Archives par mot-clé : IPCC

La croissance du CO2 dans l’atmosphère est-elle exclusivement anthropique? (3/3)

by J.C. Maurin, 19 juillet 2019 in ScienceClimatEnergie


Effet Bombe et Modèles du GIEC

Les prévisions du climat sont générées par des modèles informatiques. Leurs concepteurs pensent pouvoir décrire l’état moyen de l’atmosphère en 2100, en prenant comme principale donnée d’entrée, le taux futur de CO2 qui constituerait donc le ‘bouton de commande’ du climat.

Il y a deux étages de modélisation : on commence par prévoir le taux de CO2 en 2100 avec des modèles sélectionnés par le GIEC (ces modèles « IRF » du GIEC sont l’objet de l’article).
Cette prévision constitue ensuite l’entrée du second étage, à savoir les modèles types « échanges radiatifs » ou « effet de serre » qui ne sont pas traités ici (mais on peut consulter ceci).
Le présent article ( qui est la suite de deux autres ici et ici) compare la réponse impulsionnelle théorique de ces modèles « IRF » avec la réponse impulsionnelle observée du 14CO2(effet Bombe).

NO EXPERIMENTAL EVIDENCE FOR THE SIGNIFICANT ANTHROPOGENIC CLIMATE CHANGE

by J. Kauppinen and P. Malmi, July 13, 2019 in Physics.gen-ph


Abstract. In this paper we wil lprove that GCM-models used inI IPCC report AR5 fail to calculate the influences of the low cloud cover changes on the global temperature. That is why those models give a very small natural temperature change leaving a very large change for the contribution of the green house gases in the observed temperature. This is the reason why IPCC has to use a very large sensitivity to compensate a too small natural component. Further they have to leave out the strong negative feedback due to the clouds in order to magnify the sensitivity. In addition, this paper proves that the changes in the low cloud cover fraction practically control the global temperature.

1. Introduction

The climate sensitivity has an extremely large uncertainty in the scientific lit- erature. The smallest values estimated are very close to zero while the highest ones are even 9 degrees Celsius for a doubling of CO2. The majority of the papers are using theoretical general circulation models (GCM) for the estimation. These models give very big sensitivities with a very large uncertainty range. Typically sensitivity values are between 2–5 degrees. IPCC uses these papers to estimate the global temperature anomalies and the climate sensitivity. However, there are a lot of papers, where sensitivities lower than one degree are estimated without using GCM. The basic problem is still a missing experimental evidence of the cli- mate sensitivity. One of the authors (JK) worked as an expert reviewer of IPCC AR5 report. One of his comments concerned the missing experimental evidence for the very large sensitivity presented in the report [1]. As a response to the com- ment IPCC claims that an observational evidence exists for example in Technical Summary of the report. In this paper we will study the case carefully.

2. Low cloud cover controls practically the global temperature

Human CO2 Emissions Have Little Effect on Atmospheric CO2

by Edwin X Berry , June, 2019 in JAtmOceanSciences


Abstract
The United Nations Intergovernmental Panel on Climate Change (IPCC) agrees human CO2 is only 5 percent and natural CO2 is 95 percent of the CO2 inflow into the atmosphere. The ratio of human to natural CO2 in the atmosphere must equal the ratio of the inflows. Yet IPCC claims human CO2 has caused all the rise in atmospheric CO2 above 280 ppm, which is now 130 ppm or 32 percent of today’s atmospheric CO2. To cause the human 5 percent to become 32 percent in the atmosphere, the IPCC model treats human and natural CO2 differently, which is impossible because the molecules are identical. IPCC’s Bern model artificially traps human CO2 in the atmosphere while it lets natural CO2 flow freely out of the atmosphere. By contrast, a simple Physics Model treats all CO2 molecules the same, as it should, and shows how CO2 flows through the atmosphere and produces a balance level where outflow equals inflow. Thereafter, if inflow is constant, level remains constant. The Physics Model has only one hypothesis, that outflow is proportional to level. The Physics Model exactly replicates the 14C data from 1970 to 2014 with only two physical parameters: balance level and e-time. The 14C data trace how CO2 flows out of the atmosphere. The Physics Model shows the 14 CO2 e-time is a constant 16.5 years. Other data show e-time for 12CO2 is about 4 to 5 years. IPCC claims human CO2 reduces ocean buffer capacity. But that would increase e-time. The constant e-time proves IPCC’s claim is false. IPCC argues that the human-caused reduction of 14C and 13C in the atmosphere prove human CO2 causes all the increase in atmospheric CO2. However, numbers show these isotope data support the Physics Model and reject the IPCC model. The Physics Model shows how inflows of human and natural CO2 into the atmosphere set balance levels proportional to their inflows. Each balance level remains constant if its inflow remains constant. Continued constant CO2 emissions do not add more CO2 to the atmosphere. No CO2 accumulates in the atmosphere. Present human CO2 inflow produces a balance level of about 18 ppm. Present natural CO2inflow produces a balance level of about 392 ppm. Human CO2 is insignificant to the increase of CO2 in the atmosphere. Increased natural CO2 inflow has increased the level of CO2 in the atmosphere.

