The report was delayed because of last-minute negotiations on the final wording of the document.
Scientists at the meeting of the Intergovernmental Panel on Climate Change (IPCC) in Brussels said that delegates from US, China and Saudi Arabia had objected to the text.
The objections sparked a protest that politicians were meddling in the scientific assessment about climate change, the delegates said.
"This is the first time that the science is being questioned by politicians," one angry delegate was quoted as saying.
The dispute centres on a "summary for policymakers" about the known effects of climate change and a prediction of these impacts for the 21st century.
The United States, China and Saudi Arabia lodged objections to sections of text and graphics that gave high-level warnings about some of these effects.
"The Europeans want to send a strong signal. The US does not want as much quantification"
The summary accompanies a 1,400-page report, a copy of which was obtained by journalists.
It predicts that damage to Earth's weather systems from greenhouse gases will change rainfall patterns, punch up the power of storms, boost the risk of drought, flooding and water stress and accelerate the existing meltdown of glaciers and erosion of ice sheets.
'Highway to extintion'
Data on the "highway to extinction" charts showed the deteriorating conditions in much of the world, particularly in poorer countries, with every degree of warming.
"What you see here this week is wrangling over text, over whether something is likely or very likely, whether it is global or regional," said Hans Verolme, director of World Wildlife Fund's global climate change program.
"By 2080, it is likely that 1.1 to 3.2bn people will be experiencing water scarcity"
IPCC draft report
"The more urgent the IPCC report is, the higher the public expectations are of the politicians, who this year will have to make a very firm decision to start new negotiations, binding negotiations, for further deep reductions in carbon pollution."
One delegate told the AFP news agency that while European members of the panel sought to include stronger language and hard statistics about the dangers of global warming, the US preferred general statements instead.
"The Europeans want to send a strong signal. The US does not want as much quantification," he said.
According to leaked details of the IPCC, the body of the document reportedly predicts that damage to weather systems from greenhouse gases will change rainfall patterns, lead to more powerful storms, increase the risk of drought, flooding and stress on water resources, and accelerate glacier meltdowns and ice sheets.
Scientists drafting the report predict that "roughly 20 to 30 per cent of species are likely to be at high risk of irreversible extinction" if global average temperatures rises by 2 to 3 degrees Celcius.
"By 2080, it is likely that 1.1 to 3.2bn people will be experiencing water scarcity," a draft of the report's summary said.
The first report by the IPCC in February laid out the scientific case for how global warming is happening, while the second, due to be released in Brussels on Friday, will try to explain what the effects could be.