Tag Archives: Skeptical Science

Confusion and distortion – has global warming stopped?

There’s a mantra circulating at the moment claiming that global warming “stopped 17 years ago.” It is of course being pushed by the pseudosceptics in the climate denial echo chamber. However, even people who should know better have been heard to repeat something like that.

Rodney Hide, a former New Zealand ultra conservative politician has assured us “The world stopped getting warmer 17 years ago. That’s incontrovertible” (see my post “Incontrovertible” is it, Rodney? for my take on that). And one of the commenters on my blog at  SciBlog seems willing to treat Rodney’s assurance as a simple fact. Of course the pseudosceptics proudly and loudly reassert similar claims.

But many of those repeating this mantra are attributing the claim to authoritative sources, like the the Intergovernmental Panel on Climate Change (IPPC) and leading climate scientists and institutions.

So what’s the truth. Has global warming “stopped?” Are climate scientists saying it has stopped?”

Short answer is actually no. Slightly longer answer is along the lines that the current rate of global temperature increase seems to have slowed, global temperatures may even have plateaued, but that doesn’t support a claim that global warming has “stopped!” Or stopped 17 years ago.

IPCC Chairman misrepresented

Firstly – lets deal with the use of Rajendra Pachauri, Chairman of the IPPC, as a source for this mantra. This appears to go back to a report in the Australian which claimed he  “acknowledged a 17-year pause in global temperature rises.”

Trouble is, there is no record to back up the claim and the IPCC communications office said it does not accurately represent Pachauri’s thoughts on the subject.

The only statement the Australian article actually attributed to Pachauri on this subject is that “global average temperatures had plateaued at record levels and that the halt did not disprove global warming.” And that is paraphrasing Pachauri and not quoting him directly.

As the blog Skeptical Science pointed out (see Did Murdoch’s The Australian Misrepresent IPCC Chair Pachauri on Global Warming?) if he “had he said that global surface air  temperatures have plateaued and that this doesn’t disprove global warming, he would be 100% correct.” And that is what a number of well-known climate scientists also have said. Usually no mention of 17 years and certainly no claim that global warming had “stopped” 17 years ago.

To help clarify I repeat below two figures from my recent post “Incontrovertible” is it, Rodney? These show global air temperatures for the last 17 years and for the long-term – since 1880.

17-years

Global temperature anomalies for 1996-2012 (Average annual temperature data from NASA’s Goddard Institute for Space Sciences),

Line plot of global mean land-ocean temperature index, 1880 to present, with the base period 1951-1980. The dotted black line is the annual mean and the solid red line is the five-year mean. The green bars show uncertainty estimates. [This is an update of Fig. 1A in Hansen et al. (2006).]

As I said about the first figure in my recent post:

“There’s a lot of noise so all we can say from that data is the warming rate is in the range of  -0.02 and 0.17 °C/decade (95% confidence level). That’s the problem with such short time periods.”

Putting short-term trends in context of long-term record

The data in the first figure must be put into the context of the longer term changes. And as the 2nd figure shows a number of short periods over the longer term which had a similar pattern to that in the first figure. It would be silly, especially with hindsight, to claim that global warming “stopped” in 1990, or 1985, or 1975, and so on. Yet this is what some people are doing.

It’s easy to find short time periods where the global temperature trend is not significantly different to zero – that’s the nature of a record with this sort of variability or noise. A record which also results from a number of factors and is therefore not a simple correlation with one cause.

So it is silly to cherry pick a short period and then make an absolute claim (global warming has stopped) – and especially to claim that somehow something happened in 1975 so that “global warming stopped 17 years ago. Think about it. Take that first figure a just select the last 10 years. The trend will also not be significantly different to zero – are we then going to claim something happened in 2002 to “stop” global warming?

No, of course not. The only reason 17 years is mentioned is that one can’t go back further than that without the trend being significantly different from zero. It’s a cherry-picked date – cherry picked to produce a non-significant trend.

Have IPCC models been disproved

Another common claim is that the very recent plateau, or decrease in the rate of global warming proves the scientific climate models are wrong.  More specifically I have often heard the claim that since this plateau has occurred while atmospheric CO2 levels continue to increase this proves that CO2 is not driving global warming. Even the claim that the plateau has somehow shown the scientific understanding of the fundamental properties of greenhouse gases is wrong.

The naivety of the last claim is to think that climate scientists  consider CO2 to be the only factor influencing the climate – they just don’t. Consequently one should not expect to see a simple correlation between global temperature and atmospheric CO2. Any attempt to understand or model climate change must include many more inputs than CO2.