Sky Abandon Facts In Favour Of Climate Propaganda

by P. Homewood, June 25, 2019 in NotaLotofPeopleKnowThat


As far as climate change is concerned, Sky News have now abandoned all pretensions to factual accuracy, in favour of blatant propaganda.

They have a new 12-minute special report, to set off a week of special reports, but if this trailer is anything to go by it’s going to be the same old garbage the BBC have served up for years:

The use of the word “storms” in the link title, along with the phrase “climate crisis” gives a good idea of the junk that is to follow.

Let’s go through the trailer’s claims and statements:

Climate science’s ‘masking bias’ problem

by Judith Curry, June 22, 2019 in WUWT


How valid conclusions often lay hidden within research reports, masked by plausible but unjustified conclusions reached in those reports.  And how the IPCC institutionalizes such masking errors in climate science.

In the previous post, we discussed the motivated biases of individual climate researchers, stimulated by the paper by Lee Jussim, Joe Duarte and others entitled Interpretations and methods: Towards a more self-correcting social psychology

The Jussim et al. paper provides additional insights that are relevant to the motivated biases in climate change, which become particularly serious and problematic once these biases are institutionalized. Here are additional excerpts from Jussim et al. for the topic I would like to discuss in this post:

<begin quotes>

“In this paper, we consider how valid conclusions often lay hidden within research reports, masked by plausible but unjustified conclusions reached in those reports. These conclusions do not necessarily involve the use of questionable research practices. Invalid conclusions may be reached based, not on failing to report dropped conditions, failed studies, or nonsignificant analyses, but on selective interpretations of data that highlight researchers’ preferred conclusions while masking more valid ones.”

JC comment: This is basically the problem that I have with the IPCC assessment reports. Deep in the chapters, there is much good information that is reliable, although the reports relatively ignore some topics. The problem is with the conclusions that are reached (particularly in the Summary for Policy Makers), and inflated levels of confidence that are ascribed to these conclusions.

La croissance du CO2 dans l’atmosphère est-elle exclusivement anthropique? (1/2) et Effet Suess

by J.C. Maurin, 13 juin 2019 in ScienceClimatEnergie


Une croissance du COatmosphérique qui serait exclusivement anthropique est contradictoire avec les observations du carbone 13 dans l’atmosphère (ici). Cet article en 2 parties va montrer qu’il existe également des contradictions avec les observations du carbone 14. Celui-ci  est utilisé à des fins de datation jusqu’à 50 000 ans BP  (Before Present)et on dispose de nombreuses études (pour calibration) sur son évolution dans l’atmosphère.  


La première partie s’intéresse, non pas aux datations, mais à la dilution du carbone 14 que provoque l’ajout de COanthropique (effet SUESS)  avant les essais thermonucléaires de 1952-1963.
Dans la seconde partie nous verrons que l’évolution du carbone 14 après 1963 est aussi en contradiction avec une croissance du COexclusivement anthropique.

1. Le carbone dans l’atmosphère [1] [5]

Le carbone existe habituellement sous 3 formes isotopiques : 12C pour ≈ 98.9% , 13C pour ≈ 1.1 % et 14C à l’état de traces (Fig. 1a).

