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According to the climate models used by the IPCC and other climate alarmists, the mid-troposphere should be rapidly warming if increasing CO2 is a forcing for warming. If this warming does not occur roughly as predicted then the climate models are proved to be worse than useless. The ‘fingerprint’ evidence of anthropogenic warming due to increasing CO2 is predicted to be a pronounced ‘hotspot’ in the troposphere between latitudes 30N and 30S (which comprises exactly half the surface of the earth) at a height of around 10km (cruising altitude for jet planes), see below for expected change during the 20th century from the latest IPCC report. Obviously, if anthropogenic global warming is going to ‘take off’ this century, then this hotspot will be considerably more pronounced in the 21st century. The models used by the IPCC predict warming of the troposphere some 12 km high at the rate of 4-5 degrees per century for this century. This hotspot is absolutely essential if the climate models have any validity at all.
Other climate models predict the same thing: here are four others (showing effect of doubling of CO2). Note that all predict a pronounced tropospheric ‘hotspot’ 10km up and between the tropics.
However, this hotspot has never been found – if it had been, we would certainly have heard about it, shouted from the rooftops by the climate alarmists. This missing fingerprint that they are peculiarly silent about (for obvious reasons) invalidates their models. It shows their models and their whole hypotheses to be trash. Below are the actual measured anomalies, and it is evident that not the slightest hotspot can be found.
Time series measured data for mid-troposphere temperature anomalies in the tropics since 1978 is shown below. Notice that there is no trend over 30 years (though a pronounced recent cooling trend!) even though the temperatures in the mid-troposphere are supposed to be shooting up! Current temperatures in the mid-troposphere are around 0.2 degrees below the 20-year 1979-98 average.
Below is a regression plot showing the historical warming/cooling rate of the mid-troposphere from this data over time periods in months (horizontal axis). [Note: it is not significant trying to look at trends over periods of less than a few years, so no values are shown for a period less than 4 years (48 months)].
What this shows us is that the trend calculated over the period from today back to 96 months (8 years) ago is strongly negative, a cooling rate of more than 3 degrees per century. Apart from one blip, one has to extend the dataset to 180 months (15 years) to find a trend that is zero (neither warming nor cooling). The trend in mid-troposphere temperature taking data as far back as 14 years is thus a cooling one – exactly the opposite of what is required by the models.
Extending the data back more than 15 years reveals a very slight warming trend over such periods, but as the dataset is enlarged further back in time, the size of this warming decreases. Taken over 360 months (30 years), the warming trend is less than 0.5 degree per century. Remember, the climate models require values an order of magnitude higher than this going forward to resist invalidation (the yellow line on the graph).
Moreover, as the dataset is extended, we see that the trend line appears asymptotic to zero. A few more months of tropospheric cooling (as we have been having in recent years) will bring the trend line even closer to the axis. In other words, the long-term trend in tropospheric heating/cooling is zero, the hotspot is not appearing, and the ‘fingerprint’ evidence of anthropogenic global warming is nowhere to be seen.
There is no doubt about it: anthropogenic global warming is a con.