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There’s brand new published, peer-reviewed literature out showing that CO2’s impact on global warming is far less than what was once previously suggested. Time to end the climate hype.

Of course some alarmism-addicted readers will insist that we ignore these findings, and blindly accept the alarmist scenarios.

CO2 getting pushed aside as a climate driver by natural climate factors like solar activity. Photo: NASA, public domain

At Dr. Sebastian Lüning’s and Prof. Fritz Vahrenholt’s Die kalte Sonne site, the two experts have reviewed the recent literature on CO2’s ability to warm the globe, which we call CO2 climate sensitivity. Their conclusion: estimations of CO2 climate sensitivity are “in a free-fall”.

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By Dr. Sebastian Lüning and Prof. Fritz Vahrenholt

(German text translated/edited by P Gosselin)

Numerous new studies show that the previously assumed estimate value used by the IPCC of 3.0°C warming per doubling of CO2 is far too high. In 2013 a publication by von Otto et al. suggested 2.0°C, a thunderbolt. […] Today again we have a collection of newly published results that vary over a broad range in equilibrium climate sensitivity (ECS) and the short-term Transient Climate Response (TCR). The usually given quoted values are the ECS values.

ECS: Equilibrium climate sensitivity



Up to 6°C Proistosescu & Huybers 2017

Press release here; A truly alarm-fraught paper that is trying to be the quoted in the 6th IPCC report and to drive the mean value of all studies upwards. Nic Lewis dismantled the paper in detail at Climate Audit.

3,7°C Brown & Caldeira 2017

This one as well is an upper range outlier. It draws the research funding.

2,8°C Cox et al. 2018; limitation to 2.2-3.4°C

Press release here. The German press reported on this energetically: FAZ, Tagesspiegel, Spektrum

1,79°C Mauritsen & Pincus 2017

Also see post here at Die kalte Sonne.

1,4°C Orssengo 2018

1,3°C Spencer 2018

Scenario: only 70% of the warming of the past 150 years is anthropogenic. The possible climate impact by the sun in most calculations of climate sensitivity is not included at all.

By comparison in our ‘Die kalte Sonne’ book we present a 1.5°C scenario. That’s in the lower range of the IPCC AR5 report, 1.5-4.5°C.

TCR: Transient Climate Response



1.32 °C Mauritsen & Pincus 2017

See Die kalte-Sonne post here.

1.29°C Bosse 2017

1.10°C Christy & McNider 2017

See report at WUWT.

By comparison: the TCR average of all climate models in the IPCC AR5 report was 2.31°C.

“Seismic shift”

All this points to a seismic shift in the understanding of CO2 climate sensitivity in the now being drafted 6th IPCC Report.

The ‘best estimated value’ will in any case move considerably downward. That of course is already causing a lot of bellyaching among the climate warriors, and so the world is preparing in advance for the changes. For example Knutti et al. 2017 wrote in Nature Geoscience, that in any case greenhouse gas emissions will have to limited, no matter if the CO2 climate sensitivity value is possibly lower:

Beyond equilibrium climate sensitivity

[…] Newer metrics relating global warming directly to the total emitted CO 2 show that in order to keep warming to within 2 °C, future CO 2 emissions have to remain strongly limited, irrespective of climate sensitivity being at the high or low end.”

Here the authors are not mentioning that values at the lower end of the spectrum represent a less dramatic situation than a value at the higher end of the spectrum, which probably would have really supported a climate catastrophe.

The time for justification has already started. Also just a few months ago Millar et al. 2017 had to admit that the climate models indeed had been running much too hot and that the 1.5°C target can be reached as well with a tripling of CO2 emissions.

Others, however, simply just do not want to accept the new reality. A team led by Kate Marvel (among them also the known climate activist Gavin Schmidt) claimed in February, 2018, in the Geophysical Research Letters that the real temperature trend of the last decades are not suitable for calculating CO2 climate sensitivity. Much more correct would be the theoretical computer simulations. This left some speechless. Nic Lewis analyzed the paper and discovered a number of problems.

Let the climate sensitivity bazar open!

The run-up to the IPCC 6th Report is already seeing much wrangling. Both sides are going full throttle in the effort of getting their view documented for future quoting. Now the most absurd publications can make their way through if peer-reviewers with similar views can be found.