One of the many frustrations for climate change researchers arising from the current hacked climate emails saga has been the way that so-called sceptics have been given so much uncritical coverage by journalists who are not properly scrutinising their misleading and inaccurate claims.

Take Professor Ian Plimer, for instance, who is now wheeled out by many sceptic groups who are seeking a veneer of academic credibility.

Prof Plimer helped the UK Independence party last week to launch its declaration of climate change denial and is a member of the academic advisory board of Lord Nigel Lawson's new lobby group, the Global Warming Policy Foundation.

Plimer is gaining lots of new publicity as an "expert sceptic" from parts of the UK media, with numerous TV and radio interviews, full-page opinion pieces in The Mail on Sunday and even a splash on the front page of the Daily Express.

The trouble is that Professor Plimer is not a climate researcher and has not published any scientific papers on the change in climate that we have been witnessing over the past century. He is an Australian mining geologist who gained fame in his native country for publicly tackling creationists over their denial of the evidence for evolution.

But Prof Plimer has published a book, Heaven and Earth which has become the bible for many climate change sceptics. His book is riddled with inaccurate information about climate change.

The very first graph in the book, for instance, purports to show temperature observations and projections between 1990 and 2025. One of the lines on this graph is labelled "HADCRUT", indicating that the data source was, allegedly, the Met Office's Hadley Centre and the Climatic Research Unit at the University of East Anglia.

However, almost none of the data points accurately reflect the official records from the source, and 2008 is completely misrepresented as the coldest year since 1993. Elsewhere in his book, Professor Plimer claims 2007 was the coldest year since 2005, contradicting his own graph, and also disagreeing with all of the official records of global temperature.

But perhaps the most staggering inaccuracy is in the third graph in his book, which is supposed to show global average temperature between 1880 and about 2002. It appears to show that the amount of global warming prior to 1945 was much bigger than that since the late 1970s. This is in complete contrast to the official records maintained by the Met Office, Nasa and the US National Oceanic and Atmospheric Administration, which all show that the warming since the 1970s has been much greater.

So what is the origin of Prof Plimer's alternative record of global temperatures? The book does not cite a source and Prof Plimer has so far refused requests to reveal its provenance.

But one eagle-eyed blogger spotted that it was identical to a graph used in the very first broadcast of the discredited UK TV programme The Great Global Warming Swindle. Soon after it was broadcast in March 2007, the programme-makers admitted that the graph had been altered by taking an original graph (posted on a website to collect names on a petition against ratification of the Kyoto protocol by the United States), purporting to show global temperatures up to the mid-1980s.

They had wanted a more up-to-date graph and so had simply stretched the bottom axis and relabeled it as if it extended up to the present. As a result they missed out all of the warming that has occurred since the mid-1980s, giving the false impression that more warming had occurred before 1945.

When a UK newspaper revealed the maniupulation, the programme-makers dropped it from repeat broadcasts and the DVD version. But Prof Plimer appears to have revived it.

Now he is being interviewed around the world as an "expert sceptic" on climate change with some newsworthy alternative views to "balance" the mainstream consensus among researchers. And his dodgy graphs and inaccurate claims about global temperatures are being portrayed by some parts of the media as a "different side of the story", when really they are just mistakes presented as fact.

• Bob Ward is policy and communications director at the Grantham Research Institute on Climate Change and the Environment