It Isn’t How Climate Scientists Communicated their Message; It’s the Message

Over the past few months, there have been a number of articles about how the climate science community could have presented their message differently, or responded differently, so that they could have avoided the problem they’re now facing with the halt in global warming.  Example: the problems with communications by climate scientists to the public were the subject of a recent editorial, and linked webpages, at Nature Climate Change titled Scientist communicators.  In reading it, you’ll find the editorial is really nothing more than a rephrasing of manmade-global-warming dogma.

One of the climate science community’s primary problems was a very basic message…an intentionally misleading message.  That is, it wasn’t how it was communicated; it was the message itself.  I ran across that message again as I was searching for links for a chapter on atmospheric temperatures for my upcoming book The Oceans Ate My Global Warming.  It appeared on the Remote Sensing Systems (RSS) Climate Analysis webpage. That webpage includes data that runs through 2013 in many cases, so it’s relatively new. Under the heading of TROPOSPERIC TEMPERATURE, RSS write (my boldface):

Over the past decade, we have been collaborating with Ben Santer at LLNL (along with numerous other investigators) to compare our tropospheric results with the predictions of climate models.  Our results can be summarized as follows:

• Over the past 35 years, the troposphere has warmed significantly.  The global average temperature has risen at an average rate of about 0.13 degrees Kelvin per decade (0.23 degrees F per decade).
• Climate models cannot explain this warming if human-caused increases in greenhouse gases are not included as input to the model simulation.
• The spatial pattern of warming is consistent with human-induced warming.  See Santer et al 2008, 2009, 2011, and 2012 for more about the detection and attribution of human induced changes in atmospheric temperature using MSU/AMSU data.

The message from the climate science community has been and continues to be:

• If climate models are not forced by manmade greenhouse gases, then the models cannot simulate the warming from the mid-1970s to the turn of the century, and
• If climate models are forced by manmade greenhouse gases, then the models can simulate the warming from the mid-1970s to the turn of the century,
• Both of which lead to the stated conclusion that only manmade greenhouse gases can explain the observed warming from the mid-1970s to the turn of the century.

IPCC 4^th ASSESSMENT REPORT

The IPCC was blatant in their presentation of that misleading message in the 4^th Assessment Report.  It appeared in the AR4 Summary for Policymakers.  The fourth bullet-pointed paragraph on their page 10 reads (my boldface):

It is likely that there has been significant anthropogenic warming over the past 50 years averaged over each continent except Antarctica (see Figure SPM.4). The observed patterns of warming, including greater warming over land than over the ocean, and their changes over time, are only simulated by models that include anthropogenic forcing. The ability of coupled climate models to simulate the observed temperature evolution on each of six continents provides stronger evidence of human influence on climate than was available in the TAR. {3.2, 9.4}

Figure SPM.4 from AR4 is presented as my Figure 1.

Figure 1 (Figure SPM.4 from AR4)

They then further reinforced that message with their Figure 9.5 of AR4’s Chapter 9.  The accompanying text, under the heading of “9.4.1.2 Simulations of the 20th Century” reads:

Figure 9.5 shows that simulations that incorporate anthropogenic forcings, including increasing greenhouse gas concentrations and the effects of aerosols, and that also incorporate natural external forcings provide a consistent explanation of the observed temperature record, whereas simulations that include only natural forcings do not simulate the warming observed over the last three decades.

Figure 9.5 from AR4 is presented as my Figure 2.

Figure 2 (AR4 Figure 9.5)

IPCC 5^th ASSESSMENT REPORT

The IPCC continued with their misleading presentation of climate models (with and without anthropogenic forcings) in AR5.  It was presented as Figure TS.9 on page 60 of the Full Working Group 1 AR5 Report (Caution 357MB). The IPCC writes:

Observed GMST anomalies relative to 1880–1919 in recent years lie well outside the range of GMST anomalies in CMIP5 simulations with natural forcing only, but are consistent with the ensemble of CMIP5 simulations including both anthropogenic and natural forcing (Figure TS.9) even though some individual models overestimate the warming trend, while others underestimate it. Simulations with WMGHG changes only, and no aerosol changes, generally exhibit stronger warming than has been observed (Figure TS.9). Observed  temperature trends over the period 1951–2010, which are characterized by warming over most of the globe with the most intense warming over the NH continents, are, at most observed locations, consistent with the temperature trends in CMIP5 simulations including anthropogenic and natural forcings and inconsistent with the temperature trends in CMIP5 simulations including natural forcings only. A number of studies have investigated the effects of the Atlantic Multi-decadal Oscillation (AMO) on GMST. Although some studies find a significant role for the AMO in driving multi-decadal variability in GMST, the AMO exhibited little trend over the period 1951–2010 on which the current assessments are based, and the AMO is assessed with high confidence to have made little contribution to the GMST trend between 1951 and 2010 (considerably less than 0.1°C). {2.4, 9.8.1, 10.3; FAQ 9.1}

My Figure 3 is the IPCC Figure TS.9 from AR5.

