by Willis Eschenbach, March 24, 2018 in WUWT
Much has been made of the argument that natural forcings alone are not sufficient to explain the 20th Century temperature variations. Here’s the IPCC on the subject:
(…)
I’m sure you can see the problems with this. The computer model has been optimized to hindcast the past temperature changes using both natural and anthropogenic forcings … so of course, when you pull a random group of forcings out of the inputs, it will perform more poorly.
by David Archibald, March 10, 2018 on WUWT
This recent post discussed the end of the Modern Warm Period and the year that global cooling began. That post was inspired by a comment to a post on WUWT six to eight years ago to the effect that climate is controlled by the Sun’s magnetic flux – no need to worry about much else. The comment seemed to come from a warmer scientist – they are well funded, have plenty of time on their hands, some are smart and idle curiosity would get a few looking into what controls climate. The results would not be published of course. To paraphrase Mussolini, everything within the narrative, nothing outside the narrative, nothing against the narrative. If the Sun’s magnetic flux controls climate, you don’t have to worry about what goes on under the hood – the effect of EUV on the NAO, the GCR flux, the F10.7 flux, any other flux apart from the magnetic flux (…)
by Dr Roy Spencer, February 22, 2018 in GlobalWarming
UPDATE(2/23/18): The previous version of this post had improper latitude bounds for the HadCRUT4 Tsfc data. I’ve rerun the results… the conclusions remain the same. I have also added proof that ENSO is accompanied by its own radiative forcing, a controversial claim, which allows it to cause multi-decadal climate change. In simple terms, this is clear evidence the climate system can cause its own, natural, internally-generated climate changes. This is partly what has caused recent warming, and the climate modelling community has assumed it was all human-caused.
by K. Richard, February 22, 2018 in NoTricksZone
According to the United Nations Intergovernmental Panel on Climate Change (UN-IPCC) and computer modeling, the Sun’s role in modern-era climate change checks in at somewhere slightly above nothing.
And yet it is increasingly evident that more and more scientists across the globe do not take the position that the Sun’s influence on climate change is negligible.
In 2016 and 2017, for example, over 250 papers (see here and here) linking the Sun to climate changes were published in scientific journals.
by Ron Clutz, January 31, 2018 inClimateChangeDispatch
The question could be paraphrased in these words: Why are there differences between various graphs that report changes in global temperatures?
The short answer is: The differences arise both from what is measured and how the measurements are processed. (…)
by FLORIDA MUSEUM OF NATURAL HISTORY, January 23, 2018, in WUWT, A. Watts
The researchers published their findings this week in the Proceedings of the National Academy of Sciences.
Scientists frequently look to the Eocene to understand how the Earth responds to higher levels of carbon dioxide. During the Eocene, the concentration of carbon dioxide in the atmosphere was more than 560 parts per million, at least twice preindustrial levels, and the epoch kicked off with a global average temperature more than 8 degrees Celsius – about 14 degrees Fahrenheit – warmer than today, gradually cooling over the next 22 million years. These characteristics make the Eocene a good period on which to test our understanding of the climate system, said Laura Cotton, study co-author and curator of micropaleontology at the Florida Museum of Natural History.
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.
(…)
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.
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.
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.
by Paul Gosselin, December 23, 2017 in NoTricksZone
At the German Die kalte Sonne site here, Dr. Sebastian Lüning and Prof. Fritz Vahrenholt present another two recent papers showing that models are failing to simulate the climate and cannot be used to make prognoses.
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).
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.
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.
by Antero Ollila, November 21, 2017 in WUWT
The error of the IPCC climate model is about 50% in the present time. There are two things that explain this error:
1) There is no positive water feedback in the climate, and 2) The radiative forcing of carbon dioxide is too strong.
See also here
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.
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?
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.
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.
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.”
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.
by Douglas Maraun et al., November 2, 2017 in Nature
Biases in climate model simulations introduce biases in subsequent impact simulations. Therefore, bias correction methods are operationally used to post-process regional climate projections. However, many problems have been identified, and some researchers question the very basis of the approach.
by Pat Frank, October 23, 2017 in WUWT
Regular readers at Anthony’s Watts Up With That will know that for several years, since July 2013 in fact, I have been trying to publish an analysis of climate model error.
The analysis propagates a lower limit calibration error of climate models through their air temperature projections. Anyone reading here can predict the result. Climate models are utterly unreliable. For a more extended discussion see my prior WUWT post on this topic (thank-you Anthony).
by CERN Courier, November 11, 2017
Future global climate projections have been put on more solid empirical ground, thanks to new measurements of the production rates of atmospheric aerosol particles by CERN’s Cosmics Leaving OUtdoor Droplets (CLOUD) experiment
by T. Edimburgh and J. Day, November 21, 2017, in TheCryopshere
In stark contrast to the sharp decline in Arctic sea ice, there has been a steady increase in ice extent around Antarctica during the last three decades, especially in the Weddell and Ross seas. In general, climate models do not to capture this trend and a lack of information about sea ice coverage in the pre-satellite period limits our ability to quantify the sensitivity of sea ice to climate change and robustly validate climate models
by Michel de Rougemont, September 30, 2017 in WUWT
(…) We are left with conjectures and other speculation, both in the recent past and for the future. For this, climatologists develop models with which they can test their hypotheses. But these models are obviously overheating. (…)
See also here