Tag: AGW

Our changing climate – what is the truth?

A video on YouTube raises some fundamental questions about our changing climate.

Let me say straight away that my belief in Anthropogenic Global Warming (AGW) is based on instinct, and not on me understanding the science, simply because I am not a scientist; far from it! As I share on this blog:

Paul Handover is a child of the post-war era in Great Britain having been born in London a few months before the end of WWII. After a rather shaky attempt at being educated, including 2 years studying for a Diploma in Electrical Engineering, Paul’s first job was as a commercial apprentice at the British Aircraft Corporation. He then joined the sales desk of British Visqueen, a polythene film and products manufacturer located in Stevenage, Hertfordshire, and part of ICI Plastics Division. In 1968, he travelled out to Sydney, Australia and became part of the sales team at ICIANZ’s Inorganic Chemicals Division.

I am a fundamentally a retired salesman/entrepreneur with a very out-of-date knowledge of electrical engineering and radio communications (G3PUK), and now struggling to be an author. 😉

Plus, my generally sceptical view of how countries are governed, my awareness of a terrible lack of integrity in politicians, plays to those instincts of mine that humanity is, indeed, responsible primarily for our changing climate. And there is no shortage of supporting evidence!

A very quick web search found this NASA site that included the following graph and text (in part):

This graph, based on the comparison of atmospheric samples contained in ice cores and more recent direct measurements, provides evidence that atmospheric CO2 has increased since the Industrial Revolution. (Credit: Vostok ice core data/J.R. Petit et al.; NOAA Mauna Loa CO2 record.)
This graph, based on the comparison of atmospheric samples contained in ice cores and more recent direct measurements, provides evidence that atmospheric CO2 has increased since the Industrial Revolution. (Credit: Vostok ice core data/J.R. Petit et al.; NOAA Mauna Loa CO2 record.)

The Earth’s climate has changed throughout history. Just in the last 650,000 years there have been seven cycles of glacial advance and retreat, with the abrupt end of the last ice age about 7,000 years ago marking the beginning of the modern climate era — and of human civilization. Most of these climate changes are attributed to very small variations in Earth’s orbit that change the amount of solar energy our planet receives.

Scientific Consensus
Ninety-seven percent of climate scientists agree that climate-warming trends over the past century are very likely due to human activities, and most of the leading scientific organizations worldwide have issued public statements endorsing this position.

Click here for a partial list of these public statements and related resources.

However, a dear and close friend of nearly 40 years, Dan Gomez, is sceptical and simply says to me: “Paul, follow the money!” Dan is a very widely-read person and a great thinker.

Plus, among our wonderful neighbours there is a couple, Dordie and Bill, that we get on with extremely well. Bill is a sceptic of AGW and recently sent me the link to the following video.

Please watch it. If you have evidence that all or many of the facts on this video are incorrect then I would love to hear from you.

For this is way too important for the truth not to be widely promoted.

AGW – summing up.

“If there’s any doubt, there’s no doubt!”

I opened the first post on Monday with the sub-heading: “Certainty is perfect knowledge secure from error or doubt.” going on to write that, “Whatever your views on the effect of man’s behaviours on our planet’s climate, it’s a long way from the logical idea of ‘2 + 2‘!”

Within that very strict definition, I remain unmoved.  The argument that mankind is the cause of the present change in the climate of Planet Earth is not certain!

However, if only life was that simple! The change in our planet’s atmosphere is possibly the most emotionally-laden topic of all time.  For some reason that quotation attributed to Hiram Johnson comes to mind, “The first casualty when war comes is truth.” because the supporters and deniers of AGW are engaged in what amounts to a verbal war.

Each side can draw on much information.

For example, a very recent article in The New York Times by their Justin Gillis offered this:

The rise in the surface temperature of earth has been markedly slower over the last 15 years than in the 20 years before that. And that lull in warming has occurred even as greenhouse gases have accumulated in the atmosphere at a record pace.

The slowdown is a bit of a mystery to climate scientists. True, the basic theory that predicts a warming of the planet in response to human emissions does not suggest that warming should be smooth and continuous. To the contrary, in a climate system still dominated by natural variability, there is every reason to think the warming will proceed in fits and starts.

