Archives par mot-clé : IPCC

Exagérations climatiques extrêmes

by Jean N., 14 mars 2019 in ScienceClimatEnergie


Il ne se passe pas une journée sans que l’on entende ou lise dans les médias que le climat est “déréglé” et qu’il y a de plus en plus d’évènements climatiques extrêmes. Et de nombreux scientifiques semblent penser la même chose. Par exemple, une pétition publiée fin janvier 2019 et signée par 3400 scientifiques belges, déclare au point 3 : “Le seul réchauffement actuel de 1°C entraîne déjà une augmentation de l’occurrence et de l’intensité des extrêmes climatiques tels que les canicules, les sécheresses ou encore les inondations.” Aucune référence n’est malheureusement donnée par les signataires de la pétition… Ces phénomènes climatiques sont-ils exagérés? Consultons donc le dernier rapport du GIEC, l’AR5 publié en 2013, et particulièrement le chapitre 2 qui traite des évènements climatiques extrêmes (depuis 2013, le GIEC n’a plus rien publié d’aussi complet sur le sujet). Préparez-vous à être surpris!

Figure 1. Extrait de la Table SPM.1 concernant les évènements climatiques extrêmes dans le résumé pour décideurs du rapport AR5 du GIEC. Sur 9 phénomènes climatiques extrêmes seulement 5 sont présentés dans la table par le GIEC. Le texte noir sont des conclusions tirées par l’AR5. Les textes en rouge et en bleu sont des conclusions plus anciennes (AR4 et rapport SREX). A droite, “OK Ch.2” indique que le résumé est correct par rapport au texte; le triangle rouge “attention”, indique que des informations importantes sont manquantes et peuvent induire en erreur.

Circular reasoning with climate models

by Dr. Wojick, March 1, 2018 in CFact


Climate models play a central role in the attribution of global warming or climate change to human causes. The standard argument takes the following form: “We can get the model to do X, using human causes, but not without them, so human causes must be the cause of X.” A little digging reveals that this is actually a circular argument, because the models are set up in such a way that human causes are the only way to get change.

The finding is that humans are the cause of global warming and climate change is actually the assumption going in. This is circular reasoning personified, namely conclude what you first assume.

This circularity can be clearly seen in what many consider the most authoritative scientific report on climate change going, although it is actually just the most popular alarmist report. We are talking about the Summary for Policymakers (SPM), of the latest assessment report (AR5), of the heavily politicized UN Intergovernmental Panel on Climate Change (IPCC). Their 29 page AR5 SPM is available here.

40387018 – the raging whirlpool

Global-scale multidecadal variability missing in state-of-the-art climate models

by S. Kravstov et al. 2018, in Nature


Reliability of future global warming projections depends on how well climate models reproduce the observed climate change over the twentieth century. In this regard, deviations of the model-simulated climate change from observations, such as a recent “pause” in global warming, have received considerable attention. Such decadal mismatches between model-simulated and observed climate trends are common throughout the twentieth century, and their causes are still poorly understood. Here we show that the discrepancies between the observed and simulated climate variability on decadal and longer timescale have a coherent structure suggestive of a pronounced Global Multidecadal Oscillation. Surface temperature anomalies associated with this variability originate in the North Atlantic and spread out to the Pacific and Southern oceans and Antarctica, with Arctic following suit in about 25–35 years. While climate models exhibit various levels of decadal climate variability and some regional similarities to observations, none of the model simulations considered match the observed signal in terms of its magnitude, spatial patterns and their sequential time development. These results highlight a substantial degree of uncertainty in our interpretation of the observed climate change using current generation of climate models.

ClimateGate continues – the Mann Hockeystick University of Arizona emails are now public

by Anthony Watts, March4, 2019 in WUWT


After years of trying to suppress their release, and finally being ordered to be released by a judge, they are now public, and we have them here. This will remain as a “top post” for a day, new stories will be below this one.

There’s quite a treasure trove, but also some duplications from previous releases.

L’art de gommer les incertitudes

by Jean, N. 2 mars 5019 in ScienceClimatEnergie


Comme déjà mentionné dans un article précédent publié sur SCE, la variation de la couverture nuageuse a probablement un effet majeur sur la température moyenne globale de la basse atmosphère. Si l’on veut prédire le climat du futur comme le prétend le GIEC il faut savoir modéliser la formation des nuages. Que nous dit le dernier rapport scientifique (AR5) du GIEC à ce sujet? Le but du présent article est simplement de vous présenter quelques phrases tirées de ce rapport. La science est-elle dite?