Figure 3 (AR5 Figure TS.9)

Then the IPCC added a new wrinkle…they shifted focus.  Instead of stating that the warming is “only simulated by models that include anthropogenic forcing”, they use the misleading model comparisons as proof that the “human influence has been detected”.

The Summary for Policymakers for their 5^th Assessment Report (AR5) reads:

D.3 Detection and Attribution of Climate Change

Human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, in global mean sea level rise, and in changes in some climate extremes (see Figure SPM.6 and Table SPM.1). This evidence for human influence has grown since AR4. It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century. {10.3–10.6, 10.9}

Their Figure SPM.6 from AR5 is presented as my Figure 4.

Figure 4 (Figure SPM.6 from AR5)

The IPCC continues on page 74 of the full AR5 WG1 report.  The simulations with anthropogenic and natural forcings are described as “emerging anthropogenic and natural signals”, while simulations with only natural forcings are being described as “the alternative hypothesis of just natural variations”:

The coherence of observed changes with simulations of anthropogenic and natural forcing in the physical system is remarkable (Figure TS.12), particularly for temperature-related variables. Surface temperature and ocean heat content show emerging anthropogenic and natural signals in both records, and a clear separation from the alternative hypothesis of just natural variations. These signals do not appear just in the global means, but also appear at regional scales on continents and in ocean basins in each of these variables. Sea ice extent emerges clearly from the range of internal variability for the Arctic. At sub-continental scales human influence is likely to have substantially increased the probability of occurrence of heat waves in some locations. {Table 10.1}

My Figure 5 is AR5 Figure TS.12.

Figure 5 (Figure TS.12 from AR5)

The IPCC then presents a series of similar graphs on page 930 in their Figure 10.21, and continues with their misrepresentation of climate model capabilities. On page 927, under the heading of “10.9.2 Whole Climate System”, they write (my boldface), again using the “emerging anthropogenic and natural signals” and “alternative hypothesis of just natural variations”:

To demonstrate how observed changes across the climate system can be understood in terms of natural and anthropogenic causes Figure 10.21 compares observed and modelled changes in the atmosphere, ocean and cryosphere. The instrumental records associated with each element of the climate system are generally independent (see FAQ 2.1), and consequently joint interpretations across observations from the main components of the climate system increases the confidence to higher levels than from any single study or component of the climate system. The ability of climate models to replicate observed changes (to within internal variability) across a wide suite of climate indicators also builds confidence in the capacity of the models to simulate the Earth’s climate.

The coherence of observed changes for the variables shown in Figure 10.21 with climate model simulations that include anthropogenic and natural forcing is remarkable. Surface temperatures over land, SSTs and ocean heat content changes show emerging anthropogenic and natural signals with a clear separation between the observed changes and the alternative hypothesis of just natural variations (Figure 10.21, Global panels). These signals appear not just in the global means, but also at continental and ocean basin scales in these variables. Sea ice emerges strongly from the range expected from natural variability for the Arctic and Antarctica remains broadly within the range of natural variability consistent with expectations from model simulations including anthropogenic forcings.

My Figure 6 is the IPCC’s Figure 10.21 from AR5.

Figure 6 (Figure 10.21 from AR5)

The IPCC must like those model-data comparisons, because they certainly do like to offer variations of them.

Unfortunately for the IPCC, the models they show with only natural forcings (the blue curves) do not present natural variability.  The climate models employed by the IPCC cannot simulate naturally occurring, coupled, ocean-atmosphere processes that cause multidecadal variations in surface temperatures.  These variations are most evident in the surface temperatures of the Northern Hemisphere, and they are driven by the naturally occurring multidecadal variations in North Atlantic sea surface temperatures (known as the Atlantic Multidecadal Oscillation) and the naturally occurring multidecadal variations in North Pacific sea surface temperatures (not represented by the Pacific Decadal Oscillation/PDO data).  See the post Multidecadal Variations and Sea Surface Temperature Reconstructions.

