A Worry of Climate Change Scientists

A friend of mine, JP, started all of this when writing:

If you were to ask me 2 years ago what my key understandings were about climate change, I would have said the following:

Sea ice is rapidly shrinking (summer arctic sea ice to be gone by 2015)

Sea levels are rising and accelerating

Polar bear populations are under stress (have increased in the last 20 years)

The levels of glacial retreat around the world are unprecedented (similar retreats have been seen in the last century)

97% of scientists agree that global warming is real and an urgent problem

Any scientist who is skeptical about the claims made about climate change is a "denier" and is funded by oil/resource companies

We are seeing an increase in extreme weather events (they are actually getting less common)

Climate models are accurate in their predictions 

Every one of those things is either totally false, or a largely exaggerated claim.

This is the fifth in a series based on my response, which itself was split over a few emails.  The first was Ice Extent Challenge (in which I provided a little more context about JP) and was followed by Sea Levels Rising, Polar Bears and Climate Change and Glacial Retreat.  Some of the issues may also be touched on in a series of articles on the nature of climate denialism.  Please also note the caveat.

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JP’s Claim: The statement “97% of scientists agree that global warming is real and an urgent problem” is either totally false or largely exaggerated

First, I should point out that the title of this post is quite misleading.  By “worry” in this context, I am introducing a new collective noun (like a “murder” of crows, or a “parliament” of owls, or an “embarrassment of climate deniers”), when you get sufficiently many climate change scientists grouped together and agreeing on something, then you have a “worry”.  I suggest that 97% sounds like a nice round number.

Second, it is well known that 98.23% of ridiculously precise statistics are made up (more on that here).  JP seems to have taken the 97% figure from NASA, who got their figure from Environmental Research Letters (albeit via an intermediate paper, also at Environmental Research Letters).  It should be noted that this is specifically related to publishing climatologists.  If one includes non-publishing climatologists, the figures drop markedly – although there is a notable increase in certainty over time even on the part of non-publishing climatologists over time – 66% in 1991 (Gallup – AMS/AGU members) and 87% in 2015 (Pew – AAAS members).  There’s an interesting chart that relates:

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The 97% figure is of great interest to denialists such as Joanne Nova who called for the paper to be retracted (and it’s quite enlightening to read her commenters).  What she seems to have overlooked is that the paper (by John Cook among others) clearly indicates that the work was “conceived as a 'citizen science' project by volunteers contributing to the Skeptical Science website”.  There’s no hiding the weaknesses of the methodology and it’s hardly their fault that media may have picked up the conclusions and presented them as if they represented stone cold fact rather than a rough indication of where the consensus lies.

She ignores that an NAS research article in 2010 resulted in very similar findings.  She also ignores that around 200 scientific organisations world-wide concur with the consensus on anthropogenic climate change (198 are listed, but it’s unlikely that this list put together by the Californian Governor’s Office of Planning and Research is entirely comprehensive).

While we can quibble about the precise figure, it is clear that a large percentage of scientific organisations and scientists, particularly those working in related areas, agree that there is an element of human influence in climate change.  But even if the figure of 97% was adjusted down to say 80% or 70%, this would not change the fact of climate change.  Scientists who argue the anthropogenic climate change case do not rely on authority or numbers of people who agree with them.  They use evidence, both in the form of measurements over many decades and in the form of modelling which relies on physical understanding of the climate (more on that in a later post).

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In this instance, JP’s position – as stated – is correct.  It is an exaggeration to say that “97% of scientists agree that global warming is real and an urgent problem”, but both the primary source (Quantifying the consensus on anthropogenic global warming in the scientific literature) and secondary sources (Environmental Research Letters and NASA's page Scientific Consensus: Earth's Climate is Warming) make it clear that this figure refers to “actively publishing climate scientists”, not scientists in general.  Additionally, the consensus in question is with respect to the notion that “humans are causing global warming”, not that “global warming is real and an urgent problem”.  As far as I can tell, there simply isn’t any data on the latter.

Is JP’s position relevant though?  Not really, on-going rebuttals of the 97% figure by denialists are little more than a distraction.

