Howard Bloom is a fairly good author, and his book, The Lucifer Effect, one of my favorites - as it penetrated the mystery of memes and how they altered human history. Especially, the notorious memes connected to zealous religious belief - as manifested in radical Islam and Christian Fundamentalism. However, his article appearing in today's Wall Street Journal ('Climate Change is Nature's Way') begs way too many questions, and merely confuses more than it deciphers on the climate front.
Bloom contends that we have "been deceived by a stroke of luck" - namely that our brains flourished most prominently in a hospitable climate between glaciations, and we have somehow come to view a more or less fortuitous confluence of factors as a happy "norm". He adds that we have also lived through "20 sudden global warmings" more or less in the 120,000 years since we acquired our current physiological shape. No mention is made that none of these warmings were remotely connected to a possible runaway greenhouse effect, or even that - as Prof. Gale Christianson has noted ('Greenhouse', 1998) no warmings have ever occurred when the CO2 concentration was less than 250ppm, nor have glaciations occurred when the concentration was over that level.
About midway through, he addresses "the real cause" of the Earth's variable climate. Not surprisingly, like most today, he ascribes it to the Earth being a "traveler" and undergoing orbital and precession deviations at periodic intervals - every 22,000, 41,000 and 100,000 years. In other words, the "Milankovitch cycle".
In fact, the Milankovitch cycles are mostly irrelevant here, as I noted in one early blog entry. The grandiose name “Milankovitch theory” purports to account for the recurrence of the ice ages. In fact, it is more correct to call it the “Milankovitch hypothesis” especially as few astronomers that I know accept it. On that note, I would like to discuss the basis for general non-acceptance of Milankovitch’s theory into conventional astrodynamics and astrometry.. (The former is what has been called “celestial mechanics” in the past, while the latter focuses on methods of position updating for celestial objects)
Start with its contention that the obliquity of the ecliptic (inclination of Earth to its orbital axis) varies from 21 to 24 degrees over a 41,000 period in a process called ‘nutation’. This is certainly a magnitude in excess of a half degree (1800”) on either side of its current 23.5 deg.
Astronomers-astrometrists recognize no such period or differential of axial tilt. The following is from the book, Astronomy- Principles and Practice by A.E. Roy and D. Clarke, 1978, Adam Hilger Books, p. 118:
“Because of the nutational wobble in the Earth’s axis of rotation, the obliquity of the ecliptic (KP in Fig. 10.32) varies about its mean value. The magnitude on either side is about 9.”2.”
For the benefit of non-astronomers, the magnitude cited (9.”2) isn’t even one hundredth of a degree! Indeed it is nearly a factor 4 LESS than a hundredth of a degree! (which translates to 36”- there are 3600” = 1 degree))
Nowhere in any part of this basic text is any larger magnitude cited, not even in a footnote. The same is true for the standard textbook in astrometry by Heinrich Eichhorn and P. Mueller, who quantitatively give the first six terms of the expression for nutation in obliquity. Most interesting - which I merely give for the sake of completeness- is that even jacking up the value of the terms containing t by 41,000 yrs. (e.g. 410 JC inserted in each t value) doesn’t appreciably alter the magnitude from seconds of arc – very small seconds of arc (e.g. about 8.”85 with Z = 160 deg and counting only the first order term).
Beyond the inability to encompass the quantitative details, other problems arise.
For example, when conditions are favorable for an ice age in the northern hemisphere, they’re not favorable for one in the southern hemisphere. How could the Milankovitch Cycles cause a global change in climate then? Also, Milankovitch cycles can only account for a temperature difference of 1° to 2°. How is it possible then that sediment records show temperature differences of 7° to 10°? The 100,000 yr cycle is dominant in the record, yet it has the weakest astronomical effect; moreover, in the record, it doesn’t always occur at 100,000 years - ranges from 80,000 to 125,000. How can these variances be explained? Until they are – most astronomers won’t embrace the theory.
Adding to that, in the paper ‘A Causality Problem for Milankovitch”, Daniel B. Karner and Richard A. Muller from the Dept. of Physics, University of California, note an earlier paper by W. Broeker (1992) ‘Upset for Milankovitch Theory’ – in which he discussed a troublesome new measurement. That is, oxygen isotope data from a cave in Nevada called ‘Devils’ Hole’ appeared to show that the timing of the penultimate termination of the ice ages- called ‘Termination II’ – was incompatible with the standard Milankovitch theory (cf. Winograd et al, Science, Vol. 258, p. 255; Ludwig et al, Science, Vol. 258, p. 284)
The data indicated a shift in (delta 16) to interglacial values that was essentially complete by 135 thousand years ago (ka). But at this time, the Northern Hemisphere summer insolation had not yet warmed to the point at which it should have triggered anything extraordinary, let alone a glacial termination. The termination event appeared to precede its cause.