But given how much is riding on the scientific forecast, the practitioners of climate science would like to understand exactly what is going on. They admit that they do not, even though some potential mechanisms of the slowdown have been suggested. The situation highlights important gaps in our knowledge of the climate system, some of which cannot be closed until we get better measurements from high in space and from deep in the ocean.

As you might imagine, those dismissive of climate-change concerns have made much of this warming plateau. They typically argue that “global warming stopped 15 years ago” or some similar statement, and then assert that this disproves the whole notion that greenhouse gases are causing warming.

Rarely do they mention that most of the warmest years in the historical record have occurred recently. Moreover, their claim depends on careful selection of the starting and ending points. The starting point is almost always 1998, a particularly warm year because of a strong El Niño weather pattern.

Dan Gomez, a long-time friend of over 40 years and a regular contributor to items on Learning from Dogs, wrote in a recent email,

I’m not sure what is meant by “believer”, Paul.  The Universe unfolds as it should.  Because many have been led to “believe” that AGW is inevitable and that all the facts are the ‘Truth”, we’ve created a religious substitute, almost a new “industry” with significant “tithing” obligations, etc. (e.g. Cap and Trade). Presumptions and facts are being manipulated to fulfill the prophecy.

Interesting to note in our daily lives, that weather prediction is very good 24-36 hrs out.  This drops precipitously just a few days out.  More than 7-10 days is nearly impossible. Even though both Europe and the USA have decreased CO2 levels by multiple percentage points over the last 20 years, the rest of the world does not care and the impact is very problematic.  Recently, CO2 gas has increased overall but heat has not. In the past, warming has occurred followed by CO2 levels increasing. Global politics and redistribution of wealth schemes continue to interfere with common sense.

Let’s just deal with the facts as Science reveals its secrets. New information is discovered every day about the interaction of the  Earth/Sun/Atmosphere/Lithosphere/Hydrosphere. New information is learned every day about the Universe.  These are not closed subjects. Climatology, meteorology, geology and solar system dynamics will continue to shape the Earth’s future for millennia to come whether Man is involved or not.

There is much in what Dan writes that has me nodding my head; stimulates my recollection of what Luther Haave and Derek Alker wrote in 2009:

With the explosion of knowledge, particularly in the past 100 years, each of us has found it a requirement for being successful, and to being able to earn a living, to concentrate our knowledge in an ever increasingly narrow field. Just as we have come to expect others to defer to our expertise in our narrow area, we have come to assume that we need to defer to others who have a deeper comprehension of seemingly complex topics such as the science related to climate change. [Apologies, can’t find the web link for this.]

However, if we broaden the perspective from that tight definition of certainty to an analysis of probabilities, then it all changes for me and I can embrace the views so strongly put forward by Martin Lack.

For example, Martin left a comment on Monday, “ACD is not a matter of opinion or belief; it is a matter of probability. As such, all that matters now is the extremely high probability that the scientific consensus is real, reasonable and reliable.”  That comment included a link to a discussion on the website Skeptical Science, Is the science settled? Let me quote from that:

Some aspects of the science of AGW are known with near 100% certainty. The greenhouse effect itself is as established a phenomenon as any: it was discovered in the 1820s and the basic physics was essentially understood by the 1950s. There is no reasonable doubt that the global climate is warming. And there is also a clear trail of evidence leading to the conclusion that it’s caused by our greenhouse gas emissions. Some aspects are less certain; for example, the net effect of aerosol pollution is known to be negative, but the exact value needs to be better constrained.

What about the remaining uncertainties? Shouldn’t we wait for 100% certainty before taking action? Outside of logic and mathematics, we do not live in a world of certainties. Science comes to tentative conclusions based on the balance of evidence. The more independent lines of evidence are found to support a scientific theory, the closer it is likely to be to the truth. Just because some details are still not well understood should not cast into doubt our understanding of the big picture: humans are causing global warming.

In most aspects of our lives, we think it rational to make decisions based on incomplete information. We will take out insurance when there is even a slight probability that we will need it. Why should our planet’s climate be any different?

That, ultimately, delivers for me what truly counts.

I am not a scientist; just a Brit living in Southern Oregon trying to make sense of the world while I still have a functioning head and body – time is not on my side! 😉  The powerful common-sense in the sentence, “Outside of logic and mathematics, we do not live in a world of certainties.” is beyond argument.

