A science presenter, writer, speaker & former TV host; author of The Skeptic's Handbook (over 200,000 copies distributed & available in 15 languages).


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BOM Scandal: One second records in Australia — how “noise” creates history and a warming trend

 Instrument errors, noise, may account for a quarter to one half of our national warming trend in the last century.

When the newspapers run a headline with Sydney hits, say, 44.4 degrees and that number gets engraved in history, who realizes that the extreme heat may have only lasted one second? You might think the maximum temperatures were above 44 for at least ten minutes, but the BOM will write it into the record books even if that heat lasts one second, and if the temperature a minute before was more than a whole degree cooler. We’re writing puffs of jet emissions, car exhaust, or random packets of hot (or cold) air into history books, and comparing these new records with old ones done in slow reacting liquid in glass thermometers. No wonder we are setting records!

In the last twenty years, electronic sensors have replaced most of the old fashioned thermometers. It’s for exactly this reason that we need the side-by-side comparison data that Bill Johnston asked for and which the BOM can’t supply because it is deleting the data – as a matter of routine practice.

Back in 1910, or even 1990, thermometers were not able to record [...]

Scandal: Australian Bureau of Meteorology caught erasing cold temperatures

Front page scandal today in Australia: BoM opens cold case on temperature data

Jennifer Marohasy, Lance Pidgeon, at the Stevenson screen, Goulburn Airport.

Amazing, the power of the media. Suddenly, the Bureau of Meteorology needs to replace equipment and answer questions and set up an internal inquiry. But they’ve had weeks of warning. Lance Pidgeon and Jennifer Marohasy have been watching the automatic weather stations record very cold temperatures, and then astonished when those same readings either got entered into our national raw database as warmer, or simply disappeared. The BOM apparently has a filter set so that super cold temperatures need to be manually checked. Yet the filter is set so high, in Thredbo’s case, nearly five whole degrees warmer than temperatures already recorded.

Wow. Just wow. What does raw data mean anymore?

The lack of respect for real observations is profoundly unscientific. How much does the BOM even care about understanding our climate if they are so flagrantly uninterested in the data?  As I have said, the Bureau of Meteorology behaves more like PR agency than an institute of science. Based on past practice their internal inquiry will find excuses, not answer the questions, and will not [...]

On Sunday, Goulburn got colder than the BOM thought was possible (and a raw data record was “adjusted”).

The BOM got caught this week auto-adjusting cold extremes to be less cold. Lance Pidgeon of the unofficial BOM audit team noticed that the thermometer at Goulburn airport recorded – 10.4°C at 6.17am on Sunday morning, but the official BOM climate records said it was -10.0°C. (What’s the point of that decimal place?) Either way this was a new record for Goulburn in July. (The previous  coldest ever July morning was -9.1°C. The oldest day in Goulburn was in August 1994 when it reached -10.9°C).

Apparently this was an automated event where the thermometer recorded something beyond a set limit, and the value put into the official database was the artificial limit. Since colder temperatures have already been recorded in Goulburn, who thought it was a good idea to trim all future minus-ten-point-somethings as if they were automatically “spurious”?

Yesterday, the BOM have acknowledged the error and at first deleted the -10.0 figure, replacing it with a blank space. Then today, after Jennifer Marohasy’s post, they’ve corrected it.

You might think a half degree between friends is not that significant, but this opens a whole can of worms in so many ways — what are these “limits”, do they apply [...]

Sydney Observatory where warming is created by site moves, buildings, freeways

The iconic Sydney Observatory is Australia’s longest running weather station. But everything around the site has changed. Bill Johnston has spent months researching, photographing, and hunting through historic files to document those changes. He wasn’t paid for this work, but what he found was that the BOM has missed that the area around the thermometers has changed dramatically over the last century, so much so, that he claims it’s scientifically meaningless to try to construct climate trends from this data. Aerial photographs show exposure of the instruments changed in 1950, when Stevenson screens were moved, and after a brick wall was built metres from the screen in about 1972. It is suspicious that the changes are undocumented in Bureau reports, especially given they are responsible for much of the “unprecedented warming” in Sydney’s temperature data.  The BOM may counter that this site is not used to calculate warming trends across Australia, but as Bill points out, Sydney Observatory is used to homogenize other sites that are. So site changes and the urban heat island effect infects many country sites, and the traffic in Sydney “warms the nation”.  — Jo


Its fake news week! Guest post by Dr. Bill Johnston[1]. [...]

BOM September failure — but who can predict the climate a whole month ahead?

The World’s Best Practice climate models predicted Australia would be hotter than normal in September, instead the maximum temperature anomaly was 1 to 5 degrees below average across most of Australia.

That long range prediction was made all the way back on August 21. Four weeks later it was obvious it was wrong.

Prediction of a hot September versus actual outcome. (Click to enlarge).

Thanks to Warwick Hughes who saw this failure coming and The Marcus Review who points out the mismatch and goes on to log how much the BOM predictions for October have transformed from hotter than average to cold cold cold.

The BOM bravely predicted Tasmania would have an 80% chance of having hotter than average maximums. Temperatures ended up being spot on average. What’s 80% certainty worth? About the same as 95%.

Thanks to Chris Gillham who pointed out the big cold blob of ocean surrounding Australia on the south and west that gave Perth its coldest ever September nights. Wasn’t that cold blob present on August 21 when those models were run? On August 25th, the BOM predicted Perth’s chances of being cooler than average at 50:50. Toss a coin, or use a climate [...]

