copenlu/druid huggingface dataset:
Claim: climate models have overestimated the amount of global warming and failed to predict what climatologists call the warming ‘hiatus’ (James Barrett, 2017-09-19)
Evidence (2017-05-04): Between about 1998 and 2012, a time that coincided with political negotiations for preventing climate change, the surface of Earth seemed hardly to warm. This phenomenon, often termed the ‘global warming hiatus’, caused doubt in the public mind about how well anthropogenic climate change and natural variability are understood. Here we show that apparently contradictory conclusions stem from different definitions of ‘hiatus’ and from different datasets. A combination of changes in forcing, uptake of heat by the oceans, natural variability and incomplete observational coverage reconciles models and data. Combined with stronger recent warming trends in newer datasets, we are now more confident than ever that human influence is dominant in long-term warming. [...] After a spike in global-mean temperature associated with the 1998 El Niño, the climate system experienced several years of reduced warming, and perhaps even slight cooling. This period, variously termed the 'hiatus', 'pause' or 'slowdown', should have come as no surprise given our understanding of El Niño and natural climate variability. However, soon after the recognition of the reduced warming, it appeared that models and observations were diverging, raising the question of whether the models were missing important processes. Although global warming has since recommenced, the hiatus sparked an enormous research effort. Iselin Medhaug et al. synthesize the literature and reassess the model and observational evidence. Their assessment reconciles the apparent contradictions between models and data and obviates the need to revise our understanding of the underlying physics of climate systems. The hiatus was an episode of natural variability after all.
Claim: climate models have overestimated the amount of global warming and failed to predict what climatologists call the warming ‘hiatus’ (James Barrett, 2017-09-19)
Evidence (2017-09-22): Climate models have, in fact, successfully projected the rate of global warming, comparing well with observed global temperature in recent years. The idea that models should be faulted for not predicting the "hiatus"—the period in the early 2000s during which temperatures stayed below the long-term trend—reflects a misunderstanding of what a model projection is. [...] Misleading: Climate model projections show average long-term trends—by nature they will not "predict" short-term variability such as the "hiatus" period. [...] Statements that climate models overestimate the warming in response to CO2 are incorrect; they are based on either too short time periods that are dominated by natural variability, by the comparison of models with datasets that do not have global coverage, by comparing to models that were run many years ago with emissions and forcings that differed from what actually happened, by the use of oversimplified energy balance models1, or a combination of these. Recent studies have shown that once the changes in climate feedbacks over time2, datasets with full coverage3, and all forcings are considered, the agreement between predicted and observed warming is excellent, even over the recent hiatus period4.
Claim: climate models have overestimated the amount of global warming and failed to predict what climatologists call the warming ‘hiatus’ (James Barrett, 2017-09-19)
Evidence (2019-06-28): The article selectively quotes from interviews and scientific papers to create the false perception that climate models significantly overestimate the rate of warming. The article also falsely implies that the cited paper is about the so called "hiatus" while the paper is actually about the carbon budget for the 1.5 ºC target. [...] FEATURED ANNOTATIONS "Climate Models Have Overestimated Global Warming" [...] - Santer et al (2017) Causes of differences in model and satellite tropospheric warming rates, Nature Geoscience "The team of climate scientists notes that in failing to predict the warming ‘hiatus’ in the beginning of the 21st century, the Intergovernmental Panel on Climate Change (IPCC) models overestimated temperature increases…"
Claim: climate models have overestimated the amount of global warming and failed to predict what climatologists call the warming ‘hiatus’ (James Barrett, 2017-09-19)
Evidence (2017-02-06): The report claimed that the ‘pause’ or ‘slowdown’ in global warming in the period since 1998 – revealed by UN scientists in 2013 – never existed, and that world temperatures had been rising faster than scientists expected. Launched by NOAA with a public relations fanfare, it was splashed across the world’s media, and cited repeatedly by politicians and policy makers. [...] The paper was published in June 2015 by the journal Science. Entitled ‘Possible artifacts of data biases in the recent global surface warming hiatus’, the document said the widely reported ‘pause’ or ‘slowdown’ was a myth. [...] Some scientists argued that the existence of the pause meant the world’s climate is less sensitive to greenhouse gases than previously thought, so that future warming would be slower. One of them, Professor Judith Curry, then head of climate science at the Georgia Institute of Technology, said it suggested that computer models used to project future warming were ‘running too hot’.
