The Ultimate Environmental Cataclysm: Asteroid and Comet Impacts and their Effects on Climate

The Cretaceous-Tertiary (K-T boundary) extinction ~66 million years ago is perhaps the most famous extinction event in Earth’s history. It featured a massive asteroid impact which led to the extinction of an estimated 76% of all fossilizable species, and marked the end of the ~170 million+ year reign of the dinosaurs (Pope 1998). Initially regarded as a radical proposition, this is the Alvarez hypothesis, after Luis Alvarez, the lead scientist of the team that discovered the first of multiple lines of smoking gun evidence for the impact of an asteroid ~10 km across under Chicxulub on the coast of the Yucatan Peninsula right around the time of the K-T boundary (Alvarez 1979, Smit 1981, Smit 1980, Bohor 1984, Bohor 1987, Bourgeois 1988 & Hildebrand 1991).


An artist’s interpretation of a hypothetical asteroid impact. Sources: Here and here.

In addition to the famous K-T extinction, which is also sometimes referred to in the literature as the Cretaceous-Paleogene (or K-Pg boundary) extinction, I also mentioned that one or more meteoroid impact may have been one of several contributing factors of Earth’s worst mass extinction event of all time: the Permian extinction. So, such impacts may have affected life on Earth on more than one occasion, but in precisely what ways can such impact events affect the climate? First of all, let’s clarify the difference between an asteroid, comet, bolide, meteoroid or meteorite:

The degree to which an asteroid impact affects the climate depends on its size and mass. It’s estimated that an impact which releases a million megatons of energy (representing an asteroid roughly 2 km in diameter) would produce about 10^16 kg of ejecta, which is approximately on par with an M9 Super Volcano (Morrison 2006). That’s near the upper limit of what is considered possible. In terms of energy, such an impact would also be on par with an earthquake of magnitude 10, which is beyond the range considered to be possible (Morrison 2006). This would likely also be accompanied by a subsequent tsunami as well as wild fires due to thermal radiation. Insofar as climatological effects, an impact in this range would have significant global effects on the ozone (ostensibly destroying it), and would produce enough stratospheric dust and sulfates to induce global cooling (Toon 1997, & Pierazzo 1998).

The Chicxlub K-T boundary event in particular may have also indirectly triggered global warming effects by releasing large amounts of carbon monoxide (CO) (Kawarigi 2009). Although only a weak greenhouse gas, CO tends to react with hydroxyl (OH) radicals in the atmosphere. This reduces their abundance. The OH radicals normally help limit the lifetime of stronger greenhouse gases like methane, so the idea is that CO released by the K-T boundary impact event may have led to global warming by reducing atmospheric OH radical concentrations, thus increasing greenhouse gases by extending their lifetime.

So as you can see, some of these effects can sometimes work in opposition to one another, and it’s not always obvious which effects will “win out” in either the short term or the long term for a particular impact. In this example, the resultant warming effects may have potentially been compounded by the 0.8 million years of Deccan Traps basalt eruptions overlapping the K-T boundary, and were ultimately more than offset by the acute sulfate aerosol cooling effects (Keller 2008, & Pope 1997).

The impact event is believed to have caused so-called Impact Winter effects for a few decades; these consisted of darkness and cooling from ash, debris and sulfate aerosols, which thus inhibited photosynthesis for up to a year (Vellekoop 2014, Schulte 2010, Ohno 2014, Pope 1998). It also likely led to acid rain and ocean acidification (Schulte 2010, & Ohno 2014)  There is evidence of a relatively fast post-climatic recovery (Pierazzo 2003), but insofar as 76% of fossilizable species on Earth were concerned, the damage was already done.

I should mention that this is just the most well-known scientific hypothesis for the primary cause of the K – T boundary extinction. There are alternative hypotheses regarding the causes of the extinction itself, such as the aforementioned Deccan Traps (Keller 2008), the Multiple Impact Hypothesis, the Maastrichtian Sea Regression hypothesis (li 1998), and research which proposes combinations of two or more of these factors (Peterson 2016). But the fact that the Chicxlub Impact occurred is not a matter of serious contention. The evidence for it is about as close to a proverbial smoking gun as one could expect to get in science. These alternatives don’t contradict that. Rather, they merely posit that the impact was not the sole and/or primary cause of the mass extinction, which is not germane to my focus here, which has been on using the Chicxlub event as an example of how such impacts can affect Earth’s climate.

That said, it should go without saying that the current climate change we are experiencing is not attributable to meteorite and asteroid impacts. Their climatic effects are proportional to their magnitude, but we track them, and the big ones are far too conspicuous to go unnoticed.

Oh, and in case the prospect of a massive impact has anyone alarmed, just realize that potential impact threats are closely monitored, so we’d most-likely know well ahead of time (at least for the larger ones). For smaller ones, which might not be detected until weeks or days before impact, there is also ATLAS: the Asteroid Terrestrial – impact Last Alert System. Of course knowing in advance is only as useful as our best impact avoidance and/or evacuation protocols. But hey! The really big impacts are even less frequent than Super Volcanoes. There are plenty of more probable calamities to worry about than having one’s home city vaporized by an asteroid impact.

Besides, mass extinctions are 100% natural! And nobody ever said that the Universe was nothing but sunshine and rainbows, right?

Okay, so maybe some people have alluded to that, but oh well. She was wrong.

  • Credible hulk


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The Climatological effects of Volcanic Eruptions: The End Permian Extinction, the Toba Super-Volcano, and the Volcanic Explosivity Index

Volcanic eruptions can have both short-term and long term effects on Earth’s climate. In the short term, they release large quantities of ash and sulfur dioxide (SO2) into the stratosphere, which quickly gets blown all around the globe. The sulfur dioxide subsequently reacts to form droplets of sulfuric acid (H2SO4), which then condense into fine aerosols. These aerosols reflect sunlight back into space, thereby cooling the troposphere below. These effects can last for 1 – 3 years. In the long term, they can increase atmospheric concentrations of CO2 which can lead to global warming via the greenhouse effect over long periods of heightened volcanic activity

For years it was thought that the volcanic ash was primarily responsible for cooling effects by blocking sunlight. However, it was later discovered that its effects are short-lived, and that the total amount of sulfur-rich gases released in an eruption was a more important determinant of an eruption’s global cooling effects.

Cooling from Volcanic Sulfide Aerosols (source).

Cooling from Volcanic Sulfide Aerosols (source).

In rare cases of exceptionally large “Super Volcano” eruptions, there is evidence that the ash can contribute significantly to climate change – largely through changes in the surface albedo of the affected area, but these are estimated to occur only about once every 50,000 years on average. It’s worth noting however that eruptions of that magnitude still occur roughly twice as frequently as asteroid, comet, or meteoroid impacts with comparable climate effects (diameter ≥1 km). The Toba eruption of about 74,000 years ago in Sumatra, Indonesia was perhaps the greatest Super Volcano eruption of human pre-history. Some estimates posit that its initial 3 – 5 degree Celsius cooling effect may have triggered the first couple of centuries of a nearly 1,000 year cooling period. There is even a hypothesis that the Toba eruption may have been largely responsible for an apparent genetic bottleneck in human evolution around that time, but other research disputes the extent to which Toba could have been to blame for that.

Eruptions are rated on a scale called the Volcanic Explosivity Index (VEI) from 0 – 8 based on the resultant volume of ash and debris (tephra) and cloud height, as well as on subsequent developments of this index based on the mass of magma from an eruption (magnitude). Scales based the rate of mass ejection (intensity), and the area covered by lava (destructiveness). All of these are logarithmic scales (pg. 263 – 269).

Particularly explosive eruptions with high levels of halogen emissions may also exacerbate ozone depletion, possibly via interactions with human emitted Chlorofluorocarbons (CFCs).


Take for instance the following reaction of chlorine and ozone:

CFCl3 + UV photon ==> CFCl2 + Cl
Cl + O3 ==> ClO + O2
ClO + O ==> Cl + O2

This leaves another chlorine atom free to react with another ozone molecule

Cl + O3 ==> ClO + O2
ClO + O ==> Cl + O2

And so on and so forth. This can occur thousands of times.

