Archives par mot-clé : Climate Sensivity

Press Release: Important new paper challenges IPCC’s claims about climate sensitivity

by P. Homewood, Sep 20, 2022 in NotaLotofPeopleKnowThat


London, 20 September – A new paper reduces the estimate of climate sensitivity – the amount of warming expected for a doubling of carbon dioxide concentrations – by one third. The results therefore suggest that future global warming will be much less than expected.
The paper, by independent scientist Nic Lewis, has just appeared in the journal Climate Dynamics. It is an important challenge to the official view of the Intergovernmental Panel on Climate Change (IPCC).
Lewis has critiqued a 2020 assessment of climate sensitivity by Sherwood et al., which strongly influenced the IPCC’s Sixth Assessment Report, in 2021. Lewis commented:
“It is unfortunate that Sherwood et al.’s assessment of climate sensitivity, which underpinned the UN Framework Convention on Climate Change, contained such serious errors, inconsistencies and deficiencies in its methods”.
After correcting the Sherwood et al. methods and revising key input data to reflect, primarily, more recent evidence, the central estimate for climate sensitivity comes down from 3.1°C per doubling of CO2 concentration in the original study to 2.16°C in the new paper.
This large reduction shows how sensitive climate sensitivity estimates still are to input assumptions, and that values between 1.5°C and 2°C remain quite plausible.

  • Climate sensitivity represents the long-term global temperature increase caused by a doubling of atmospheric CO2 concentration. There are different measures of climate sensitivity. Both the Sherwood and Lewis papers estimate the so-called ‘effective’ climate sensitivity, which reflects a new equilibrium state projected from centennial changes after a doubling of the CO2 concentration. This measure is considered the most relevant one for predicting climate change in the coming two centuries.
  • Climate sensitivity has always been a very important, but also highly uncertain, parameter in the climate change discourse. Earlier IPCC reports assessed its value as likely to be somewhere between 1.5°C and 4.5°C, with a best estimate of 3°C. However, prompted by the Sherwood paper, the 2021 Sixth Assessment Report moved that range upwards, to 2.5 to 4°C. Although for outsiders this might sound boring, for insiders it was a revolutionary change.
  • Lewis’s corrections and revisions lead to a likely range of 1.75 to 2.7°C, which is not only lower but is also much less uncertain than either the 2021 official IPCC assessment or the very similar Sherwood et al. estimate (2.6 to 3.9°C).
  • Nic Lewis is the lead or sole author of ten peer-reviewed papers on climate sensitivity. He was a participant in the 2015 workshop that kicked off the World Climate Research Programme project that led to the Sherwood et al. 2020 paper, but he was not a co-author of that paper.

Lewis commented:
“The substantial reduction in assessed climate sensitivity upon updating key input data suggests that the increase in the bottom of the climate sensitivity range in the IPCC Sixth Assessment Report was unjustified”.
Lewis’s paper is entitled ‘Objectively combining climate sensitivity evidence’. It can be freely downloaded here. A detailed explanatory article about the paper is available here.

“Revolution Has Begun”: 75,000 Brits To Stop Paying Power Bills Amid Inflation Storm

by T. Durden, Aug 8, 2022 in ZeroHedge


The resistance is growing as more than 75,000 irritated people in the UK have pledged not to pay their electricity bill this fall when prices jump again.

“75,000 people have pledged to strike on October 1st! If the government & energy companies refuse to act then ordinary people will! Together we can enforce a fair price and affordable energy for all,” tweeted “Don’t Pay UK,” an anonymous group spearheading the effort to have more than one million Brits boycott paying their power bill by Oct. 1.

 

Don’t Pay UK believes 6.3 million UK households will be pushed into power bill poverty this winter, with millions more feeling the stress of out-of-control inflation.

People on Twitter responded to the moment by saying, “the Revolution has begun” and “a bit of civil unrest on its way onto our streets & rightly so.”

Perhaps the movement’s involvement will be an excellent proxy for the growing discontent festering among Brits that could result in civil unrest this winter as millions will struggle with keeping the lights on, the furnace hot, and putting food on the table.

New Study: Modelers Got Aerosols All Wrong…CO2 Climate Sensitivity Likely Another 0.4°C Overstated!

by P. Gosselin, Nov 26, 2021 in WUWT


Die kalte Sonne reports on a new aerosol study by Liu et al.

The results are a major blow to the high greenhouse-gas climate sensitivity modelers.

IPCC scientists have a favorite wild card they often use to explain serious model discrepancies: aerosols. Mysterious cooling events in the past are often explained away by aerosols from major volcanic eruptions, for example. They act to filter out sunlight.

ccording to IPCC climate models, the mean global temperature should have risen by 1.5°C since 1850 due to the higher CO2 concentrations. But best estimates show that it has instead risen by only 1.1°C. So what about the missing 0.4°C?

Naturally, the missing 0.4°C of warming since 1850 gets explained by the higher 20th century aerosol levels in the atmosphere – due to the burning of fossil fuels. Air pollution by man over the course of the late 19th century and entire 20th century are said to have dimmed the earth, and thus this explains the 0.4°C less warming.

