by Michel de Rougemont
Not so innocent as it looks, a pertinent question is asked by Judith Curry on Twitter:
How much of a change in cloudiness would it take to account for the 0.53 W/m2 increase in TOA radiative forcing since 2003?
https://twitter.com/curryja/status/1375144537522204672
Posted in Sensitivity & feedbacks
By Nic Lewis
An important paper, Wang et al.[1], on the relationships between cloud feedback, climate sensitivity (ECS) and aerosol-cloud interaction in the latest generation of global climate models (CMIP6) has just been published. The key conclusion of the paper is:
The seeming consistency of global-mean temperature evolution between more positive cloud feedback (high ECS) models and observations requires a strong aerosol indirect cooling effect that leads to an interhemispheric temperature evolution that is inconsistent with observations.
Posted in climate models, Sensitivity & feedbacks
By Nic Lewis
A critique of the paper “Greater committed warming after accounting for the pattern effect”, by Zhou, Zelinka, Dessler and Wang. Continue reading
Posted in Sensitivity & feedbacks
by Kenneth Fritsch
Abstract. An analysis is presented of he disconnection between the CMIP5 and CMIP6 Historical and Future periods when considering the relationship of the individual model GMST changes and the climate sensitivity. I have included a simple model that can account for the period disconnection using the negative forcing of aerosol/cloud effects in the Historical period that is carried forward into the Future period. I attribute some of the uncertainty in simulations of this simple model to endogenous model decision (selection) uncertainty that leads to variations in the changes of the negative forcing in the Historical period carried forward into the Future period.
Posted in climate models, Sensitivity & feedbacks
By Nic Lewis
An important new paper by Thorsten Mauritsen, Associate Professor at Stockholm University[i] and myself has just been accepted for publication (Lewis and Mauritsen 2020)[ii]. Its abstract reads: Continue reading
Posted in Sensitivity & feedbacks
By Nic Lewis
This is a brief comment on a new paper[i] by a mathematician in the Exeter Climate Systems group, Femke Nijsse, and two better known colleagues, Peter Cox and Mark Williamson. I note that Earth Systems Dynamics published the paper despite one of the two peer reviewers recommending against acceptance without further major revisions. But neither of the reviewers appear to have raised the issue that I focus on here. Continue reading
A new paper finds higher than expected CO2 fertilization inferred from leaf to global observations. The paper predicts that the Earth is going to gain nearly three times as much green matter as was predicted by the IPCC AR5.
Posted in Sensitivity & feedbacks
by Judith Curry
A range of scenarios for global mean surface temperature change between 2020 and 2050, derived using a semi-empirical approach. All three modes of natural climate variability – volcanoes, solar and internal variability – are expected to act in the direction of cooling during this period.
Posted in climate models, Sensitivity & feedbacks, Solar, Uncertainty
by Ross McKitrick
Challenging the claim that a large set of climate model runs published since 1970’s are consistent with observations for the right reasons.
Posted in climate models, Sensitivity & feedbacks
by Judith Curry
Is 3 C warming over the 21st century now the ‘best estimate’? A reframing of how we think about climate change over the 21st century, and my arguments for 1 C.
Posted in Sensitivity & feedbacks
By Nic Lewis
In an earlier article here I discussed a Comment on Lewis and Curry 2018 (LC18) by Kevin Cowtan and Peter Jacobs (CJ20), and a Reply from myself and Judith Curry recently published by Journal of Climate (copy available here). I wrote that I would defer dealing with the differences between observed and CMIP5 model-simulated historical warming, which formed the basis of CJ20’s numerical analysis, until a subsequent article. I now do so. Continue reading
Posted in climate models, Sensitivity & feedbacks, Uncategorized
Tagged climate feedback, climate sensitivity
By Nic Lewis
A comment on LC18 (recent paper by Lewis and Curry on climate sensitivity) by Cowtan and Jacobs has been published, along with our response.
Posted in Sensitivity & feedbacks
By Nic Lewis
The recently published open-access paper “How accurately can the climate sensitivity to CO2 be estimated from historical climate change?” by Gregory et al.[i] makes a number of assertions, many uncontentious but others in my view unjustified, misleading or definitely incorrect.
Posted in Sensitivity & feedbacks, Uncategorized
Tagged climate feedback, climate sensitivity, regression, statistics
Posted in climate models, Prediction, Sensitivity & feedbacks
by Alberto Zaragoza Comendador
How sensitive is the Earth’s climate to greenhouse gases? Speaking about carbon dioxide in particular, how much would air temperatures increase if we doubled atmospheric concentrations of said gas?
Posted in Sensitivity & feedbacks
by Frank Bosse
A demonstration that multidecadal variation since 1950 leads to overestimation of the Transient Climate Response (TCR).
Posted in Sensitivity & feedbacks
By Nic Lewis
An observational estimate of transient (multidecadal) warming relative to cumulative CO2 emissions is little over half that per IPCC AR5 projections.
AR5 claims that CO2-caused warming would be undiminished for 1000 years after emissions cease, but observations indicate that it would halve. Continue reading
Posted in climate models, IPCC, Sensitivity & feedbacks
By Nic Lewis
A critique of of a new paper by Andrews et al., Accounting for changing temperature patterns increases historical estimates of climate sensitivity.
Posted in climate models, Sensitivity & feedbacks
by Judith Curry
We need to raise the bar on how we think about the possible worst case scenario for climate change.
Posted in Sensitivity & feedbacks
by Nic Lewis
We have now updated the LC15 paper with a new paper that has been published in the Journal of Climate “The impact of recent forcing and ocean heat uptake data on estimates of climate sensitivity“. The paper also addresses critiques of LC15.
Posted in Sensitivity & feedbacks, Uncategorized
Posted in Sensitivity & feedbacks