As for models in general here is a couple of factors:

  1. All models are inaccurate. That’s just the nature of the attempt to understand complex systems – we can’t expect to get things perfect. And when anomalies occur this may actually help us improve the models by incorporating other factors or more realistic physical parameters. Despite this models have important uses as long as we understand their limitations.
  2. Models require inputs – inputs which may change, often unpredictably, over time. Therefore it is silly to expect model projections to always be correct or accurate further down the track.

For example, there could be weather conditions increasing heat inputs into the deep ocean which could not have been incorporated several years ago. Or there could have been an increase of particulates from increased coal use which had not been predicted. Political changes can produce economic changes which influence inputs. These are some of the ideas that have been suggested to help explain the current plateau or reduced rate of global temperature increase.

So the real test of the model is not to use inputs based on predictions made several years before, but to update inputs so that the model more correctly represents current situations.

But, more basically, it’s important to recognise that the global climate is complex. Simple mechanisms are not going to explain the details in the global temperature record. So be careful of people who advance simple explanations to discredit the science.

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“Incontrovertible” is it, Rodney?

I wonder if many politicians, or in this case ex-politicians, are capable of seeing the irony and contradictions in their public statements. Or perhaps porkies are just the stock in trade of politicians so irony doesn’t even come into it.

But hows this for irony – Rodney Hide is lecturing scientists about the nature of scientific knowledge (see Faith, not facts, drives global warming). Here’s what he says about claims by climate scientists that greenhouse gases like CO2 can lead to global warming.

That’s religious zealotry in action. Science is never that certain. The best-ever scientific knowledge was Newtonian mechanics. And Einstein blew it to bits. That’s the nature of science. It gets nearer the truth but can never declare the truth.

Only religious fundamentalists have certitude. Their knowledge is a belief system that’s immune to real world experience and facts.

I guess Rodney sees himself as more a religious fundamentalist than a scientifically literate person because he then goes on to declare – with the ultimate amount of “certitude:”

“The world stopped getting warmer 17 years ago. That’s incontrovertible.”

“Incontrovertible” is it Rodney? That sounds like a statement of faith.

Let’s look at some data

Firstly global temperatures: Here’s the data for the last 17 years:

17-years

Global temperature anomalies for 1996-2012 (Average annual temperature data from NASA’s Goddard Institute for Space Sciences),

Yeah – I know. There’s a lot of noise so all we can say from that data is the warming rate is in the range of  -0.02 and 0.17 °C/decade (95% confidence level). That’s the problem with such short time periods. Perhaps we should put that data in the context of the long-term trends:

Line plot of global mean land-ocean temperature index, 1880 to present, with the base period 1951-1980. The dotted black line is the annual mean and the solid red line is the five-year mean. The green bars show uncertainty estimates. [This is an update of Fig. 1A in Hansen et al. (2006).]

Still believe that “The world stopped getting warmer 17 years ago. That’s incontrovertible,” Rodney? Willing to put money on it? More important – would you as a politician be willing to commit the fate of your grandchildren on such an extreme claim?

Well, if you still think your claim is “incontrovertible” have a look at some more data. Here’s data for the change in the total earth’s heat content – storage in the ocean as well as atmosphere, land and ice.

Total_Heat_Content_2011_med

And some more detailed data for the melting of ice – globally, Antarctic and Arctic (Click on the image if the animated gif is not changing):

GlobalSeaIce

(The last two figures are from Skeptical Science: A Big Picture Look at Global Warming)

Rodney assures us that “Anyone can do science. And scientists can often fall short.” Sure – but we surely expect more than this from scientists – professional or not. Rodney has simply taken a bit of non-representative data, extracted it from context, ignored everything else and declared his firmly held belief (one could even say “religiously” held belief) as “incontrovertible!”

Worse, while he is telling such porkies he is dishonestly demanding something from scientists which is extremely silly. That they just shut up with their ideas and conclusions until their data is completely “incontrovertible.” Until it can be presented with absolute “certitude.” They should STFU till they have the absolute truth – after he has already acknowledged that science “gets nearer the truth but can never declare the truth.”

He would love that, wouldn’t he? It would give him and his ultra-conservative political mates a completely clear field.

But wouldn’t it be irresponsible to gag scientists like that? Surely we want governments to use the country’s scientist to get the best current data and conclusions – even as we acknowledge that it is never the final story.


