American Geophysical Union's statement on human-induced climate change

The American Geophysical Union (AGU) has revised and reaffirmed its position on climate change caused by human activities, which was adopted for the first time in the year 2003. Position statements like this by the AGU expire after four years, unless it is reaffirmed. I personally agree with this statement. Here, I document the text:

"Human-induced climate change requires urgent action.

Humanity is the major influence on the global climate change observed over the past 50 years. Rapid societal responses can significantly lessen negative outcomes.

'Human activities are changing Earth’s climate. At the global level, atmospheric concentrations of carbon dioxide and other heat-trapping greenhouse gases have increased sharply since the Industrial Revolution. Fossil fuel burning dominates this increase. Human-caused increases in greenhouse gases are responsible for most of the observed global average surface warming of roughly 0.8°C (1.5°F) over the past 140 years. Because natural processes cannot quickly remove some of these gases (notably carbon dioxide) from the atmosphere, our past, present, and future emissions will influence the climate system for millennia.

Extensive, independent observations confirm the reality of global warming. These observations show large-scale increases in air and sea temperatures, sea level, and atmospheric water vapor; they document decreases in the extent of mountain glaciers, snow cover, permafrost, and Arctic sea ice. These changes are broadly consistent with long-understood physics and predictions of how the climate system is expected to respond to human-caused increases in greenhouse gases. The changes are inconsistent with explanations of climate change that rely on known natural influences.

Climate models predict that global temperatures will continue to rise, with the amount of warming primarily determined by the level of emissions. Higher emissions of greenhouse gases will lead to larger warming, and greater risks to society and ecosystems. Some additional warming is unavoidable due to past emissions.

Climate change is not expected to be uniform over space or time. Deforestation, urbanization, and particulate pollution can have complex geographical, seasonal, and longer-term effects on temperature, precipitation, and cloud properties. In addition, human-induced climate change may alter atmospheric circulation, dislocating historical patterns of natural variability and storminess.

In the current climate, weather experienced at a given location or region varies from year to year; in a changing climate, both the nature of that variability and the basic patterns of weather experienced can change, sometimes in counterintuitive ways -- some areas may experience cooling, for instance. This raises no challenge to the reality of human-induced climate change.

Impacts harmful to society, including increased extremes of heat, precipitation, and coastal high water are currently being experienced, and are projected to increase. Other projected outcomes involve threats to public health, water availability, agricultural productivity (particularly in low-latitude developing countries), and coastal infrastructure, though some benefits may be seen at some times and places. Biodiversity loss is expected to accelerate due to both climate change and acidification of the oceans, which is a direct result of increasing carbon dioxide levels.

While important scientific uncertainties remain as to which particular impacts will be experienced where, no uncertainties are known that could make the impacts of climate change inconsequential. Furthermore, surprise outcomes, such as the unexpectedly rapid loss of Arctic summer sea ice, may entail even more dramatic changes than anticipated.

Actions that could diminish the threats posed by climate change to society and ecosystems include substantial emissions cuts to reduce the magnitude of climate change, as well as preparing for changes that are now unavoidable. The community of scientists has responsibilities to improve overall understanding of climate change and its impacts. Improvements will come from pursuing the research needed to understand climate change, working with stakeholders to identify relevant information, and conveying understanding clearly and accurately, both to decision makers and to the general public.'

Adopted by the American Geophysical Union December 2003; Revised and Reaffirmed December 2007, February 2012, August 2013."

(Source: http://www.agu.org/sci_pol/pdf/position_statements/AGU_Climate_Statement_new.pdf)

Emerging new El Nino?

There has been some interesting development in the equatorial subsurface temperatures in the Pacific for the last two months. The positive temperature anomaly, which has been dominant in the upper 300 meters of the equatorial water body of the Western Pacific has spread eastward. Now we have a positive subsurface anomaly over the whole longitude range from 130E to 100 W. Only the far Eastern Pacific still shows a negative anomaly.

(Source: http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf, pg. 11)

The last model simulations are from June 2013. Most of the models predicted ENSO neutral conditions through 2013 back then.

(Source: http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf, pg. 26)

I am curious what the new model simulations, initialized with updated input data are going to say.

If one looks at the table of cold and warm episodes of ENSO, there has not been any period longer than four years from the end of an El Nino to the start of the following El Nino, going back to the year 1950. We are in the third year since the end of the last El Nino episode now. If it does not happen this year a new El Nino really will be due next year. Otherwise it would be unusual, if none occured compared to the frequency of occurrence for the period between 1950 and present.

