What IPCC scientists actually say

True science — I mean confessions

The Summary for Policy Makers (SPM) for each IPCC report is written by bureaucrats and politicians for people who cannot follow scientific language. It is not authoritative, frequently misrepresents the science and is always written before the longer scientific report is finished. If the SPM is challenged, one must resort to the WG1 report, written by scientists. What do the scientists say?

We present here, from the AR4 (2007) (pdf, 106.9 MB) and AR5 (2013) (pdf, 375 MB) reports, a selection of passages that speak against extremist climate change forecasts widely circulated by activists. They are not much referred to by warmsters but they should be widely known, especially by those spending our hard-earned taxes. Dip into these facts — discover the real science and prepare to be amazed by the discord between the claims of the warmsters and the sober consideration of scientists (emphasis added).

IPCC Fifth Assessment Report (AR5)

08 to 0.14

The scientists actually say:

The attribution section highlights whether observations are “consistent with” the output of models, and in AR5 climate models are used to determine whether extreme events might have been less severe if not for human influences on climate. Neither use of models acknowledges that models might be very wrong and AR5 turns a blind eye to AR4, Chp 9, Box 9.1, that clearly shows the models to be wrong.
Dr John McLean

(NB: Curiously, the word ‘chaotic’ doesn’t appear in the chapters of AR4 and AR5 that discuss the evaluation of climate models.)

The fifth and latest IPCC assessment report, published in 2013, showed that climate models failed to predict the absence of warming from 1998 to 2012, and that climate scientists have no clear idea of why they failed.
Dr John McLean, IPCC reviewer, 3 Feb, 2017.

  1. “… the rate of warming over the past 15 years (1998–2012; 0.05 (–0.05 to 0.15) °C per decade) … is smaller than the rate calculated since 1951 (1951–2012; 0.12 (0.08 to 0.14) °C per decade).” [AR5 WGI SPM, B.1, 3rd para, p.5, and in full Synthesis Report on page SYR-6]
    J McL: According to statistical practices the trend in temperature from 1998 to 2012 (the 15 years prior to the report being drafted) falls somewhere between slight warming and slight cooling. In other words there is no certainty that warming occurred.
  2. “… an analysis of the full suite of CMIP5 historical simulations … reveals that 111 out of 114 realisations show a GMST trend over 1998–2012 that is higher than the entire HadCRUT4 trend ensemble …” [AR5 WGI contribution, Chp 9, Box 9.2, p.769, and in full Synthesis Report on page SYR-8]
    J McL: Despite claims of the accuracy of climate models most of the model runs (97%) wrongly predicted warming from 1998 to 2012.
  3. “There may also be a contribution from forcing inadequacies and, in some models, an overestimate of the response to increasing greenhouse gas and other anthropogenic forcing (dominated by the effects of aerosols).” [AR5 WGI SPM, D.1, p.15, 2nd para, and full Synthesis Report on page SYR-8]
    J McL: The IPCC is admitting that “some models” – we are not told how many, so maybe it’s almost all – exaggerate the influence of CO2 and other greenhouse gases.
  4. “This difference between simulated [i.e., model output] and observed trends could be caused by some combination of (a) internal climate variability, (b) missing or incorrect radiative forcing and (c) model response error.” [AR5 WGI contribution, Chp 9, Box 9.2, page 769]
    J McL: The models could be wrong for a number of very basic and general reasons; the IPCC really doesn’t know why the models failed.
  5. There has been a strengthening of the evidence for human influence on temperature extremes since the AR4 and IPCC Special Report on Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX) reports. It is very likely that anthropogenic forcing has contributed to the observed changes in the frequency and intensity of daily temperature extremes on the global scale since the mid-20th century. Attribution of changes in temperature extremes to anthropogenic influence is robustly seen in independent analyses using different methods and different data sets. It is likely that human influence has substantially increased the probability of occurrence of heatwaves in some locations. [AR5 Chp 10, p.871]
  6. In land regions where observational coverage is sufficient for assessment, there is medium confidence that anthropogenic forcing has contributed to a global-scale intensification of heavy precipitation over the second half of the 20th century. There is low confidence in attributing changes in drought over global land areas since the mid-20th century to human influence owing to observational uncertainties and difficulties in distinguishing decadal-scale variability in drought from long-term trends. [AR5 Chp 10, p.871]
  7. There is low confidence in attribution of changes in tropical cyclone activity to human influence owing to insufficient observational evidence, lack of physical understanding of the links between anthropogenic drivers of climate and tropical cyclone activity and the low level of agreement between studies as to the relative importance of internal variability, and anthropogenic and natural forcings. This assessment is consistent with that of SREX. [AR5 Chp 10, p.871]
  8. At present, therefore, the evidence does not support the claim that we are observing weather events that would, individually, have been extremely unlikely in the absence of human-induced climate change. [AR5 Chp 10, p.917]
  9. Despite these advances, there is still a range in plausible projections for future global and regional climate — what scientists call an ‘uncertainty range’. These uncertainty ranges are specific to the variable being considered (precipitation vs. temperature, for instance) and the spatial and temporal extent (such as regional vs. global averages). Uncertainties in climate projections arise from natural variability and uncertainty around the rate of future emissions and the climate’s response to them. They can also occur because representations of some known processes are as yet unrefined, and because some processes are not included in the models. [IPCC AR5 Chp 1, FAQ 1.1, p.140]
  10. There are fundamental limits to just how precisely annual temperatures can be projected, because of the chaotic nature of the climate system. Furthermore, decadal-scale projections are sensitive to prevailing conditions — such as the temperature of the deep ocean — that are less well known. Some natural variability over decades arises from interactions between the ocean, atmosphere, land, biosphere and cryosphere, and is also linked to phenomena such as the El Niño-Southern Oscillation (ENSO) and the North Atlantic Oscillation (see Box 2.5 for details on patterns and indices of climate variability). [IPCC AR5 Chp 1, FAQ 1.1, p.140]
  11. In general, a component of an observed change is attributed to a specific causal factor if the observations can be shown to be consistent with results from a process-based model that includes the causal factor in question, and inconsistent with an alternate, otherwise identical, model that excludes this factor. The evaluation of this consistency in both of these cases takes into account internal chaotic variability and known uncertainties in the observations and responses to external causal factors. [IPCC AR5 Chp 10, 10.2.1, p.872]