Claim: climate models have overestimated the amount of global warming and failed to predict what climatologists call the warming ‘hiatus’ (James Barrett, 2017-09-19)
Evidence (2015-08-01): As the MDV was overlooked, its contribution to global warming is wrongly attributed to the secular trend, resulting in an overestimate of anthropogenic warming rate in the second half of the twentieth century, which can lead to poor capability of climate models to predict the recent hiatus (Scafetta 2010, 2012, 2013). However, the MDV has contributed to the evolution of GMST considerably, accounting for 40% of the warming over the last half century (Tung and Zhou 2013) or 60% since 1970 (Scafetta 2010), and the warming and cooling decades were the visible manifestation of different phases of MDV. So, its significance needs to be reflected in the definition of warming hiatus. Tung et al. (2014) described warming hiatus as a recurrent pause in the global warming rate. This motivated us to develop a method to define the global warming hiatus based on the rate of temperate change. According to the phases of MDV extracted from the ensemble GMST time series by local and adaptive ensemble empirical-mode decomposition (EEMD) method, a quantitative definition of warming hiatus is introduced. Section 2 describes the data and method used in this study. Section 3 elaborates the quantitative definition of warming hiatus and other three critical episodes in GMST multidecadal evolution. Section 4 shows 50-yr statistical predictions of MDV and secular trend. Summary and discussion are given in section 5.
Claim: climate models have overestimated the amount of global warming and failed to predict what climatologists call the warming ‘hiatus’ (James Barrett, 2017-09-19)
Evidence (2014-04-23): The climate change resulting from human-caused emissions of carbon dioxide will persist for decades to millennia. Self-reinforcing cycles within the climate system have the potential to accelerate human-induced change and even shift Earth’s climate system into new states that are very different from those experienced in the recent past. Future changes outside the range projected by climate models cannot be ruled out, and due to their systematic tendency to underestimate temperature change during past warm periods, models may be more likely to underestimate than to overestimate long-term future change. [...] While climate models incorporate important climate processes that can be well quantified, they do not include all of the processes that can contribute to feedbacks, compound extreme events, and abrupt and/or irreversible changes, including key ice sheet processes and arctic carbon reservoirs.25,185,200 The systematic tendency of climate models to underestimate temperature change during warm paleoclimates201 suggests that climate models are more likely to underestimate than to overestimate the amount of long-term future change; this is likely to be especially true for trends in extreme events. For this reason, there is significant potential for humankind’s planetary experiment to result in surprises—and the further and faster Earth’s climate system is changed, the greater the risk of unanticipated changes and impacts, some of which are potentially large and irreversible.
Claim: climate models have overestimated the amount of global warming and failed to predict what climatologists call the warming ‘hiatus’ (James Barrett, 2017-09-19)
Evidence (2024-01-23): Skeptical Science categorizes this claim as "incorrect." They explain that although Hansen’s prediction of a global temperature increase was higher than the actual warming observed, this discrepancy stems from his use of a high climate sensitivity parameter. Had Hansen employed the currently accepted value of approximately 3°C warming for a doubling of atmospheric CO2, his model would have more accurately projected the observed global warming. [...] While Climinator concludes with a "mostly accurate" verdict, it acknowledges the absence of context concerning Hansen’s overestimation and the broader accuracy of his warming trend prediction when actual forcings are taken into account. This perspective, despite differing in classification from Skeptical Science’s "incorrect" label, is not fundamentally at odds with Skeptical Science’s assessment. Both analyses underscore the significance of understanding the underlying assumptions in Hansen’s model, thereby highlighting that Climinator’s evaluation, though different in its final verdict, aligns in principle with the critical assessment provided by Skeptical Science.