Stratospheric ozone protects life on earth from damage from harmful UV radiation.

Although possible mechanisms have been proposed by which ozone depletion might indirectly affect the climate by suppressing terrestrial carbon sinks in the carbon cycle, its effects on the climate are not well understood, and usually take a back seat to concerns over the deleterious effects of the resultant influx of UV radiation on human, plant and animal health. Although subordinate to CFCs emitted by humans, volcanoes can have some effect on the ozone too.

In the long term, extended periods of heightened volcanic activity can also result in warming via the greenhouse effect. For instance, about a million years of severe volcanism spanned the Permian-Triassic boundary in what is referred to as the Siberian Traps. This released large quantities of CO2 and methane into the atmosphere and led to significant warming about 250 million years ago (albeit likely preceded with short term cooling effects from the aforementioned sulfate aerosols). These were flood basalt eruptions in which ferromagnetic lava of relatively low viscosity covered as much as 1.3*10^6 km^2 in Northern Pangea.

Artist’s rendering of the landscape during end-Permian extinction. Image: Jose-Luis Olivares/MIT

This is suspected to have been a major contributing factor to the worst mass extinction in Earth’s history: The End Permian Extinction: known colloquially as The Great Dying. The End Permian event is estimated to have included the extinction of up to 96% of marine species and 70% of terrestrial vertebrates (though estimates vary).

I should mention that volcanism and subsequent warming via the greenhouse effect were likely not the sole determinants of the Permian extinction event: there is also evidence that these events triggered the eruption and burning of coal deposits, and of possibly one or more asteroid (or large comet) impacts, and possibly even a contribution from a methane producing genus of archaea.

However, tremendous volcanism and global warming almost certainly played key roles in the End Permian extinction as well. As the authors of this study put it:

“When the end-Permian extinction is compared with other short-lived events such as the end-Triassic and end-Cretaceous extinctions and the PETM, we see in common, a short-lived perturbation of the carbon cycle followed by a rise in atmospheric pCO2 and temperature, evidence for ocean acidification, anoxia, and rapid extinction (10s of thousands of years) (485657).”


In my articles on plate tectonics and continental drift (here and here), I used the Rodinia Supercontinent and Snowball Earth hypothesis as an example of how continental drift could dramatically affect climate. I did not, however, discuss how that extreme glaciation is thought to have come to an end. Well, models suggest that atmospheric greenhouse gas concentrations would have needed to get extremely high to break out of such a glaciation. Global glaciation would entail that that the carbonate and silicate rock weathering reactions (which I discussed in the continental drift articles) would not have been able to sequester atmospheric CO2, so CO2 from volcanic eruptions should have been allowed to accumulate unmitigated in the atmosphere over millions of years, which could explain how the Earth warmed enough to end the glaciation period.

Knowing this, it’s not unreasonable to wonder whether GHG emissions from volcanoes could be contributing to current global warming. However, we track volcanic activity closely, and it turns out that volcanic CO2 contributions since 1750 have been at least 100 times smaller than the contributions by human’s burning fossil fuels. This fact runs contrary to the common climate myth that states that a single volcanic eruption releases more CO2 than humans have emitted throughout all of history. The myth attempts to portray anthropogenic contributions as a drop in the bucket compared to volcanic CO2 emissions. In actuality, the opposite is the case. If anything, volcanic activity may have even slowed down warming from 2008 – 2011 via sulfuric acid aerosol forcing.


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Milankovitch Cycles and Climate: Part III – Putting it All Together

In parts I and II, we looked at axial obliquity, axial precession, apsidal precession, orbital eccentricity and orbital inclination, and how their cycles can affect the climate. In this installment of the series, we’ll look briefly at how these cycles look when combined, and then discuss one of the most prominent unsolved problems raised by the theory: The 100,000 Year problem.

Putting it all together

Putting it all together

Notice that the peaks and valleys in temperature are roughly periodic, and that with the possible exception of apsidal precession, there are slight fluctuations in the periods and amplitudes of these orbital cycles. One reason for this has to do with fluctuations in solar output, but another likely reason has to do with the very causes of these orbital cycles themselves: namely, these cycles are driven by mutual gravitational perturbations between the Earth, Sun, Moon, and to a lesser extent, Jupiter and the other planets in the solar system (Borisenkov 1985, Spiegel 2010) .

These are what are referred to in physics as “n-body problems.” Isaac Newton recognized early on that some such orbital fluctuations would have to occur, but it turns out that n-body problems cannot be solved analytically for systems of n ≥ 3 (Heggie 2005). That means the resultant systems of differential equations has to be solved using what are called numerical methods, rather than being solved for a set of analytic functions describing the precise trajectories of each body in the system over time. As a result, the actual precise paths that celestial bodies take and the variations in their tilt and precession can be more complex than just a fixed elliptical path. To add insult to injury, these problems become even more complicated in General Relativity than in classical Newtonian Celestial Mechanics.

Milankovitch Cycle/Insolation animation c/o Cal Tech

Milankovitch Cycle/Insolation animation c/o Caltech

I want to also emphasize the fact that even though Milankovitch first proposed his ideas nearly a century ago, this is still an area of active research. There are still unsolved questions about how these cycles combine to help produce the glaciation data we see in the paleo-climatological records. For instance, there’s what is known as The 100,000 Year Problem. This refers to the fact that during the past million years, glacial-interglacial periods have occurred on roughly a 100,000 year cycle, which has been difficult to reconcile with the fact that the insolation changes due to the 100,000 year orbital eccentricity cycle are very small. The effect appears to exceed the magnitude of the cause.

There is no shortage of plausible hypotheses, each with their respective strengths and weaknesses, but as of yet there’s still no unified theory that explains how precisely the cycles all work together to produce the observed pattern of glacial and interglacial periods.

For instance, researchers such as Muller et al have hypothesized that orbital inclination may be more important in producing the observed 100kyr glaciation cycle than the other cycles (Muller 1997). The only physical mechanism thus far proposed for this is the possibility that different inclinations of the orbital plane may correspond to different densities of meteoroid and dust accretion. Such a change could alter stratospheric concentrations of dust and aerosols, which would change the amount of sunlight reflected back into space. So far there’s no evidence for sufficiently different amounts of accretion at different orbital inclinations for this to be the case, but it’s a testable hypothesis whose strengths and weaknesses are outlined by the lead author here (Muller 1995).

Other researchers have been able to reproduce the 100,000 year cycles in models involving the non-linear phase locking of interactions between the known orbital forcings and internal oscillations in the climate system (Tziperman et al 1997). The basic idea behind the non-linear phase locking models is that axial obliquity and/or precession may act as pacemakers for the glaciation cycle in a manner that is distinct from models based on mere amplifications of the effects of the eccentricity cycle.

The minutia of the actual physical mechanisms involved in the non-linear phase locking models is left quite vague. No definite conclusion is attempted regarding whether the dominant cycle is obliquity, precession or both; the models work just as well with CO2 changes driving glaciation in synchrony with the orbital cycles as they do with the orbital cycles driving them with CO2 changes merely amplifying the signal. But that’s because the goal with that paper was merely to figure out whether such models could reproduce the cycle. The same lead author (Tziperman) has also co-authored work that explored a sea ice triggering mechanism for glaciation (Gildor 2000).

Others have even argued that the last 800,000 or so of climate records extends insufficiently far back to establish that the apparent 100,000 year glaciation cycle and its relationship to the eccentricity cycle are even statistically significant (Wunsch 2004).

This is not the only unresolved problem related to Milankovitch cycles. In addition to the 100k year problem, there’s also a similar 400k year problem, which exists because a strong variation in the eccentricity cycle doesn’t appear to correspond to an extra strong 400k period climatological cycle.

Then there’s also what’s called the “Stage 5” Problem: aka the Causality Problem (Oppo et al 2001). This refers to the fact that the penultimate interglacial period (corresponding to Marine Oxygen-Isotopic Stage 5) appears to have occurred about 10k years prior to the forcing hypothesized to have caused it. Another issue is what’s called the Split Peak Problem, which refers to the fact that eccentricity cycles have cleanly resolved variations at both 95k and 125k years which don’t appear to translate into two cleanly resolved peaks in insolation (Zachos et al 2001).  Instead, what’s observed is a single peak on a roughly 100k frequency.