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This issue is explored in far greater detail at Skeptical Science.

Infectious Statistics

In A Worry of Climate Change Scientists (coming soon), I address a claim associated with the 97% consensus figure which the media, such as the Guardian, picked up and ran with.  It’s possible that they are using it ironically in the rubric “Climate Consensus - the 97%”, echoing the 99% quoted by the Occupy movement.

Any statistic, like the 97% figure, should be taken with a pinch of salt and an assortment of questions.  What does it actually mean?  What is it really measuring?  Were there any caveats associated with the figure?  And so on and so on and so on.

A recent example of a similar problem came to mind as I was developing that post, a time at which the novel coronavirus recently dubbed COVID-19 had been confirmed to have infected more than 60,000 people and killed more than 1300.  It’s a bit messy because China released additional figures based on a new detection technique, leading to a one day jump of more than 15,000 cases and the day after 100 people miraculously came back to life (that is during the early reporting hours, the numbers were adjusted down by 122 and later down by about 100).  For the purposes of this discussion, I am going to work from the basis of it being 12 February 2020 when the figures, although probably not accurate, were at least consistent.

There was a question occupying the minds of many people trying to work out whether they should be bothered by a virus that has, so far, killed in the order of 0.2-0.4% as many people as die each year from influenza.  Sure, the flu is everywhere, while COVID-19 had so far been largely contained to China, but it seemed unlikely that, by the end of the year, more than half a million people would die from it.

The question was: what is the mortality rate due to COVID-19?  An easy question, but not so easy to answer.  The official answer, to avoid any unnecessary concerns, is about 2%.  The figures are rubbery because we are unlikely to have a good idea of precisely how many have been infected until much later, we only knew the confirmed case numbers and these might have just been those who were sickest – sick enough to present to a medical clinic of some kind.

A simple way to calculate the mortality rate is to take the number of deaths and divide that by the number of (confirmed) cases (all figures taken from here with downloadable datasets here):

Deaths	Cases	Mortality Rate
12 Feb 2020	12 Feb 2020	D/C
1117	45206	2.5%

So that seems accurate, about 2% just like the authorities were telling us.

However, there is going to be a lag between a person presenting with symptoms, being confirmed as having COVID-19, getting progressively sicker and finally succumbing.  Surely the mortality rate should be compared not against the number of people confirmed to have the virus at the time of death, but at time of confirmation.  The question then is what is the lag between confirmation and death?

For the man who died in the Philippines, that lag was seven days.  There appears to be a six-day lag between the downturn in the rate of new cases (6 Feb) and the downturn in the rate of new deaths (12 Feb).   Let’s use six days:

Deaths	Cases	Mortality Rate
12 Feb 2020	6 Feb 2020	D/C
1117	30808	3.6%

But it could be worse than that, should we not consider it from the time that the virus was contracted, which is two to fourteen days prior to symptoms developing.  Let’s split the difference there and say eight days before being confirmed as having the virus and fifteen days before succumbing:

Deaths	Cases	Mortality Rate
12 Feb 2020	28 Jan 2020	D/C
1117	6082	18%

Whoa Nelly!

That would be something to be worried about.

Another way to calculate the figure is to consider those who had run the course of the disease.  Some recovered, some died which permits another calculation to be made, the percentage who run the course of the disease but succumb to it:

Deaths	Recovered	Mortality Rate
12 Feb 2020	12 Feb 2020	D/(D+R)
1117	5123	18%

My rounding here hides the fact that one 18% is actually 17.7% and the other is 18.3%, making them look precisely the same when they are different by more than half a percent.  Also, an interesting thing happens when you push back a couple of days and run the previous calculation (deaths/cases, fifteen-day lag):

Deaths	Cases	Mortality Rate
10 Feb 2020	26 Jan 2020	D/C
910	2829	32%

What?!

Another two days:

Deaths	Cases	Mortality Rate
8 Feb 2020	24 Jan 2020	D/C
725	941	77%

Of course, that can’t be right.  I’m conflating the notion of people who contract the virus on a particular day with figures reported as confirmed on that day.  Phew!