In the year 2012, the total number of passengers carried by US Airlines and other carriers in and out of the USA was a staggering 815 million people. 815,000,000 people!

Remember the sub-heading from the start of this post!  “If there’s any doubt, there’s no doubt!” Years ago I heard that from Bob Derham, a long-time friend and a commercial airline Captain since the time God was a boy!  It’s that cautious, safety-focused attitude that has made airline transport such an amazing mode of transport for all those millions of passengers.

Should we not travel with the same cautious, safety-focused attitude on the ‘vehicle’ that carries every man, woman and child; every animal, plant and living thing: Planet Earth!

The answer is obvious – more than obvious!

Exploring the certainty of AGW!

“Certainty is perfect knowledge secure from error or doubt.”

You may wonder what this post is all about opening, as it does, with a definition of ‘certainty’.

What that definition might imply is that ‘certainty’ is a tantalising ‘will of the wisp’ creature.  Excepting for pure mathematics, of course! “Pure mathematics is, in its way, the poetry of logical ideas.” – Einstein quotation.

Whatever your views on the effect of man’s behaviours on our planet’s climate, it’s a long way from the logical idea of ‘2 + 2‘!  So when Oakwood, a reader of Learning from Dogs, submitted a long, carefully written comment rejecting Anthropogenic Global Warming (AGW), the idea came to me that perhaps this comment should stand on its own two feet, so to speak, as a separate post.  I asked Martin Lack, a passionate believer in AGW, to counter the points set out by Oakwood.  Both Martin and Oakwood are scientists; both hydrogeologists.

Now please take a moment to read and assimilate the next few sentences.  The length of the ‘dialogue’ runs to two posts.  Making it without question the longest post that has ever been published on Learning from Dogs.  It is also the most important!  If there is one question above all others for these times, it is the question of whether or not mankind is changing the climate of this planet; the only one we have.

These posts are not an easy read.  They can’t be skim read. They don’t have pictures! But I hope with all my heart that you will settle down today and tomorrow and read each post carefully to the end.

Now to some background information on the two gentlemen.  ‘Oakwood’ is a nom-de-plume.  However, he and I have exchanged emails and I support his need for anonymity. This is how Oakwood describes himself:

  • I am an Earth systems scientist
  • I have followed the AGW scientific arguments on both sides for many years
  • Hydrogeology (my field) and climate science have quite a lot in common, the main one being they require some knowledge and expertise in a wide range of disciplines. It’s not a simple case of saying ‘you are an expert or not’.
  • For example, I need to know quite a bit about chemistry, although I am not an ‘expert chemist’.
  • I am experienced in studying long-time period data, and judging its credibility (this also in common with climate science). Many of the key AGW arguments are based on data and statistics.
  • There are many reasons for being an AGW-sceptic, needing many pages. I give one main example: The ‘divergence problem’ applies to tree ring proxy temperature graphs. Most (perhaps all), proxy graphs cannot reproduce modern temperature data from about the 1980s onwards (in fact the very period of detectable man-made global warming). Because of this, we cannot rely on proxy graphs to conclude now is warmer than the past. Although climate scientists claim the divergence problem is only a modern thing, and does not affect historic data, this is purely a statement or belief. There is no convincing science to back that view.
  • For that reason, I am sceptical of the value of proxy graphs to show current temperatures are unprecedented.
  • I list a number of other brief examples.
  • I do not believe in conspiracy theories and have no problem with climate scientists believing in AGW. But in view of the examples I give, I do have a problem in them saying ‘the science is settled’.
  • There are some benefits from acting on the AGW scare now, such as improved energy efficiency and reduced pollution. There are also negatives, such as wind-farms on pristine countryside and biofuels causing increased hunger.
  • Too much focus on the AGW threat (based on relatively weak scientific arguments) diverts effort and money from more immediate and certain problems.
  • I am an environmentalist who cares about the future of our planet and sustainability. My views on AGW are based purely on the science.

Martin‘s background is encapsulated on his Blog, from which I extract:

I have 25 years of professional work experience, as a geologist and hydrogeologist, in both public and private sectors.