So, as you can see, determining the precise manner in which the combinations of these cycles affect global climate is no easy task, and we still don’t know everything.

That said, what we DO know is that these cycles are not sufficient to explain the rate of the current warming. For one, they occur over much longer periods of time than the current trend (on the order of tens or hundreds of thousands of years versus a couple hundred years).

Moreover, Earth’s Orbital Eccentricity is nearly circular, and both Axial Obliquity and Axial Precession are currently changing in opposition to the warming trend; Axial Obliquity is getting smaller: not larger, which means if anything that we in the Northern Hemisphere should be cooling (or at least not warming). Similarly, precession is changing such that it should be moderating the warming, but it’s not. If anything, other variables (i.e. human activities) may be delaying the next glacial period (Berger 2002). So, even though we don’t know everything about how Milankovitch cycles affect the climate, we do know that they can’t explain the current warming trend.


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Rial, J. A. (2004). Earth’s orbital eccentricity and the rhythm of the Pleistocene ice ages: the concealed pacemaker. Global and Planetary Change41(2), 81-93.

Rial, J. A. (1999). Pacemaking the ice ages by frequency modulation of Earth’s orbital eccentricity. Science285(5427), 564-568.

Spiegel, D. S., Raymond, S. N., Dressing, C. D., Scharf, C. A., & Mitchell, J. L. (2010). Generalized Milankovitch cycles and long-term climatic habitability.The Astrophysical Journal, 721(2), 1308.

Tziperman, E., Raymo, M. E., Huybers, P., & Wunsch, C. (2006). Consequences of pacing the Pleistocene 100 kyr ice ages by nonlinear phase locking to Milankovitch forcing. Paleoceanography21(4).

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Zachos, J. C., Shackleton, N. J., Revenaugh, J. S., Pälike, H., & Flower, B. P. (2001). Climate response to orbital forcing across the Oligocene-Miocene boundary. Science, 292(5515), 274-278.

Photo Credits:

Incredio –, CC BY-SA 3.0,


Milankovitch Cycles and Climate: Part II – Orbital Eccentricity, Apsidal Precession and Orbital Inclination

In part I, we looked at some of the ways in which changes in axial obliquity and precession can affect the climate. In this article, we’ll look at orbital eccentricity, apsidal precession and orbital inclination, and some of their climatological consequences.

Orbital Eccentricity: This refers how elliptical earth’s orbital path is. The greater the eccentricity of a planet’s orbital path, the less circle-like and more elliptical (oval-like) it is. An ellipse has an eccentricity greater than or equal to zero, but less than one. An eccentricity value of e = 0 corresponds to a perfect circle, whereas e = 1 corresponds to a parabola, and e > 1 corresponds to a hyperbola. At higher eccentricity values (albeit less than one), there is a greater discrepancy between a planet’s perihelion and aphelion: a planet’s nearest and furthest points from the Sun during its orbit.

Earth’s orbital eccentricity changes over cycles of about 100,000 and 413,000 years or so due to the gravitational influence of massive planets such as Jupiter and Saturn. During these cycles, earth’s orbital eccentricity varies between about e = 0 (perfectly circular) to about e = 0.06.

Orbital Eccentricity

Orbital Eccentricity

Orbital eccentricity is the only Milankovitch cycle that affects total annual insolation on the earth: the total amount of solar energy per unit area reaching the earth, and it does so by a factor of 1/(1- e2 )1/2 for a given solar irradiance (Spiegel 2010). That means that while eccentricity (e) varies between 0 and 0.06, insolation should vary between a factor of 1/(1-(0)2)1/2 = 1 and a factor of 1/(1- (0.06)2 )1/2 = 1.0018 for a given solar output. Currently, Earth’s eccentricity is approximately e = 0.017, which works out to 1/(1-(0.017)2)1/2 = 1.00014. So the variation in insolation isn’t very significant. However, that doesn’t mean that these cycles don’t have a significant effect on climate. At greater eccentricity values, the seasons occurring while Earth is closer to the aphelion are of longer duration than the ones occurring while the Earth is closer to the perihelion.

Additionally, the regional and seasonal climatological effects of changes in axial obliquity and precession are more pronounced during periods of greater orbital eccentricity than when Earth’s orbit is circular (or nearly circular). This is because greater eccentricity values correspond to greater differences between the closest point to the sun (perihelion) and furthest point (aphelion) in Earth’s orbital path. In turn, those greater differences between the perihelion and aphelion can either amplify or moderate the discrepancies in seasonal insolation caused by axial tilt and precession. A hemisphere tilted towards the sun at the perihelion and away from the sun at the aphelion would have its summers and winters slightly reinforced, while a hemisphere tilted away from the sun at the perihelion and towards the sun at the aphelion would experience a slight moderating effect on its summers and winters.

Apsidal precession: The theory of Milankovitch cycles also predicts that the orientation of earth’s entire elliptical orbital path rotates in cycles of 21,000 years. That is to say that the location of the perihelion in Earth’s orbit changes over thousands of years (Greenberg 1981). The following graphic should clarify what is meant by this:

Apsidal Precession and the Seasons.

Apsidal Precession and the Seasons.

There is some evidence to suggest that these changes in the orientation of the perihelion work together in combination with the axial precession cycle to affect temporal and geographical insolation and precipitation patterns (Merlis 2013). In other words, it affects where and when higher and lower local levels of sunshine and rain occur.

Orbital Inclination: Although the planets and asteroids follow elliptical orbits in accordance with Kepler’s first law, they don’t all orbit in precisely the same plane. Their orbital planes are often inclined with respect to one another, and their angles of inclination can change slightly over time. The Earth’s orbital plane is also called the Plane of the Ecliptic (or simply the ecliptic).

By Lasunncty (talk). (Lasunncty (talk)) [CC-BY-SA-3.0 ( or GFDL (], via Wikimedia Commons

Orbital Inclination.

The orbital inclination angles of planets, asteroids and other celestial objects are usually computed with respect to Earth’s ecliptic, and thus the Earth’s inclination with respect to its own ecliptic would therefore be zero by definition, but this is primarily for purposes of convenience. The inclination of the ecliptic changes over time on a cycle of approximately 70,000 years. This is known as Precession of the Ecliptic. Milankovitch did not study this cycle, but I’ve included it anyway for the sake of completeness. Additionally, its climatological effects are still a matter of scientific debate. Earlier calculations suggested that its effect on insolation would be negligible (Berger 1976), but other researchers have postulated that it may play a role in the explanation of one of the hitherto unsolved problems raised by the theory of Milankovitch cycles (Muller 1995). In fact, Muller et al even went as far as to argue that when the inclination is computed with respect to the Invariable Plane of the solar system: the plane through the solar system’s barycenter (center of mass) and perpendicular to its angular momentum vector (approximately the orbital plane of Jupiter), rather than with respect to Earth’s 1850 orbital plane, the cycle works out to closer to 100,000 years rather than the traditionally accepted 70,000 years (Muller 1995).

The relevance of this claim will become clearer in part III when we discuss how these cycles combine together to affect climate, and when we take a look at one of the most prominent unsolved questions raised by the theory.


Berger, A. L. (1976). Obliquity and precession for the last 5 000 000 years.Astronomy and Astrophysics51, 127-135.

Greenberg, R. (1981). Apsidal precession of orbits about an oblate planet.The Astronomical Journal86, 912-914.

Merlis, T. M., Schneider, T., Bordoni, S., & Eisenman, I. (2013). The tropical precipitation response to orbital precession. Journal of Climate26(6), 2010-2021.

Muller, R. A., & MacDonald, G. J. (1995). Glacial cycles and orbital inclination. Nature377(6545), 107-108.

Spiegel, D. S., Raymond, S. N., Dressing, C. D., Scharf, C. A., & Mitchell, J. L. (2010). Generalized Milankovitch cycles and long-term climatic habitability.The Astrophysical Journal, 721(2), 1308.