Greens claim about typhoon is not only sick but inaccurate

Because the scientists actually say:

Robin Grieve, Pastural Farming Climate Research, wrote an article in 2013 criticising the Greens and citing IPCC reports that directly contradicted their claims.

This is what the IPCC Fifth Assessment Report (AR5), 2013, says about tropical cyclones. A typhoon is a mature tropical cyclone that occurs in certain latitudes (these are direct quotes from AR5).

  1. Current data sets indicate no significant observed trends in global tropical cyclone frequency over the past century, and it remains uncertain whether any reported long-term increases in tropical cyclone frequency are robust. [AR5 Chp 2, p.216]
  2. There is low confidence in basin-scale projections of changes in intensity and frequency of tropical cyclones (TCs) in all basins to the mid-21st century. [AR5 Chp 11, p.956]
  3. Modes of climate variability that in the past have led to variations in the intensity, frequency and structure of tropical cyclones across the globe—such as the ENSO … —are very likely to continue influencing TC activity through the mid-21st century. Therefore, it is very likely that over the next few decades tropical cyclone frequency, intensity and spatial distribution globally, and in individual basins, will vary from year to year and decade to decade. [AR5 Chp 11, p.993]
  4. … this assessment does not revise the SREX conclusion of low confidence that any reported long-term (centennial) increases in tropical cyclone activity are robust, after accounting for past changes in observing capabilities. More recent assessments indicate that it is unlikely that annual numbers of tropical storms, hurricanes and major hurricanes counts have increased over the past 100 years in the North Atlantic basin. [AR5 Chp 2, p.217]
  5. There is low confidence in attribution of changes in tropical cyclone activity to human influence owing to insufficient observational evidence, lack of physical understanding of the links between anthropogenic drivers of climate and tropical cyclone activity and the low level of agreement between studies as to the relative importance of internal variability, and anthropogenic and natural forcings. This assessment is consistent with that of SREX. [AR5 Chp 10, p.871]
  6. Overall global average cyclone activity is expected to change little under moderate GHG forcing. [AR5 Chp 10, p.913]
  7. … projections based on the SRES A1B scenario [only one scenario among many] concluded that It is likely that the global frequency of tropical cyclones will either decrease or remain essentially unchanged … The annual frequency of tropical cyclones is generally projected to decrease or remain essentially unchanged in the next century in most regions. [AR5 Chp 14, p.1249]
  8. At present the evidence does not support the claim that we are observing weather events that would, individually, have been extremely unlikely in the absence of human-induced climate change. [AR5 Chp 10, p.916]

But observe the developing group think:

  1. “The most important development since AR4 is an emerging consensus that the role of external drivers of climate change in specific extreme weather events, including events that might have occurred in a pre-industrial climate, can be quantified using a probabilistic approach.” [AR5 Chp 10, p.917]

This can be translated: “There’s no evidence for attributing extreme weather events to human influence. However, if we approximate evidence with our collective expert opinions of the probability of a human influence, we’ll probably get close. We can certainly scare everyone.”