St Albans School, Hertfordshire, 1976-1983.
BSc (Hons) in Geology (Portsmouth), 1983-1986.
MSc in Hydrogeology (Birmingham), 1989-1990.
Postgrad. Cert. in Education (Keele), 1998-1999.
MA in Environmental Politics (Keele), 2010-2011.

Professional Qualifications:
Fellow of the Geological Society (FGS) since 1992.
Chartered Geologist (CGeol) since 1998.
Member of Chartered Institution of Water and Environmental Management (MCIWEM) since 2000.

Martin’s MA dissertation topic was “A Discourse Analysis of Climate Change Scepticism in the UK“  An abstract of that dissertation may be read here.

So two highly professional persons with diametrically different views.  Here’s the ‘debate’.



I have been posed a couple of questions [by Martin Lack, Ed.] which Paul has invited me to respond to.

  1. Why do you think the vast majority of relevantly-qualified and active researchers in earth systems science have reached the conclusion that we need to stop pumping CO2 into the atmosphere as fast as we possibly can because it will get harder to avoid excessive climate change the longer we take to do so?
  2.  Explain why you think the time to act has not yet arrived?

If I may, I’m going to treat those questions more like this:

  1. Why do the majority of climate scientists claim to believe man-made climate change (AGW)  is significant and serious?
  2. Why am I an AGW-sceptic?

Martin Lack

I am grateful to Paul for inviting me to respond to Oakwood’s thesis.

My carefully constructed question was:

Why do you think the vast majority of relevantly-qualified and active researchers in earth systems science have reached the conclusion that we need to stop pumping CO2 into the atmosphere as fast as we possibly can because it will get harder to avoid excessive climate change the longer we take to do so?

I am very pleased to see that Oakwood does not dispute the reality of a scientific consensus regarding AGW although I prefer – because it is more accurate – to call it anthropogenic climate disruption (ACD). Sadly, however, he does not appear to accept its validity. Although I asked Oakwood not to deconstruct the question, he clearly felt it necessary to both deconstruct it and re-word it (emphasis here is mine):

  1. Why do the majority of climate scientists claim to believe man-made climate change is significant and serious?
  2. Why am I an AGW-sceptic?

Right from the start, therefore, Oakwood appears to suggest that the majority of climate scientists are either being stupid, unprofessional, or deceitful. I say this because, by replacing my “have reached the conclusion” with his “claim to believe”, Oakwood would appear to think that the majority of climate scientists have reached a conclusion that is:

  1. Reasonable when it is in fact unreasonable; or
  2. Highly-probable when it is highly-improbable; or
  3. Near-certain when they know it is very uncertain.

Bearing this in mind, let us look at the arguments Oakwood then uses to justify his ‘scepticism’.


I am an ‘earth-systems’ scientist with degrees in Geophysics and Hydrogeology and around 25 years working experience in both those fields, but mostly hydrogeology.

Note: working scientists are every bit as important to our advancement as academics and researchers. Academia is a career choice available to the better scientists. (Though a few ‘duds’ manage to survive by playing the right games.) But many excellent scientists and engineers choose to work in the ‘real world’ where science is applied which often includes active research, written up in reports, but not necessarily in peer-reviewed journals. Those scientists and engineers often have a far more immediate level of responsibility in terms of the quality and implications of their work.

If an academic ‘gets it wrong’, the worst things that may happen are embarrassment, loss of research grant or even loss of job. If a working scientist or engineer gets it wrong, then bridges may collapse, planes may crash, people may be poisoned, etc. Also ‘peer review’ doesn’t mean its right, but just that it adds to the debate.

I have followed the scientific debate for many years, reading much that is written on both sides, including a big proportion of the IPCC reports.

Martin Lack

Oakwood starts by attacking academics for being detached from the real world and suggesting that some  may be “duds” that are just playing games, (although he does not say whom exactly)!

He then attacks the peer review process but fails to provide any reasonable explanation as to why only 24 out of nearly 14 thousand articles about ongoing climate change do not consider human activity to be its primary cause (unless the science is of course near certain).

Oakwood claims to have read a big proportion of IPCC reports (more than me I suspect) but, even so, fails to address the reality that IPCC reports have consistently under-reported the scale and urgency of the problems we face. The AR5 report due out later this year will also do this because it still does not include positive feedback mechanisms causing current rates of change to accelerate.