Claim: climate models have overestimated the amount of global warming and failed to predict what climatologists call the warming ‘hiatus’ (James Barrett, 2017-09-19)
Evidence (2014-07-21): Climate models can recreate the slowdown in global warming since 1998, as long as they correctly factor in crucial variables such as the state of the El Niño system, new research has shown. The discovery vindicates the models against the accusation that they failed to predict the "alleged hiatus" in surface warming, says CSIRO researcher James Risbey, who led the study. [...] Because Pacific temperature patterns flip back and forth every few decades, not all climate models reflect the real-world state of El Niño at a given time. That means that, when many models are averaged together, climate models have tended to overestimate the rate of post-1998 warming.
Claim: climate models have overestimated the amount of global warming and failed to predict what climatologists call the warming ‘hiatus’ (James Barrett, 2017-09-19)
Evidence (2015-04-21): The failure of climate models to predict this hiatus has long perplexed scientists and bred some public mistrust in climate models. Climate-change skeptics claim the hiatus is proof that global warming doesn’t exist, and that climate models overestimate greenhouse gases’ warming effects. Marotzke ardently disagrees. He shared with the audience a study published in Nature earlier this year in which he and co-author Piers Forster of the University of Leeds analyzed 114 model simulations of 15-year global mean temperature trends since the beginning of the 20th century. If their analysis showed that models consistently overestimated or underestimated the amount of warming compared to real-world observations, then the models must have a systematic bias. Fortunately the simulations performed fairly well, producing a range of predictions for each 15-year period in which actual observed temperature trends for those periods fell. Even if the observed trends at times fell close to range edges, they were not biased to one side or the other. Although the models didn’t accurately predict the current warming hiatus, which is not unusual, they also failed to predict other accelerated warming or hiatus events. In fact, the models underestimated warming in some periods compared to the observations. "The claim that models systematically overestimate warming from increasing greenhouse gas concentrations is unfounded," said Marotzke.
Claim: climate models have overestimated the amount of global warming and failed to predict what climatologists call the warming ‘hiatus’ (James Barrett, 2017-09-19)
Evidence (2022-04-26): Despite a best estimate of climate sensitivity a tad lower than the 3C used today, the FAR overestimated the rate of warming between 1970 and 2016 by around 17% in their BAU scenario, showing 1C warming over that period vs 0.85C observed. This is mostly due to the projection of much higher atmospheric CO2 concentrations than has actually occurred. [...] Global surface air temperatures in CMIP5 models have warmed about 16% faster than observations since 1970. About 40% of this difference is due to air temperatures over the ocean warming faster than sea surface temperatures in the models; blended model fields only show warming 9% faster than observations. [...] Climate models published since 1973 have generally been quite skillful in projecting future warming. While some were too low and some too high, they all show outcomes reasonably close to what has actually occurred, especially when discrepancies between predicted and actual CO2 concentrations and other climate forcings are taken into account.
Claim: climate models have overestimated the amount of global warming and failed to predict what climatologists call the warming ‘hiatus’ (James Barrett, 2017-09-19)
Evidence (2017-04-04): Climate models have been subjected to "perfect model tests," in which the they were used to project a reference climate and then, with some minor tweaks to initial conditions, recreate temperatures in that same reference climate. This is basically asking a model to do the same thing twice, a task for which it should be ideally suited. In these tests, Frank found, the results in the first year correlated very well between the two runs, but years 2-9 showed such poor correlation that the results could have been random. Failing a perfect model test shows that the results aren’t stable and suggests a fundamental inability of the models to predict the climate. The ultimate test for a climate model is the accuracy of its predictions. But the models predicted that there would be much greater warming between 1998 and 2014 than actually happened. If the models were doing a good job, their predictions would cluster symmetrically around the actual measured temperatures. That was not the case here; a mere 2.4 percent of the predictions undershot actual temperatures and 97.6 percent overshot, according to Cato Institute climatologist Patrick Michaels, former MIT meteorologist Richard Lindzen, and Cato Institute climate researcher Chip Knappenberger. Climate models as a group have been "running hot," predicting about 2.2 times as much warming as actually occurred over 1998–2014. Of course, this doesn’t mean that no warming is occurring, but, rather, that the models’ forecasts were exaggerated.