Photo Credits:

Orbital Eccentricity: By NASA, Mysid – Vectorized by Mysid in Inkscape from NASA image at, Public Domain,

Apsidal Precession and the Seasons:  By Krishnavedala (Own work) [CC BY-SA 3.0 (], via Wikimedia Commons.

Orbital Inclination: By Lasunncty (talk). (Lasunncty (talk)) [CC-BY-SA-3.0 ( or GFDL (], via Wikimedia Commons

Milankovitch Cycles and Climate: Part I – Axial Tilt and Precession

The theory of Milankovitch cycles is named after Serbian astronomer and geophysicist, Milutin Milanković, who in the 1920s postulated three cyclical movement patterns related to Earth’s orbit and rotation and their resultant effects on the Earth’s climate. These cycles include axial tilt (obliquity), elliptical eccentricity, and axial precession. In aggregate, these cycles contribute to profound long term changes in earth’s climate via orbital forcing.

Axial Obliquity: The Earth’s rotational axis is always tilted slightly; currently, its axis is about 23.4 degrees from the vertical. Alternatively, you could say that its equatorial plane is tilted about 23.4 degrees relative to its orbital plane. This tilt is responsible for Earth’s seasons. During the Northern Hemisphere (NH) summer, Earth is further away from the Sun than it is during the NH winter due to its slightly elliptical orbit, yet it receives more sunlight because it’s tilted towards the Sun. During this same time period, the Southern Hemisphere (SH) is tilted away from the Sun, which is why NH summer coincides with SH Winter and vice versa. Contrastingly, during the NH winter, the Earth is closer to the Sun, yet receives less sunlight because it’s tilted away from it. During that same period, the SH is tilted towards the Sun, and is thus experiencing summer.

However, that axial tilt slowly varies between about 22.1 degrees and 24.5 degrees over long quasi-periodic cycles of roughly 41,000 years. The last maximum is estimated to have occurred around 8,700 BCE, and the next minimum should occur roughly around the year 11,800 CE. A more exaggerated tilt corresponds to more severe seasons: warmer summers and colder winters. As you may have guessed, less exaggerated tilt corresponds to milder seasons: cooler summers and warmer winters. The latter phases can lead to increased glaciation. This is because cooler summers mean less ice loss per year, and warmer winters mean more precipitation (rain or snow) to build up ice sheets. Now, you might be wondering why exaggerated tilt wouldn’t build ice sheets with its extra cold winters, but remember that the freezing point of water at 1 ATM of pressure is still going to be 0 degrees Celsius. Reaching negative 50 degrees C in the winter isn’t likely to facilitate much greater glaciation than reaching negative 10 degrees C, and those extra cold winters would involve less precipitation. To add insult to injury, the extra hot summers would melt greater portions of the existing ice each year. That’s why smaller axial tilt values are thought to correspond to increased glaciation and larger tilt values to deglaciation. Moreover, greater surface areas of ice cover can function to resist warming via the ice-albedo feedback (or snow-albedo feedback), which I mentioned briefly in my article on how continental drift affects climate (here and here).

Axial Tilt (photo credit).

Axial Tilt (photo credit).

Axial Precession: At any given obliquity, the direction of the earth’s rotational axis can “wobble” around the vertical in its own cycles (called precession) even while maintaining a more or less constant angle between the rotational axis and the vertical. This is caused by gravitational influences on the earth from the sun and moon. It takes roughly just under 26,000 years for the earth to complete an entire cycle of precession. Estimates differ from different sources, in part due to the fact that the rate of precession is not constant. This is also the reason earth’s axis points either towards Polaris or Vega as the “North Star” roughly every 13,000 years.

Axial Precession.

Axial Precession.

In the contrasting case (i.e. precession in the opposite phase of its current configuration), NH Winters would occur when Earth was furthest away from the sun and summers would occur when it was closest. That would mean extra hot summers, and thus more glacial melting. It would also mean extra cold winters, but those colder winters also correspond to less precipitation. That’s why our current precession should be more conducive to building the NH ice sheets, but the opposite is occurring due to reasons we’ll delve into soon enough. Again, loss of ice also means less help from the ice-albedo feedback effect, which could otherwise help resist further warming. Although axial precession does not affect total annual insolation, it can have a profound effect on where and when that solar energy is distributed, and consequently on the formation or disintegration of ice sheets. Right now, the northern hemisphere is closer to the sun in the NH Winter and further away in the NH Summer. This makes NH Summers less hot and NH Winters less cold than would be the case if Earth were in the opposite phase in its precession cycle. Presumably, the warmer NH Winters should be conducive to more precipitation (snow fall), which would contribute to glaciation, whereas the moderate summers would be conducive to less glacial melting than if the precession were in the opposite configuration from its current phase.

Keep in mind that the magnitude of these seasonal effects also depends on how eccentric our orbit is around the sun, and neither obliquity nor precession affects the total amount of energy coming in from the sun. Their immediate warming or cooling effects are only regional, but regional warming can lead to global warming by altering ocean circulation patterns, redistributing heat throughout the oceans, and consequently causing the oceans to release stored CO2, by decreasing its solubility, which can drive additional warming via the greenhouse effect.

In part II, we’ll look at three other orbital cycles: orbital eccentricity, apsidal precession and orbital inclination. After that, we’ll look at their combined effects on climate in part III, and then discuss the limitations of our current knowledge by examining some unsolved problems regarding the relationship between these cycles and Earth’s glaciation cycles.


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Toggweiler, J. R., Russell, J. L., & Carson, S. R. (2006). Midlatitude westerlies, atmospheric CO2, and climate change during the ice ages.Paleoceanography21(2).

How Continental Drift affects Climate: Part II – Possible Snowball Earth Triggering Mechanisms + Regional Effects of Mountain Ranges

In Part 1 of this article, I outlined some of the variables which can affect Earth’s climate, and gave a brief overview of plate tectonics, and how continental drift can lead to climate change through albedo feedback and via the alteration of ocean circulation and heat distribution patterns. In doing so, I used the example of the Rodinia Supercontinent and the Snowball Earth hypothesis of the Neoproterozoic era in order to relate the concepts to events in Earth’s prehistory. For the sake of completeness, I want to finish up that example by briefly going over a few proposed triggering mechanisms that could have made a runaway albedo feedback loop possible in the Cryogenian period. After that, I want to go over the ways in which the presence of mountain ranges can affect local and regional climate.

Although the exact causal sequence (and even the SnowBall Earth hypothesis itself) is still an unresolved area of active scientific debate, there are multiple candidates for such a cooling trigger mechanism: decreased solar luminosity, global cooling from a Super Volcano eruption, or perhaps a reduction in atmospheric methane – a much stronger greenhouse gas than CO2 – due to reactions with atmospheric oxygen could plausibly have contributed. There is also evidence suggesting increased sequestration of CO2 by rocks due to weathering effects from high precipitation levels. The idea behind the latter hypothesis is the following: Carbonate and Silicate rock weathering reactions are important carbon sinks in Earth’s carbon cycle:

Carbonate rock weathering reaction:

CaCO3 + CO2 + H2O → 2HCO3 + Ca2+

Silicate rock weathering reaction:

CaSiO3 + 2CO2 + H2O → 2HCO3 + Ca2+ + SiO2

Precipitation levels tend to be high around the equator, which therefore increases these weathering reactions, and thus increases CO2 sequestration, thereby decreasing the greenhouse effect, and leading to global cooling. Once sufficient equatorial land ice could accumulate, the aforementioned ice albedo feedback effect could ensue.

The end of the extreme Neoproterozoic glaciation is an interesting story in its own right, but in addition to the breakup of Rodinia via continental drift, it involves a greenhouse effect facilitated by a very long period of extreme volcanism, which I’ll be covering in a subsequent post. It also directly preceded the Cambrian explosion.

Rodinia was not the last time Earth had a tropical continental arrangement, but a critical change occurred: the evolution of forests. The Devonian Period (419 – 372 mya) featured the Greening of the Continents, and the evolution of forests, which serve as carbon sinks. So, by the time the Pangea Supercontinent formed (about 250 mya), an equatorial continental arrangement did not necessarily mean excessive rock weathering reactions, let alone runaway ice albedo feedback.

