David M. Hoffer: Is The IPCC Hiding The Decline Yet Again?

  • Date: 30/12/12
  • David M Hoffer, Watts Up With That

In my first two articles on the leaked AR5 Chapter 11 (near-term projections) I looked at the caveats with which the IPCC is now surrounding their projections, and the lengths to which they are going to preserve the alarmist narrative. The caveats go to such ridiculous lengths that there is actually a quote suggesting that reality may well be within, above, or below the range projected by the models. Falsify that! To maintain the alarmist narrative , they characterize record ice extent in the Antarctic as a “slight increase” and make no mention in the executive summary of the projection buried deep in the report that tropical cyclones may decrease in frequency by as much as one third by 2100.

But what of their temperature projections? Do they say how much they expect it to warm up in the next few decades? They do. But these are the high stakes projections for the IPCC because, unlike most of their projections, these ones will be falsified (or not) within the life times of most of this readership. True to form, they’ve surrounded their temperature projections with caveats while taking an interesting approach to maintaining the alarmist narrative.

The projection is for between 0.4 and 1.0 degrees of warming for the period 2016-2035 compared to the period 1986-2005. Now normally when the IPCC gives a range, we expect that their “best guess” is in the centre of the range. But oddly we find this phrase in Chapter 11:

[...] it is more likely than not that actual warming will be closer to the lower bound of 0.4°C than the upper bound of 1.0°C

In fact, they go out of their way elsewhere to suggest that the most likely outcome will be about 0.2 degrees per decade. With 2035 only a smidge over two decades away, how do they justify an upper bound 2.5 times their most likely scenario? While delving into this, I came across some rather interesting information. Here’s the graphs they provide with their projections for the beginning of the reference period (1986-2005) through to the year 2050:

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Figure 11.33: Synthesis of near-term projections of global mean surface air temperature. a) 4 Projections of global mean, annual mean surface air temperature (SAT) 1986–2050 (anomalies relative to 1986–2005) under all RCPs from CMIP5 models (grey and coloured lines, one ensemble member per model), with four observational estimates (HadCRUT3: Brohan et al., 2006; ERA-Interim: Simmons et al., 2010; GISTEMP: Hansen et al., 2010; NOAA: Smith et al., 2008) for the period 1986–2011 (black lines); b) as a) but showing the 5–95% range for RCP4.5 (light grey shades, with the multi-model median in white) and all RCPs (dark grey shades) of decadal mean CMIP5 projections using one ensemble member per model, and decadal mean observational estimates (black lines). The maximum and minimum values from CMIP5 are shown by the grey lines. An assessed likely range for the mean of the period 2016–2035 is indicated by the black solid bar. The ‘2°C above pre-industrial’ level is indicated with a thin black line, assuming a warming of global mean SAT prior to 1986–2005 of 0.6°C. c) A synthesis of ranges for the mean SAT for 2016–2035 using SRES CMIP3, RCPs CMIP5, observationally constrained projections (Stott et al., 2012; Rowlands et al., 2012; updated to remove simulations with large future volcanic eruptions), and an overall assessment. The box 1 and whiskers represent the likely (66%) and very likely (90%) ranges. The dots for the CMIP3 and CMIP5 estimates show the maximum and minimum values in the ensemble. The median (or maximum likelihood estimate for Rowlands et al., 2012) are indicated by a greyband.

Is the first graph serious? 154 data plots all scrambled together are supposed to have some meaning? So I started to focus on the second graph which is presented in a fashion that makes it useful. But in examining it, I noticed that something is missing. I’ll give everyone 5 minutes to go back and see if they can spot it for themselves.

Tick

Tick

Tick

Did you spot it?

They hid the decline! In the first graph, observational data ends about 2011 or 12. In the second graph though, it ends about 2007 or 8. There are four or five years of observational data missing from the second graph. Fortunately the two graphs are scaled identically which makes it very easy to use a highly sophisticated tool called “cut and paste” to move the observational data from the first graph to the second graph and see what it should have looked like:

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Well oops. Once on brings the observational data up to date, it turns out that we are currently below the entire range of models in the 5% to 95% confidence range across all emission scenarios. The light gray shading is for RCP 4.5, the most likely emission scenario. But we’re also below the dark gray which is all emission scenarios for all models, including the ones where we strangle the global economy.

It gets worse.

I did a little back of the envelope math (OK, OK, a spreadsheet, who has envelopes anymore these days?) and calculated that, assuming a linear warming starting today, we’d need to get to 1.58 degrees above the reference period to get an average of +1.0 over the course of the reference period itself. If my calcs are correct, extarpolating a straight line from end of current observations through 1.6 degrees in 2035 ought to just catch the top of that black bar showing the “Likely Range” in the centre of the graph:

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Hah! Nailed it!

But now it is even worse for the IPCC. To meet the upper bound of their estimated range, the IPCC would need warming that (according to their own data) is below projections for all their models in all emission scenarios to suddenly increase to a rate higher than all their projections from all their models across all emission scenarios. In brief, the upper range of their estimate cannot be supported by their own data from their own models.

In fact, just based on their own graph, we’ve seen less than 0.4 degrees over the last 26 years or so, less than 2 degrees per century. That brown line I’ve drown in represents a warming trend beginning right now and continuing through 2035 of 6 degrees per century, triple recent rates. Since the range in their own graph already includes scenarios such as drastic reductions in aerosols as well as major increases in CO2, there simply is no justification in their own data and their own models to justify an upper bound of 1.0 degrees.

That’s not to say it is impossible, I suppose it is possible. It is also possible that I will be struck by lightning twice tomorrow and survive, only to die in airplane crash made all the more unlikely by the fact that I’m not flying anywhere tomorrow, so that plane will have to come and find me. Of course with my luck, the winning Powerball ticket will be found in my wallet just to cap things off.

Is it possible? Sure. Is it likely?

Not according to their own data and their own models. The current version of IPCC AR5 Chapter 11 takes deception (intended or otherwise) to new heights. First, by hiding the fact that observational data lies outside the 95% confidence range of their own models, and second by estimating an upper range of warming that their own models say is next to impossible.

Watts Up With That, 30 December 2012