1. Le chapitre 7 du rapport AR5 publié par le GIEC en 2013

Le chapitre 7 du rapport AR5 du GIEC[1] fait 60 pages et est consacré aux nuages et aux aérosols (le rapport AR5 complet fait au total 1535 pages). Ce chapitre 7 comporte 22 pages de références et cite plus de 1100 articles scientifiques publiés dans des revues aussi prestigieuses que Science, Nature ou PNAS. Le chapitre 7 a été écrit sous la direction de Olivier Boucher (France) et David Randall (USA), deux spécialistes du domaine. Nous n’allons pas ici remettre en question la validité de ce chapitre. Nous allons simplement vous présenter quelques phrases tirées du rapport. Comme le rapport est écrit en anglais nous vous proposerons ci-dessous une “traduction maison” des phrases qui nous paraissent les plus importantes, assorties parfois de quelques explications pour bien les comprendre. Les lettres entre crochets ([A] à [P]) renvoient simplement au texte original en anglais, donné en Annexe du présent article.

Refutation of the the Belgian climate manifesto by the Climate Intelligence Foundation.

by Dr. Hans Labhom, February 8, 2019, in WUWT


Terrifying climate propaganda

Irresponsible misuse of models

Science differs from religion because theoretical claims have to be verified with observations. If model results can predict measurements in advance (which is quite different than explaining them afterwards!) then you can say the model validated and then apply it in practice. But if that is not the case, then you cannot sell the model as truth and using it in practice is irresponsible.

Far more complicated than simple, linear CO2 relationship

The current climate model (‘IPCC model’) systematically yields highly overstated predictions compared to measurements and can therefore not be used to form climate policy – especially if that policy results in extremely high costs and destabilises vital parts of the energy infrastructure.
We are not just saying that. Already some of the most renowned scientists have preceded us (e.g. Freeman Dyson, Frederic Seitz, Robert Jastrow, William Nierenberg), including Nobel Prize winners (e.g. Ivar Giaever and Robert Laughlin). They also argue that the earth’s climate is far too complicated to be explained by a simple one-dimensional CO2 relationship.

Reassessing the RCPs

by Kevin Murphy in Judith Curry, January 28, 2019 in ClimateEtc.


A response to: “Is RCP8.5 an impossible scenario?”. This post demonstrates that RCP8.5 is so highly improbable that it should be dismissed from consideration, and thereby draws into question the validity of RCP8.5-based assertions such as those made in the Fourth National Climate Assessment from the U.S. Global Change Research Program.

Analyses of future climate change since the IPCC’s 5th Assessment Report (AR5) have been based on representative concentration pathways (RCPs) that detail how a range of future climate forcings might evolve.

Several years ago, a set of RCPs were requested by the climate modeling research community to span the range of net forcing from 2.6 W/m2 to 8.5 W/m2 (in year 2100 relative to 1750) so that physics within the models could be fully exercised. Four of them were developed and designated as RCP2.6, RCP4.5, RCP6.0 and RCP8.5. They have been used in ongoing research and as the basis for impact analyses and future climate projections.

Figure 2. History and forecasts of CO2 concentration. RCP8.5 is defined by 936 ppm in 2100.

NEW PAPER DOCUMENTS MAIN REASONS FOR INTERNATIONAL CONTROVERSY ABOUT THE IPCC’S SR1.5 REPORT

by  Press Release, GWPF, December 20, 2018


London, 20 December: One of Europe’s most eminent climate scientists has documented the main scientific reasons why the recent UN climate summit failed to welcome the IPCC’s report on global warming of 1.5°C.

In a paper published today by the Global Warming Policy Foundation Professor Ray Bates of University College Dublin explains the main reasons for the significant controversy about the latest IPCC report within the international community.

The IPCC’s Special Report on a Global Warming of 1.5°C (SR1.5) was released by the Intergovernmental Panel on Climate Change (IPCC) in advance of the recent COP24 meeting in Katowice, Poland, but was not adopted by the meeting due to objections by a number of governments.

Professor Bates examines some key aspects of the SR1.5 report. He assesses if the IPCC report exhibits a level of scientific rigour commensurate with the scale of its extremely costly and highly disruptive recommendation that carbon emissions be reduced to zero by mid-century.

The paper concludes that such a level of scientific rigour is not present in the report. Specifically, SR1.5 is deficient in scientific rigour in the following respects:

 

Simplest climate model yet – a bathtub

by Charles the moderator, January 18, 2019 in WUWT


Climate change: How could artificial photosynthesis contribute to limiting global warming?