Note that the 18% for deaths divided by the number of people for whom the virus has run its course still stands, but if I go back in time and check the figures, the mortality appears to be worse the further back I go, so that doesn’t seem right either.

What about the seven-day lag figure?  If I do the same thing, pushing back a couple of days:

Deaths	Cases	Mortality Rate
10 Feb 2020	4 Feb 2020	D/C
910	24506	3.7%

It’s not as much of an increase, but as I push back further, the apparent mortality rate goes up – slowly, but inevitably, eventually getting into the 20% range in the early days of the outbreak.

So what I did was project into the future, assuming that the number of case and deaths increases linearly (which as of 12 Feb was worst case, given that there seemed to be a slowdown in both new cases and deaths), and found that the mortality rate based on cases, irrespective of the lag time, tended towards about 3%.  Mortality based on number of people who run the course of the viral infection, assuming a fifteen-day illness and borrowing case numbers from the previous projection, also tends towards about 3%.

So, as of 12 Feb and depending on whether my objective was to be accurate, informative, calming, inflammatory or some combination thereof, I could possibly justify saying that the mortality rate was:

2% (official)

2.5% (current deaths divided by current cases)

3% (long term trend)

3.6% (current deaths divided by cases six days ago), or

18% (current death rate divided by current number of people who have run the course of the viral infection, one way or the other)

That’s quite a spread.

The point that I am trying to make here, long-windedly, is that unless I went to some serious effort to explain to the reader how I arrived at whatever percentage I provided, my use of an apparently more accurate figure (3.6% versus 2% or 3%) should not be thought of as providing you with any more confidence that my figure was accurate, or that it gave you the information that you thought it was giving.

The same applies to the climate consensus 97% figure – for the most part, when quoted by a denialist, it’s being used as a distraction with the intent to keeping rational people engaged on minutiae and, therefore, not on the scientific evidence that is so damaging to the denialist cause.

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Note, since writing this, the topic came up on More or Less.  I am not “Ian” so someone else out there is maintaining a spreadsheet and arrived at a figure of 18%.

Statistical Argument for the Non-Existence of a God

Here’s a simple statistical argument as to why any given theist’s god probably doesn't exist.  The argument is possibly a variation on the problem of evil, but it's combined with the divine hiddenness issue and the inefficacy of prayer.

Let's suppose that theism was true and that scriptural instructions were true, but only applicable to those who are saved.  Let's further suppose that there is some necessary evil in the world, for whatever reasons a theist might posit and that suffering includes a certain number of children not being born (due to infertility, illness that kills a youth before being able to breed, death of children during childbirth and possibly even some number of abortions).  Say also that a theist takes the instruction from her god literally and "goes forth and multiplies", but not so literally as to become a mathematician.  Say also that non-theists don't have such an imposition and they therefore have fewer children than theists (this seems to be statistically accurate, given than christians have 2.2 children on average, while atheists have 1.6).

What efficacy of prayer would we need for there to be a significant effect on populations?

I did a little spreadsheet on this, with the following assumptions:

Theists have 4.4 children per family (matching the average of 2.2 children per christian)

Atheists have 3.2 children per family (matching the average of 1.6 children per atheist)

Start with a population of 100,000 evenly divided between theists and atheists

A generation is 25 years

Average lifespan is 75 years

The base probability of making it to maturity (and producing children) is 30%

A millennium is a good period to check out

Note that I assume a rather low base probability of making it to maturity to take into account wars, plagues and so on, and I picked that figure because if I go too far above that, the population after a mere 1000 years is ridiculous.  Note also that I am assuming no transfer from the atheist ranks to the theist ranks and vice versa.  I’m simplifying things by assuming even numbers of males and females make it to breeding age and assuming that all those who can couple up do so thus ignoring the possibility of non-breeding couples.

I'm aware that the 2.2 and 1.6 figures could possibly be per family, but I am thinking of pre-modern societies, like the ones that we have lived in for the vast majority of human history.  In the past, and even today in the third world, parents have more children as a sort of insurance policy against all the vectors of death pointing at them.  We need also to remember that the theist's god has told them to go forth and multiply, not to go forth and maintain something that is slightly above a steady population.