Footnote:

Perhaps this is what is leading Rodney Hide astray. In a comment at the climate pseudosceptic/denier/contrarian blog Climate Conversation Group Rodney acknowledged he is using that blog as a resource (a fabulous resource and mine of information“) Bloody hell, no wonder he has it so wrong. He really has to widen his reading.

Mind you, one of the resources he may have used is Richard Cummings who claims in comments on that blog he has shown that our scientific understanding of the fundamental properties of greenhouse gas molecule is all wrong! I suggested that he should present his findings at this year’s New Zealand Climate Change Conference. And this crowd could also present their analysis of New Zealand’s temperature record which they produced as an alternative to that of NIWA. However, they seemed to consider these suggestions offensive and banned my comment!

Incontrovertible my arse.

See also: Dear Rodney Hide

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Deconstructing climate change, and its deniers

I presented these IPCC graphs some time back in Climate change is complex. They underline the fact that climate changes are caused by a number of factors (natural and human-caused) so any successful modelling of global temperature changes needs to take all the factors into account. The graphs show how omission of human caused factors produces model results inconsistent with measured values.

Figure a included all the natural and anthropogenic influences. The black line is the actual measured global temperature anomaly (obtained by subtracting the average temperature for 1901 to 1950). The individual simulations are shown as thin yellow curves. The red line is the multi-model ensemble mean (see Figure 9.5 – AR4 WGI Chapter 9: Understanding and Attributing Climate Change).
Figure b is a similar plot using simulations which consider only the natural influences on climate. The individual simulations are shown as thin blue curves. The thick blue line is the multi-model ensemble mean.

These figures show how simple plots of global temperate over time cannot identify causes – a more complex investigation involving modelling was required. This enabled contributions from non-natural and natural causes to be identified.


Now the blog Skeptical science has produced a video showing a similar deconstruction of the factors causing global temperature change. The purpose was to show the falseness of recent claims by climate change deniers/contrarians/sceptics of no human contribution to climate change because they have observed no warming in the last 16 years.

Short term temperature changes are the results of several natural and human caused factors. But only the human caused emissions of CO2 is causing a steady effect which becomes clear when long-term changes are considered (even if not clear in the short term).

http://youtu.be/u_0JZRIHFtk


(Thanks to Still warming after all these years (again) at Hot Topic).


Finally, here is another graph which has the climate change deniers/contrarians/sceptics buzzing. It’s from the UK Met Office (see Decadal forecast). The buzz arises from the Met Offices revisions of “near-term’ climate prediction because of improvements in the modelling.

fcst_global_t4

Observed (black, from Hadley Centre, GISS and NCDC) and predicted global average annual surface temperature difference relative to 1971-2000. Previous predictions starting from June 1960, 1965, …, 2005 are shown as white curves, with red shading representing their probable range, such that the observations are expected to lie within the shading 90% of the time. The most recent forecast (thick blue curve with thin blue curves showing range) starts from November 2012. All data are rolling annual mean values. The gap between the black and blue curves arises because the last observed value represents the period November 2011 to October 2012 whereas the first forecast period is November 2012 to October 2013.

Actually, the denier/contrairan/sceptic buzz arises because the revised (improved) predictions are a “little lower” than the previous one. This has caused them (the deniers/contrarians/etc) to claim this proves global warming has stopped, and that human-caused climate change has consequently been proven wrong!
Of course this is wishful, and motivated, thinking on their part. The predictions produced by the Met Office rely on simulations using the best and most up to date models. The models incorporate all the factors known to influence global temperatures – including that caused by human burning of fossil fuels!

It’s a strange old world. The deniers/contrarians/sceptics who wish to deny human contributions to climate change have been sucked in by the Met Office sort term predictions of global temperatures. These deniers/contrarians/etc., are now touting models in support of their claims which in fact are based on the effects of such human contributions.

They are relying on the very thing they wish to deny!

See also:
Updates to our decadal forecast
Has global warming ground to a halt?

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Who is committing fraud here?

Richard Treadgold, whose blog Climate Conversations appears to be the sole active NZ blog devoted entirely to climate change denial, is rehashing an old argument (See Well, where’s your evidence, Renowden?). He claims:

“Global warming has not happened for about 15 years, unless you take a micrometer to the thermometer. And if you have to do that just to detect warming, then it’s hardly dangerous, is it?”

Of course this has been explained to him and his mates many times. Either his brain is just not capable of comprehending the simple story – or he continues to raise it despite the fact it has been well refuted. After all, if your real purpose is political, to manufacture doubt, honesty is your last concern. That’s why he claims climate scientists are committing “fraud” on this question (and others).