Though the Milankovitchites attempted valiantly to rebut this, as the authors noted, the “causality” problem remained and it was really all an (initially) skeptical community needed to keep the Milankovitch theory from being cemented into standard celestial mechanics. Too many loose ends!
Worse, the Devils Hole data had not been the first to indicate a problem. As far back as 1974,Bloom et al. (Quatr. Research, Vol. 4, p.185) had suggested that sea level had reached a high point, from melting glacial waters, by as early as 142 ka. Their work was based on U-Th ages of coral terraces from the Huon Peninsula in Papua New Guinea. These results were not used when Imbrie et al. (‘Milankovitch and Climate – Part I’, Doredrecht Reidel)) created the SPECMAP template, the most widely used model for explaining how insolation could drive ice age cycles. Instead, Imbrie et al. set the termination at 127 ±6 ka, based on radiometric dates from Barbados corals by Mesolella et al. (J. Geology, Vol. 77, p. 250) and Shackleton and Matthews (‘Nature’, Vol. 6, p. 445)
All of the above provides just enough ‘ammunition’ to those already skeptical – to justify their resistance to Milankovitch theory and to preventing supporters from nudging it into text books (like evolutionists seek to prevent ID’ers)
This is reinforced by the fact that most astronomers’ prevailing skepticism is fuelled by the lack of a precise dynamic time scale, which would make it possible to test the match between the supposed cycles recorded in ocean sediments and the Milankovitch cycles calculated on the basis of the Earth's orbit in standard celestial mechanics. Until this is done, the Milankovitch theory will rightly not be regarded as a part of legitimate celestial mechanics – but rather a marginal or fringe spinoff.
While the cycles with periods near 100,000 years, 41,000 years, and 23,000 years, based on sediment data are intriguing – they don’t get an astronomer’s blood boiling. They merely show circumstantial evidence for the claim. Ultimately, the claim has to be tested and verified in space – to get an astronomer to invest credulity.
Theoretically, at least, there is more than enough Earth orbital data right now to be able to make solid predictions, even if ex-post facto. The trick is to be able to make testable predictions, and then, meld those into a coherent theory of exactly how the orbital forcing occurs and what it does.
A first start would be using sophisticated numerical simulations – piping in the orbital (a, e, pi, Omega etc.) elements and their perturbations claimed by the Milankovitch crew. Thus, use standard equations of celestial mechanics (e.g. Kepler’s equation, n(t – T) = E – e sin E) and show that the assumed changes actually occur in space. Show that 100,000 yrs. from now Earth will be in such and such predicted position (according to the Milankovitch "theory"), and ditto for the 41,000 year scale, and so on. Capture these graphics, then publish them.
Interestingly, this was exactly the method used by space physicists to make their case for accepting dynamo processes as applicable to solar flares! Years of work finally paid off, when the most elaborate numerical simulations could no longer be disputed.
The bottom line here is that Bloom's invocation of Milankovitch cycles to account for repeated glaciations is contrived, and doesn't work. A much more compelling hypothesis is that glaciations occur during dips in solar luminosity when the ambient CO2 concentration is below 250 ppm at the time of occurrence or onset. (The upper limit of 400 ppm may be more applicable, because some recent papers published in Eos Transactions appear to show that no ice ages can occur when that level holds. Right now, we are at 390 ppm and increasing).
A reduction in the solar insolation of even 10%, say down to 1220 W/m^2 could likely trigger a prolonged (~10,000 yrs) ice age if the CO2 level were simultaneously below 400 ppm, and certainly if the concentration is less than 250 ppm.
Bloom's factoid that the "Sun is 43% warmer today than it was when Earth first gathered itself into a globe of planetesimals" is neither here nor there, and bears no relation to the current climate crisis (where we are seeing CO2 concentrations approach the thresholds for the runaway greenhouse effect) . Of course, the Sun is 43% warmer! Doh! At the time Earth was "gathering planetesimals" the Sun was still a basically red (spectral class M) proto-star not yet on the Main sequence! Hydrogen burning had not yet commenced. This is mixing chalk and cheese in the context of the discussion.
His other reference to one mass extinction "every 26.5 million years" is also not very illuminating. Obviously, we don't know the exact reasons, but it is interesting that immense, Torino -scale 9 asteroids are predicted to strike at about that frequency. Such an event occurred around 65 million years ago, setting off the equivalent of a nuclear winter, which exterminated most of the then dinosaurs.
Yes, as Bloom points out, Nature does "toss us tests" and we need to try to survive "by outwitting her".
However, if the runaway greenhouse kicks in there will be no going back, and nothing we do technologically or otherwise will make a difference. The Earth will become permanently uninhabitable - probably within two generations, or sooner. The only "adaptation" then on offer will be death, not just of the human species, but all.
This is something that one would have thought Bloom would have processed. but perhaps not given that he's a psychologist.