Very much like hydrogeology, climate science is a multi-disciplinary science dependent on a level of knowledge and expertise in a whole range of disciplines. For example, I need to understand quite a lot about chemistry, although I don’t have a degree in chemistry.

I have to keep learning; by reading, researching, learning from expert colleagues, etc. I also need to know something of maths, statistics, fluid mechanics, weather patterns, computer modelling, microbiology, water treatment, etc.

There are better experts in each one of those subject areas, but that’s their focus and they would not normally be able to pull things together to develop a ‘conceptual model’ of a hydrogeological system.

Martin Lack

Oakwood highlights the similarities between hydrogeology and climate science but fails to mention that both make extensive use of probabilistic computer models (of the kind used by climate scientists). These are models that deal with uncertainty in modelled parameters by being run hundreds if not thousands of times using parameter values picked at random from within user-defined ranges. This produces a range of modelled outcomes with accompanying probabilities of being realised.


There is much overlap between scientific disciplines, especially in ‘Earth systems’. Therefore, to suggest you must be a ‘climate scientist’ to understand all of the scientific and statistical arguments, is incorrect. For example, the hockey stick tree ring studies are principally statistical exercises rather than ‘climate science’, and require an understanding of how the Earth’s climate has changed in the past, which geologists are only too aware of.

As a hydrogeologist, I am very experienced in studying time-series data, and judging whether conclusions drawn from them are plausible and reliable. Of course, my conclusions may not always be correct. Others may disagree with me. But that’s how science develops.

It would take me pages to explain all my reasons for being an AGW-sceptic, so instead I will focus on one key example of where I find a key conclusion unreliable.


I will refer to a ‘typical’ paper by Michael Mann et al, 2008, Proxy-based reconstructions of hemispheric and global surface temperature variations over the past two millennia, Proceedings of the National Academy of Sciences of the United States of America – PNAS.

Its main conclusions are:

Recent warmth appears anomalous for at least the past 1,300 years whether or not tree-ring data are used. If tree-ring data are used, the conclusion can be extended to at least the past 1,700 years, but with additional strong caveats. The reconstructed amplitude of change over past centuries is greater than hitherto reported, with somewhat greater Medieval warmth in the Northern Hemisphere, albeit still not reaching recent levels.

Thus, they claim their work shows current temperatures are unprecedented in at least the past 1,300 years, including the Medieval Warm Period (MWP). This is extremely important. If current temperatures are not warmer than the MWP, then there is far less reason for alarm about the current climate. For example, we don’t have records of such things as droughts, hurricanes, tornadoes, etc.,  being noticeably worse or more common during the MWP. (I know, some will respond: ‘regardless of whether its warmer now, predictions are it will get much worse’. But that is a separate argument). Thus, it seems to be very important to the AGW-case that current temperatures are unprecedented, and changing more quickly than in the past 1,000 to 2,000 years.

Despite, their stated conclusions, their work does not show that now is warmer than the MWP. On their graphs in their Figure 3, current temperatures show as warmer. But the proxy data themselves do not show this. The only data that do are the instrumental data. So if proxy data do not align with instrumental data since the 1980’s onwards, how can we rely on them to show us the MWP was cooler than now? We can’t.

They try to address this with the following statement:

The observed warming rises above the error bounds [ie., the highest possible temperature indicated by proxy data – my words] of the estimates during the 1980s decade, consistent with the known ‘‘divergence problem’’, wherein the temperature sensitivity of some temperature-sensitive tree-ring data appears to have declined in the most recent decades. Interestingly, although the elimination of all tree-ring data from the proxy dataset yields a substantially smaller divergence bias, it does not eliminate the problem altogether. This latter finding suggests that the divergence problem is not limited purely to tree-ring data, but instead may extend to other proxy records.

If you look around at other literature, despite what we hear about ‘settled science’ nobody knows the cause of the ‘divergence’ problem. There is only speculation that it might be something to do with modern air pollution or perhaps CO2 itself.