  1. There continues to be a lack of evidence and thus low confidence regarding the sign of trend in the magnitude and/or frequency of floods on a global scale over the instrumental record. There is high confidence that past floods larger than those recorded since 1900 have occurred during the past five centuries in northern and central Europe, western Mediterranean region, and eastern Asia. There is medium confidence that modern large floods are comparable to or surpass historical floods in magnitude and/or frequency in the Near East, India and central North America. [AR5 TS, p.112]
  2. The global number of extratropical cyclones is unlikely to decrease by more than a few percent. [AR5 TS, p.108]
  3. Confidence in large scale changes in the intensity of extreme extratropical cyclones since 1900 is low. There is also low confidence for a clear trend in storminess proxies over the last century due to inconsistencies between studies or lack of long-term data in some parts of the world (particularly in the SH). Likewise, confidence in trends in extreme winds is low, owing to quality and consistency issues with analysed data. [AR5 Chp 2, p.220]

Extreme events in AR5

You’ll hear some tall stories, but listen to the scientists

In the process of updating Senate testimony I compiled some key statements from the IPCC AR5 WGI Chapter 2 on extreme events. – Roger Pielke Jr

  1. “Overall, the most robust global changes in climate extremes are seen in measures of daily temperature, including to some extent, heat waves. Precipitation extremes also appear to be increasing, but there is large spatial variability.”
  2. “There is limited evidence of changes in extremes associated with other climate variables since the mid-20th century.”
  3. “Current datasets indicate no significant observed trends in global tropical cyclone frequency over the past century … No robust trends in annual numbers of tropical storms, hurricanes and major hurricanes counts have been identified over the past 100 years in the North Atlantic basin.”
  4. “In summary, there continues to be a lack of evidence and thus low confidence regarding the sign of trend in the magnitude and/or frequency of floods on a global scale.”
  5. “In summary, there is low confidence in observed trends in small-scale severe weather phenomena such as hail and thunderstorms because of historical data inhomogeneities and inadequacies in monitoring systems.”
  6. “In summary, the current assessment concludes that there is not enough evidence at present to suggest more than low confidence in a global-scale observed trend in drought or dryness (lack of rainfall) since the middle of the 20th century due to lack of direct observations, geographical inconsistencies in the trends, and dependencies of inferred trends on the index choice. Based on updated studies, AR4 conclusions regarding global increasing trends in drought since the 1970s were probably overstated. However, it is likely that the frequency and intensity of drought has increased in the Mediterranean and West Africa and decreased in central North America and north-west Australia since 1950.”
  7. “In summary, confidence in large scale changes in the intensity of extreme extratropical cyclones since 1900 is low.”

There is really not much more to be said here—the data says what it says, and what it says is so unavoidably obvious that the IPCC has recognized it in its consensus. Of course, I have no doubts that claims will still be made associating floods, drought, hurricanes and tornadoes with human-caused climate change—Zombie science—but I am declaring victory in this debate. Climate campaigners would do their movement a favour by getting themselves on the right side of the evidence.

Special Report on Extreme Events (SREX)

What do the scientists really say about the big stuff?

  1. There is low confidence in any observed long-term (i.e., 40 years or more) increases in tropical cyclone activity (i.e., intensity, frequency, duration), after accounting for past changes in observing capabilities. It is likely that there has been a poleward shift in the main Northern and Southern Hemisphere extra-tropical storm tracks. There is low confidence in observed trends in small spatial-scale phenomena such as tornadoes and hail because of data inhomogeneities and inadequacies in monitoring systems.
  2. There is medium confidence that some regions of the world have experienced more intense and longer droughts, in particular in southern Europe and West Africa, but in some regions droughts have become less frequent, less intense, or shorter, e.g., in central North America and northwestern Australia.
  3. There is limited to medium evidence available to assess climate-driven observed changes in the magnitude and frequency of floods at regional scales because the available instrumental records of floods at gauge stations are limited in space and time, and because of confounding effects of changes in land use and engineering. Furthermore, there is low agreement in this evidence, and  thus overall low confidence at the global scale regarding even the sign of these changes. [IPCC SREX, SPM, p.5]

You can download the SREX (pdf, 43.46 MB) from the IPCC.