Plate tectonics can also influence climate through the formation of mountains (orogeny). Mountains can have profound effects on climate, particularly in their effect on precipitation patterns on the surrounding lands. Higher points on mountains tend to correspond to lower temperatures, so as rising moist warm air makes its way up the windward side of a mountain, it cools down, thus causing its ability to hold water to decline, which in turn leads to precipitation (rain or snow). Consequently, the leeward side of the mountain will often receive less precipitation, and by the time that air reaches the adjacent flat lands, it may not have any moisture left. This is one reason deserts are sometimes located directly next to mountain ranges. Mountains can also affect air circulation patterns great distances away. You can read more about how mountains affect climate and weather patterns at the Mountain Professor.

It’s perfectly natural to wonder what (if any) role continental drift has played in the global warming and climate change we’ve been experiencing currently. The answer is very little (if any). The issue is the RATE at which the current change has been occurring. These processes I’ve described take place over tens or even hundreds of millions of years. The continents tend to move at roughly 2 cm a year, and even faster moving plates rarely exceed 10 cm even on a fast year. The continents haven’t moved all that much in the last few hundred thousand years, and less than meter or so within the last 150 years during which the recent changes have been occurring. So continental drift is ruled out as a principle causal determinant of the current warming. It simply doesn’t induce climatic changes fast enough to explain the rapidity with which the recent warming has been occurring. However, its effects on the planet over the long term can be quite profound indeed.


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10 Reasons Why Hidden Cancer Cure Conspiracy Theories Fail (UPDATED)

Extremely popular on Facebook and other social media is the idea that an inclusive cure for cancer has been found but is being suppressed. The reason given for the suppression is universally the same. The premise is that companies stand to make more money by treating a chronic disease than from curing it. It’s a simple idea with a simple justification, but the implications are staggeringly complicated. If we consider what the world would have to look like for this conspiracy hypothesis to be true, we immediately see numerous holes and contradictions.

It is the nature of human thinking to become upset with behavior we see as unfair. If we are told that the rich and powerful are allowing human suffering to continue for the sake of their wallets, the inclination is to be outraged.  Unfortunately, it’s also human nature to justify such feelings once we have them.  This causes many to focus on the outrage and forget to think things through and, when presented with the various logical snags inherent to this trope, to rationalize with whatever justifications and compartmental logic is necessary to maintain the outrage. It’s a basic phenomenon we see with virtually all forms of pseudoscience: Start with a conclusion and do whatever it takes to support it.

Here we present 10 reasons why the hidden cures narrative is untenable. Most of these points hold even if one tacitly entertains the assumption that people in the medical and drug industries are sociopaths who put profits over ethics: a theme common to many versions of this narrative. Contrastingly, some of these points also draw into question whether such an assumption is realistic. We encourage people to not only consider these points, but to also pay attention to how they are dismissed or explained away by conspiracy speculationists. We believe the methods used to counter these points go a long way to explain why the hidden cure trope exists and persists, and that they reveal a flawed thought process rather than any sort of evidential substance. Extraordinary claims require extraordinary evidence, and promoters of the hidden cure conspiracy have no evidence whatsoever: just a narrative. Even worse, the narrative has no internal logical consistency.

We have used a cancer cure to illustrate these points, but a hidden cure conspiracy for any disease faces similar criticism. We have also chosen to temporarily put aside the fact that there are many types of cancer, and that different types of cancer would likely require different cures, in order to focus on the implausible logistics that the narrative would require.

1. Not all organizations involved in medical research are for-profit.

It is a myth that all research funding comes from organizations with corporate interests. Universities across the world regularly engage in research, and charities such as American Cancer Society regularly contribute funds.  Major breakthroughs in cancer treatments have come from such sources, and in principle there is nothing stopping them from finding the “ultimate” breakthrough. This is inconvenient to the conspiracy because without a profit motive the narrative immediately falls apart.  It’s like saying that charities dedicated to ending hunger secretly want children to starve just so they have reason to keep the charities active.  While it’s true that charitable organizations sometimes become corrupted or were never sincere in the first place, that is usually due to the actions of one or a few people.  This conspiracy demands that virtually all people in every organization be perfectly corrupt without fail.

2. Medical researchers and their families are just as susceptible to cancer and other diseases as anyone else.
An obvious implication of a “hidden cure” conspiracy is that researchers and business owners are willing to put the company and shareholders ahead of the lives of themselves and their loved ones. It implies that the thousands of individuals involved in research and healthcare are flawlessly obedient drones never giving into the temptation to help someone they care for deeply, or to better the world. It means doctors and and scientists must be willing to sit and silently watch their mothers, their children and their spouses suffer and struggle with a disease they themselves know to be curable. It requires a single-minded hive-mentality immune to compassion or grief and a willingness to put a single goal above all personal comfort and well-being. There is no company or government on Earth that’s ever been able to operate in that manner. It would literally require an army of sociopaths that, despite feeling no sympathy for others, are somehow able to come together and mutually agree on a course of action which necessitates self-sacrifice for the sake of their co-conspirators.

3. Even the CEOs of companies won’t be able to utilize their billions if they’re dead from something their companies could have cured.
Even if you buy into the idea that powerful people do not care about their friends and families, the very appeal to selfishness made by the greed and profit angle says they care a great deal about themselves. If we were to notice that an overwhelming majority of corporate heads and government officials have managed to escape cancer, then we might have reason to be suspicious that a cure has been found and is being saved for a select few. But that’s not what’s happening. With each passing year the list of rich and powerful people who die from cancer becomes more populated. It includes corporate CEOs, politicians, government leaders, Big Pharma employees, and heads of state from around the world. We would have to believe that these people know of a cure but decide not to use it so as to avoid suspicion. It’s silly to think that any of these people, many who already have fantastic amounts of money, would be willing to face the specter of a slow lingering death just to have a little more. It can’t be true that these people are so selfish as to hide a cure in favor of their own gain, yet so selfless that they are willing to die so the conspiracy can remain secret. These sorts of contradictions arise not from evidence or reasoning, but from making as many assumptions as needed to justify the trope of a hidden cure without contemplating their logical implications in sufficient depth.

4. Many if not most researchers are more likely to value fame, prestige and personal achievement over sheer quantity of money.

Even if we tacitly accept that scientists and doctors do not care about making a difference the world or helping sick people, we still can’t assume that the only thing they care about is money. Any scientist who finds or participates in research leading to a breakthrough cure is going to be instantly famous among colleagues and peers. It’s a chance to show all the foes and detractors from your entire life that you are not a loser, that you are in fact the very best at what you do. It not only means a Nobel Prize, it virtually guarantees statues and entire buildings erected in your honor and a mention in virtually every medical and science textbook. It means you can set your salary and work for any company you choose, doing whatever research you like. It means adoration from millions of victims and family members whom you have saved. Finding a cancer cure would mean a reputation to rival that of Einstein’s and a legacy which will persist throughout history. It’s not very easy to believe that any scientist would be willing sweep these benefits under the rug along with the cure, and the more shallow and selfish the conspiracy claims the scientists to be, the more likely it is that they value total personal gain over mere financial gain alone.

Via Sheeple.

Image via Sheeple.

5. While all governments would have to be in on it, not all would make money.

Many such conspiracy theories rely on cooperation between governments and pharmaceutical companies, yet there are countries with socialized medicine who could dramatically reduce their healthcare costs if they were to expose hidden cures that were being suppressed. Is it likely that they’d be sitting idly by, losing money while everyone else gets rich Wouldn’t any country like to reduce healthcare costs and instead spend the money on things like defense and energy development No, we’d have to believe that, in a world where the “hidden cure” conspiracy can be uncovered by anyone with a laptop and WiFi connection, these countries had somehow missed it.

6. Pushback from insurance companies.

Again, if any conspiracy theorist with a computer can find evidence of a hidden cure, then insurance companies must also be aware of it. Why would big insurance companies continue paying for expensive yet inefficacious treatments when a cheap and effective cure is available If hiding the cure brings in the big bucks, then insurance companies are the ones largely responsible for paying the bill. They’d have every incentive imaginable to uncover and expose the suppression of superior and cheap treatments. Why would they be motivated to keep quiet while forking over huge sums of money to something they know to be a fraud. Again, we’d have to believe that they had somehow missed it.