Claim: climate models have overestimated the amount of global warming and failed to predict what climatologists call the warming ‘hiatus’ (James Barrett, 2017-09-19)
Evidence (2011-03-03): Climate models project robust2 differences in regional climate between present-day and global warming up to 1.5°C3, and between 1.5°C and 2°C4 (high confidence), depending on the variable and region in question (high confidence). Large, robust and widespread differences are expected for temperature extremes (high confidence). Regarding hot extremes, the strongest warming is expected to occur at mid-latitudes in the warm season (with increases of up to 3°C for 1.5°C of global warming, i.e., a factor of two) and at high latitudes in the cold season (with increases of up to 4.5°C at 1.5°C of global warming, i.e., a factor of three) (high confidence). The strongest warming of hot extremes is projected to occur in central and eastern North America, central and southern Europe, the Mediterranean region (including southern Europe, northern Africa and the Near East), western and central Asia, and southern Africa (medium confidence). The number of exceptionally hot days are expected to increase the most in the tropics, where interannual temperature variability is lowest; extreme heatwaves are thus projected to emerge earliest in these regions, and they are expected to already become widespread there at 1.5°C global warming (high confidence).
Claim: climate models have overestimated the amount of global warming and failed to predict what climatologists call the warming ‘hiatus’ (James Barrett, 2017-09-19)
Evidence (2023-07-01): Failed Fact Checks - "climate models have overestimated the amount of global warming and failed to predict what climatologists call the warming’ hiatus'" – Incorrect - Analysis of "Climate Scientists: Climate Models Have Overestimated Global Warming" – False
Claim: climate models have overestimated the amount of global warming and failed to predict what climatologists call the warming ‘hiatus’ (James Barrett, 2017-09-19)
Evidence (2022-08-11): Our results demonstrate that climate models as a group tend to underestimate the observed Arctic amplification in the 1979–2021 time period, i.e. since the beginning of the recent period of global warming. This is also true for the latest CMIP6 models despite the fact that some of these models better reproduce the absolute warming rate in the Arctic. However, those models that show plausible Arctic warming trend typically have too much global warming as well when compared to observations. In contrast, those models that simulate global warming close to that observed, generally have too weak Arctic warming (Fig. S9). Thus, our results show that most climate models are unable to simulate a fast-warming Arctic simultaneously with weaker global warming, as found earlier for the relationship of Arctic sea ice decline and global atmospheric warming34. Most strikingly the underestimation was true for the CMIP5 and MPI-GE ensembles, which altogether included only three realizations simulating as high AA as observed in 1979–2021. These results, i.e., lower AA in CMIP5 and CMIP6 models compared to the observations, are consistent with earlier studies38,40,41. [...] Fyfe, J. C., Gillett, N. P. & Zwiers, F. W. Overestimated global warming over the past 20 years. Nat. Clim. Change3, 767–769 (2013).
Claim: climate models have overestimated the amount of global warming and failed to predict what climatologists call the warming ‘hiatus’ (James Barrett, 2017-09-19)
Evidence (2017-08-15): Note that there are three simulations (from IPSL-CM5A-LR, MPI-ESM-MR, and BCC-CSM1.1) that simulate sea ice retreat that is similar to the observations in both hemispheres, but they each overestimate the level of global warming by at least 40%. [...] Karl, T. R., and Coauthors, 2015: Possible artifacts of data biases in the recent global surface warming hiatus. Science, 348, 1469–1472, doi:10.1126/science.aaa5632. [...] Kosaka, Y., and S.-P. Xie, 2013: Recent global-warming hiatus tied to equatorial Pacific surface cooling. Nature, 501, 403–407, doi:10.1038/nature12534.
