Category Archives: IPCC

Is ocean warming accelerating faster than thought?

by Nic Lewis

*** UPDATE : response to comments by Zeke Hausfather appended

There are a number of statements in Cheng et al. (2019) ‘How fast are the oceans warming’, (‘the paper’) that appear to be mistaken and/or potentially misleading. My analysis of these issues is followed by a reply from the paper’s authors.

Contrary to what the paper indicates:

  • Contemporary estimates of the trend in 0–2000 m depth ocean heat content over 1971–2010 are closely in line with that assessed in the IPCC AR5 report five years ago
  • Contemporary estimates of the trend in 0–2000 m depth ocean heat content over 2005–2017 are significantly (> 95% probability) smaller than the mean CMIP5 model simulation trend.

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Climate sensitivity to cumulative carbon emissions

By Nic Lewis

An observational estimate of transient (multidecadal) warming relative to cumulative CO2 emissions is little over half that per IPCC AR5 projections.

AR5 claims that CO2-caused warming would be undiminished for 1000 years after emissions cease, but observations indicate that it would halve. Continue reading

Remarkable changes to carbon emission budgets in the IPCC Special Report on Global Warming of 1.5C

by Nic Lewis

A close reading of Chapters 1 and 2 of the IPCC Special Report on Global Warming of 1.5°C (SR15) reveals some interesting changes from the IPCC 5th Assessment Report (AR5), and other science-relevant statements. This article highlights statements in SR15 relating to carbon emission budgets for meeting the 1.5°C and 2°C targets.

It seems fairly extraordinary to me that the AR5 post-2010 carbon budget for 1.5°C, which was only published four years ago, has in effect been now been increased by ~700 GtCO2 – equal to 21st century emissions to date – despite SR15’s projections of future warming being based very largely on the transient climate response to cumulative emissions (TCRE) range exhibited by the models used in AR5. Continue reading

1.5 degrees

by Judith Curry

The IPCC Special Report on Global Warming of 1.5C  is now published [link].

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Manufacturing consensus: the early history of the IPCC

by Judith Curry

Short summary: scientists sought political relevance and allowed policy makers to put a big thumb on the scale of the scientific assessment of the attribution of climate change.

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IPCC in transition

by Judith Curry

Will Pachauri’s karma run over IPCC’s dogma? – Peter Foster

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‘Most’ versus ‘more than half’ versus ‘> 50%’

by Judith Curry

Seeking once again to clarify the problems in communicating the IPCC climate change attribution statements.

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Groups and herds: implications for the IPCC

by Judith Curry

Group failures often have disastrous consequences—not merely for businesses, nonprofits, and governments, but for all those affected by them. – Cass Sunstein and Reid Hastie

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Politicizing the IPCC report

by Judith Curry

UK Energy and Climate Change Committee report on IPCC AR5 – another pointless exercise in circular reasoning, confirmation bias and division? – Paul Matthews

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U.S. House Hearing on the IPCC Process

by Judith Curry

The U.S. House of Representatives Committee on Science, Space & Technology is holding a Hearing today at 11 a.m.: Examining the UN Intergovernmental Panel on Climate Change Process

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IPCC: Functional stupidity?

by Judith Curry

Our point is that the IPCC has bought into a very specific framing of “the problem” that has rendered climate policy ineffective and has foreclosed the possibility of public consent. – Silke Beck et al.

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Lennart Bengtsson speaks out

by Judith Curry

The whole concept behind IPCC is basically wrong. – Lennart Bengtsson

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IPCC TAR and the hockey stick

by Judith Curry

Regarding the Hockey Stick of IPCC 2001 evidence now indicates, in my view, that an IPCC Lead Author working with a small cohort of scientists, misrepresented the temperature record of the past 1000 years by (a) promoting his own result as the best estimate, (b) neglecting studies that contradicted his, and (c) amputating another’s result so as to eliminate conflicting data and limit any serious attempt to expose the real uncertainties of these data. – John Christy

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Stavins and Tol on IPCC WG3

by Judith Curry

Many of the more worrying impacts of climate change really are symptoms of mismanagement and underdevelopment. – Richard Tol

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UK Parliamentary Hearing on the IPCC

by Judith Curry

A fascinating hearing on the IPCC was held today by the UK Parliament Energy and Climate Climate Change Committee.

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UK Parliament: IPCC 5th Assessment Review

by Judith Curry

The UK House of Commons Energy and Climate Change Committee has invited submissions to an inquiry on the IPCC 5th Assessment.

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Mutually Assured Delusion (MAD)

by Judith Curry

Groupthink:   A pattern of thought charaterized by self-deception, forced manufacture of consent, and conformity to group values and ethics.

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IPCC: fit for its purpose?

The IPCC is showing typical signs of middle age, including weight gain, a growing rigidity of viewpoint, and overconfidence in its methods. It did a great job in the early days, but it’s become ritualized and bureaucratic, issuing big bulk reports that do little to answer the hard questions facing policymakers.  – David Keith, as cited by Fred Pearce

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Spinning the climate model – observation comparison: Part II

by Judith Curry

IPCC model global warming projections have done much better than you think. – Dana Nuccitelli

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Negotiating the IPCC SPM

by Judith Curry

A fascinating look at the how the deliberations in Stockholm influenced the final IPCC AR5 WG1 Summary for Policy Makers

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IPCC: solar variations don’t matter

Nevertheless, even if there is such decrease in the solar activity, there is a high confidence that the TSI RF variations will be much smaller in magnitude than the projected increased forcing due to GHG. – IPCC AR5 Chapter 8

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IPCC’s pause ‘logic’

by Judith Curry

Well here it is, the pause discussion is buried in Box 9.2 of the IPCC Working Group I Report.

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IPCC diagnosis – permanent paradigm paralysis

by Judith Curry

Diagnosis: paradigm paralysis, caused by motivated reasoning, oversimplification, and consensus seeking; worsened and made permanent by a vicious positive feedback effect at the climate science-policy interface.

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95% (?)

Ok, it is now official:

“The long-term climate model simulations show a trend in global-mean surface temperature from 1951 to 2012 that agrees with the observed trend (very high confidence). There are, however, differences between simulated and observed trends over periods as short as 10 to 15 years”

It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together. The best estimate of the human induced contribution to warming is similar to the observed warming over this period.

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Five critical questions for the IPCC

by Judith Curry

If you had the opportunity to ask 5 critical questions for the IPCC, what would you ask?

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