Global temperatures may be 4 degrees Celsius hotter by the mid-2050s if current greenhouse gas emissions trends continue. The new study, by Britain's Met Office Hadley Centre, echoed a United Nations report last week which found climate changes were outpacing worst-case scenarios forecast in 2007 by the UN's Intergovernmental Panel on Climate Change. In July, leaders of the main greenhouse gas-emitting countries recognised a scientific view that temperatures should not exceed 2 degrees above pre-industrial levels, to avoid more dangerous changes to the world's climate.<br/> <br/>