Scientists calculate areas needed for forestation and artificial photosynthesis.

After several years during which global emissions at least stagnated, they rose again somewhat in 2017 and 2018. Germany has also clearly missed its climate targets. In order to keep global warming below 2 degrees Celsius, only about 1100 gigatonnes of CO2 may be released into the atmosphere by 2050[1]. And In order to limit global warming to 1.5 degrees, only just under 400 gigatonnes of CO2 may be emitted worldwide. By 2050, emissions will have to fall to zero even. Currently, however, 42 gigatonnes of CO2 are added every year.

Almost all the various scenarios require “negative emissions”

Does the IPCC say we have until 2030 to avoid catastrophic global warming?

by Patrick T. Brown, January 12, 2019 in WUWT


In late 2018 the Intergovernmental Panel on Climate Change (IPCC) released a report on the impacts associated with global warming of 1.5°C (2.7°F) above preindustrial levels (as of 2019 we are at about 1.0°C above pre-industrial levels) as well as the technical feasibility of limiting global warming to such a level. The media coverage of the report immediately produced a meme that continues to persist. The meme is some kind of variation of the following:

The IPCC concluded that we have until 2030 (or 12 years) to avoid catastrophic global warming

However, these headlines are essentially purveying a myth. I think it is necessary to push back against this meme for two main reasons:

1) It is false.

2) I believe that spreading this messaging will ultimately undermine the credibility of the IPCC and climate science more generally.

Taking these two points in turn:

1) The IPCC did not conclude that society has until 2030 to avoid catastrophic global warming.

The credibility gap between predicted and observed global warming

by Christopher Monckton of Brenchley, January 10, 2019 in WUWT


The prolonged el Niño of 2016-2017, not followed by a la Niña, has put paid to the great Pause of 18 years 9 months in global warming that gave us all such entertainment while it lasted. However, as this annual review of global temperature change will show, the credibility gap between predicted and observed warming remains wide, even after some increasingly desperate and more or less openly prejudiced ever-upward revisions of recent temperatures and ever-downward depressions in the temperatures of the early 20th century in most datasets with the effect of increasing the apparent rate of global warming. For the Pause continues to exert its influence by keeping down the long-run rate of global warming.

Going Nowhere Fast on Climate, Year After Year

by Paul Bledsoe, December 2018 in TheNewYorkTimes


Three decades after a top climate scientist warned Congress of the dangers of global warming, greenhouse gas emissions keep rising and so do global temperatures.

Thirty years ago, a NASA scientist, James Hansen, told lawmakers at a Senate hearing that “global warming is now large enough that we can ascribe with a high degree of confidence a cause-and-effect relationship with the greenhouse effect.” He added that there “is only 1 percent chance of accidental warming of this magnitude.”

By that, he meant that humans were responsible.

His testimony made headlines around the United States and the world. But in the time since, greenhouse gas emissions, the global temperature average and cost of climate-related heat, wildfires, droughts, flooding and hurricanes have continued to rise.

Recently Dropping Global Temperatures Demonstrate IPCC Claims are Impossible

by Tim Ball, December 29, 2018 in WUWT


When you put the claims of the Intergovernmental Panel on Climate Change (IPCC) in perspective, you get a very different picture that defies logic. I decided to do this because of their recent hysterical claims in Special Report 15 (SR-15) designed to frighten and bully the world into completely unnecessary and enormously expensive environmental and energy policies. Charles Steele summarized their claims and proposed policies in his article, “Climate Doom Ahead? Think Twice,”

IPCC’s Special Report Slammed By Eminent Climate Scientist

by P. Homewood, December 20, 2018 via GWPF


The significance of this new GWPF report by Prof Ray Bates of the Meteorology and Climate Centre at University College Dublin cannot really be overstated:

GWPF Briefing 36

This is the press release:

London, 20 December: One of Europe’s most eminent climate scientists has documented the main scientific reasons why the recent UN climate summit failed to welcome the IPCC’s report on global warming of 1.5°C.
In a paper published today by the Global Warming Policy Foundation Professor Ray Bates of University College Dublin explains the main reasons for the significant controversy about the latest IPCC report within the international community.
The IPCC’s Special Report on a Global Warming of 1.5°C (SR1.5) was released by the Intergovernmental Panel on Climate Change (IPCC) in advance of the recent COP24 meeting in Katowice, Poland, but was not adopted by the meeting due to objections by a number of governments.