  1. There is evidence from observations gathered since 1950 of change in some extremes. Confidence in observed changes in extremes depends on the quality and quantity of data and the availability of studies analyzing these data, which vary across regions and for different extremes. Assigning ‘low confidence’ in observed changes in a specific extreme on regional or global scales neither implies nor excludes the possibility of changes in this extreme.

This and the remainder of page 8 reveals low confidence in an increase in extreme events, including extreme coastal high water. It follows there can be no anthropogenic responsibility for rising sea level, among other things. [IPCC SREX, SPM, p.8]

  1. There is evidence that some extremes have changed as a result of anthropogenic influences, including increases in atmospheric concentrations of greenhouse gases. It is likely that anthropogenic influences have led to warming of extreme daily minimum and maximum temperatures at the global scale. There is medium confidence that anthropogenic influences have contributed to intensification of extreme precipitation at the global scale. It is likely that there has been an anthropogenic influence on increasing extreme coastal high water due to an increase in mean sea level. The uncertainties in the historical tropical cyclone records, the incomplete understanding of the physical mechanisms linking tropical cyclone metrics to climate change, and the degree of tropical cyclone variability provide only low confidence for the attribution of any detectable changes in tropical cyclone activity to anthropogenic influences. Attribution of single extreme events to anthropogenic climate change is challenging. [IPCC SREX, SPM, p.9]
  2. Increasing exposure of people and economic assets has been the major cause of long-term increases in economic losses from weather-and climate-related disasters (high confidence). Long-term trends in economic disaster losses adjusted for wealth and population increases have not been attributed to climate change, but a role for climate change has not been excluded (high agreement, medium evidence). … These conclusions are subject to a number of limitations in studies to date. … most studies focus on cyclones, where confidence in observed trends and attribution of changes to human influence is low. [IPCC SREX, SPM, p.9]

IPCC Fourth Assessment Report (AR4)

This report is 11 years old now; what did it say?

The attribution section lays emphasis on whether observations are “consistent with” the output of models, and in AR5 climate models are used to determine whether extreme events might have been less severe if not for human influences on climate. Neither use of models acknowledges that models might be very wrong and AR5 turns a completely blind eye to AR4, Chp 9, Box 9.1, that clearly shows them to be wrong.
John McLean
(NB: There’s no occurrence of the word ‘chaotic’ in the chapters of AR4 and AR5 that discuss the evaluation of climate models.)

  1. There is also, however, a continuing awareness that models do not provide a perfect simulation of reality, because resolving all important spatial or time scales remains far beyond current capabilities, and also because the behaviour of such a complex nonlinear system may in general be chaotic. [IPCC AR4, Chp 1, p.113]
  2. A different type of uncertainty arises in systems that are either chaotic or not fully deterministic in nature and this also limits our ability to project all aspects of climate change. [IPCC AR4, Chp 1, Box 1.1, p.120]
  3. ‘Attribution’ of causes of climate change is the process of establishing the most likely causes for the detected change with some defined level of confidence (see Glossary). As noted in the SAR (IPCC, 1996) and the TAR (IPCC, 2001), unequivocal attribution would require controlled experimentation with the climate system. Since that is not possible, in practice attribution of anthropogenic climate change is understood to mean demonstration that a detected change is ‘consistent with the estimated responses to the given combination of anthropogenic and natural  forcing’ and ‘not consistent with alternative, physically plausible explanations of recent climate change that exclude important elements of the given combination of forcings’ (IPCC, 2001). [IPCC AR4, Chp 9, p.668]

Extreme events in AR4

  1. Observed changes in temperature extremes are consistent with the observed warming of the climate (Alexander et al., 2006) and are summarised in Section 3.8.2.1. There has been a widespread reduction in the number of frost days in mid-latitude regions in recent decades, an increase in the number of warm extremes, particularly warm nights, and a reduction in the number of cold extremes, particularly cold nights. A number of regional studies all show patterns of changes in extremes consistent with a general warming, although the observed changes in the tails of the temperature distributions are generally not consistent with a simple shift of the entire distribution alone. [IPCC AR4, Chp 9, p.698]

Finally, from The Rightful Place of Science: Disasters & Climate Change, by Roger Pielke, Jr., 2014:

Extreme Precipitation and Flooding

Absent an increase in peak streamflows caused by increasing extreme precipitation, it is impossible to find a causal linkage between increasing precipitation and increasing floods, much less between precipitation and flood damage. There are of course good reasons why a linkage between increasing precipitation and peak streamflow would be difficult to make, such as the seasonality of the increase in rain or snow, the large variability of flooding, and the human influence on river systems. Those difficulties of course translate directly to a difficulty in connecting the effects of increasing greenhouse gases in the atmosphere to flood disasters.

