Friday, June 05, 2009

Analysis of Australian Temperature - Part 4 - Summer/Winter Effect

If CO2 was the major cause of global warming, then we should see a constant increase of temperature in summer as in winter. The blanket of Co2 should increase the temperature constantly over the year. Likewise it should increase the temperature constantly over the day and night, however I have showed previously that this does not happen.

So are summer and winter temperatures in Australia in increasing at around the same rate? Even according to the Australian Bureau of Meteorology this isn't quite happening. Summer temperatures are increasingly, well, slightly as shown here, whilst winter temperatures are increasing at a rapid rate as shown here.

One could argue here that this occurs mainly because of the different tropical climates that Australia has, and indeed this may well be the case. As northern Australia's summer temperatures do not increase at all, whilst their winter does. And conversely, southern Australia's summer and winter temperatures seem to be increasing. I'm not 100% sure why the tropics summer tends not to increase in temperature. It might be a threshold (its damn hot up there already in summer), or it might be something to do with the humidity. I'm also not sure why the BOM only have a trend going back to 1950 on these graphs, when there clearly is more data available.

In fact, the more data that they could use is that of shown below which compares the summer and winter temperatures based on the standard times of midnight, 3am, 6am, 9am, noon, 3pm, 6pm and 9pm. We have showed previously how the minimum temperature is not a good indication of long term trends at night, so the analysis to come should be interesting.

If CO2 were the major cause of global warming, then we should see a relatively constant increase in temperature in summer when compared to winter across all the times given above. Lets see if we do:

So what do we find? We find that there is no difference between summer and winter trends at night (namely Midnight, 3am and 6am). This is no surprise as we previously found that overnight temperatures have hardly increased over the past 60 years. However something happens at 9am which is quite drastic. All of a sudden summer temperatures at 9am are decreasing at such a rate when compared to winter temperatures.

What does this mean? It means basically that at 9am winter temperatures are increasing quite drastically when compared to summer. This trend is not small either, it is at a rate of 3.1 degrees per 100 years, more than 3 times the world average. Similar trends, but decreasing in nature occur at Noon and 3pm, where as at 6pm and 9pm the trend is reversed.

Interestingly, at 6pm and 9pm the sun will generally still be in the sky and have an influence in summer in Australia, but not in winter. Perhaps this is the reason why summer temperatures are increasing at a greater rate than winter temperatures at this time?

Either way, the trends are extremely strong and disturbing. If CO2 were the major cause of global warming, then we should see a constant trend throughout the day, and when comparing summer and winter trends throughout the day. We see none of this, but rather the opposite.

Perhaps Australia's Cloud Cover levels could be a major contributor to the increasing temperatures that Australia is recording? We shall look at this in the next post.


Chris M said...

"If CO2 were the major cause of global warming, then we should see....... We see none of this, but rather the opposite."

Ha ha... another DENIER! ;-)

Heh, maybe there is just sooooo much CO2 and cow fart gas now the whole climate thing has flicked into reverse or something. Uncle Tim or Uncle Al will explain it all to us in glorious detail no doubt.

Jonathan Lowe said...

want to comment on the analysis chris, or perhaps just involve yourself in a bit of character assignation instead?

Anonymous said...

Welcome back Jonathan.

What does this mean? It means basically that at 9am winter temperatures are increasing quite drastically when compared to summer. This trend is not small either, it is at a rate of 3.1 degrees per 100 years, more than 3 times the world average.

The reason is there to see any any Australian house more than 50 or so years old - An open fire place.

I grew up in the UK, but I doubt it was much different in any southern Australian city in winter, the morning ritual of lighting the fire - very smoky exercise with coal or wood that was not fully dry.

Then in the 60s and 70s came clean air acts that reduced the smokiness of the fuel, and along with increasing gas and electric heating, a dramatic reduction in particulate pollution occured, especially in the early morning in winter.

Less particulate pollution = more sunshine = warmer mornings in winter.

This not only explains your data, it explains the entire 'global warming' phenomena. As almost all the surface warming (GISS, HADCRU) is in Tmin, and Tmin occurs in the early morning precisely when the morning smokiness was at its maximum. And as smokiness declined more sunshine resulted in higher Tmins.


