Talking about the implications of any given climate model, or any suite of model projections, is very tricky as '... all models are wrong but some models are useful". Thus when reading the information from the first linked reference (& associated article), please bear in mind the limitations of the cited analyses and also the message from my immediate prior post (Reply #2131) that a CERN-type of global modeling effort (comparable to E3SM on steroids) following physical laws is justified by the many climate uncertainties:
Zeke Hausfather et al. (04 December 2019), "Evaluating the performance of past climate model projections", Geophysical Research Letters,
https://doi.org/10.1029/2019GL085378https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL085378AbstractRetrospectively comparing future model projections to observations provides a robust and independent test of model skill. Here we analyse the performance of climate models published between 1970 and 2007 in projecting future global mean surface temperature (GMST) changes. Models are compared to observations based on both the change in GMST over time and the change in GMST over the change in external forcing. The latter approach accounts for mismatches in model forcings, a potential source of error in model projections independent of the accuracy of model physics. We find that climate models published over the past five decades were skillful in predicting subsequent GMST changes, with most models examined showing warming consistent with observations, particularly when mismatches between model‐projected and observationally‐estimated forcings were taken into account.
Plain Language SummaryClimate models provide an important way to understand future changes in the Earth's climate. In this paper we undertake a thorough evaluation of the performance of various climate models published between the early 1970s and the late 2000s. Specifically, we look at how well models project global warming in the years after they were published by comparing them to observed temperature changes. Model projections rely on two things to accurately match observations: accurate modeling of climate physics, and accurate assumptions around future emissions of CO2 and other factors affecting the climate. The best physics‐based model will still be inaccurate if it is driven by future changes in emissions that differ from reality. To account for this, we look at how the relationship between temperature and atmospheric CO2 (and other climate drivers) differs between models and observations. We find that climate models published over the past five decades were generally quite accurate in predicting global warming in the years after publication, particularly when accounting for differences between modeled and actual changes in atmospheric CO2 and other climate drivers. This research should help resolve public confusion around the performance of past climate modeling efforts, and increases our confidence that models are accurately projecting global warming.
See also:
Title: "Early climate modelers got global warming right, new report finds"
https://news.berkeley.edu/2019/12/04/early-climate-modelers-got-global-warming-right-new-report-finds/Extract: "Climate skeptics have long raised doubts about the accuracy of computer models that predict global warming, but it turns out that most of the early climate models were spot-on, according to a look-back by climate scientists at the University of California, Berkeley, Massachusetts Institute of Technology and NASA.
Of 17 climate models published between the early 1970s and the late 2000s, 14 were quite accurate in predicting the average global temperature in the years after publication, said Zeke Hausfather, a doctoral student in UC Berkeley’s Energy and Resources Group and lead author of a new paper analyzing the models.
“The real message is that the warming we have experienced is pretty much exactly what climate models predicted it would be as much as 30 years ago,” he said. “This really gives us more confidence that today’s models are getting things largely right as well.”
…
One of the iconic climate models, and one that first brought the issue of climate change to broad public attention, was published by James Hansen of NASA in 1988. However, his predictions for temperatures after 1988 were 50% higher than the actual global mean temperatures in those years.
That is in part because Hanson did not anticipate the Montreal Protocol, a treaty that went into effect in 1989 and which banned chlorofluorocarbons, which are potent greenhouse gases. His estimates of future methane emissions were also off, Hausfather said.
“If you account for these and look at the relationship in his model between temperature and radiative forcing, which is CO2 and other greenhouse gases, he gets it pretty much dead on,” he said. “So the physics of his model was right. The relationship between how much CO2 there is in the atmosphere and how much warming you get, was right. He just got the future emissions wrong.”"
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Title: "Even 50-year-old climate models correctly predicted global warming"
https://www.sciencemag.org/news/2019/12/even-50-year-old-climate-models-correctly-predicted-global-warmingExtract: "Climate change doubters have a favorite target: climate models. They claim that computer simulations conducted decades ago didn’t accurately predict current warming, so the public should be wary of the predictive power of newer models. Now, the most sweeping evaluation of these older models—some half a century old—shows most of them were indeed accurate.
“How much warming we are having today is pretty much right on where models have predicted,” says the study’s lead author, Zeke Hausfather, a graduate student at the University of California, Berkeley."
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J. Hansen et al. (28 Aug 1981), "Climate Impact of Increasing Atmospheric Carbon Dioxide", Science, Vol. 213, Issue 4511, pp. 957-966, DOI: 10.1126/science.213.4511.957
https://science.sciencemag.org/content/213/4511/957AbstractThe global temperature rose by 0.2°C between the middle 1960's and 1980, yielding a warming of 0.4°C in the past century. This temperature increase is consistent with the calculated greenhouse effect due to measured increases of atmospheric carbon dioxide. Variations of volcanic aerosols and possibly solar luminosity appear to be primary causes of observed fluctuations about the mean trend of increasing temperature. It is shown that the anthropogenic carbon dioxide warming should emerge from the noise level of natural climate variability by the end of the century, and there is a high probability of warming in the 1980's. Potential effects on climate in the 21st century include the creation of drought-prone regions in North America and central Asia as part of a shifting of climatic zones, erosion of the West Antarctic ice sheet with a consequent worldwide rise in sea level, and opening of the fabled Northwest Passage.
Edit, see also:
http://www.realclimate.org/index.php/archives/2019/12/how-good-have-climate-models-been-at-truly-predicting-the-future/