Tropical Cyclones

With respect to the central question that is the focus of this short volume, the data are clear. Those who assert that disasters are getting more costly because of climate change (human caused or not) are going to have to look at phenomena other than U.S. hurricanes or tropical cyclones around the world. There is no evidence to suggest that hurricanes have become more common, intense or costly for any reason other than more people and their property exist in locations vulnerable to the impacts of these powerful storms.

Floods

As with tropical cyclones, there is little evidence in support of claims that floods have become more common or more intense.

Tornadoes

In our analysis we concluded that the data are “suggestive” of an actual decline in tornado incidence, but do not say anything stronger, and recommend further research.

Drought

As with tropical cyclones, floods, and tornadoes, there is little evidence to support claims that drought has increased globally on climate time scales.

Conclusion

This short volume has sought to answer a straightforward question:

Have disasters become more costly because of human-caused climate change? 

Only one answer to this question is strongly supported by the available data, the broad scientific literature, and the assessments of the IPCC:

No. There is exceedingly little evidence to support claims that disasters have become more costly because of human-caused climate change.

Nonetheless, one point should be abundantly clear. The evidence available today points to a clear answer to the central question at the focus of this short volume: Human-caused climate change has not led to a detectable increase in the costs of disasters.


From Chapter 5, The Rightful Place of Science: Disasters & Climate Change by Roger Pielke, Jr., 2014. ISBN: 0692297510 ISBN-13: 978-0692297513

3 Thoughts on “What IPCC scientists actually say

  1. Barry Brill on February 1, 2018 at 6:59 pm said:

    In commenting on another post, Simon refers to two articles in support of his contention that some weather extremes somewhere can sometimes be attributed to temperature increases.

    The first article from NAS says that warmer air is associated with (a) increased moisture, which can mean more precipitation and (b) evaporation, which can exacerbate droughts. Of course the abstract does not mention that precipitation prevents or ameliorates droughts while evaporation reduces temperatures.

    The second, a 2016 letter to Nature Journal, is mainly concerned with model runs. It notes that rain might increase in wet areas and decrease in dry areas, but says “this has been disputed for changes over land”. It then confirms that precipitation extremes seem to increase with temperature in both wet and dry areas. It might therefore be thought that AGW might contribute (something) to a flood in a wet area.

    This is all pretty tepid and tentative stuff when compared to the clear statements by the IPCC and all the other scientific literature cited by Richard T. It seems AGW attributions are no more than a media beat-up.

  2. Barry Brill on February 1, 2018 at 7:11 pm said:

    Adding further authority to this post, Dennis Horne has set to find some scientific papers to rebut the IPCC’s views on extreme weather events. He fails miserably, coming up with two newspaper articles! The one in the Washington Post is merely an op-ed (by Michael Mann, no less) while the other is from The Guardian.

    Dennis has a third eminent authority. It is an unauthorised opinion piece on a website with a masthead “where every day is Earth day”. The first sentence reads:
    “Climate change may not be responsible for the recent skyrocketing costs of natural disasters (sic) but IT IS VERY LIKELY THAT IT WILL impact future catastrophes.” (emphasis added) .

    Yep. Simply a media beat-up.

  3. Brett Keane on February 8, 2018 at 2:28 pm said:

    We are finding a possible new paradigm – the Quiet Sun. Definitely, equatorial meso/thermosphere heights and T have fallen, so Hubble can still orbit. It does seem, tentatively, that this reduced high frequency sunlight is also lessening ocean warming so enso is losing full nino/nina discharge-recharge ability.

    The change that has ensued is more meridionality of weather patterns. This can be violent because of steepened energy gradient and unusual patterns. Hence Piers Corbyn’s “little ice age” warnings. At 70yo, I have noticed a difference in that more events are powerful. Not so much a matter of worse maxima, I have seen that before….as a farmer and commercial fisherman.

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