Friday, September 20, 2013

IPCC didn't predict the global warming 'hiatus', but now claims it did

The forthcoming IPCC report conveniently claims “Fifteen-year-long hiatus periods are common” for the climate model simulations, suggesting that the halt of global warming was predicted by the models. However, NOAA stated in the State of the Climate 2008 report that climate model simulations "rule out" hiatus periods of 15 years or more. Furthermore, NOAA states that if observations show no surface warming for 15 years or more, the climate models have been falsified at a confidence level of 95%:
“Near-zero and even negative trends are common for intervals of a decade or less in the simulations, due to the model’s internal climate variability. The simulations rule out (at the 95% level) zero trends for intervals of 15 yr or more, suggesting that an observed absence of warming of this duration is needed to create a discrepancy with the expected present-day warming rate.”
In addition, a recent paper published in Nature Climate Change finds that the models did not predict 'hiatus' periods greater than 5 years. Thus, the new IPCC claim that  “Fifteen-year-long hiatus periods are common” for the climate model simulations is contradicted by the literature. The climate models have been falsified by observations at a confidence level of 95% per the NOAA requirements, as well as two recent papers falsifying the models at a confidence levels of >98% over the past 15 years and 90% over the past 20 years.

Since almost the entire IPCC report hinges on the output of climate models, the entire report and its Summary for Policymakers are invalidated prior to publication. Every single one of the 73 IPCC climate models in the upcoming report exaggerate global warming. Even the IPCC admits the models have not been validated and that they don't know how to validate the models. 

Related: Dr. Judith Curry: Well, I am afraid I must conclude that the IPCC “has no idea what’s going on“.


A “hiatus” in global warming so far this century is partly caused by natural variations in a chaotic climate and is unlikely to last, a draft United Nations report by leading climate scientists says.

The 127-page draft, and a shorter summary for policymakers that is due for release in Stockholm on September 27 after editing, say factors including a haze of volcanic ash and a cyclical dip in energy emitted from the sun may also have contributed to a slower warming trend…
“Fifteen-year-long hiatus periods are common” in both historical records and in computer models, the technical summary says. But scientists were caught out – in one computer model, 111 of 114 estimates over-stated recent temperature rises.

UK newspaper The Independent:
Climate change 'hiatus': Scientists seek to qualify evidence of apparent global warming slowdown

International panel fear sceptics will pounce on data that suggests global warming has decreased since 1998, despite rising greenhouse gas emissions


Authors of a landmark UN report on climate change remain adamant that humans are heating up the planet by burning fossil fuels and cutting down CO2-absorbing forests, despite data from the report suggesting a purported slowdown in global warming over the past 15 years.

The Intergovernmental Panel on Climate Change’s (IPCC) full 127-page document - due for release in Stockholm next week - is expected to suggest the link between human activity and global warming is clearer than ever, regardless of the recent lower rate of warming.

In a draft leaked in June, the IPCC said that while the rate of warming between 1998 and 2012 was about half the average rate since 1951, the globe is still heating up in the long term.

The leaked report qualified the apparent slowdown by citing natural variables in the climate system, the cooling effects from volcanic eruptions and the fact that an uncommonly hot year was picked as the starting point for the 15-year chart.

“Barring a major volcanic eruption, most 15-year global mean surface temperature trends [of the falsified computer models] in the near-term future will be larger than during 1998-2012,” a technical summary from the report said.

“Fifteen-year-long hiatus periods are common,” it added.

The Associated Press says it has obtained comments made to the IPCC by several governments concerned with how to tackle the apparently anomalous data.

Germany called for the 15 year slowdown to be dismissed as a blip, saying climate change needed to be measured in decades and centuries, rather than smaller intervals.

Belgium objected to using 1998 as a starting year for the statistics, citing the exceptionally warm temperature of the year, while Hungary were concerned the finding would be fodder for global warming sceptics.

Jonathan Lynn, a spokesman for the IPCC, said: “a comprehensive picture of all the science relevant to climate change, including the thousands of pieces of scientific research published since the last report in 2007 up to earlier this year.”

Conclusions reached by the IPCC are significant as they provide the basis for UN discussions on the treatment of CO2 emissions and other greenhouses gases. A global climate treaty is scheduled to be reached in 2015.


  1. Thanks for the great job you do here at the hockeyschtick, I often gleefully post links and text from here to the dumbtoid alarmist blog

    Karen :)

    1. Thanks very much Karen for your support & spreading the word!

  2. Page 9 – finally something substantial about the failure to anticipate the “pause”:

    “There is very high confidence that models reproduce the more rapid warming in the second half of the 20th century, and the cooling immediately following large volcanic eruptions. Models do not generally reproduce the observed reduction in surface warming trend over the last 10–15 years. There is medium confidence that this difference between models and observations is to a substantial degree caused by unpredictable climate variability, with possible contributions from inadequacies in the solar, volcanic, and aerosol forcings used by the models and, in some models, from too strong a response to increasing greenhouse-gas forcing.”