Figure 1a.  La seule différence entre COanthropique et COatmosphérique réside dans les proportions du mélange des isotopes: le COanthropique est appauvri en 13C et 14C.  L’ajout de COanthropique va modifier, au fil des années, les proportions du mélange isotopique dans l’atmosphère.

German Government Falsified Key IPCC Statement In The Translation Of “IPCC Summary Report To Policy Makers”!

by Prof. dr. H.J. Lüdecke, May 26 2019 in


(German text translated/edited by P Gosselin)
Was it sloppiness or intent? In the IPCC Summary Report for Policymakers published by the Federal Government in German, the most important statement of the original English report was falsified.

IPCC reports are available as comprehensive status reports and get strongly condensed as reports for policymakers. The latter are not to be taken as IPCC-authorized extracts as the governments concerned are allowed contribute in the writing. As a result, information or formulations from the English IPCC original which do not agree with German politics are often omitted in the German IPCC reports for policymakers. This is popularly called censorship. As a result of such falsifications, the status reports and the corresponding reports for policymakers are often contradiction.

Key finding deleted from Summary for Policymakers

One example in the past was the famous Chapter 2.6 of the AR5 Report, in which the IPCC explained in detail that no increase in extreme weather events could be found in climate periods (about 30 years) from 1950 onwards (beginning of more extensive measurements and statistics). EIKE reported on this. But in the accompanying German IPCC report for policymakers, this IPCC finding, which is hardly trivial, was nowhere to be seen.

Climatologist: Climate Models Are Predicting Too Much Warming

by Dr. Benny Peiser, May 23, 2019 in GWPF


A leading climatologist has said that the computer simulations that are used to predict global warming are failing on a key measure of the climate today and cannot be trusted.

Speaking to a meeting in the Palace of Westminster in London, Professor John Christy of the University of Alabama in Huntsville told MPs and peers that almost all climate models have predicted rapid warming at high altitudes in the tropics:

A paper outlining Dr. Christy’s key findings is published today by the Global Warming Policy Foundation.

Refuting the Smear Machine – Part 1

by Donna Laframboise, Lay 22, 2019 in BigPictureNews


When a journalist thinks for herself about climate change, insults and fabrications follow.

Two days ago I reported that a Washington, DC organization called the Government Accountability Project is smearing me on its website. I explained that PR firms target non-conformist climate reporting in an attempt to police what journalists say.

This story begins with a September 2013 opinion piece written by me and published in the Wall Street Journal. It concerned the Intergovernmental Panel on Climate Change (IPCC), and was headlined:

Warming Up for Another Climate-Change Report
Every six years, a U.N. panel issues its findings, and the media hail them as definitive. Skepticism may be in order.

Within hours, a Rockefeller Foundation funded entity called Climate Nexus released an error-riddled 600-word rebuttal that now resides on the Government Accountability Project’s official-looking website. An organization with ‘accountability’ in its name is smearing me by reprinting material whose actual author remains in the shadows, anonymous to this day.

Line by line, over the course of two blog posts, I will now respond to this collection of factual errors and lazy insults. Let us begin with the first sentence:

‘Gimme Gimme Shock Treatment’

by Joe Bastardi, May 17, 2019 inThePatriotPost


Apparently, the new strategy to fight climate change is shock therapy. It’s like today’s environmental crusaders are channeling the Ramones song “Gimme Gimme Shock Treatment.” Here are some illustrations.

Shock treatment is for extreme measures. But take, for example, this Dr. Willie Soon plot of solar irradiance (a measure of solar energy) vs. water vapor:

Water vapor is the number-one greenhouse gas. So it’s no secret what temperatures do when water vapor increases.

New satellite data confirm real world temperature cooler than climate models

by CFACT, May 2nd, 2019


Newly published data gathered by NASA’s AIRS satellite confirm the Earth is warming more slowly than has been forecast by climate activists and the United Nations Intergovernmental Panel on Climate Change (IPCC). Data gathered from 2003 through 2017 confirm temperatures remained essentially flat from 2003 through 2015, finally rising briefly as a strong El Nino formed in 2015 and lasted into 2016 (https://ggweather.com/enso/oni.htm). Even with El Nino adding an illusory warming spike at the end of the period, temperatures still rose just over 0.2 degrees during the 15-year period. That pace works out to less than 1.5 degrees of warming per century.