I dealt with the issue in my post “What, me worry?” – distorting climate change data. It is simply the issue of how to detect a relatively small trend in temperature against a background of relatively large natural variations which don’t contribute to the underlying trend. A common problem is sciences of all sorts.

It’s a question of observation period. We know, for example, that organic carbon builds up in soils under pasture. But try measuring the carbon levels over one season or one year and you just won’t see it. It’s buried in the inevitable noise of the variation in carbon levels over short times. But collect the data over 10 or more years and you will start to see the trend.

Its the same with global temperatures. The overall trend is not obvious, can’t be extracted from the data, over relatively short terms, because of the relatively large natural variations. When someone bases their claims on such a short perod you have to wonder about their honesty because its simple enough to produce any result you desire by chossing your time period. This is clear from The Escalator produced by Skeptical science.

Its a classic example of the activity that goes on in the climate change denier echo chamber (of which Treadgold is a part).

Here’s another give away. Why is Treadgold talking about 15 years – these guys used to use 10 years? Well the reason is their desire to preserve 1998 data. Global temperatures that year were exceptionally high so that data point has an over-riding effect on determining trends over a short term. If Treadgold has stuck to 10 or 12 years he was in danger of actually finding a statistically significant trend. That is the last thing he wants.

Statistical confidence in the observed increase in global temperatures comes from data collected over a long period. Selectively cherry-picking the data in the way Treadgold and his mates does is a no -no in science.

But of course science is the last thing they are interested in. Their purposes are political – and the manufacture of doubt.

Its obvious who is committing the fraud here.

The silliness of a self-proclaimed “investigative journalist”

Just imagine it. You call on your car mechanic when you have a serious health problem. Or ask your oncologist to service your car.

Who would be so stupid?

Ian Wishart's "investigative journalism"

Well its amazing the lengths some people go to when they are in denial. New Zealand’s self-described leading “investigative journalist,” Ian Wishart, seems to be advocating doing just that with his article NASA rocked by climate change revolt.

NASA rocked by a revolt – my arse!

Ian is referring to the latest little “scandal” occupying the climate denial echo chamber. The letter from 49 retired or former NASA engineers and astronauts asking NASA to refrain from making statements on the findings of their climate scientists.  Skeptical Science points out that the 49 signatories  “include 23 administrators, 8 astronauts, 7 engineers, 5 technicians, and 4 scientists/mathematicians of one sort or another (none of those sorts having the slightest relation to climate science).”

So these guys want the public statements of NASA on climate science to be determined by anyone but the climate scientists! And local climate change deniers are delusional, (or dishonest) enough to describe these signatories as “specialists with intimate knowledge of the nature of atmosphere and space. “

This letters supported by lists of inappropriate non-experts on the subject are a common tactic of climate (evolutionary science, tobacco harm, etc.) deniers. They are not news. And Wishart’s promotion of this one just shows the pathetic levels of his “investigation” skills.

I like this comment made at Think Progress post about this “news:” – NASA Climate ‘Skeptics’ Respond With Science! Just Kidding:

Let’s put the astronauts in this group in a press conference and ask for volunteers from among them to serve as crew members on the maiden flight to Mars onboard a spacecraft designed, engineered, and built by 49 climate scientists.”

Make that retired climate scientists! And perhaps throw in a few self-described “investigative journalists.”

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“What, me worry?” – distorting climate change data

Mad

Peter Gleick has a simple useful article in Forbes illustrating various ways that climate change deniers/contrariness cherry pick data to support claims that global warming is not occurring (see “Global Warming Has Stopped”? How to Fool People Using “Cherry-Picked” Climate Data). He is referring to an increasingly common argument that deniers/contrarians are promoting in OpEd columns and opinion pieces in newspapers. We have seen it here too, and the comments at New Zealand’s premium climate change denier blog Climate Conversation Group are full of such claims.

Recently I dealt with that argument as expressed by an old colleague of mine in a letter to the NZ Listener (see Open letter across the barricade). In the “open letter’ I reconstructed my own example of how global temperature data can be cherry picked to promote the “global warming has stopped” myth. But I had in the back of my mid  an animated graph which showed this more clearly.  Now I have found it – and reproduce it below. It’s from Skeptical Science (a mine of information) and is usually referred to as The Escalator.