7. Actually, companies WOULD make a lot of money from cures.

In what universe would a treatment of such monumental efficacy not be marketable? If it could be patented, then the inventors would go down in history for their achievements (which to many scientists is more valuable than just being ridiculously rich but unrecognized for their accomplishments), and the company they worked for would make billions. Sometimes conspiracy speculationists respond to this by claiming that the hidden cures might not be patentable, but that’s not a valid argument either (for two reasons).

Firstly, companies can and do make a lot of money from non-patented products and services all the time (including pharmaceutical companies). This may consist of selling generic drugs, which in some countries comprises the majority of drugs legally sold, or over-the-counter natural supplements, which already comprise a $30 billion industry in  their own right.

Secondly, the fact that a particular compound is naturally occurring would not preclude a drug company from patenting something similar IF they had good reason to suspect it was a viable research avenue for a treatment. It’s not uncommon for a company to come up with a spinoff of a natural substance which CAN be patented. In fact, that’s the case with a sizable portion of the medications already out there (Talapatra 2015). Often all that is required is the isolation and purification of the active compound, and/or perhaps a slight modification of its chemical structure, or the introduction of a particular drug delivery system. Pharmacologically active molecules typically possess regions called pharmacophores, which are the aspects of a compound’s molecular structure responsible for its specific action, and regions called auxophores, which are regions that, if altered slightly, don’t alter which receptors the resultant compound acts on, but may or may not alter the strength with which the pharmacophore region binds, thereby possibly affecting its potency. This allows chemists to start with a compound with properties conducive to a particular goal (called a lead compound), and then come up with useful variations of it (Prisinzanno 2015). Considering the overwhelming past success of making slight molecular alterations to known pharmacologically active compounds to create new drugs of variable potency and receptor retention duration, it’s highly implausible that lack of patentability has played much of a role in drug companies’ disinterest in any particular naturally occurring substance.

8. Companies are already choosing cure or prevention over profit.

There are already examples of inexpensive products which are very effective at eradicating a particular disease despite the fact that letting people get sick and then treating them would yield more profit per patient. However, companies still create them, which would seem to contradict the claim that companies are so ruthless they’d rather people suffer so they can milk a little more money out of them than to market a cure. Why haven’t vaccines and antibiotics been suppressed?  Is there not more money to be made from tuberculosis by treating the symptoms instead of administering the cure?  Would no one stand to profit if measles were rampant in America instead of rare?  Why would companies be so selective about which cures to hide and which to utilize? Again, this only makes sense if you use logic and reasoning not with the aim of finding truth, but with the aim of rationalizing away facts which clash with the narrative. It involves starting with the idea that a cure is being hidden, and then using whatever unsupported assumptions needed in order to maintain the narrative, despite confounding details.

Also interesting is when these people learn of the HPV vaccine, which is intended to help prevent cancer, they use the same flimsy logic to dismiss it. They tell you not to trust it because it’s just a ploy to make money. In true conspiracy speculationist fashion, everything becomes reframed as evidence of a conspiracy, even when companies are trying to prevent cancer rather than treat it. This is yet more indication that these speculationists are motivated only to serve suspicion and conspiracy mongering while having no allegiance to candid investigation or intellectual honesty.

9. There’s more than one for-profit company out there, which means competition.

If you assert that a cure would destroy a pharmaceutical company’s profits, then you are also asserting that finding a cure would be a good way for one particular company to beat down all the rest. If all other companies are selling a lifelong regimen which treats symptoms but doesn’t cure, then it doesn’t take an entrepreneurial genius to realize that any company who came up with an inclusive cancer cure would mop the floor with their competition and make hundreds of billions. You only need to set the cost of your cure somewhere just below the cost of that regimen to make tons of money while also devastating your rivals. You then can leverage the prestige that comes with your cure as weight when asking for donations, when seeking investors, when choosing partners and when applying for loans. You can enjoy the millions of dollars in free marketing and promotion which attaches your company name to success. You also have the added benefit of not watching your loved ones die of a curable disease just so you can protect the profits of your shareholders.

In fact, it isn’t even necessary for a company to find their own cure first. They could still use the conspiracy against itself. If one of them blew the lid off of some alleged secret cure, or exposed a fatal flaw in a treatment developed by a competitor, they would mop up the floor with their competition. They could then market themselves as The Company You Can Trust. Imagine all the nefarious things they could then get away with if the public saw them as being above suspicion. Even if it were true that there is no money in a cure, the conspiracy itself creates an extraordinary opportunity for any one company to rise to the top and then have cover to do whatever other corrupt thing they please. The more greedy and ruthless a company is, the more likely they are to take advantage of this opportunity. It’s silly to think these companies have no problem double-crossing the public, but would never think of double-crossing each other.

10. Hiding the cure would cost more.

Game theoretic calculations are a lot more subtle than the overly simplistic worldview that hidden cures conspiracy theorists tend to hold. Each company complicit in the conspiracy would have to weigh the likelihood and consequences of being double-crossed by their competitors and of every single scientist currently and formerly on their payroll against the predicted benefits. As we’ve pointed out, a conspiracy this large would require cooperation from many entities that would actually lose money. In order for the conspiracy to work, each of those entities would need to be incentivized to stay quiet; in other words, they’d have to be paid more than they would lose. That’s every country with socialized healthcare and every insurance company which pays for treatments. Don’t forget that each doctor, researcher and scientist involved in any aspect would need to be paid an amount sufficient to overcome any temptation to squeal. Clinical trials are an integral part of drug discovery and necessary to establish a cure. That’s even more information to suppress and more people who need paid off. All of this comes after the billions spent on research and development to find the cure in the first place. Also needed would be a small army of henchmen capable of dispatching with those who will not cooperate, and with a budget sufficient to cover this all up. This army would also be required to monitor independent and rival researchers, and would need to get to them before they stumbled onto the cure themselves, so as to either pay them off or kill them. At that point, the price tag for having the privilege of holding the hidden cure would likely be in the trillions. To any corporation in this position, having a cure to hide would be a burden not a boon.

Strictly speaking, it may be possible to continually amend the hidden cures conspiracy theory with a never ending regress of evidence-free ad hoc assumptions to make the narrative seem to hang together. Indeed, that is a quintessential feature and attraction of most grand scale conspiracy theories. However, the more ad hoc assumptions and the more people who’d have to be involved in order to preserve the secrecy of the conspiracy, the less likely the story is to actually be possible. This has been studied (Grimes 2016). So, at some point one has to simply apply Ockham’s razor, and concede the monumental implausibility of the hidden cures conspiracy hypothesis.

*This piece was a collaboration between Credible Hulk and I Fucking Hate Pseudoscience, and is cross posted here.


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How Continental Drift affects Climate: Part I – Plate Tectonics, Albedo, and the SnowBall Earth Hypothesis

About 700 – 800 MYA, during the Neoproterozoic era (in the late Precambrian), it has been proposed that the Supercontinent, Rodinia occupied an equatorial position on the Earth. Perhaps counter-intuitively, this tropical arrangement of the continents may have set the stage for a massive glaciation known as “Snowball Earth” during the Cryogenian period, despite equatorial regions receiving the most sunlight due to the orientation of the Earth with respect to the sun. Indeed, the fact that equatorial regions receive the most sunlight is part of the reason why tropical rainforest biomes exist where they do. So how could this have happened? Why would an equatorial continental arrangement render such a glaciation more likely? More on the Snowball Earth hypothesis in a moment: More generally however, what factors are capable of inducing changes in the climate?

There are several of them. First of all though, what do we mean by climate, and how does it differ from weather?

Weather refers to short term local fluctuations in temperature, precipitation, humidity, sunlight, atmospheric pressure, cloud cover and wind patterns, whereas climate refers to the average distribution of weather patterns over longer periods of time (usually decades or longer).

