Archives par mot-clé : Model(s)

Emergent constraint on equilibrium climate sensitivity from global temperature variability

by P.M. Cox et al., January 18, 2018 in Nature


Equilibrium climate sensitivity (ECS) remains one of the most important unknowns in climate change science. ECS is defined as the global mean warming that would occur if the atmospheric carbon dioxide (CO2) concentration were instantly doubled and the climate were then brought to equilibrium with that new level of CO2.

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This metric of variability can also be calculated from observational records of global warming3, which enables tighter constraints to be placed on ECS, reducing the probability of ECS being less than 1.5 degrees Celsius to less than 3 per cent, and the probability of ECS exceeding 4.5 degrees Celsius to less than 1 per cent.

Study: Climate models underestimate cooling effect of daily cloud cycle

by Princeton University, January 10, 2018 in WUWT


Princeton University researchers have found that the climate models scientists use to project future conditions on our planet underestimate the cooling effect that clouds have on a daily — and even hourly — basis, particularly over land.

The researchers report in the journal Nature Communications Dec. 22 that models tend to factor in too much of the sun’s daily heat, which results in warmer, drier conditions than might actually occur. The researchers found that inaccuracies in accounting for the diurnal, or daily, cloud cycle did not seem to invalidate climate projections, but they did increase the margin of error for a crucial tool scientists use to understand how climate change will affect us.

Study: Climate models underestimate cooling effect of daily cloud cycle

by Princeton University, January 10, 2018 in A. Watts WUWT


Princeton University researchers have found that the climate models scientists use to project future conditions on our planet underestimate the cooling effect that clouds have on a daily — and even hourly — basis, particularly over land.

The researchers report in the journal Nature Communications Dec. 22 that models tend to factor in too much of the sun’s daily heat, which results in warmer, drier conditions than might actually occur. The researchers found that inaccuracies in accounting for the diurnal, or daily, cloud cycle did not seem to invalidate climate projections, but they did increase the margin of error for a crucial tool scientists use to understand how climate change will affect us.

La modélisation du climat, science ou scientisme ?

by Uzbek, 21 novembre 2017, in Climato-Réalistes


Les prévisions climatiques à très long terme (2100) sont établies à l’aide de modèles qui ne sont rien d’autre des logiciels très complexes, dont le but est de reproduire le comportement du climat terrestre.

Comme on ne peut pas décrire ce qui se passe en tous les points de la terre, celle-ci est découpée en mailles de quelques centaines de kilomètres de côté. Les modèles utilisés par le GIEC pour son cinquième rapport d’évaluation (2013) avaient des résolutions relativement grossières (supérieures à 100 km). La situation évolue toutefois rapidement et les modèles climatiques les plus récents auraient une résolution plus fine (de l’ordre de 20 km).

Egalement ici et ici

Causal feedbacks in climate change

by E.H. van Nes et al., March 30, 2015 in Nature Climate Change


The statistical association between temperature and greenhouse gases over glacial cycles is well documented, but causality behind this correlation remains difficult to extract directly from the data.

We show that such variable time lags are typical for complex nonlinear systems such as the climate, prohibiting straightforward use of correlation lags to infer causation.

Core of climate science is in the real-world data

by Eric Worrall, November 22, 2017 in WUWT


Figure 1 shows one example of data derived from such proxy sources. The top panel of the figure shows a declining temperature trend over the 8,000-year period from the Holocene Climate Optimum to the modern warm period (left-hand scale). It also shows that this location experienced numerous cycles of warming and cooling that involved temperature changes of the order of two degrees Celsius.

John Christy’s Testimony To Congress NOVEMBER 2

by Paul Homewood, November 25, 2017 in NotaLotofPeopleKnowThat


“Science” is not a set of facts but a process or method that sets out a way for us to discover information and which attempts to determine the level of confidence we might have in that information. In the method, a “claim” or “hypothesis” is stated such that rigorous tests might be employed to test the claim to determine its credibility. If the claim fails a test, the claim is rejected or modified then tested again.

Reconciling Model-Observation Reconciliations

by Steve McIntyre, November 18, 2017 in ClimateAudit


(…) What does this all mean? Are models consistent with observations or not?  Up to the recent very large El Nino, it seemed that even climate scientists were on the verge of conceding that models were running too hot, but the El Nino has given them a reprieve. After the very large 1998 El Nino, there was about 15 years of apparent “pause”. Will there be a similar pattern after the very large 2017 El Nino?

Israeli Astrophysicist rejects UN IPCC – Finds ‘the sun completely overturns the way we should see global warming’

by Dr. Shaviv, November 9, 2017 in ClimateDepot


(…)The body of evidence however clearly shows that the climate sensitivity is on the low side, about 1 to 1.5 degree increase per CO2 doubling. People in the climate community are scratching their heads trying to understand the so called hiatus in the warming. Where is the heat hiding? While in reality it simply points to a low sensitivity.

Freeman Dyson on ‘heretical’ thoughts about global warmimg

by Freeman Dyson, November 10, 2017 in WUWT FREEMAN DYSON is professor of physics at the Institute for Advanced Study, in Princeton. His professional interests are in mathematics and astronomy


My first heresy says that all the fuss about global warming is grossly exaggerated. Here I am opposing the holy brotherhood of climate model experts and the crowd of deluded citizens who believe the numbers predicted by the computer models. Of course, they say, I have no degree in meteorology and I am therefore not qualified to speak.

But I have studied the climate models and I know what they can do.

New Literature Strongly Suggests CO2 Residence Time In The Atmosphere Is Exaggerated!

by Dr S. Lüning and Prof. F. Vahrenholt, March 26, 2017,  in NoTricksZone


In addition, we consider temperature dependent natural emission and absorption rates, by which the paleoclimatic CO2 variations and the actual CO2 growth rate can well be explained. The anthropogenic contribution to the actual CO2concentration is found to be 4.3%, its fraction to the CO2 increase over the Industrial Era is 15% and the average residence time 4 years.”

What You Won’t Find in the New National Climate Assessment

by Dr Pat Michaels, November 3, 2017 in WUWT


Under the U.S. Global Change Research Act of 1990, the federal government has been charged with producing large National Climate Assessments (NCA), and today the most recent iteration has arrived. It is typical of these sorts of documents–much about how the future of mankind is doomed to suffer through increasingly erratic weather and other tribulations. It’s also missing a few tidbits of information that convincingly argue that everything in it with regard to upcoming 21st century climate needs to be taken with a mountain of salt.