Coldest Perth September recorded in 120 years of records (must be climate change)

In the last 120 years in Perth there has never been a September as cold as this one. We know that thanks to Chris Gillham, who has been tracking Western Australian weather in detail for years at

The headline in The West Australian today was Perth shivers through it’s coldest ever September. For some reason (I can’t think why) the extreme weather journalists did not mention climate change (has that ever happened on a hottest ever record story?). It’s so unusually cold here that wheat farmers, only weeks away from harvest*, are struggling with frost damage on crops. They are making snowmen from the frosts. It is supposed to be rapidly heating up but it is three degrees below normal.

Given the freak weather, Will Steffen immediately announced that “This is a prelude to a disturbing future. And it’s only going to get worse if we don’t address climate change.”  No. Wait. Scratch that. That was South Australia, where one bad storm was caused by coal fired electrons. A record cold month is just weather.

Curiously, The Bureau of Meteorology(BOM) announced it was the coldest ever September for Perth since 1994 when records started at Mt Lawley, and [...]

Australian temperatures unchanged for 20 years: Plus Malcolm Roberts first Senate speech is tomorrow

Malcolm Roberts will give his maiden Senate speech tomorrow (Tuesday) at 5pm at the Australian Parliament House in Canberra. To reserve seating contact Leon Ashby leon.ashby AT or phone (02) 6277 3151. He has asked for updated graphs of the UAH data for Australia. His speech may be available via the APH website. (h/t Jim S)

Luckily for us the UAH satellite database can be filtered to track temperatures in the lower troposphere over the Australian land mass. Thanks to John Christy for providing an Australian specific dataset.

We’ve put out a third of all the CO2 homosapiens has ever made in the last 20 years, and it apparently has made no meaningful difference to temperatures here. We’ve put out 60% of all our CO2 since the satellite record began.

Here is the full Australian monthly data from 1979 – now for all seasons graphed below. There are breathless news articles hyping every hot month, every hot week, for records in every little region, and even for a single record hot nights, but no press release to say that temperatures in Australia have not really changed in a meaningful way since 1995.

Thanks to  KensKingdom [...]

Met Bureau Bingo: warm autumn nights sold as “Hottest Ever” March extreme

It’s another month of BOM Bingo. The ABC and BOM are trumpeting a “hottest” ever headline yet again, and Warwick Hughes is onto them already.

Conveniently the ABC forgets to mention that March Maximum Temps have been hotter before many times and with a pattern that has nothing to do with CO2. How many in the ABC audience would know that?

March temperatures sets record as hottest ever, Bureau of Meteorology says

“You could be forgiven for not noticing the end of summer — March was a hot one.” says Sara Phillips. But actually, if you are human, you could be forgiven for thinking this was just another hot March like so many before. For SE Australia where most humans live, the hottest March, and wildly so, was in 1940. Across the whole of Australia these kinds of maximum temperatures in March have been occurring for decades and 1986 was much much hotter. See the BOM graph below.

Hands up who can spot the horrid effect of CO2 in this graph?

Stick with the logic. Must be CO2 that caused the cold spike in 2011 (and 1967, 1942 and 1913). This is witchcraft.

You could be forgiven [...]

Blockbuster: Are hot days in Australia mostly due to low rainfall, and electronic thermometers — not CO2?

Blame dry weather and electronic sensors for a lot of Australia’s warming trend…

In this provocative report, retired research scientist Bill Johnston analyzes Australian weather records in a fairly sophisticated and very detailed way, and finds they are “wholly unsuitable” for calculating long term trends. He uses a multi-pronged approach looking at temperatures, historical documents, statistical step changes, and in a novel process studies the way temperature varies with rainfall as well.

His two major findings are that local rainfall (or lack of) has a major impact on temperatures in a town, and that the introduction of the electronic sensors in the mid 1990s caused an abrupt step increase in maximum temperatures across Australia. There will be a lot more to say about these findings in coming months — the questions they raise are very pointed. Reading, between the lines, if Johnston is right, a lot of the advertised record heat across Australia has more to do with equipment changes, homogenisation, and rainfall patterns than a long term trend.

Bill Johnston: On Data Quality [PDF]

“Trends are not steps; and temperature changes due to station changes, instruments and processing is not climate change”, he [...]

Camouflage illusions in the matrix: same mysterious temperature, same day, year after year

Wait til you see what Lance Pidgeon has found. He was looking at the BOM website temperature archive maps of Australia for early last century (using AWAP data). He was wondering how the Bureau of Meteorology could possibly create maps this detailed for specific days that long ago. He was especially curious about the remote, vast areas where there were no thermometers, yet there were wiggly jiggly temperature lines on the map, shaded as if they had meaning. I’ve heard that more people have visited the South pole, than have stood at the point in central Australia where the three large western and central states meet.

Then he noticed something positively strange — April 14th in 1915 and one year later in 1916 looked almost identical, as did the same day in 1917. The more he looked, the weirder things got. He plodded, year after year, all the way from 1911 to 1917, then through Jan, Feb, March, and so on.  Worse, he tells me he could keep going right through to 1956 without seeing much change (though there are interesting exceptions). After that, temperatures of the area start to vary from year to year, like the “weather” we’d expect if we [...]