AGW denier Marc Morano of Climate Depot and CFACT suggests, "global warming skeptics" are defined by fantasies about lynching climate scientists

Besides Morano did not get the facts right with respect to my employment, since I am not a NASA scientist (I am a Columbia University scientist at GISS), why am I saying this? Because Morano asserts on the Climate Depot website, "NASA scientist Jan Perlwitz publicly warns global warming skeptics, 'I shoot you dead'".

The actual fact is that I strongly responded on my own behalf to a lynch fantasy against climate scientists (which came combined with a delusional analogy to Nazi-Germany), articulated by a specific anonymous individual with the alias Allencic who said,

Morano's claim my response to Allencic's lynch fantasy was addressed at "global warming skeptics" is a lie. Thus, when Morano interprets my response to this as a "warning" against "global warming skeptics" in general, he suggests this kind of lynch fantasies against climate scientists was a defining feature of "global warming skeptics". I did not say, and I do not think it was.

Also, by displaying my statement as something condemnable, even though it was a conditional statement for the case the addressed individual really tried to tar, feather and torch me, i.e., murder me, because I was a climate scientist, Morano also suggests that I did not have any right to self-defense in such a situation. Thus, AGW denier Marc Morano, who is paid by the conservative think thank  Committee for a Constructive Tomorrow (CFACT) for spreading his propaganda and lies on his website, implicitly suggests that climate scientists did not have a right to self-defense, when someone tried to murder them.

Marc Morano is an appalling example of lack of ethics and honesty on the side of the AGW deniers.

Statement of Macquarie University regarding the termination of Professor Murry Salby

Yesterday, anti-science blogger Anthony Watts of wattsupwiththat.com posted an article, "Professor Murry Salby, who is critical of AGW theory, is being disfranchised, exiled, from academia in Australia", in which Watts claims that Murry Salby was wronged by Macquarie University. The claim is based solely on assertions in an email by Salby to Anthony Watts. I participated in this thread until I got permanently banned, saying that I do not believe Salby's accusations just at face value. The anti-science crowd of "skeptics", being not very skeptical at this point, rushed to the usual judgement, ranting about the evil establishment suppressing "the truth" and punishing critical scientists. In one case the desire of violence against those evil climate scientists who say anthropogenic global warming was real, was articulated.

I think, one should not just listen to what Salby claims, one also should listen what the other side has to say. If Salby was wronged he can and should choose the legal means available to him. But I am not going to assume he was wronged just because he claims so in some email to an AGW denier website.

Macquarie University has released following statement regarding the matter on July 10, 2013, which reads,

"Macquarie University does not normally comment on the circumstances under which employees leave the University. However, we feel in this instance it is necessary to do so in order to correct misinformation.

The decision to terminate Professor Murry Salby’s employment with Macquarie University had nothing to do with his views on climate change nor any other views. The University supports academic freedom of speech and freedom to pursue research interests.

Professor Salby’s employment was terminated firstly, because he did not fulfil his academic obligations, including the obligation to teach. After repeated directions to teach, this matter culminated in his refusal to undertake his teaching duties and he failed to arrive at a class he had been scheduled to take.

The University took this matter very seriously as the education and welfare of students is a primary concern. The second reason for his termination involved breaches of University policies in relation to travel and use of University resources.

The termination of his employment followed an extensive and detailed internal process, including two separate investigations undertaken by a committee chaired by a former Australian Industrial Relations Commissioner and including a union nominee."

(Source: Macquarie University, http://www.mq.edu.au/newsroom/2013/07/10/statement-regarding-the-termination-of-professor-murry-salby/)

The third time is the charm and the anti-science blog wattsupwiththat.com

Previously, I had reported here that I had been declared "persona non grata" on Anthony Watts' anti-science blog wattsupwiththat.com (WUWT). The story then developed with Anthony Watts posting a comment on the blog here to the previous posting on July 7, 2013, where he retracted the announcement previously made on his blog (here is a screenshot of the previous announcement once more),

and where he also made a pathetic attempt to present it as if the banning had been only in my head. Later, he also publicly claimed that the statement about my banning were "unsubstantiated facts on display", despite the evidence above to the contrary. But he basically said I was allowed to comment again at WUWT.

So, I went back to WUWT. It lasted only as long.

I am usually trying to reply with polite words, even when faced with the most vicious and hateful attacks or with displays of extreme ignorance, although I may not have always been successful with my tries. However, I have some problems with diplomatic approaches. I rather tend to speak my mind, sometimes up to a fault, which can escalate situations, and it has caused me some troubles and scary moments in the past, e.g., in the country where I came from.

