A leaked draft report by the world’s top climate scientists has found that is virtually certain that humans are causing climate change but parts of it have been wildly misinterpreted by climate change deniers, experts said.

The fifth assessment report of the Intergovernmental Panel on Climate Change (IPCC) was prematurely published on a blog called Stop Green Suicide by blogger Alec Rawls, who obtained the document as a reviewer.

The draft report, which was still undergoing a peer review process, said that “there is consistent evidence from observations of a net energy uptake of the earth system due to an imbalance in the energy budget.”

“It is virtually certain that this is caused by human activities, primarily by the increase in CO2 concentrations. There is very high confidence that natural forcing contributes only a small fraction to this imbalance.”

Rawls drew attention to another part of the report about the effect of cosmic rays on global warming, saying in a statement that “admission of strong evidence for enhanced solar forcing changes everything.”

However, this section had been taken out of context and could not be used to cast doubt on the idea that human activity is warming the globe, said Steve Sherwood, one of the authors of the report and Co-Director of the Climate Change Research Centre at the University of New South Wales.

“I think the most interesting aspect of how this has been blogged by the climate deniers is that it reveals how deeply in denial they are,” he said in an email to The Conversation.

“If they can look at a short section of a report and walk away believing it says the opposite of what it actually says, and if this spin can be uncritically echoed by very influential blogs like WattsUp, imagine how wildly they are misinterpreting the scientific evidence. This should open people’s eyes as to the credibility of the alternative ‘views’ they are serving up.”

Prof Sherwood said he had no comment on the contents of the report, which he described as “an unfinished work in progress.”

“It has not fully incorporated feedback from the broader science community, has not been approved by the government bodies or UN, has not yet incorporated the most up-to-date work,” he said.

“The official version will come out in September and will be a better, more accurate, more readable and more consistent reflection of the science.”

Professor Stephan Lewandowsky, a researcher of climate change denial at the Cognitive Science Laboratories at the University of Western Australia, said the premature leak of the report was “dishonourable.”

“Science is one of the most transparent endeavours humans have ever developed. However, for the transparency to be effective, preliminary documents ought to remain confidential until they have been improved and checked through peer review,” he said in an emailed comment.

“The leak of a draft report by a reviewer who has signed a statement of confidentiality is therefore regrettable and dishonourable.”

“However, what is worse than the leak itself is the distortion of the content of the draft chapter by some deniers (no, they are not skeptics),” he said.

Prof Lewandowsky said that the report’s statement that humans have caused global warming was a “virtual certainty” meant it’s authors had 99% confidence in that view.

“That’s up from ‘very high confidence’ (90% certain) in the last report published in 2007,” he said.

“In other words, the scientific case has become even stronger and has now reached a level of confidence that is parallelled only by our confidence in some very basic laws of physics, such as gravity or thermodynamics.”

To claim otherwise by cherry-picking part of a sentence out of context is absurd, he said.

“Although it illustrates the standard approach by which climate deniers seek to confuse the public. Climate denial lost intellectual respectability decades ago, and all that deniers have left now is to misrepresent, distort, or malign the science and the scientific process.”

Dr Kevin Trenberth, Distinguished Senior Scientist at the US’ University Corporation for Atmospheric Research said Rawls was able to access a draft copy of the report because “any reviewer can sign up to get access to it all, although they sign a pledge not to do what has been done here.”

“He should be thoroughly castigated,” said Dr Trenberth.

“With regard to the report, I think it has a long ways to go to be up to previous standards, but there is still time,” he said.

“The IPCC work is based upon published peer reviewed material and so it is not new. Some of it is, in fact, old and not up to date.”

The IPCC said in a statement it regretted the leak, which “interferes with the process of assessment and review.”