Surprise: global aerosol emissions have been flat over past 250 years

But now results by a new study appearing in the journal Science Advances by Liu et al tells us that the forcing by aerosols had to have been overestimated by climate modelers. IPCC modelers insisted that 20th century aerosol concentrations were higher than during the pre-industrial times, and this is what kept the climate from warming by 1.5°C.

According to the scientists led by Liu, however, atmospheric aerosols in the preindustrial times were just as high as they were just recently. They were in fact more or less constant over the past 250 years. No change means it could not have been aerosols putting the brakes on temperature rise:

That’s a real embarrassment for the IPCC modelers. It means CO2 climate sensitivity has been overestimated.

Climate Sensitivity to CO2, what do we know? Part 2.

by A. May, July 8, 2021 in WUWT


In Part 1, we introduced the concepts of climate sensitivity to CO2, often called ECS or TCR. The IPCC prefers a TCR of about 1.8°C/2xCO2 (IPCC, 2013, p. 818). TCR is the short-term, century scale, response of surface temperature to a doubling of CO2, we abbreviate the units as “°C/2xCO2.” In these posts we review lower estimates of climate sensitivity, estimates below 1°C/2xCO2. In parallel, we also review estimates of the surface air temperature sensitivity (SATS) to radiative forcing (RF, the units are °C per W/m2 or Watts per square meter). The IPCC estimates this value to be ~0.49°C per W/m2.

The previous post discussed two modern climate sensitivity estimates, by Richard Lindzen and Willie Soon, that range below 1°C/2xCO2. Next, we review climate sensitivity estimates by Sherwood Idso, Reginald Newell and their colleagues.

Many comments to part 1 tried to discredit the “ECS” or “TCR” estimates made by Lindzen and Soon, completely missing their point and my point. ECS and TCR are artificial climate model constructs, with little meaning outside the confines of computer modeling. TCR is a little more realistic since we might be able to observe or measure something close to it over the next century. But ECS, or the “Equilibrium Climate Sensitivity” is a totally abstract and unworldly number that could never be measured. It means if CO2 doubled suddenly, and nothing else changed for several hundred years while the oceans came into equilibrium with the new surface air temperature, what would the final surface temperature be? Air temperature would never be close to equilibrium for several hundred years, even 70 to 100 years (TCR) is a stretch.

Climate models are not the real world and the numbers that come out of them, like ECS or TCR, can be useful for showing the likely direction of temperature movement in response to changes in parameters or different model scenarios, but the numbers themselves are meaningless unless the models have previously been validated against the real world. With the possible exception of the Russian INM-CM4 model, no other IPCC model has successfully predicted future global surface temperatures. Ron Clutz discusses INM-CM4 here.

Model calculations are not observations. ECS and TCR are not real numbers, real numbers are based on observations. Thus, the model extracted values of ECS and TCR are not information, they can be used to detect the direction of change in climate forcing, if the climate model is an accurate reflection of that portion of the real world. The direction of movement of ECS and TCR, when model parameters or data tables change, is the information, not the computed value. I’m often amazed, as a former petrophysical modeler of 42 years, how often otherwise intelligent people confuse unvalidated model calculations with observations.

Settled Science? New Climate Study Shifts the Goalposts to 2.6-3.9C

by Eric Worall, July 24, 2020 in WUWT


A new climate study has dismissed utterly implausible high end climate models. But the new study also seeks to raise the low end of the range of estimated climate sensitivity into the discomfort zone.

The treatment of cloud feedback is interesting. The study acknowledges large cloud feedback uncertainties, mentions the Lindzen et al. (2001) “iris effect”, and admits GCMs cannot be trusted to reproduce observed cloud response, yet still appears to attempt to derive a cloud feedback factor based on satellite observations, and mix this observational cloud factor with model predictions.

The treatment of clouds may turn out to be one of the most controversial assumptions in the study – as Pat Frank has pointed out on a number of occasions, the magnitude of model cloud response error is significantly greater than the CO2 driven warming which models attempt to project, which calls into question whether climate models have any predictive skill whatsoever.

To the author’s credit they have described their method in great detail, so I’m looking forward to detailed responses to this study.

Climate Scientists Step Up the Climate Emergency Narrative

by E. Worrall, June 13, 2020 in WUWT


 

MIP6 Climate Sensitivities. Source Carbon Brief

Guest essay by Eric Worrall

Even worse than we thought ™. Despite a recent sanity test study which demonstrated that high end climate models hindcast impossible Eocene temperatures, climate scientists are pushing ahead anyway with their new, even more extreme climate projections.

 

Continuer la lecture de Climate Scientists Step Up the Climate Emergency Narrative

The List Grows – Now 100+ Scientific Papers Assert CO2 Has A Minuscule Effect On The Climate

by K. Richard, December 12, 2019 in NoTricksZone


Within the last few years, over 50 papers have been added to our compilation of scientific studies that find the climate’s sensitivity to doubled CO2 (280 ppm to 560 ppm) ranges from <0 to 1°C. When no quantification is provided, words like “negligible” are used to describe CO2’s effect on the climate. The list has now reached 106 scientific papers.

Link: 100+ Scientific Papers – Low CO2 Climate Sensitivity

A few of the papers published in 2019 are provided below: