An independent confirmation of global land warming, not using temperatures from meteorological stations

It has been hypothesized in some scientific publications (e.g., Pielke et al, JGRA, 2007, doi:10.1029/2006JD008229) and sometimes outright asserted (by AGW "skeptics" or in some media outlets; e.g., here, here, and here) that temperature analyses like GISTEMP, HadCRUT, or NCDC were not reliable, and the global warming, seen in these analyses over the last century, using direct temperature measurements from meteorological stations was largely just an artefact of faulty measurements, data adjustments (homogenization), the urban heat island effect, and other factors.

Gilbert P. Compo, Prashant D. Sardeshmukh, Jeffrey S. Whitaker, Philip Brohan, Philip D. Jones, and Chesley McColl have just published a new study (for the abstract: Compo et al., GRL, 2013, doi:10.1002/grl.50425), where the land near surface air temperature is derived using a state-of-the-art data assimilation system (20th Century Reanalysis). The temperature is calculated from other variables (surface pressure) and parameters in the reanalysis. The measured land surface air temperature is not part of the input data. Thus, any possible contamination of the measured land near surface air temperature by other factors than the state of the atmosphere does not have any effect on the land near surface temperatures calculated in the reanalysis system. The correlation between the land near surface temperature, calculated from other variables in the data assimilation system, and the land near surface temperature data series, derived using direct measurements over land is very high. This increases the confidence in that the statistically significant global warming trend of the atmosphere near the surface, seen in the GISTEMP, HadCRUT, or NCDC analyses over the last century is real, and those data sets can be used as reliable references for other scientific analyses.

  

Figure from: Compo, G. P., P. D. Sardeshmukh, J. S. Whitaker, P. Brohan, P. D. Jones, and C.McColl (2013), Independent confirmation of global land warming without the use of station temperatures, Geophys. Res. Lett., 40, 3170–3174, doi:10.1002/grl.50425.

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?