There have been several instances, when commenters on WUWT articulated their wish that violence was applied against climate scientists, including me as a person. For instance, the late Robert E. Phelan who even was a moderator at WUWT, wrote on April 14, 2012, addressed at me, "When the peasants come for you with their pitchforks and torches, you will have brought it on yourselves."

Yesterday (July 10, 2013), some other commenter, posting under the alias Allencic, from the anti-science crowd on WUWT articulated a similar wish, (combined with the delusional notion that the AGW deniers were in a situation like Jewish scientists in Nazi-Germany. The articulation of the wish for violence against climate scientists needs a strong rationalization to justify it), even though the commenter claimed later it just had been irony.

"God help us from these fools who claim to be climate scientists. When this finally blows up and the public realizes how badly they’ve been had you might want to invest in pitchforks and torches and tar and feathers."

Anthony Watts is growing a quasi-religious anti-science cult with his blog. And he is not the only one who makes propaganda against the findings of climate science and against climate scientists, using a combination of disinformation, junk science, inciting accusations against scientists and outright lies. There are other anti-science blogs and groups who are publicly agitating (e.g., the Heartland Institute) in the same way. If Watts does not do it himself, he tolerates it when it comes from his guest authors or followers. Therefore, I consider it very possible that some AGW-denier fanatics are going to use violence against climate scientists and scientific institutions, equally motivated, for instance, as religious fanatics are attacking abortion clinics. The grounds are laid. The hate is there, the viciousness is there.

I am a peaceful person, but I am not a pacifist. I am in favor of the right to self-defense, including armed one, if someone tries to apply violence against climate scientists (or any other innocent people). I articulated this on Watts' blog, although not as elaborated and with different words. Now, I am banned again. Permanently.

Is there evidence for a statistically significant trend change in the global surface temperature data?

Update: When one starts the trend analysis in 1999, using the the same tools as below, it takes the year 1998 with the strong El Nino out of the picture. Both the year 1999 and 2000 were years with La Nina present. One still gets some weak/medium statistical significance for the difference between the trends from 1975 to present and from 1999 to present.

Just to clarify. This has nothing to do with the denier talking point about a "global warming stop" or similar. Global warming has not stopped as one can see from the continuing increase in the ocean heat content also in recent years (the acceleration in the melting of the Arctic sea ice is another indicator):

Source: http://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/

It has more to do with how the additional energy available from the radiative perturbation from increasing greenhouse gases in the atmosphere is redistributed in the Earth system. There may be years, when the fraction of this energy that heats the deeper layers of the oceans increases at the expense of the fraction that heats the atmosphere. This may have been the case in the recent decade, and it could last a few more years. Some recent research supports this possibility (see Meehl et al., Journal of Climate (2013), doi: 10.1175/JCLI-D-12-00548.1).

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Update: I have asked the question below also at Tamino's blog "Open Mind". He gave an interesting answer, pointing me to another post by him, according to which cherry-picking of a start year, which I exactly did by choosing 1998, actually changes the results from the statistical significance test and requires much higher t-values to be exceeded to make the result statistically significant. Keep this in mind, when doing such a thing. I learn something new every day.

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Has anyone else noticed that the trend estimates in the data sets for the globally averaged surface temperature anomaly since 1998 have become statistically significantly different from the multi-decadal trend estimates since the mid 1970s? Not yet at the 95% level, but almost, except for the BEST land only data. This is different to the beginning of year 2012. Both the trend estimates and the 2 sigmas since 1998 have come down since then.

I use the Skeptical Science tool (http://www.skepticalscience.com/trend.php), which is based on the methodology according to the Foster and Rahmstorf, IOPS (2011) paper (http://dx.doi.org/10.1088/1748-9326/6/4/044022). For autocorrelation I use 1975 to present (What is the correct choice of the autocorrelation period?)

These are the trends and 2 sigmas in K/decade for the two time periods. The statistical Null-hypothesis is that there has been no change of the trends since 1975.

                    1975-present            1998-present         Significance level
GISTEMP:    0.169+/-0.039           0.057+/-0.14          >85%
NOAA:          0.159+/-0.036           0.033+/-0.131        >90%
HadCRUT4:  0.169+/-0.041          0.038+/-0.149        >90%

For land only data:
BEST:           0.264+/-0.063          0.144+/-0.26            < 1 sigma
NOAA:          0.275+/-0.052          0.101+/-0.205         >90%


This may be all just a statistical artifact due to the cherry picked start year of 1998 and the very strong El Nino in that year, the prevalence of La Ninas in recent years, and the deeper and prolonged solar minimum of cycle 23. The statistical significance may go away again with the adding of the data from coming years. Even a 95% significance level still allows for one false rejection of the Null-hypothesis out of 20. However, with these numbers I do not feel comfortable to reject that some empirical, statistical evidence for a significant trend change toward a lower warming trend in recent years has emerged. Those numbers actually indicate a quite high probability for such a change.

