Climate May Days in Oz

Some regions of Australia are experiencing a warm month of May. And like clockwork, out pop the climate alarmists, raising concerns over "why Australia's endless summer is bad for trees, fruit, insects -- and shops."

According to the Guardian,

"Autumn leaves aren't shedding, fruits crops are being fooled into flowering and shops can't sell winter coats as unseasonably warm weather continues to break records across Australia's south east."

A warmer than normal May in southeast Australia, or Australia in general, will occur from time to time. But in today's hypersensitive world, events such as these are being directly linked to anthropogenic climate change. Indeed, the article in the Guardian does exactly that, whereby Karl Braganza of the Australian Bureau of Meteorology is quoted with the following explanation for the unusually warm May in some regions down under:

"A shift in the baseline temperature associated with climate change means the air being trapped is warmer, too, by about one degree, Braganza said."

According to the Australian Bureau of Meteorology's own data, there hasn't been a significant trend in southeast Australia's mean temperature for May since at least before 1970. Two of the last three, and 6 of the last 14, months of May in this region have been cooler -- not warmer -- than the long-term average. The maximum temperature anomaly for May in southeast Australia also does not have a significant trend since at least 1970. This simply does not square with claims that May is becoming warmer in southeast Australia due to anthropogenic climate change.

Southeast Australia is not unusual in its lack of temperature trends during May over the past five decades. In 2010, Australia as a whole had its coldest May since 1968. Two of the last three, 3 of the last 5, and 7 of the last 14 months of May in Australia have been colder than the long-term average. None of Australia's climate regions (eastern, northern, southeastern, southwestern, southern, and the Murray Darling basin) have significant trends in mean May temperatures since at least 1980. All but southwestern Australia have no trends dating back even further -- since before the 1970s. Australia's overall mean May temperature also has no significant trend since at least 1970. For the maximum temperature anomaly during May, no regions of Australia other than the southwest have seen a significant trend since at least 1970.

The article at the Guardian mentions the cities of Melbourne, Sydney, and Adelaide by name in terms of the extreme May heat. And yet, when I look at the historical data for these cities, I see absolutely no trends towards increasing mean maximum or highest temperatures in May since at least the 1970s. As a couple graphical examples, here are the figures (since records began at both sites) of the mean maximum May temperature at the Sydney Airport and the May highest temperature at the Melbourne Regional Office.


I am just not seeing a clear anthropogenic climate change signature in the data. Are you? I get no trend in Melbourne's highest May temperature since at least before 1880 -- i.e., at least 130 years of no change.

Some regions of Australia may be having an unusually warm May 2014. So what? Warm months will come and go, as will cold months. But in Australia overall, and the southeast in particular, there doesn't appear to be any hints of a trend towards generally warmer months of May over the past number of decades.