I think this demonstrates the dishonesty of cherry-picking beautifully.
Mind you, it doesn’t stop motivated deniers and bloggers picking up these dishonest articles and promoting them to similarly motivated reader. Have a look at Local Whale Oil’s No Need to Panic About Global Warming.”
A classic example of the activity that goes on in the climate change denier echo chamber.

Our fingerprints are all over it!

Skeptical Science has just posted A Comprehensive Review of the Causes of Global Warming. The review’s conclusion are well illustrated by this figure which attributes the inputs from human and natural causes over the last 50 years.

Net human and natural percent contributions to the observed global surface warming over the past 50-65 years according to Tett et al. 2000 (T00, dark blue), Meehl et al. 2004 (M04, red), Stone et al. 2007 (S07, green), Lean and Rind 2008 (LR08, purple), Huber and Knutti 2011 (HK11, light blue), and Gillett et al. 2012 (G12, orange).

The different colours show the different studies reviewed. These used different and independent methods and Skeptical Science concludes they “provide multiple lines of evidence that humans are the dominant cause of global warming over the past century, and especially over the past 50 to 65 years.”

These studies considered different human and natural causes:

  • Human greenhouse gas (GHG) emissions,
  • Solar activity,
  • Volcanic activity,
  • Human aerosol emissions,
  • The El Niño Southern Oscillation (ENSO).

GHG and human aerosol (primarily sulphur dioxide, SO2)  are the two largest human influences, and solar and volcanic activity and ENSO are the dominant natural influences on global temperature. The figure below illustrates the breakdown of their contributions in these studies.

Percent contributions of various effects to the observed global surface warming over the past 100-150 years according to Tett et al. 2000 (T00, dark blue), Meehl et al. 2004 (M04, red), Stone et al. 2007 (S07, green), Lean and Rind 2008 (LR08, purple), Stott et al. 2010 (S10, gray), and Huber and Knutti 2011 (HR11, light blue).

Clearly, human inputs have provided the largest effect on global temperature over recent years. Greenhouse gas emission have had a positive effect and aerosol emissions a negative, partly balancing, effect. This negative human factor is decreasing as humanity cleans up its act in terms of SO2 and other aerosol pollution.

As Skeptical Science summarises these findings:

“A wide variety of statistical and physical approaches all arrived at the same conclusion: that humans are the dominant cause of the global warming over the past century, and particularly over the past 50 years.  This robust scientific evidence is why there is a consensus amongst scientific experts that humans are the dominant cause of global warming.”

Our fingerprints are all over it!

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Check out those climate change claims on the internet

This looks interesting. Skeptical Science has introduced a Firefox add-on which enables an internet surfer to rapidly check out the arguments found on web pages and blogs. Great for those without a specialist knowledge in the area of climate science. So much of this information on the internet is distorted or downright wrong. This could save the interested surfer the time and effort required to research claims for themselves.

As the image above shows  the report includes information on the real science. I can see people wishing to place comments at an offending blog using this feature.

The add-on also enables interested surfers to make their own reports on blogs and web pages. Those supporting the science as well as the offending ones.

This will provide a chance for the more interested surfer to contribute information and links to the Daily Climate Links email and Global Warming Links page. A chance to contribute to a very useful resource.

Go to Skeptical Science Firefox Add-on: Send and receive climate info while you browse for more information on the add-on. Looks like it could be fun.

You can download the SkS Firefox Add-on at Skeptical Science 1.0.

See also: Get your climate change science on the run for details of Skeptic Science’s iPhone and ipod Touch application. Another useful way of checking our the science of climate change.

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Get your climate change science on the run

Skeptical Science available on Itunes Iphone App StoreSomebody said that “lies are half way around the world before truth gets its boots on.” An underestimate, I would say.

With the current hysterical attack on climate science and climate scientists this is so true. It takes time to marshal the evidence needed to counter some of the claims being made. And most likely the perpetrator has moved on, in a Gish gallop, to a new issue and avoids facing up to the facts about the old one.

The internet is a great resource for people checking out some of the wild claims being made – providing you use reliable websites. One reliable site is Skeptical science, which has a byline of “Getting skeptical about global warming skepticism.” This site provides the actual scientific facts relevant to most claims made by climate change sceptics and deniers.

Now they have produced an application for the iPhone and ipod Touch. This will bring the much needed scientific information about climate change to your mobile device. Just imagine being able to check out a speaker during a lecture or debate – maybe even obtain the information of a sensible question.

Here’s a description of how to use the application taken from Skeptical Science now an iPhone app. at Skeptical science: Continue reading