It is not inconsistent with the somewhat smaller increase in the ocean heat content (OHC) in the upper 700 m over the last decade compared to the decades before. http://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/

It may be worth to check whether the smaller slope of the 700 m OHC in recent years is statistically significantly different from the slope in the decades before.

Any opinions on those numbers and what conclusions can be drawn from it?

Declared persona non grata at wattsupwiththat.com

Update, 07/07/2013: See Anthony Watts' comment below and my reply.

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I just have tested the new approach, announced in April by Anthony Watts who is host of the blog, to the treatment of comments at wattsupwiththat.com, to see whether anything has changed for me. I commented on an article with the title "No significant warming for 17 years 4 months" by the notorious Christopher Monckton. Well, I tried. This is the result:

Thus, the only change for me is that me being banned is official now. They want to be more among themselves, without being too much interrupted by someone informed rebutting their pseudo-science. It is like with a cult. This is Anthony Watts' big change. I am certainly not the first one who actually works in the field of climate science and who got declared persona non grata over there. I feel honored.

Here is what I had submitted in reply to Monckton's article:

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Anthony Watts seems to think this article posted under the title "No significant warming for 17 years 4 months", written by Christopher Monckton has an important message to deliver to have it put as sticky first post on his blog for a number of days. But with closer examination, it is only the x-th repetition and variation of the "skeptic" talking point about the "global warming stop/pause" or "no warming", observed allegedly for x-number of years (the x varies according to convenience).

Mr. Monckton asserts in his article right away in the first paragraph, that "there has been no global warming statistically distinguishable from zero for getting on for two decades."

Now we are already up from 17 years and 4 months to alleged "two decades", which would make it 20 years, for which there hadn't been any warming that was statistically distinguishable from Zero, according to Mr. Monckton. Why not boldly claim "two decades", if he is at it, right?

On what does Mr. Monckton base his assertion about the alleged lack of warming for > 17 years? He bases this assertion on the fact that the temperature trend in the HadCRUT4 data set does not exceed the 95% statistical significance threshold. As correct this fact is, technically, it's also the point where Mr. Monckton misleads the audience. He equalizes a temperature trend, which does not pass the 95% significance threshold when a statistical test is done with "no warming" at all. And this is just jumping to conclusions.

Let's examine the trend since the start of 1996. There is a tool at the Skeptical Science blog, with which this can be done for the major temperature data sets: http://www.skepticalscience.com/trend.php

HadCRUT4 shows a trend with a 2*sigma (=2*standard deviation, which is equal to about 95% statistical significance threshold) of 0.089+/-0.118 Kelvin/decade. Does this mean this warming is not distinguishable from Zero, generally, because the trend was smaller than 2 sigma? No, it does not necessarily mean that, because it is still possible that the trend exceeds a lower significance threshold.

So, let's check that. The trend of 0.089 in the HadCRUT4 data since the start of 1996 equals to about 1.51*sigma. The 80% threshold of statistical significance is about 1.28*sigma. Thus, even though the 95% threshold has not been exceeded (yet) since the start of 1996, one can distinguish the temperature trend in HadCRUT4 from Zero with more than 80% statistical significance. The probability to err is less than 20%. The other data sets, except for RSS that deviates to the cold side, show similar or higher warming trends since 1996, compared to HadCRUT4 (e.g., Spencer and Christy's UAH data: 0.12+/-0.2 Kelvin/decade). The satellite retrieved data have larger 2 sigma intervals, though. There is a larger interannual variability in the troposphere temperature data compared to the surface temperature data.

BTW: Even if the temperature trend was not statistically significant even at 1 sigma, this would not allow the conclusion that there was "a global warming stop/pause", since non-detectability of a trend in a time series, which is composed of trend and fluctuations is not sufficient to conclude absence of the trend in the time series. This is particularly true in this case, since there is a multi-decadal warming trend going back to the mid 70s, which is statistically significant with more than eight sigma in the surface temperature records.