So, what was the outcome?  After 1000 years, there are a little over 5000 atheists and 1.5 billion theists if prayer is totally ineffective.  The atheists are, in fact, on their way to extinction – they do linger for a quite a while though, only disappearing entirely around Year 3600).  Note that this is assuming that prayer is totally ineffective, that theists are only benefitting from a tendency to produce more children.  If we introduce a very minor efficacy of prayer, making it so that 31% of children grow up to be parents, then after 1000 years, there’ll be 5.7 billion theists.  If we say that prayer is 25% effective, saving a quarter of the children who would otherwise have died, then there’d be 142 million billion theists compared to the 5000 atheists.

We can fiddle with the numbers in other ways.  We could assume, for example that all families, theist or atheist, had the same average number of children.  Let’s take the median, at 3.8.  If prayer is totally ineffective, then the numbers of atheists and theists will remain about equal – after 1000 years, there’ll be almost 5 million of each.  So, what happens if we make prayer effective in a minor way (30%->31%)?  After 1000 years, there will be 3.7 times more theists than atheists.  And if prayer is 25% effective (30%->48%), then there’ll be 647 thousand billion theists compared to the 5 million atheists, or 13.8 million times more theists than atheists.

There is, therefore, a very low-key way for a good god to not get too involved, still maintain plausible deniability (so as to remain hidden), not make prayer appear too effective (again perhaps to remain hidden) and still effectively wipe out the atheists over an extended period.  All the god needs to do is demotivate the atheists from breeding, decrease the base rate of survival to breeding age and bump up the effectiveness of prayer (from the current rate of 0%).  Note that I am not suggesting that theists want atheists to be effectively wiped out, but if atheists are going to suffer for eternity, then a good god would have some motivation for minimising the number of atheists.  For example, in the original scenario with prayer being very slightly effective, over the 1000 years, there will be about 15 billion theists and only 370 thousand atheists, quite a good ratio of eternally saved to eternally damned at 41,500:1.

Of course, this is just a simple model.  A good god could also touch some of the atheists to shift the balance.  Say that in each generation, there was a one-way defection rate of 10%.  That results not only in almost total eradication of atheists, who are now down to only 54 after 1000 years, but a quintupling of the number of theists (from the original 1.5 billion after a 1000 years with completely ineffective prayer), to 7.25 billion, and a saved to damned ratio of more than 125,000:1 over the period!  Make prayer 25% effective on top of that and that ratio goes to 2,190,000,000,000:1.

So, why does the theist’s god not do something like this?  Such a small effort could make a huge difference.  The theist could fiddle with the figures to make it less impressive, if they liked, but remember that their god is apparently in control, so it can choose to make the results even better than I have suggested.  But it doesn't, which is a very real problem for a world view that contains a god that is supposed to be even slightly good, slightly powerful and has the vaguest clue about what is going on in this universe.

cnearing's argument, subjective probability and the whole Reverse Monty debacle

Over at Craig-Land, in his thread on what constitutes a "good argument", a forum member called cnearing wrote this:

I would point out that I take a strictly subjectivist approach to probability.  Probability is not an objective feature of reality (probably--set aside potential quantum weirdness for the moment) but rather a representation of the uncertainty one has about the way things behave.

Probability comes from models.  Models are built through inference from experience.  Both are subjective.

This reminded me of the terrible trouble I got myself into with respect to the "Reverse Monty Hall Problem".  I went into it with an assumption which, for one reason or another, had become implicit rather than explicit and which then became forgotten, hidden and/or overlooked.

There are a lot of articles connected with the one I've provided a link to, so I'll try to distil it down to essentials.

If we don't know, and have no way to know, the probability of a particular claim or premise in terms of it being true or false, we are required by the principle of indifference to assign it a notional probability of 1/2.  If we know more, for example that there are more options, say:

A is true, B and C are false.

B is true, A and C are false.

