A Free-Market Energy Blog

On RCP 8.5 IPCC Exaggeration

By Robert Bradley Jr. -- April 12, 2023

“The IPCC reports have become ‘bumper sticker’ climate science—making a political statement while using the overall reputation of science to give authority to a politically manufactured consensus. With such explicit political advocacy, combined with misleading information, the IPCC risks losing its privileged position in international policy debates.” (- Doug Sheridan)

Doug Sheridan speaks truth to power on energy and climate issues. In a recent social media post, he brings attention to an article by Judith Curry in The Australian, “UN’s Climate Panic Is More Politics than Science,” that emphasized how the IPCC markets a warming extremism that is three times the size of its medium-case scenario. [1]

Sheridan’s summary follows:

Judith Curry writes in the Australian, all but few holdouts now recognize that the IPCC‘s worst-case RCP8.5 climate scenario never really deserved the attention it was given. Few now believe global temps ever had a chance to rise by 4.3C in 2100 as forecasted in the oft-cited scenario.

For these and other reasons, the climate “crisis” clearly isn’t what it used to be. Yet, rather than acknowledging this fact as good news, the IPCC and United Nations officials are doubling down on the “alarm” regarding the urgency of reducing emissions by eliminating fossil fuels.

This is odd. You’d think that if warming is less than thought, then the priorities would shift away from emissions reductions and towards reducing our vulnerability to weather and climate extremes. However, that hasn’t been the case.

To those paying attention, this isn’t surprising. For years, the IPCC has been characterised as a “knowledge monopoly,” with its dominant authority in the UN climate deliberations. It claims it is “policy-neutral” and “never policy-prescriptive.” In reality it has strayed far from its chartered role of assessing the scientific literature in support of policymaking. The entire framing of IPCC reports is now around the mitigation of climate change through emissions reductions.

Not only has the IPCC increasingly taken on a stance of explicit political advocacy, but it is misleading policymakers by its continued emphasis on extreme climate outcomes driven by the implausible extreme emissions scenarios.

The impact of these alarming IPCC reports and rhetoric by UN officials is that climate change has become a grand narrative in which human-caused climate change has become a dominant cause of societal problems. Everything that goes wrong reinforces the conviction that there is only one thing we can do to prevent societal problems—stop burning fossil fuels.

This grand narrative leads us to think that if we solve the problem of burning fossil fuels, then these other problems would also be solved. This belief leads us away from a deeper investigation of the true causes of these other problems.

The end result is a narrowing of the viewpoints and policy options that we are willing to consider in dealing with complex issues such as energy systems, water resources, public health, weather disasters, and national security.

To Sum It Up: The IPCC reports have become “bumper sticker” climate science—making a political statement while using the overall reputation of science to give authority to a politically manufactured consensus. With such explicit political advocacy, combined with misleading information, the IPCC risks losing its privileged position in international policy debates.

Judith Curry remains the most unpolarizing climate scientist in the world today, offering her sober comments on the peer-reviewed literature at Climate Etc. Her forthcoming book, Climate Uncertainty and Risk: Rethinking Our Response, is scheduled for release this June. (Previous posts at MasterResource on Dr. Curry can be found here.)

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[1] Curry notes in her article:

The most important finding of the past 5 years is that the extreme emissions scenarios RCP8.5 and SSP5-8.5, commonly referred to as “business-as-usual” scenarios, are now widely recognized as implausible. These extreme scenarios have been dropped by UN Conference of the Parties to the UN Climate Agreement. However, the new Synthesis Report continues to emphasize these extreme scenarios, while this important finding is buried in a footnote:

“Very high emission scenarios have become less likely but cannot be ruled out.”

…  the amount of warming projected for the remainder of the 21st century under the medium emissions scenario is only about one third of the warming projections under the extreme emissions scenario.

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