Another point would be that the atmosphere is one thing, and not the major component regarding global warming. The oceans have continued to warm in the time period during which global warming allegedly has "stopped/paused". About 90% of the additional energy from the radiative perturbation due to increasing greenhouse gases in the atmosphere goes in the ocean. The ocean releases a part of this accumulated energy into the atmosphere over time. This energy release is not a linear process. A large part of this energy is released during El Ninos. And the ice caps at both poles of the planet (that includes the glaciers) have continued to melt. No one should have missed the melting trend of the Arctic sea ice, which has even accelerated over the last decade. These are strong indicators that global warming has continued also in recent years, contrary to what "skeptics" want to make believe.

In summary, Mr. Monckton's assertion of "no warming" for > 17 or even 20 years is false. It does not have any scientific validity, because it is not based on empirical, statistical evidence. And it ignores other indicators for global warming than the tropospheric/surface temperature trends.

Another assertion by Mr. Monckton is about something he calls "Dr. Santer's 17-year test", according to which "models may have failed", because the temperature trend hadn't exceeded the 95% threshold. Now, one could expect that Mr. Monckton provides some proof of source for this assertion about such a test, allegedly stated by Ben Santer. However, the link he provides leads only to another article in this opinion blog here, which was obviously not written by Ben Santer. So, is it the link to the one press release in the other article?
https://www.llnl.gov/news/newsreleases/2011/Nov/NR-11-11-03.html

The press release states something that refers to 17 years. It states:

"In fingerprinting, we analyze longer, multi-decadal temperature records, and we beat down the large year-to-year temperature variability caused by purely natural phenomena (like El NiÃ'±os and La NiÃ'±as). This makes it easier to identify a slowly-emerging signal arising from gradual, human-caused changes in atmospheric levels of greenhouse gases," Santer said.

The LLNL-led research shows that climate models can and do simulate short, 10- to 12-year "hiatus periods" with minimal warming, even when the models are run with historical increases in greenhouse gases and sulfate aerosol particles. They find that tropospheric temperature records must be at least 17 years long to discriminate between internal climate noise and the signal of human-caused changes in the chemical composition of the atmosphere.

The talk in the press release is about the fingerprinting method applied by Santer. Regarding this method, it is said that one needs at least 17 years of observed tropospheric temperature data to detect the human-caused warming signal. However, there is no statement whatsoever in the press release according to which a lack of 95% statistical significance for more than 17 years meant that the model had "failed".

I actually have read Santer et al.'s paper (doi:10.1029/2011JD016263), I suspect, unlike Mr. Monckton. There is nothing in the original paper either that says anything about such a test for model predictions of the kind as asserted by Mr. Monckton. Apparently, Mr. Monckton has just made something up here, regarding the alleged "Dr. Santer's 17-year test" for model predictions using the 95% threshold of significance in the observed data.

Also, I seem to have a different understanding of the English language compared to many "skeptics", because, in my world, "at least" marks a lower boundary, whereas many "skeptics" seem to think that "at least" has equal meaning to "at most".

As for Mr. Monckton's assertion about the alleged IPCC predictions regarding the temperature increase since 2005. Mr. Monckton writes:

It is better to focus on the ever-widening discrepancy between predicted and observed warming rates. The IPCC’s forthcoming Fifth Assessment Report backcasts the interval of 34 models’ global warming projections to 2005, since when the world should have been warming at a rate equivalent to 2.33 Cº/century. Instead, it has been cooling at a rate equivalent to a statistically-insignificant 0.87 Cº/century:

Mr. Monckton asserts here that the IPCC had predicted the temperature would nearly linearly increase by 0.0233 Kelvin/year since 2005, and because the temperature in the real world had behaved differently, the model predictions were wrong. I can't call this claim by Mr. Monckton anything else than absurd nonsense. Mr. Monckton just takes the model ensemble average calculated from many individual model simulations and interprets this as a prediction of how the temperature will behave in the real world. Of course, the ensemble mean does not show the same variability as the temperature in Nature, because it's a mean! Nature only provides one single realization of all possible realizations for the same boundary conditions in a chaotic system. Each individual model simulation is like a single possible realization. It is nowhere predicted by anyone that the one single realization from Nature would follow the model ensemble mean from year to year, or even from decade to decade. A proper comparison, for instance, would be to take the full range of all model simulations, among which, BTW, there are some that actually show a "cooling" over the same time period as well, obtain the 95% range spanned by the model simulations, and then see whether the observed temperature record lies within this range, or marches outside of the range. Mr. Monckton has not done that. According to the real Figure 11.33a in the leaked draft of the AR5 report, the observed global mean surface temperature still lies within the range of the model simulations, although near the lower end.
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