Jonathan Lowe said...

Hi Phillip,
that is a very interesting observation. It might well be the case. If it were, we would expect weather observations from places that are not located near houses or any other commercial or industrial buildings (eg Giles), to be pretty flat across the years.

This is exactly what we find as shown here where there was no increasing or decreasing maximum and minimum temperatures, as well as time based temperatures over the years.

One of the issues with this theory is that there are few and far between weather observation stations that are subject to not being around any nearby structures that might be influenced by smoke or pollution. If anyone knows of any others in Australia, please let me know, but I will look more into this.

Great post Phillip, awesome

Jonathan Lowe said...

Going through this list of what John Daly describes as non urban weather stations in Australia, probably the most non urban stations apart from giles are

Cape Otway
Gabo Island
and Wilsons Prom to a smaller extent

We should also see, if your theory is correct, a smaller increase in temperature closer to the tropics than the south. This is something however that we do not see in Australia according to the BOM's data as shown here

Pollution might be an issue, but it might be a lot more in depth than just smoke pollution.

Phil said...


It's a general misconception that deserts are hot. Most of the time they are cold, relative to higher humidity areas.

Without knowing the distribution of BOM's northern stations, It's hard to say whether morning fires have a similar effect in the North.

If you want to make a comparison look at humid tropical stations where winter fires would be unlikely.

Gotta go. The Test match is about to start. Hope you put some money on Australia. I think they will bowl out England by tea.


Phil said...

looking again at the BoM's data, the winter minimum anomaly trend is much larger in southern Australia than northern Oz. Which is what I would expect.

interestingly the largest trend is here in SW Australia, which may reflect a later switch to gas heating. Wood stoves were common here as recently as 20 years ago.

There is currently a thread at WUWT on aerosol effects on climate. There may well be an aerosol effect on climate, but I'd say the morning smoke effect is larger.

Once again you really need to publish. The whole CO2/GHG theory is built on the argument ' we can't explain the warming any other way.'

Showing that most of the warming is an artifact of using Tmin to determine average temperature is a bombshell.

Phil said...

looking more at the seasonal Tmin trends. There are large trends in spring and summer.

I'd suggest the cause is decreases in agricultural burning and/or perhaps bushfires.

I have no idea how common agricultural burning was in Australia (and google wasn't any help). I know it used to be very common in the UK and has now been stopped completely.

Jonathan Lowe said...

yes burning in the backyard was big. no-one can do it now in Australia. its been gradually pulled out from about 1980 to 1990 and now no longer exists.

Phil said...

Jonathan, you should check out the new thread at WUWT on the Christy paper. Right up your street.

BTW, my comments are under Philip_B

Anonymous said...

Hi Jonathan; great series; the idea that AGW has a variable effect on climate indices and in different regions is a staple of the AGW debate and allows for AGW to fail regionally, daily, globally and annually as Koutsoyiannis showed. The time of day measurement is a vexed one and your analysis goes along way to dealing with that issue. You may be interested in this recent study which purports to predict regional and seasonal differences in climate under the auspices of AGW;

Rafe said...

Hi Jonathan,

have you seen the recent activity on the Pielkes' blogs? This quote in particular struck me:

“[F]rom our papers (Pielke and Matsui 2005 and Lin et al. 2007), a conservative estimate of the warm bias resulting from measuring the temperature near the ground is around 0.21 C per decade (with the nightime T(min) contributing a large part of this bias) . Since land covers about 29% of the Earth’s surface (see), the warm bias due to this influence explains about 30% of the IPCC estimate of global warming. In other words, consideration of the bias in temperature would reduce the IPCC trend to about 0.14 degrees C per decade, still a warming, but not as large as indicated by the IPCC”

Dr T Burns said...

Could this be a UHI effect ?
A low angled sun in winter, would be more influenced by UHI than a summer sun.

Anonymous said...

"If CO2 were the major cause of global warming, then we should see a constant trend"

Why do you propose that? As I understand it, CO2 is a greenhouse gas, and its effect is to amplify other forcings, but why would we expect it to remain constant when you turn a forcing off at night (the sun for instance)

Has this hypothesis (that an increase in CO2 will create a constant trend) been tested?