C is true, A and B are false.

One of A, B and C is true.

Then, knowing nothing else, we are required to assign a notional probability of 1/3 to A, B and C.  We don't know anything that makes A more or less likely than the others.

Say then, that we have an urn in which there is an arbitrarily large number of balls that are identical in size and that is all we know.  We draw out all but one of them (say 999 of them), and they are all white.

What is the likelihood that the last one is also white?  If we know nothing else, then the answer is one in a thousand, the same likelihood of a single non-white ball being placed in any specific position in a sequence of one thousand extractions.

What was the likelihood, after having drawn 99 balls, that the 100th was non-white?  The same logic applies and it was one in one hundred.  As more white balls were drawn, the likelihood of a non-white ball being drawn went down.

Now, compare this to the likelihood of drawing a non-white ball as assigned by someone who has one more piece of information, the knowledge that the balls were initially drawn from an enormous barrel in which there were 900,000 white balls and 100,000 black balls.

Unlike us, who had no additional information and could only work on the basis of what balls we had drawn out, this other person will know that there is an increasing likelihood of drawing a black ball after each white ball is removed.  In fact the likelihood of the 1000th ball being non-white after a sequence of 999 white balls is very slightly higher than one in ten.  The likelihood of drawing 999 non-white balls in a row is extremely low, but that is immaterial, since we are only looking at the likelihood associated with the next draw once this extremely unlikely scenario has already played out.

We can fiddle with the figures to make it more explicit.  Say we only know about 999,999 balls that we've drawn, over a period of a couple of boring days.  All of them are white.  We have to say that the likelihood of the next ball being non-white is one in a million.

But if our more knowledgeable friend knows also that there is one black ball in the barrel, then she will have to say that the likelihood of the next ball being non-white is one in one, 100%.

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My point here is that we have evidence, and we might also have assumptions.  The assumptions that we make about the distribution of balls in the urn will change our assessment of the likelihood of a non-white ball being drawn.  If we characterise our (potentially false) assumptions as "knowledge" - as theists are often wont to do - we will consistently misjudge the likelihood of our premises (and subsequent conclusions) being true.

Add to this the possibilities that we don't consider (i.e. thinking only of A being true or false, rather than factoring in other possibilities like B and C), then we end up with very little likelihood of reaching reliable conclusions.

A Trickle is Not a Flood

In May of this year, Twenge et al. published a research article Generational and Time Period Differences in American Adolescents’ Religious Orientation, 1966–2014.  At first there was very little interest in it.  Here's the abstract to the article, as partial explanation for the lack of interest:

In four large, nationally representative surveys (N = 11.2 million), American adolescents and emerging adults in the 2010s (Millennials) were significantly less religious than previous generations (Boomers, Generation X) at the same age. The data are from the Monitoring the Future studies of 12th graders (1976–2013), 8th and 10th graders (1991–2013), and the American Freshman survey of entering college students (1966–2014). Although the majority of adolescents and emerging adults are still religiously involved, twice as many 12th graders and college students, and 20%–40% more 8th and 10th graders, never attend religious services. Twice as many 12th graders and entering college students in the 2010s (vs. the 1960s–70s) give their religious affiliation as “none,” as do 40%–50% more 8th and 10th graders. Recent birth cohorts report less approval of religious organizations, are less likely to say that religion is important in their lives, report being less spiritual, and spend less time praying or meditating. Thus, declines in religious orientation reach beyond affiliation to religious participation and religiosity, suggesting a movement toward secularism among a growing minority. The declines are larger among girls, Whites, lower-SES individuals, and in the Northeastern U.S., very small among Blacks, and non-existent among political conservatives. Religious affiliation is lower in years with more income inequality, higher median family income, higher materialism, more positive self-views, and lower social support. Overall, these results suggest that the lower religious orientation of Millennials is due to time period or generation, and not to age.

It wasn't ignored entirely however.  There was one report on it the very next day, filed at the on-line version of the Pacific Standard magazine, in a piece titled Millennials are Less Religious-and Less Spiritual Too.  Here's a sample:

It’s common knowledge that many members of the Millennial generation in the United States are rejecting religion. But some analysts argue that, while these emerging adults are less likely to participate in organized religion, they retain an interest in spirituality.

