Archive for December, 2013

No Warming in North Australia for 31 Years

December 23, 2013

I’m nearly a year late with this, but I’ve only just noticed.

According to the Bureau of Meteorology’s official temperature records, for all of the Northern Australian region- the half of the continent north of 26 degrees South- the minimum temperatures are steadfastly refusing to rise.  From 1982 to 2012, the linear trendline for minima is on the decreasing side of dead flat.

Acorn tmin Nth Oz 82-12

This is longer than the 3o years regarded as the minimum period for analysing climate trends, and in spite of the massive increase in amount of CO2 emissions.  Note that 1982 and 2011-2012 were almost equally cooler than normal.

Remember  that one of the fingerprints of greenhouse warming is that minima should be increasing more than maxima.

Here is the 365 day running mean of daily minima anomalies of all Acorn sites in Northern Australia (more about this next year) up to early December this year:

tmin nth aust 1910-13a

Rather than a smoothly rising trend, the record is characterised by 10 to 15 year rapid rises and falls, responding to events in the Pacific and Indian Oceans.

This is a diagram of Australia’s climate regions:summer1213  regions

After New Year I will post about minima for other regions and Australia as a whole.

Merry Christmas to all.

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It’s Official: a 27 Year Hiatus

December 13, 2013

Australia’s Bureau of Meteorology (BOM) has been publishing its brand new (less than 2 years old) temperature dataset, the Australian Climate Observations Reference Network- Surface Air Temperatures (ACORN-SAT, or Acorn), and using this to make scary pronouncements about our climate.

Back in March, I showed that there had been an 18 year pause in Australia’s mean temperatures.  In April I showed how Dr Braganza’s “Fingerprints of Global Warming” (from an article in The Conversation on 14/06/2011) are absent in Australia.  I included a passing reference to minima, which really needs a separate post, so here it is.

Why minima?  To quote Dr Braganza,

…Patterns of temperature change that are uniquely associated with the enhanced greenhouse effect, and which have been observed in the real world include:

………

  • greater warming of night time temperatures than daytime temperatures

Greenhouse theory suggests that greenhouse gases slow the normal rapid night time radiation into space, therefore minima should be increasing.  Australia as a region is roughly the same size as the USA, or Greenland, or Europe, or the Arctic or Antarctic, and is supposed to be at great risk from the effects of global warming, so the behaviour of minima in Australia should be of some interest.

So let’s see if this unique pattern of temperature change has been observed in the real world.

This is a graph of annual minimum temperature anomalies across Australia from 1986 (updated!) to 2012, sourced directly from Acorn data at the BOM website at http://www.bom.gov.au/web01/ncc/www/cli_chg/timeseries/tmin/0112/aus/latest.txt:Acorn tmin Australia

Which clearly shows that minimum temperatures have been cooling, not warming, for 27 years.

Strange, but true.  You won’t see that mentioned in any BOM publication.

Weather predictions: December

December 1, 2013

At the start of November, I said:

“November
5 to 10 unstable; 13 to 21 unstable with several events; 26-27-28-29-30 unstable.”

All correct, 1 miss.  Instability with some very wild storms marked much of November especially in the South-East of the state.

Now I suppose anyone could have predicted storms for November.  But remember, back in August I had said:

“November

5-6-7, 9-10, 13-14-15, 17-18-19-20, 27-28-29.”

Here’s a chart showing August predictions in light green and early November predictions in dark green.octdec13resultsnov

5 right, I miss.  I should have stuck with my original predictions!

So the method is holding.

Predictions for December to 31 March remain the same as I predicted last month.  As well, I expect weather events around these dates in April and May (+/- 1 day):

2,4,7,11,15,20,23,25, May 1, 8,11.

April should have unstable weather, and I would not be surprised if we get significant rain.