IPCC initial forecasts called for 0.3 degrees Celsius of warming per decade, while skeptic forecasts have tended to hover around 0.1 degrees. As temperatures warmed more slowly than IPCC predicted, IPCC reduced its forecasts to meet skeptics in the middle, moving to a predicted 0.2 degrees warming per decade. Even so, the newly published data indicate IPCC continues to forecast more warming than real-world data indicate.

Le GIEC au pays des merveilles

by Drieu Godefridi, 2 mai 2019 in Contrepoints


Réduire le réchauffement global sur Terre de 1,5° ? Dans un récent rapport, le Giec échafaude quatre scénarios pour y parvenir. Mais aucun d’eux ne tient la route.

es quatre scénarios mettent en œuvre à des degrés divers les techniques dites de Carbon Dioxide Removal (CDR), qui compensent les émissions humaines de CO2. Écoutons les experts « scientifiques » du GIEC — dont la plupart ne sont pas scientifiques. Lisons les experts du GIEC :

What’s the worst case? Climate sensitivity

by Judith Curry, April 1, 2019 in WUWT


Are values of equilibrium climate sensitivity > 4.5 C plausible?

For background, see these previous posts on climate sensitivity [link]

Here are some possibilistic arguments related to climate sensitivity.  I don’t think the ECS example is the best one to illustrate these ideas [see previous post], and I probably won’t include this example in anything I try to publish on this topic (my draft paper is getting too long anyways).  But possibilistic thinking does point you in some different directions when pondering the upper bound of plausible ECS values.

5. Climate sensitivity

Equilibrium climate sensitivity (ECS) is defined as the amount of temperature change in response to a doubling of atmospheric CO2 concentrations, after the climate system has reached equilibrium. The issue with regards to ECS is not scenario discovery; rather, the challenge is to clarify the upper bounds of possible and plausible worst cases.

The IPCC assessments of ECS have focused on a ‘likely’ (> 66% probability) range, which has mostly been unchanged since Charney et al. (1979), to be between 1.5 and 4.5 oC. The IPCC AR4 (2007) did not provide any insight into a worst-case value of ECS, stating that values substantially higher than 4.5 oC cannot be excluded, with tail values in Figure 9.20 exceeding 10 oC. The IPCC AR5 (2013) more clearly defined the upper range, with a 10% probability of exceeding 6 oC.

Since the IPCC AR5, there has been considerable debate as to whether ECS is on the lower end of the likely range (e.g., < 3 oC) or the higher end of the likely range (for a summary, see Lewis and Curry, 2018). The analysis here bypasses that particular debate and focuses on the upper extreme values of ECS.

Methane warming exaggerated by 400%

by Barry Brill, March 30, 2019 in WUWT


The IPCC’s AR5 estimated the global warming caused by a tonne of livestock methane would be 28 times that of a tonne of carbon dioxide. New research destroys that estimate.

The war on meat has been gathering pace amongst our Western elites. The Economist makes a detailed case for “plant-based food” in the interests of quelling climate change –

The FAO calculates that cattle generate up to two-thirds of the greenhouse gases from livestock, and are the world’s fifth largest source of methane. If cows were a country, the United Herds of Earth would be the planet’s third largest greenhouse-gas emitter.

These calculations are based on figures supplied by the IPCC’s AR5, which contends that the global warming potential (GWP) of methane over 100 years is no less than 28 times the global warming it expects to be caused by an equivalent weight of carbon dioxide. This estimate is up from the GWP of 21 put forward in the IPCC’s previous report.

All this is now challenged by a new and authoritative research paper, Allen et al (2017): “A solution to the misrepresentations of CO2-equivalent emissions of short-lived climate pollutants, under ambitious mitigation”. This paper finds that conventional GWPs misrepresent the impact of short-lived gases (such as methane) on global temperature – and recommends the adoption of a new metric, denoted as GWP*.

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.