Not so, concludes a newly published study.

“American adolescents in the 2010s are significantly less religiously oriented, on average, than their Boomer and Generation X predecessors were at the same age,” writes a research team led by San Diego State University psychologist Jean Twenge. Confirming earlier evidence, the study finds they are less likely than members of previous generations to attend religious services, and less supportive of religious organizations.

After that there was nothing for more than two weeks.  A wider subset of the general population then became aware of the research article through Reddit towards the end of May, after Twenge got some assistance from her university.  The publicity article, published by the San Diego State University NewsCenter and picked up by the AAAS science news aggregator Eureka, was titled The Least Religious Generation.  Here's how they kicked off their release:

In what may be the largest study ever conducted on changes in Americans’ religious involvement, researchers led by San Diego State University psychology professor Jean M. Twenge found that millennials are the least religious generation of the last six decades, and possibly in the nation’s history.

The researchers — including Ramya Sastry from SDSU, Julie J. Exline and Joshua B. Grubbs from Case Western Reserve University and W. Keith Campbell from the University of Georgia — analyzed data from 11.2 million respondents from four nationally representative surveys of U.S. adolescents ages 13 to 18 taken between 1966 and 2014.

The distribution of interest at Reddit is interesting.  The article was linked to eight times, at the following sub-reddits (in order of popularity of the article within the sub-reddit [as gauged by score]): r/HowGodWorks [1], r/Christianity [3], r/lostgeneration [10], r/UUreddit [11], /r/theworldnews [14], /r/NoShitSherlock [74], /r/atheism [182] and /r/science [4397].  Not only was the article more popular at /r/science, but there were far more comments there as well, so people got involved in discussions about it.

There was a little more interest after The Raw Story published their take on the article, in a piece titled Teens are fleeing religion like never before: Massive new study exposes religion’s decline.  Here's their intro:

Religion is rapidly losing the youngest generation of Americans, according to new research.

America’s rising generation of adults are the least religiously observant of any generation in six decades, determined an expansive study led by Jean Twenge, a psychology professor at San Diego State.

Oddly though, although this seems to be the sort of article that the atheists would be keen on, it was once again the science sub-reddit that gave it the most votes and who commented on it the most.  There were quite a few other likely sources that covered Twenge's article from various perspectives that got no reddit interest at all - such as patheos, whose focus was on females who are apparently departing religion at a higher rate than males.  (Note, I rectified this total lack of interest by linking the patheos article.  At last count, this has received more positive interest than the last two articles put together.)

So, why was so little interest from atheists?

My hope is that it is because many atheists responded to The Raw Story's breathless commentary on Twenge's research in much the same way as I did.  By noticing that it's misleading.  By noticing that even Twenge's far more restrained abstract is misleading.

Let's look at that abstract a little more closely.  It is claimed that "twice as many 12th graders and college students, and 20%–40% more 8th and 10th graders, never attend religious services".  The next sentence implies that this means as compared to cohorts in the 1960s and 1970s.

For anyone with an interest in promoting rationality and secularism, a significant decrease in religiosity in the dominant exporter of culture in this world has got to be good news, right?  Well, yes.  But this isn't really what is being said here - even if what is being said is entirely true (which I question).

Twenge is writing about reported irreligiosity, which in the case of 12th graders and college students has doubled.  But double "not very much" is still not very much, especially when compared to more advanced nations.  For example, the Christian Research Association estimates that "10 per cent of all Australian young people in secondary school attend" (church monthly or more often) while Wikipedia reports that only 2% of Swedes are reported to be regular attendees at church services.  Note however that this Swedish data is more than 20 years old and only refers to one church - when other churches are considered, as reported by the Swedish Institute, "only eight per cent of Swedes attend any religious services regularly".  In neither Sweden nor Australia is it possible for irreligiosity to increase by 20%, let alone double.