Here’s what SkepticalScience says:

The divergence problem is a physical phenomenon – tree growth has slowed or declined in the last few decades, mostly in high northern latitudes. The divergence problem is unprecedented, unique to the last few decades, indicating its cause may be anthropogenic. The cause is likely to be a combination of local and global factors such as warming-induced drought and global dimming. Tree-ring proxy reconstructions are reliable before 1960, tracking closely with the instrumental record and other independent proxies.

So, the proxies are “reliable before 1960’s”. But back until when? Around 1880, when temperatures were cooler. There is no evidence whatsoever that the proxies were reliable at other periods of higher temperatures. And we are expected to accept this as ‘settled science’.

In fact, it is possible the divergence problem happens every time it’s warmer. They certainly don’t know this is not the case. The real answer is from very basic statistics:

If the proxy data cannot reproduce the higher temperatures of today, we cannot rely on them to compare with other warmer periods in the past. I don’t care if 99.9% of climate scientists tell me this is acceptable science, I will not agree with them, unless they can produce convincing scientific evidence (not just speculation) to back it up.

(I’ve seen one very comical response more than once: ‘We don’t need recent proxy data to be accurate because we have instrumental data to tell us the temperature.’ For example, a John Havery Samuel says: “A technical concern with one proxy since 1960, when we have perfectly good temperature records already, is an irrelevance.” This COMPLETELY misses the point (and I don’t know whether through ignorance or deliberate distortion). Accurate proxy data today are needed, not to tell us the temperature, but to demonstrate that proxy data are reliable for understanding historical temperatures. That’s simple, basic science. )

Martin Lack

Much of what Oakwood writes is an attack upon the Hockey Stick graph of palaeoclimatic temperature reconstructions first produced in 1998 (MBH98).

However, the fatal flaws in Oakwood’s scepticism regarding MBH98 are as follows:

  1. MBH98 has been validated by at least 14 other reconstructions (as cited in IPCC AR4 in 2007) using a wide variety of other proxy data(see Wikipedia for relevant links)
  2. Hockey Stick-shaped graphs turn up in reconstructions of CO2 levels and temperature – now going back over thousands of years – because they are not ‘statistical noise’ –
  3. Arguments about splicing instrumental data onto proxy data only serve to challenge the extent to which the speed of late 20th Century warming is unprecedented.
  4. Such arguments do not invalidate the conclusion that it is now almost certainly warmer than it has been at any time since the last Ice Age (i.e. a period of relative climate and sea level stability that has made agriculture, urbanisation and civilisation possible).

However, this is no reason for us to be complacent because, as Oakwood must know, the 50 to 100 metres of sea level rise that will be caused by the melting of terrestrial ice sheets will necessitate the mass migration of millions of people. This makes his concerns about current poverty and starvation (i.e. the main reason he eventually cites for not believing action is yet necessary) look very trivial indeed.


Part two continues tomorrow.

Sceptical voices, reflections

If there’s any doubt, there’s no doubt!

I know that expression from my days as a private pilot.  It makes such obvious sense, especially in a single-engined light aircraft with one pilot on board.  It’s all about risk.

Frederick Herzberg, the famous American psychologist, coined the term ‘hygiene factor’.  It was the second part of a two-factor approach to the management of people.  According to Herzberg’s theory, people are influenced by two sets of factors, motivation factors and hygiene factors.  More background on this aspect here.

To me, as I reflect on the messages offered in the Sceptical Voices article, Part One and Part Two, the concepts of risk and hygiene seem totally appropriate to the topic of AGW, Anthropogenic Global Warming.

Whether or not AGW is a valid theory behind the rapid change in global warming is utterly irrelevant.  It is the risk to humanity that matters.  There is absolutely no harm done from assuming that AGW is happening and that feedback processes run a grave risk of tipping planetary conditions out of control, and getting that wrong.

On the other hand, assume that AGW is such an uncertain concept that it really isn’t wise to adjust our life styles, and getting that wrong would endanger the human species.

Think of being on a commercial airline flight and you become aware that one of the two pilots in the cockpit is incapacitated through food poisoning.  No doubt that you, with all your fellow passengers, would vote for an immediate diversionary landing.  It’s to do with risk.

From the perspective of Herzberg, a co-ordinated program by the world’s leading governments to tackle AGW might also improve the overall motivation of their peoples in a whole manner of ways.

