UN IPCC AR5 climate reports: Conjecture disguised as certainty

UN IPCC WG report process fails to integrate critical information

Guest essay by Larry Hamlin

The world has experienced over the last 15+ years a remarkable absence of increasing global temperatures despite huge and growing increases in global CO2 emissions by the globes developing nations and despite claims by the UN IPCC that global temperature increases are dangerously out of control because of increasing atmospheric CO2 levels. This embarrassing dichotomy is demonstrated in the diagram below.

The UN IPCC has completed its three part (WGI, WGII, WGIII) Fifth Assessment Report (AR5) process where future climate findings are portrayed using “level of confidence” and “assessed likelihood” qualifiers that attempt to cast these outcomes in a cloak of scientific certainty.

Much of the analysis underlying these “level of confidence” and “assessed likelihood” climate findings are based upon the computer output obtained through the use of climate models identified as Representative Concentration Pathways (RCP’s) cases 2.6, 4.5, 6.0 and 8.5 scenarios. Climate model RCP2.6 represents a low future CO2 emissions scenario case and climate model RCP8.5 represents a high future CO2 emissions scenario.

Future climate model temperature projections show higher global temperatures and increased climate risk with larger levels of atmospheric CO2 scenarios (RCP8.5) and lower global temperatures and reduced climate risk with less  atmospheric CO2 scenarios (RCP2.6).

As addressed in the WGI Technical Summary report all climate model scenarios have significant scientific analysis limitations which are defined as: “The scenarios should be considered plausible and illustrative, and do not have probabilities attached to them.” Thus there are no defined standards of accuracy associated with the climate model outputs and further these computer temperature outputs are to be considered to be simply “plausible and illustrative”.

In Chapter 11 of the WGI report an analysis of the climate model scenarios is carried out for the time period 2005 through 2035 by comparing the computer projected temperature outputs to actual observed global temperatures. This analysis shows that all climate model scenarios from RCP2.6 to RCP8.5 exaggerate and overstate higher global temperatures as a function of levels of atmospheric CO2 as shown in Figure 11.25a below.

As a consequence an estimate of future likely global temperature increase to the year 2035 is developed in WGI using “expert assessment” instead of relying on the exaggerated climate model computer generated temperature projections. This “expert assessment” likely future global temperature range is shown in Figure 11.25b as shown below.

This WGI “expert assessment” estimate lies at the very low end of the RCP CMIP5 climate model 2.6, 4.5, 6.0 and 8.5 scenario projected temperature ranges as indicated in the diagram below which is derived from Figure 11.25c.

The WGI report climate model temperature projection analysis through the year 2035 demonstrates not only that the models exaggerate future higher global temperature increases but also that relying on these model scenario outputs beyond 2035 and all the way to the year 2100 is highly questionable, unjustified and an extremely speculative analytical approach.

The WGI report demonstrates and documents that the RCP climate model scenarios have significant analytical limitations with no defined standards of accuracy, outcomes that are considered to be simply “plausible and illustrative” and that these scenarios exaggerate and overstate higher global temperatures as a function of atmospheric CO2 levels even to periods as close as the year 2035 let alone the year 2100.

Yet the WGII and WGIII climate risk assessment reports conceal these significant analytical and performance shortcomings of the climate model scenarios and instead base the projected future CO2 driven global temperature levels upon the computer output from these flawed and failed climate models.

The diagram below from the WGII SPM report shows the scenarios RCP2.6 to RCP8.5 that are used to define and bound the low to high emissions global temperature range used to assess climate risks. The WGI analysis of the estimated future global temperature increase to year 2035 clearly suggests the RCP2.6 scenario range is more likely to characterize the behavior of future global temperatures than RCP8.5.

Amazingly the WGII and WGIII reports derive the majority of their future climate risk concerns not from RCP2.6 but rather from RCP8.5 despite the clear scientific evidence contained the WGI report that CO2 driven higher temperature model projections are overstated and exaggerated.

Thus the climate alarmist findings from the UN IPCC WGII and WGIII climate risk assessments are based upon computer temperature outputs which have no defined standards of accuracy, are merely considered to be “plausible and illustrative” and are known to exaggerate and overstate higher global temperatures as a function of atmospheric CO2 level. Furthermore these findings are cloaked in illusive “level of confidence” and “assessed likelihood” qualifiers that attempt to hide the conjecture underlying these results.

The UN IPCC AR5 report process is in fact a process founded upon conjecture but presented and disguised as certainty.