(For those among us who are not maths geeks, irreligiosity stands at about 92% in Sweden generally and 90% for Australian teenagers.  An increase of 20% would make the irreligiosity rate 110% in Sweden and 108% in Australia.  It just can't happen.)

Such improvement in the US is, sadly enough, still possible.  Check Twenge's chart for church attendance (but note that the question was restricted to "never" attending church - which should exclude those who traipse along for cultural events like christmas or easter):

There was no chart provided for regular attendance, but there are some entries in a table, replicated below:

weekly or more	75-79	80-84	85-89	90-94	95-99	00-04	05-09	10-14
8th	-	-	-	44%	44%	44%	42%	41%
10th	-	-	-	39%	38%	40%	37%	34%
12th	40%	39%	33%	32%	32%	33%	31%	30%

Ignoring the difference between weekly and monthly attendance and using a simple average of the figures for 8th, 10th and 12th graders, this means about 35% of American teenagers are regular churchgoers and the irreligiosity rate is therefore 65%.  It is pleasing to see that even in the US, a doubling of this rate is not possible, but an increase of 50% is still possible - to 98%.

Using the most recent figures, we can see that about 21% of 12 graders never go to church while 30% attend regularly (weekly or more).  That leaves almost 50% who attend "non-regularly", which could mean once a month, only on special days or it might include christenings, weddings or funerals but nothing else.  There's potential for a broad scope of belief in that 50%.

Overall though, what the research is telling us is that as far as the battle between the religious and the rational in American goes, there is still a long way to go.  Which is a bit of a worry.

What worried me most however was when I saw an article crowing that the American teenagers "are fleeing religion like never before".  Excuse me?  Fleeing?

How about we compare what is happening with youth and religion in America to the other sort of fleeing that American teenagers are far too often required to do.  You know, the sort of fleeing that happens when a gunman enters school grounds and starts shooting at people (I don't want to appear to be overstating the case, so I want to make clear that this has happened only 22 times so far in 2015, at the time of writing).  If we were to hear that students fled from a classroom, we would not expect to then read that the number of students absent from the classroom rose from 8% to 27% over a period of more than 30 minutes (and from 25% to 27% in the past two minutes).  This is hardly a flood of students leaving.  It's barely a trickle.

Then there is also the question of what the figures actually mean.  Twenge's research is based on survey responses but she makes only one reference to privacy and says nothing about confidentiality.  We therefore have no idea about how the respondents would have felt about their freedom to answer candidly.  America still has a problem dealing appropriately with youths who are not religiously inclined: there is talk among atheist circles of "coming out", with the same trepidation that a gay person might feel about coming out to their friends and family; there is even a movement called "Atheist Havens" dedicated to providing shelter to youths who are thrown out of home by their religious parents.  It's not a huge leap to imagine that some respondents would be disinclined to be entirely candid with respect to the survey.

That said, it has become increasingly likely that students who are not religiously inclined might be encouraged to speak openly due to the media attention given to celebrity atheists such as Sam Harris, Richard Dawkins, Michael Shermer and so on.  There's no indication that Twenge has controlled for this effect across the years.  Therefore, it's possible that the vast majority of what appears to be an increase in irreligiosity in America is merely the effect of increased confidence on the part of those who are not religious and their increased willingness to admit to it.  This too militates against any breathless claim that American youth is "fleeing" religion.

That said, I don't think that it's all doom and gloom.  Increased openness on the part of the non-religious will help provide an environment in which those who are not overly committed to their religion may reconsider their beliefs and perhaps come to see the irrationality of whatever faith they were brought up in.  Calmly walking away from religion, even if it's a slower process is a much more dignified approach than fleeing from it.

And if it is actually true that atheism isn't growing at the rate that some have been led to believe, this might galvanise proponents of rationality into action, encouraging them to review what they've been doing, to take lessons from the latest research in psychology (particularly about the creation and maintenance of beliefs and attitudes) and to consider whether other approaches might be more suitable.

Meanwhile, those of us who are lucky enough to be living in a nation that is relatively free of religion should not rest on our laurels but keep a close eye on those who would have us return to the Iron Age.