Merci voiced this perfectly in her comment to Sceptical Voices, Part One, thus,

Yes, question all we want, yes, there are other important issues to resolve in the world, but WHAT IF “Climate Change/Global Warming“ is for real, what then?

Dan wrote also in that Part One piece,

And by “peel-back-the-onion”, I mean that any ardent, independent researcher should publish both sides of the story as a matter of course.  Especially in regards to global warming.

But publishing both sides of the story is not the argument.  The argument is the risk to humanity of doing nothing, and getting it wrong.

That well-respected weekly newspaper The Economist had a recent article about the melting of Arctic ice, from which is quoted,

Arctic sea ice is melting far faster than climate models predict. Why?

Sep 24th 2011 - from the print edition

ON SEPTEMBER 9th, at the height of its summertime shrinkage, ice covered 4.33m square km, or 1.67m square miles, of the Arctic Ocean, according to America’s National Snow and Ice Data Centre (NSIDC). That is not a record low—not quite. But the actual record, 4.17m square km in 2007, was the product of an unusual combination of sunny days, cloudless skies and warm currents flowing up from mid-latitudes. This year has seen no such opposite of a perfect storm, yet the summer sea-ice minimum is a mere 4% bigger than that record. Add in the fact that the thickness of the ice, which is much harder to measure, is estimated to have fallen by half since 1979, when satellite records began, and there is probably less ice floating on the Arctic Ocean now than at any time since a particularly warm period 8,000 years ago, soon after the last ice age.

That Arctic sea ice is disappearing has been known for decades. The underlying cause is believed by all but a handful of climatologists to be global warming brought about by greenhouse-gas emissions. Yet the rate the ice is vanishing confounds these climatologists’ models. These predict that if the level of carbon dioxide, methane and so on in the atmosphere continues to rise, then the Arctic Ocean will be free of floating summer ice by the end of the century. At current rates of shrinkage, by contrast, this looks likely to happen some time between 2020 and 2050.

Re-read the sentence, “The underlying cause is believed by all but a handful of climatologists to be global warming brought about by greenhouse-gas emissions.”  In particular, “by all but a handful of climatologists”  Think of risk.

That article, which should be read in full, concludes thus,

A warming Arctic will bring local benefits to some. The rest of the world may pay the cost.

Indeed, the rest of the world may pay the cost!  As I wrote, it’s all about risk.

So whether or not one wants to believe every word of that Economist article is irrelevant.  Or whether one should have believed, or not, the article in New York’s The Sun newspaper back in 2007,

By SETH BORENSTEIN, Associated Press | December 12, 2007

WASHINGTON — An already relentless melting of the Arctic greatly accelerated this summer, a warning sign that some scientists worry could mean global warming has passed an ominous tipping point. One even speculated that summer sea ice would be gone in five years.

Greenland’s ice sheet melted nearly 19 billion tons more than the previous high mark, and the volume of Arctic sea ice at summer’s end was half what it was just four years earlier, according to new NASA satellite data obtained by the Associated Press.

“The Arctic is screaming,” a senior scientist at the government’s snow and ice data center in Boulder, Colo., Mark Serreze, said.

Last year, two scientists surprised their colleagues by projecting that the Arctic sea ice was melting so fast that it could disappear entirely by the summer of 2040. This week, after reviewing his own new data, a NASA climate scientist, Jay Zwally, said: “At this rate, the Arctic Ocean could be nearly ice-free at the end of summer by 2012, much faster than previous predictions.”

So scientists in recent days have been asking themselves these questions: Was the record melt seen all over the Arctic in 2007 a blip amid relentless and steady warming? Or has everything sped up to a new climate cycle that goes beyond the worst case scenarios presented by computer models? “The Arctic is often cited as the canary in the coal mine for climate warming,” Mr. Zwally, who as a teenager hauled coal, said. “Now as a sign of climate warming, the canary has died. It is time to start getting out of the coal mines.” [My emphasis, PH]

So, in conclusion, scepticism is healthy and is an important aspect of open debate within an open society, part of determining truth, however challenging that simple concept might be.

But eventually one needs to take a position, to take a stand on the really important issues in life and in the case of climate change the risk of being too sceptical, too cautious is to put the lives of future generations at stake.  For me, and I guess for tens of thousands of others, that is a risk too far.