Figures 7 and 8 are model-data comparisons for the sea surface temperature anomalies of the North Pacific and the North Atlantic for the period of Jan 1870 to Feb 2014. The model outputs and data have been detrended.  The models are represented by the multi-model ensemble-member mean of the CMIP5-archived model simulations of sea surface temperature for the respective ocean basins.  Those are the models used by the IPCC for their 5^th Assessment Report. The model mean represents the forced-component of the climate models, or, in other words, the model mean represents how the sea surface temperatures would vary if they varied in response to the anthropogenic and natural forcings used to drive the climate models. (For further information about that topic, see the post On the Use of the Multi-Model Mean.)  The data is the ERSST.v3b sea surface temperature data used by GISS and NCDC in their global land+sea surface temperature products. The detrended data and model outputs have been smoothed with 61-month running-average filters to minimize the annual variations, thereby highlighting the decadal and multidecadal variations.

As illustrated, the forced component of the models (the model mean) fails to produce the multidecadal variations in the sea surface temperatures of the North Pacific and North Atlantic Oceans. This indicates the sea surface temperatures of the North Pacific and North Atlantic are capable of varying over decadal and multidecadal timeframes without being forced to do so by manmade greenhouse gases and aerosols.

Figure 7

# # # #

Figure 8

Keeping in mind that we’re looking at detrended data, the models do not simulate the cooling that took place from the late-1800s to the 1910s, and they failed to simulate the warming from the 1910s to the early-1940s. Likewise, the models failed to simulate the cooling from the early-1940s to the mid-1970s, and they do a poor job of simulating the warming from the mid-1970s to the turn of the century…even though the models are tuned to the late warming period. (See Mauritsen, et al. (2012) Tuning the Climate of a Global Model [paywalled]. A preprint edition is here.)

It’s hard to imagine how the IPCC can claim that the climate models with only natural forcings could somehow represent “the alternative hypothesis of just natural variations”, when the models with natural and anthropogenic forcings cannot simulate the “natural variations”.

Let’s return to the quote from the Technical Summary about the Atlantic Multidecadal Oscillation.  They wrote:

A number of studies have investigated the effects of the Atlantic Multi-decadal Oscillation (AMO) on GMST. Although some studies find a significant role for the AMO in driving multi-decadal variability in GMST, the AMO exhibited little trend over the period 1951–2010 on which the current assessments are based, and the AMO is assessed with high confidence to have made little contribution to the GMST trend between 1951 and 2010 (considerably less than 0.1°C). {2.4, 9.8.1, 10.3; FAQ 9.1}

First, the Atlantic Multidecadal Oscillation is represented by detrended North Atlantic sea surface temperature anomalies, using the coordinates of 0-70N, 80W-0.  Refer again to the model-data comparison in Figure 8.

Second, it’s of little importance if the Atlantic Multidecadal Oscillation contributed little to the global mean surface temperature from 1951-2010.  What is important is that the IPCC is overlooking the fact that they tuned their models to naturally occurring upswings in the sea surface temperatures of the North Atlantic and North Pacific, and extended their projections from those upswings…without considering the likelihood that the upswings would be followed by a naturally occurring downturns in the surface temperatures of both basins.  In other words, they did not tune the models to the long-term trends of the Northern Hemisphere sea surface temperature datasets, which account for the multidecadal variations; they tuned the models to the recent high-trend period that represents only one-half of “cycles”.  See Figures 9 and 10.

Figure 9

# # # #

Figure 10

Yet the climate science community somehow seems surprised that global surface temperatures have stopped warming.  They look more and more foolish with every passing year and with each new IPCC assessment report.

ADDING INSULT TO INJURY

As I have presented on numerous occasions over the past 5 years, ocean heat content data and satellite-era sea surface temperature data both indicate that naturally occurring processes are responsible for the warming of the global oceans, not manmade greenhouse gases.  If this topic is new to you, please refer to the free illustrated essay “The Manmade Global Warming Challenge” (42MB) for an introduction.  The discussions and documentation are much more detailed in my ebook Who Turned on the Heat?

SIDE NOTE

You may wish to continue to read the RSS Climate Analysis webpage because they then go on to write (their boldface):

But….

The troposphere has not warmed as fast as almost all climate models predict.

And then RSS present three model-data comparisons that show the models failing to simulate lower troposphere temperatures globally and in the tropics and that only Arctic lower troposphere temperatures are warming as predicted by models.

CLOSING

As I was writing this, it occurred to me that this post would make a good supplement to my ebook Climate Models Fail.  I’ll try to prepare a pdf edition of this post for those who are collecting them.  Please check back in a couple of days.