What the climate scientists tell us:
Dr Karl Braganza in The Conversation on 14/06/2011 lists the “fingerprints” of climate change (my bold).
These fingerprints show the entire climate system has changed in ways that are consistent with increasing greenhouse gases and an enhanced greenhouse effect. They also show that recent, long term changes are inconsistent with a range of natural causes…..
…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 in polar regions than tropical regions
- greater warming over the continents than the oceans
- greater warming of night time temperatures than daytime temperatures
- greater warming in winter compared with summer
- a pattern of cooling in the high atmosphere (stratosphere) with simultaneous warming in the lower atmosphere (tropopause).
Similarly, greater global warming at night and during winter is more typical of increased greenhouse gases, rather than an increase in solar radiation.
Time for a reality check. I will look at the 3rd and 4th points above, that is, Diurnal Temperature Range and winter warming. Again, I am using publicly available data directly from the Bureau of Meteorology’s Time Series Graphs datasets at
What the Australian climate record tells us:
From 1910 to 2012, on an annual basis it is absolutely true- the Diurnal Temperature Range for Australia has indeed decreased:
But here’s a 4th order polynomial trend line:
So let’s check DTR since 1950:
Decreasing Diurnal Temperature Range, one of the “fingerprints” of climate change, “uniquely associated with the enhanced greenhouse effect”, is not happening in Australia. For 63 years, well and truly long enough to determine a trend, DTR has been flat- in fact slightly increasing.
Dr Braganza made his statement in June 2011, so here is the data from 1970 to 2010.
It is plain that there was NO decrease in DTR for the previous 41 years. By 14/06/2011 Dr Braganza, as Manager of Climate Monitoring at the Bureau of Meteorology, would have had access to this data, so he certainly should have known.
What about winters warming more than summers? Annual means 1910 to 2012:
To 2010 (available to Dr Braganza):
Can you tell the difference? Very slightly, by the tiniest margin, there was more winter warming to 2010- but remember the Bureau’s goal is to reduce temperature uncertainty to +/- 0.2C, so this increase is indistinguishable from no difference at all. Greater winter than summer warming is not detectable in the Australian data. Dr Braganza knew this too.
While winter maxima have been increasing, winter minima have been dead flat for 34 years:
and annual minima have been decreasing for 27 years, while maxima have been increasing:
and summer and winter trends are similarly diverging:
These trends will have to reverse drastically for the fingerprints of diminishing DTR and relatively warmer winters to appear. No doubt Dr Braganza is not hoping for any more “Angry Summers” as those record maxima tend to smudge the fingerprints.
Dr Karl Braganza has failed to reveal that there is absolutely no evidence for the enhanced greenhouse effect in DTR and winter warming trends in Australia.
The Australian data are NOT consistent with an enhanced greenhouse effect. There is evidence that it has been smothered by negative feedbacks.
Two of Dr Braganza’s five fingerprints are missing.
Two down, three to go before the enhanced greenhouse effect is acquitted for lack of evidence.
h/t to Lance