GLOBAL temperatures could rise 4 degrees in the next 50 years - faster than previously predicted - if greenhouse gas emissions increase unchecked, according to a report for the British Government.
The climate science update, prepared by British Met Office scientists, found that the increase this century could top 15 degrees above pre-industrial levels in the Arctic and be up to 10 degrees for parts of Africa.
In Australia, rainfall is projected to decline by at least one-fifth along parts of the coastline, worsening drought.
The Met Office Hadley Centre's head of climate impacts, Richard Betts, said the most severe scenarios outlined in the 2007 Intergovernmental Panel on Climate Change report now looked conservative.
''We've always talked about these very severe impacts only affecting future generations, but people alive today could live to see a 4-degree rise,'' Dr Betts told The Guardian.
Where the panel said a probable scenario without action to stop emissions was 4 degrees of warming by 2100, the new report says that level could be reached by 2060 in an extreme case.
The warning came as more than 2000 officials from about 190 countries met in Bangkok for the start of two weeks of climate talks crucial to shaping December's prospective Copenhagen agreement.
Analysts hold little hope of significant progress in Thailand after world leaders offered few concrete proposals at last week's meetings in the US.
Green and welfare groups expressed frustration yesterday after it was revealed that the G20 leaders' meeting in Pittsburgh watered down a climate-change communique at the last minute.
The Age understands proposals about a funding plan to help poorer countries reduce emissions and adapt to the effects of climate change were removed.
An earlier draft said rich nations needed to substantially increase spending to help the poor cope. It also stressed the importance of carbon markets and said oversight should be increased.
The final communique said G20 finance ministers would come up with options in November. US President Barack Obama had previously charged the G20 with coming up with a range of options by last week.
A finance deal is regarded as crucial to a new treaty.
Australia is yet to reveal its position on climate financing beyond promoting the use of revenue from carbon markets, but it is understood not to have argued for the change.
Australian Conservation Foundation climate change spokesman Tony Mohr said he believed the Government had expected the G20 to give direction on climate finance.
''It's hugely frustrating and a real missed opportunity,'' Mr Mohr said. ''We need Australia to start forming its position and doing our bit for financing during these two weeks in Bangkok, but the negotiating team is hamstrung without a political announcement from the Prime Minister.''
A spokeswoman for Climate Change Minister Penny Wong said countries had begun to agree on broad principles but not details.
Officials in Bangkok will this week attempt to reduce a 180-page negotiating draft text into a manageable document.
Points of disagreement include emissions targets for the wealthy, climate aid and sharing of clean energy technology.