The Sir Ivan bushfire started east of Duneedoo in the NSW Central tablelands on a day that NSW fire authorities classified as catastrophic. Credit:Dean Sewell/Oculi And, just to make you feel better, let me remind you of the big win the deniers have had. The Coalition's leading, longest-standing and most articulate supporter of action on climate change has changed sides. Malcolm Turnbull, the man who lost his job as party leader because was so keen to see action he supported the Labor government's emissions trading scheme, is now keen to ensure it never happens again. The squeakiest wheels in the party want him to demonise renewable energy, blaming it for all the blackouts and price rises? Introduce new government subsidies for coal while making the future for power generation so uncertain no one's game to invest in anything? Sure. Whatever it takes.

(Don't worry, Malcolm, I'm sure all the people inside and outside the Liberal fold who were so pleased when you became Prime Minister – me included – will learn to accept your need to abandon everything we know you believe and start doing Tony Abbott impressions.) It's the easiest thing in the world for people to imagine that whatever's been happening lately is much bigger and more terrible than ever before. Trouble is, the scientists keep confirming our casual impressions. A report this month prepared by top climate scientists for the independent Climate Council, is all bad news. They say all extreme weather events in Australia are now occurring in an atmosphere that's warmer and wetter than it was in the 1950s. "Heatwaves are becoming hotter, lasting longer and occurring more often," they say.

"Extreme fire weather and the length of the fire season is increasing, leading to an increase in bushfire risk." This fits with the findings of the latest biennial CSIRO and Bureau of Meteorology State of the Climate report. According to the bureau's Dr Karl Braganza, Australia is already experiencing the effects of climate change, with record-breaking heat now becoming commonplace across the country. "Australia experienced its three warmest springs on record in 2013, 2014 and 2015," he says. "Temperature and rainfall during this period is critical to southern Australia's fire season. "We've already seen an increase in fire weather and a longer fire season across southern and eastern Australia since the 1970s.

"In these regions the number of days with weather conducive to fire is likely to increase. "Whilst the observations show us increased rainfall in some parts of Australia, we have also seen significant seasonal decline, such as in the April-October growing season, where an 11 per cent decline in rainfall has been experienced in the continental southeast since the mid-1990s. "The changing climate significantly affects all Australians through increased heatwaves, more significant wet weather events and more severe fire weather conditions. "Some of the record-breaking extreme heat we have been seeing recently will be considered normal in 30 years' time." Oh, good.

Of course, none of this is having any effect on agriculture. It must be a great comfort to our farmers to know that, by order of Barnaby Joyce and the National Party, climate change is a figment of the climate scientists' imagination. This is good news, since I read that reliable rainfall and predictable temperature ranges are critical to agricultural production, and these are the very factors affected by a changing climate – if it was changing, which it isn't. A new CSIRO study, led by Dr Zvi Hochman, has found that Australia's average yields from wheat-growing more than tripled been 1900 and 1990 thanks to advances in technology, but have stalled in the years since then. The study found that, since 1990, our wheat-growing zone had experienced an average rainfall decline of 2.8 millimetres, or 28 per cent per cropping season, and a maximum daily temperature increase of about 1 degree. Australia's "yield potential" – determined by climate and soil type – which is always much higher than farmers' actual yields, has fallen by 27 per cent since 1990.