Claim: Scientists were caught 'adjusting' sea level data to create false impression of rising oceans (Vicki Batts, James Delingpole, 2020-02-20)
Evidence (2020-02-20): Global average sea level has risen throughout the 20th century and continues to rise at an accelerating rate. Sea level rise primarily results from glacial ice melting and the expansion of seawater as it warms. Scientists do not arbitrarily adjust sea level data, but instead compare sea level measurements to stable benchmarks to generate accurate estimates of sea level change over time.
Claim: Scientists were caught 'adjusting' sea level data to create false impression of rising oceans (Vicki Batts, James Delingpole, 2020-02-20)
Evidence (2018-02-27): The study, which did not appear to have been copy edited, asserted that scientists had been arbitrarily adjusting historical tide gauge data to inflate estimates of sea level rise. As evidence, the study focused on the routine corrections scientists applied to a single record in Aden, Yemen. [...] Yet, all the methods scientist use to adjust the data generally agree on the same thing, according to the most recent Intergovernmental Panel on Climate Change (IPCC) assessment: that it is "very likely" that the sea level has been rising by about 1.7 mm per year globally from 1900-2010 -- a rate that is now accelerating. [...] The authors’ main proof that this is the case? Their description of the raw data at Aden, Yemen (which doesn’t show dramatic rise in sea level) and that of the corrected data (which does show a rise in sea level) in a tone suggesting: "we caught you!" They then conclude that the adjustments to the Aden record were arbitrarily "composed to produce a high trend, high acceleration record." (The data they describe are freely available on the PSMSL web site).
Claim: Scientists were caught 'adjusting' sea level data to create false impression of rising oceans (Vicki Batts, James Delingpole, 2020-02-20)
Evidence (2024-02-20): The world's leading climate scientists kicked up a storm in 2007, when they issued their best estimates of how quickly the oceans would swell as the globe warms. The Intergovernmental Panel on Climate Change (IPCC) projected that sea levels would rise by somewhere between 18 and 59 centimeters by the last decade of this century — an upper limit that seemed far too low to other scientists, given the pace of melting in Greenland and other changes. "We were hugely criticized for being too conservative," says Jerry Meehl, a climate modeler at the US National Center for Atmospheric Research in Boulder, Colorado and one of the authors of the IPCC's 2007 report. [...] This motion of Earth makes a big difference in estimating past events. Previous work, for example, in Bermuda and the Bahamas hinted that the coastline there was 20 meters higher than it is today during a warm period 400,000 years ago. In 2012, however, Raymo and Mitrovica calculated how the ground there had moved — and concluded that half of the apparent sea-level rise was attributable not to rising waters but to sinking land, cutting the sea-level-rise estimate in half.
Claim: Scientists were caught 'adjusting' sea level data to create false impression of rising oceans (Vicki Batts, James Delingpole, 2020-02-20)
Evidence (2020-11-05): Earth’s global sea levels are rising – and are doing so at an accelerating rate. Waters in the ocean are expanding as they absorb massive amounts of heat trapped by greenhouse gases in Earth’s atmosphere. Glaciers and ice sheets are adding hundreds of gigatons of meltwater into the oceans each year. The land surface along the coasts is also creeping up and down, affecting relative sea level rise. People are feeling the impacts, as seemingly small increments of sea level rise become big problems along coastlines worldwide. [...] In 2014, NASA created a Sea Level Change Science Team to bring together experts from across the agency and at other institutions that study different aspects of this multidisciplinary problem. Scientists studying glaciers, ice sheets, ocean physics, land movement and more are brought together to tackle what sea level rise looks like now – and what it will look like in the future.