It’s no secret that average global temperatures have increased appreciably since the beginning of the industrial revolution. It’s a subject of endless and vehement political controversy, particularly surrounding the subject of anthropogenic causation via increased atmospheric concentrations greenhouse gases – primarily through the burning of fossil fuels – and what it might mean for policy makers.

Weather station temperature records, paleoclimatological data from ice cores and dendroclimatology (tree ring data), loss of Arctic glaciers and sea ice, and rising sea levels all converge on the conclusion that both land and sea surface temperatures have risen significantly in the last 150 years or so, and are breaking new records even as I type this.

I can delve into the current global warming phenomenon, its causes, why it’s considered a problem, and the public debate associated with it in a later post. Today however, I want to talk about something else. So for now, suffice it to say that global warming is expected to lead to broader climate change more generally. But we know that climate has changed naturally in the past, so what are the factors which can cause it?

There are several variables capable of changing earth’s climate, including the following: Plate tectonics (continental drift), changes in earth’s orbit (Milankovitch cycles), changes in solar output (sun spots and solar flares), volcanism, asteroid, comet and meteoroid impacts, as well as changes in the composition of the atmosphere (i.e. the greenhouse effect).

Plate Tectonics:

Plate tectonics is the scientific theory that the Earth’s outer shell consists of a network of rigid plates which glide slowly over the Earth’s mantle, interact with each other a various ways, and which are responsible for continental drift. The lithosphere includes the Earth’s rigid outer crust as well as the top layer of the mantle. The plates glide over the layer beneath that, a viscoelastic layer known as the asthenosphere, which is elastic and ductile under short term stress, and capable of convection and flow under long term stress. The motion of lithospheric plates results from a combination of influences such as gravity, convection currents and various forces associated with the rotation of the earth.

Tectonic plates can interact by pushing together along convergent boundaries, whereby one plate can slide beneath another other in a process called subduction. They can also pull apart at divergent boundaries; this is what occurs in seafloor spreading along oceanic ridges. They can also undergo lateral motion at what are called transform boundaries, which is when two adjacent plates slide past each other horizontally. Transform boundaries are usually associated with ocean floors where they offset the divergent sea floor spreading at ocean ridges. However, they can also occur on land, such as the San Andreas Fault in California, for example. In actuality, plates can also deform and interact in more complicated ways, but these are the Classical Plate Tectonics interactions covered in your typical 101 treatment.


U.S. Geological Survey/ map by Jose F. Vigil

Plate tectonics have been shaping the earth’s geography for billions of years via continental drift, and are responsible for the current layout of the continents (see these animated reconstructions here and here). Continental drift via the movement of tectonic plates can affect earth’s climate by changing the sizes and locations of both land masses and ice caps, and by altering ocean circulation patterns, which are responsible for transporting heat around the earth, which in turn affect atmospheric circulation processes. For instance, changes in continental area at higher latitude can lead to corresponding changes in the area of permanent ice cover, which can lead to what’s called ice-albedo feedback (or snow-albedo feedback). Earth’s albedo is simply the proportion of light from the sun that gets reflected back into the atmosphere. An albedo of 0 corresponds to a perfect black body (total light absorption), whereas an albedo of 1 corresponds to a perfect white body (total reflection).

So how does this relate to the Rodinia Supercontinent, and the Snowball Earth hypothesis? The idea here is that tropical continents reflect more light than Open Ocean, thus absorbing less heat. Today, by contrast, most of the heat is absorbed by the tropical oceans. Since the equator receives more sunlight than other latitudes, that means that a significant portion of incoming sunlight would have been reflected rather than absorbed.

Snow and ice have even higher albedos than rock and soil, so all that was needed was some sort of triggering mechanism to set a runaway ice age effect in motion: cooling leads to more snow and ice, which reflects more light, which leads to more cooling, which leads to more snow and ice, and so on and so forth.

Credit: MIT Artist concept of a planet-wide Ice Age on Earth. Credit: iStockphoto

Credit: MIT Artist concept of a planet-wide Ice Age on Earth. Credit: iStockphoto

I should mention that although the presence of glaciers during the Cryogenian is not disputed, the snowball earth hypothesis is far from settled science. There’s even a less extreme variant that has been dubbed the Slush Ball Earth hypothesis. Regardless of its details, or whether it’s even correct, the point of this section is that a tropical distribution of continents makes such a self-reinforcing feedback loop possible, and it serves as an example of what a dramatic effect continental drift can have on climate change over the long term.

In part 2, I’ll finish up the Rodinia Supercontinent and Snowball Earth example by discussing candidates for a possible triggering mechanism that could have initiated such a reinforcing albedo feedback loop, and discuss how climate can be affected by perhaps a more familiar result of plate tectonics: mountain ranges.


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Obama Signs Bill Overturning Vermont’s GE Foods Labeling Mandate: Brace for Shit Storm

July 29, 2016

Earlier today, the president signed S. 764 into law: a Federal level law that stipulates that the Secretary of Agriculture is to decide on a mandatory nation wide standard by which all foods derived from sources which have been modified by in vitro recombinant DNA techniques will be labeled. Biotechnology advocates have largely opposed any Bill which unjustifiably singles out one particular breeding method for mandatory labeling (either Federally or at the State level).

Although this Bill was intended to be a compromise, the new Bill will not satisfy GE food opponents, simply because it won’t be conspicuous enough for them to easily construe them as warning labels.


They argue that the proposed labeling methods won’t convey any real information. They are actually correct about that, but not for the reasons they likely believe. The truth is that no policy of mandatory GMO labeling would convey any objectively relevant information. It’s really just a double standard which singles out one breeding method out of many on the basis of a manufactroversy propagated by anti-science activists and organic industry marketing, and further spread by unwitting consumers who’ve been duped by the hype.

I’ve outlined what I take to be the most important of the numerous flaws in the reasoning behind the mandatory GE food labeling movement here.

The Vermont labeling Bill has not had the effect that its proponents likely desired. It has resulted in fewer food choices for Vermont shoppers. This is an issue opponents of the law warned would be problematic if a patchwork of illogical and/or inconsistent State Level labeling laws were permitted to exist.

As readers of this blog are most likely aware, there is an international scientific consensus on GE foods which stipulates that

1). All the currently approved commercially available crops that have been brought about via modern molecular genetic engineering techniques are at least as safe to consume (and are at least as safe for the environment) as their corresponding non-GE counterparts.

2). There is nothing about the process of modern genetic engineering that makes unpredicted dangers any more intrinsically likely than would be the case with other methods of altering an organism’s genome (I.e. Selective breeding radiation mutagenesis, polyploidy or wide cross hybridization).

Insofar as point one is concerned, there is a tremendous amount of evidence to corroborate that conclusion, and an international scientific consensus based on it (citations to many studies, reports and systematic reviews, as well as position statements from numerous credible scientific organizations are hyperlinked within).

Despite the science, many anti-GMO activists and organic industry front groups have pushed for a law which singles out GE for a mandatory label, despite the fact that has been shown to introduce the fewest off target DNA changes of any currently used method of altering a plant’s genome, and despite their end products being the most tested and heavily regulated category of foods in the entire food supply.

They’ve tried to demonize GE through a variety of tactics, including the use of emotive propaganda imagery, shedding doubt on the legitimacy of the science through the use of evidence-free conspiracy hypotheses, and have even resorted to attacking independent scientists and science communicators for conveying the state of the mainstream scientific position on the subject, and vandalizing both GE test crops and family farmers’ personal crops. They even produce bad studies, sometimes even fraudulent ones, under the pretense of “independent science” (often published pay-to-play predatory journals) which contradicts the thousands of other studies. In some cases these so-called “independent” studies are fraught with undisclosed conflicts of interest.

These are all common tactics employed in several areas of science denialism, from opponents of vaccine science, water fluoridation and GE foods, to AGW denial, evolution denial and young earth creationism.

Several GE food opponents have come to realize that pretending that GE foods are more dangerous than their non-GMO counterparts will be a losing battle so long as there are people in the world who can follow the science. So, instead they take a “right to know” approach to their argument. They ask “if GMOs are so safe, why won’t you label them?”

