of its absorption of excess carbon dioxide from the atmosphere. The study reports that technological options for making reductions in emissions over the long term-such as energy efficiency, nuclear energy, and renewable transport fuels-already exist.