by F. Vahrenholt, Aug 11, 2021 in NoTricksZone
Now we look at the new IPCC report.
The new IPCC report: climate change 2021 – widespread, rapid, worsening climate change
The new IPCC 6th Assessment Report published on Monday, August 9th, makes a clear statement in the title of its “Summary for Policymakers”: Climate change is continuing to spread rapidly at an accelerated pace.
What are the main changes compared to the 5th Assessment Report of 2013?
1. Global warming from 1850 to the present is reported to have been 1.07 °C. The warming from 2011 to 2020 increased by 0.19°C since the last reporting period from 2003 to 2012.
2. There are new models (CMIP6), but some of them produced completely implausible results (Science, Paul Voosen: U.N. Climate Panel confronts implausibly hot forecasts of future warming). Since CO2’s influence was assumed to be too strong, the backward modelling of the temperature development of the last millennia of some models led to unrealistically cold temperatures. Looking into the future, many models ran too hot. Even Gavin Schmidt of the NASA GISS Institute, who is close to the IPCC, stated: “insanely scary – and wrong”.
As a result, the models relied on by the IPCC were constrained. Nevertheless, the holy grail of climate research, the climate sensitivity ECS (temperature increase with doubling of CO2) was raised. Until now, the IPCC calculated a temperature increase range of 1.5° to 4.5° Celsius with a doubling of the CO2 concentration from 280 ppm (1850) to 560 ppm in the future. Against the background of the new models, the IPCC now gives a temperature range of 2° to 5°C, with a narrower confidence interval of 2.5°C to 4°C. They even venture so far as to assign a mean value for climate sensitivity of 3°C for a doubling of CO2.
Entire Holocene warmth gets airbrushed
3. Surprisingly, the IPCC has deleted the Medieval Warm Period (MWP) from 900 to 1200 from the climate report and thus from humanity’s climate memory. The first graph in the report, SPM.1, shows the temperature curve for the last 2000 years. From year 1 onwards, the curve shows a steadily decreasing trend until 1850, after which the temperature rises sharply until today. A new hockey stick has been created. So the IPCC can claim that it has never been as warm as it is today for 125,000 years.
Numerous scientific publications (I was involved in five of them) document that the Medieval Warm Period was about as warm as today (as described in the 5th State of the Climate Report).
But now even the period of 6500 to 8500 years ago is also rewritten as cold. That was the time when hippos roamed the Sahara and shortly afterwards, Ötzi wandered over the Ötztal Alps. Dozens of publications had proven that the temperatures at that time were 3 degrees higher than today. All no longer true. (see “Unwanted truths”, p.34 to p.54). In the last IPCC report of 2013 it was still stated: “On a continental scale, temperature reconstructions of the medieval climate anomaly (years 950 to 1250 show with high confidence intervals of decades that were as warm in some regions as in the late 20th century.