Framing the debate in this way allows mandatory labeling proponents to set up a useful catch-22. Before mandatory labeling laws, they get to ask loaded questions such as “If they’re so safe, why don’t you label them?” After the implementation of mandatory labeling laws, they get to ask “If they’re so safe, why did they need to be labeled?” The answer to the former question is because mandatory food labels are supposed to be for information pertinent to consumers making food choices conducive to health and nutrition. The answer to the latter question is that they DIDN’T need to be labeled.

We already have voluntary labeling, but we don’t generally make a label mandatory unless it has some kind of objectively defensible relevance to the consumer (I.e. Health, nutrition, safety etc). Genetic engineering is a process: not an ingredient, and from an objective scientific point of view, breeding method is irrelevant to health and safety. Consequently, considering how thoroughly biotech opponents have flooded the internet with propaganda misinformation against GE foods, mandatory labels could easily be misinterpreted as a warning. It would mislead people into thinking it denoted some kind of pertinent difference in safety and/or nutrition between GE foods, conventional, and organic foods, when that is simply not the case.

The bottom line is that singling out GE out of all the other breeding methods to push irrational labeling mandates is an ideological position, not an evidence based one. There is not even one single valid argument for forced labeling of GE foods that doesn’t equally pertain to non-GE crops.

Instead, my view is that we should take an approach with GMOs that perfectly parallels the way we handle Halal and Kosher foods. We permit retailers to use Kosher, Halal and GMO-Free as voluntary labels for marketing purposes, because all three are based on ideological belief systems, rather than any scientifically defensible bearing on health.

That way, the burden of cost is placed on the people who want something for ideological reasons, and that allows food companies to voluntarily target that niche market if they so choose instead of passing the extra costs of regulation on to customers who don’t want illogical policies driven by mob rule.

However, this current labeling Bill is a compromise. If nothing else, it will at least mitigate the problems with interstate commerce that would be created by having a patchwork of state-level labeling laws.

Life Expectancy Has Increased Significantly and it’s not Just Due to Child Mortality Rates

A popular theme among movements which oppose certain aspects of modern science and technology is the notion that people were healthier in the “good old days,” back before the introduction of many modern scientific advancements. The idea is that there was once a time when there were no artificial chemicals, no fluoridated water, no genetically engineered crops, no vaccines or other modern medical science, all food was organic, and everyone led longer, happier, and healthier lives. There are many variations of this particular worldview aesthetic, and different ones have different ideas as to what the biggest alleged culprits are. Some hypothesize various conspiracies involving governments and/or corporations, whereas others may simply view new technology as “unnatural” (ergo undesirable) in their estimation. The common thread, however, is the belief that people are worse off now than in centuries past, and that one or more forms of human intervention are at fault.

One of the most obvious things one might think to bring up when presented with this sort of historical revisionism is the fact that life expectancy has steadily increased in nearly every country on the planet over the last 150-200 years or so.

Child Mortality

In response, some people will attribute the rise in life expectancy solely (or at least primarily) to a decrease in child mortality. There is some truth to this. As we can see from the graph below, child mortality has indeed decreased dramatically in the past 250 years or so. It also makes sense that changes child mortality rates would obfuscate the interpretation of data indicating an increase in life expectancy.

However, putting aside the fact that a decrease in child mortality rates is one the ways in which the advancement of scientific knowledge has benefited people, the idea that that it is sufficient to account for the increase in life expectancy is a myth. I think this is worth addressing because even a lot of skeptics make this argument.

Although it’s true that child mortality can skew mean life expectancy results, it should come as no surprise that statisticians know this and take it into account. It turns out that life expectancy is still much higher today (particularly in developed countries) than in the past even when adjusted to compensate for the effects of high child mortality rates. This is relatively easy to do when comparing data from populations in recent centuries, simply because people wrote it down. For example, rather than computing life expectancy from birth, which assigns a lot of weight to the effects of child mortality by default, statisticians use “life expectancy at age x.” Child mortality is defined as the number of children dying before their 5th birthday. For example, this chart of life expectancy over time in the UK gives the numbers over time for several different values of “x.”

Click here to see the interactive version

Click here to see the interactive version


Lo and behold! It turns out that expectancy is on the rise even if adjusted for the decrease in child mortality.

“To see how life expectancy has improved without taking child mortality into account we therefore have to look at the prospects of a child who just survived their 5th birthday: In 1845 a 5-year old had a expectancy to live 55 years. Today a 5-year old can expect to live 82 years. An increase of 27 years.”


Hunter Gatherer Times

That said, in the case of Paleolithic hunter-gatherers, the data is not as straight forward to obtain. This is simply because paleoanthropologists have to apply specialized techniques to determine the age at which a specimen died, and because we’re forced to rely on the tacit assumption that the limited number of specimens available to us constitute a representative sample. These researchers included “life expectancy at age 15.” Granted, the mean life expectancy is greater than 30 (lower to upper-mid 50s is most common), compensating for people dying before age 15 does not come even close to putting the mean life expectancy in the ranges we see today (typically 70s and 80s depending on which countries one looks at).

World Population

Unsurprisingly, total world population numbers have increased dramatically as well. If Big Pharma, the Great and Terrible MonSatan, the Shilluminati Reptilian Shadow Government, or any other shadowy forces are indeed engaged in some elaborate conspiracy to harm everybody for personal gain, their execution has left much to be desired insofar as any and all outward appearances are concerned.

Of course these facts all raise additional questions and other issues. What are the most influential causes of the life expectancy increases we’ve seen, and just how much greater could human life expectancy, max longevity, and global population conceivably get?

Transhumanism and Life Extension

If you’re familiar with the transhumanism and life extension movements, you may be aware that these are some of the important questions faced by proponents of indefinite life extension. They are also the topics of some of the common criticisms of the life extension enterprise.

See, the life extension movement has a concept called “longevity escape velocity,” which describes a hypothetical situation in which the rate at which life expectancy increases actually outpaces time itself. However, despite steadily increasing life expectancy numbers, changes in maximum longevity over time have been far less dramatic. Jeanne Calment, who died in 1997 at the age of 122, still holds the official world record as the oldest verified person on record, and although several others have made it into their one hundred and teens in the subsequent years, none have verifiably broken the 120 barrier, whereas life expectancy numbers have increased by at least a few years in nearly every country between 1995 and 2015.

Without also increasing longevity numbers, life expectancy could only keep increasing for so long until the mean life expectancy would approach max longevity as a narrow bell curve with a small variance and standard deviation. The biological limits of the human life span are not well known or well understood at this point, and there is much debate and speculation as to how long a person could potentially live. Anyone interested in learning more about the challenges faced by life extension researchers (insufficient funding not withstanding) can check out the works of Aubrey de Grey and Alex Zhavoronkov for more information. 


The issues of life extension and population growth also raise the issue of Malthusian catastrophe. Biotechnology can help with agricultural efficiency and productivity to a point, but it’s unclear the extent to which our technology can continue to keep pace with a growing population, and that’s only touching on the food aspect of resource allocation. Debates on the prospect of potential overpopulation run the gamut from extreme pessimism to optimism insofar as predictions as to whether technological solutions will win in the end. I can’t claim to know, in large part because I don’t view current trends as a viable basis for reliable projections that far into the future, but I tend to lean towards the idea that technological innovation will likely surprise us for the better. Steven Novella has laid out a couple of the more salient pro and con arguments here.

As far as what has caused the steadily increasing life expectancy over the last 150 years or so, there doesn’t appear to be a solid scientific consensus on the specific minutia, but it is probably safe to say that scientific knowledge and technology have been important contributors. In the concluding synthesis section at the end of their paper, “The Determinants of Mortality,” Cutler et al argue that improved housing, sanitation, and medical technology, the germ theory of disease, vaccines, advanced pharmaceuticals, and improved nutrition have likely all contributed to varying degrees.


Life expectancy has increased steadily for the last 150 years or so, and it cannot be attributed solely to the reduction in child mortality. This may not conclusively rule out the claim that dark forces are conspiring to wipe us out with GMOs, vaccines, chemtrails and water fluoridation; but if they are, it shows that they’re failing spectacularly at that task.