The federal Liberal member for Hughes, Craig Kelly, has been ridiculed after he took to a climate change denial blog to compare Sydney’s recent heatwave to the oppressive experiences of the First Fleet.

The post, uploaded to fringe site “Watts Up With That” earlier this week, suggested the nation’s record-breaking run of hot weather wasn’t evidence of climate change because on several days in Sydney 222 years ago it was also hot.

Kelly cites the temperature records of First Fleet settler Watkin Tench to claim that because of a run of stinkers in 1790, there was no urgency to respond to the most recent national heatwave that has generated worldwide headlines and prompted a Climate Commission report making the link to global warming clear.

“I wonder if any of these people actually knew that Sydney’s so-called ‘record hot day’ on Tuesday 8th Jan this year, that had them screaming ‘Global Warming’, was actually COOLER than the weather experienced by the convicts of the First Fleet in Sydney way back in the summer of 1790/91?,” Kelly wrote.

And “the extreme heat wasn’t restricted to the 27th Dec 1790…the following day the temperature again surpassed the old 100 Fahrenheit mark, hitting 40.3C (104.5 F) at 12.30pm. And later that same summer, in February 1791, the temperature in Sydney was recorded at 42.2 C (108 F).”

Kelly quotes Tench’s report that the colonial hot air “felt like the blast of a heated oven”.

The southern Sydney backbencher defended his musings this morning, telling Crikey the measurements from “the Observatory under the pilings of the Sydney Harbour Bridge were the best standard of the day”.

“Two thermometers were given to them by the British authorities and they stopped in Rio and Cape Town on the way to Australia … both locations calibrated the instruments. There’s a good argument to say they’re fairly accurate,” Kelly said.

“You’ve also got the commentary on the numbers of dead bats and birds,” he added. “It’s important to remember the temperatures our ancestors and convicts went through 220 years ago were without the benefit of the modern marvel of airconditioning.”

Asked whether humans caused climate change, Kelly agreed that there had been a “small warming trend between 1970 and 1998” but the world was also warming in the 1930s.

Kelly — who told federal Parliament in 2011 that drinking chardonnay was one answer to global warming — said more analysis was required to gauge whether the issue was an urgent one.

“The question is how much warming has actually occurred, the second question is ‘is it dangerous?’ and the third question what can be done about it and whether that will have any effect.”

Last year, Opposition Leader Tony Abbott warned coalition MPs against “freelancing” on areas outside their portfolios that clash with the opposition’s official policy line. Party discipline will become all the more important as this year’s election campaign gathers pace.

Despite the Coalition’s bipartisan commitment to reducing carbon emissions by 5% by 2020 and a Renewable Energy Target of 20% by 2020, some Coalition caucus members struggle to accept that human-induced climate change may be real.

While climate scientists are reluctant to apportion blame for individual weather events directly to global warming, they are almost united on the core assumption that anthropogenic activity has increased the odds of such events occurring.

In its heatwave report, the Climate Commission said “climate change has contributed to making these extreme heat conditions and bushfires worse”.

Chief Climate Commissioner Tim Flannery — who edited and introduced a reissue of Tench’s writings (1788) — told Crikey the report did not cite Sydney’s temperature at all.

“The record heat was recorded elsewhere. The national average temperature was also record breaking,” Flannery said. “Sadly the planet continues to warm. Myself and all the climate scientists I know wish it were otherwise.”

A spokesperson for acting Climate Change Minister, Senator Chris Evans, said “the Member for Hughes is entitled to take his advice on climate change from a 220-year-old weather report.

“But the Gillard government prefers to listen to the advice of reputable scientific organisations such as the CSIRO and the Bureau of Meteorology, both of which are operating in 2013, not 1790.”

Controversy has continued to dog Kelly, who was elected to Hughes in 2010. Last September, Crikey revealed a tranche of New Zealand court documents showing he signed his name as a “director” of his collapsed family flat-pack furniture import business. Under Australian law, de facto or “shadow” directors are liable for claims by creditors, that in the case of the Kellys’ firm stretched to over $4 million.