Recently, there was a timeline comic from XKCD about the history of Earth’s temperature over the Holocene which got quite a bit of play, due to the fact that it had the inevitable “hockey stick” splice onto the end. Josh came up with a much less dogmatic and more detailed version, which we covered here.
That led Javier, who is a PhD level scientist in molecular biology and biochemistry who recently published an essay at Dr. Judith Curry’s website here, to come up with a similar but even more technical cartoon. We may have more on his essay later, but for right now I present his excellent timeline cartoon, that includes Earth’s obliquity and temperature over the last 20,000 years. Changes in Earth’s obliquity and thus solar insolation angles is believed to be the main driver of long term climate change, initiating and ending ice ages. As seen in the diagram below, the angle between Earth’s rotational axis and the normal to the plane of its orbit (obliquity) oscillates between 22.1 and 24.5 degrees on a 41,000-year cycle. It is currently 23.44 degrees and decreasing at a rate of about 0.013° per century.
An often-cited 1980 study by Imbrie determined that,
“Ignoring anthropogenic and other possible sources of variation acting at frequencies higher than one cycle per 19,000 years, this model predicts that the long-term cooling trend that began some 6,000 years ago will continue for the next 23,000 years”
With that in mind, have a look at Javier’s cartoon:
NOTE: an updated version of this cartoon timeline was posted on Oct 1, 2016 to fix a couple of typos in text labels pointed out by commenters.
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There will never be another ice age. The soot produced by fossil fuel burning will prevent ice accumulation. When people come agreement on that concept they will just spread black soot over ice in the NH to prevent any buildup. Simple really.
That is left for future generations, if there is anything left to burn at that time. In any case I wouldn’t hold my breath for that solution working, because it assumes that ice albedo is a major feedback factor, and perhaps it is not.
Javier. Actually, precession is key, with obliquity being secondary.
A small fact. …. Obliquity cannot warm the globe, it merely borrows warmth from the tropics and gives it to the poles. And both poles simultaneously. (Unlike precession, which warms the poles alternately.). This is how world glacial temperatures are modulated.
This is instructive. It tells us that ice age modulation is not a global phenomina, it is a regional phenomina. And interglacials only happen when precession provides a Great Summer (increased insolation) in the NH (often in conjunction with obliquity). So a global gas like Co2 is going to be far less influential, than regional insolation and albedo fluctuations in the NH.
It also tells us that another feedback agent must be operating. If global insolation remains constant, while the world warms into an interglacial, something else must be driving this change. And that feedback agent is albedo. The increased NH insolation melts the ice caps, and it is the reducing albedo that absorbs the insolation and warms the world. So albedo is key, while Co2 does – well – not a lot. (The SH is not so important, because it has smaller landmasses and no great tropic-encroaching ice sheets. Somit has smaller albedo changes.)
In addition, obliquity is only more influential now because eccentricity and therefore precession are both at minimums. And will be so for the next 100 ky. Normally it is precession that has the greatest influence on NH insolation, and therefore upon glacial and interglacial temperatures.
Modulation of Ice Ages.
http://www.sciencedirect.com/science/article/pii/S1674987116300305
R
Ralph,
“A small fact. …. Obliquity cannot warm the globe”
Evidence shows the opposite. Temperatures follow obliquity
“And that feedback agent is albedo.”
That’s your proposed feedback agent. I disagree, but to my knowledge there is no clear evidence to resolve this issue.
“In addition, obliquity is only more influential now because eccentricity and therefore precession are both at minimums.”
It is actually the opposite. Obliquity has less effect when eccentricity is at a minimum and gets less help from precession. The result is that interglacials are more spaced when eccentricity is low. The next interglacial is going to be a long wait.
>>“A small fact. …. Obliquity cannot warm the globe”
>>Evidence shows the opposite. Temperatures follow obliquity.
Total global insolation does not change at all, during the obliquity cycle. So please tell me how a steady global insolation value can change temperatures, if you do not invoke another feedback agent or causal agent.
>>It is actually the opposite. Obliquity has less effect when eccentricity
>>is at a minimum and gets less help from precession.
Completely wrong. The regional insolation variations caused by obliquity do not change significantly with changes in eccentricity. But the regional insolation provided by precession does reduce significantly with reducing eccentricity. Ergo, the proportion of obliquity insolation gets larger, with decreasing eccentricity. Plot the graphs, and see for yourself,
“Total global insolation does not change at all, during the obliquity cycle. So please tell me how a steady global insolation value can change temperatures”
Total global insolation was essentially the same at the Last Glacial Maximum and at the Holocene Climatic Optimum, so clearly the difference is made by when and where that insolation is falling.
” Ergo, the proportion of obliquity insolation gets larger, with decreasing eccentricity.”
I did not make myself clear. Obliquity needs the help of Precession to reach sufficient warming, so without enough Precession factor it doesn’t matter that obliquity becomes the dominant factor. Interglacials are more spaced when Eccentricity is low, like now, and less spaced when Eccentricity is high, like 200 kyr ago.
I thought ice core data showed that the medieval warming was warmer than now. Same for Roman. It was supposed to be world wide.
Nobody knows for sure. Most proxies usually do not include very recent dates so we don’t have an apples to apples comparison. Glaciers all over the world and some biological data, like the tree line in altitude, suggest that we are currently warmer than the medieval warm period.
Greenland ice cores have lots of issues, and they don’t reflect global climate very well.
It was supposed to be world wide.
=================
Regional warming is a red herring bit of nonsense. If only Europe warms, the average temperature of the earth increases. You have global warming. The only time this is not true is if somewhere else cools at the same time. At which time the average temperature of the earth is unchanged.
A keen observation.
Javier,
A great presentation!
But I have to disagree on some issues.
It is very important to keep things in perspective.
The earth is a sphere and receives the same amount
of direct light regardless of angle.
Especially keep in mind just how small a 2.4 degree
shift really is.
The earth’s iron core rotates slightly independent of the
outer layers and outer crust. The importance of obliquity
is not angle, but the fact that the earth is constantly shifting
in directions that are contrary to the motion of its iron core.
During an inter-glacial obliquity is a magnetic field amplifier.
During a glacial period the earth’s iron core loses its wobble
because the sun has suffered a substantial loss of acceleration.
Please visit . . Weathercycles.wordpress
” Fibonacci and climate “
At the risk of repeating myself I will again assert that the primary factors in climate change here on our world are solar, orbital and planetary dynamics. I proved it to myself through a simple mathmatical comparison of the relative energies. You can do thr same if you simply gather and objectively analyze the relevant data that has been available for decades.
https://wattsupwiththat.files.wordpress.com/2012/10/cp-8-1473-2012.pdf
A good study on glacial and inter- glacial periods of time
I have look at all the post but no one is able to address the abrupt climatic changes that took place especially 10000 years ago to 20000 years ago. Especially the sharp down turns in the temperature.
The YD being a prime example but there are so many similar events all I would have to say are not solved.
The change to abrupt cold periods such as the YD remain a mystery in contrast the abrupt warm ups do have some good theories one I will pass along in my next post.
https://wattsupwiththat.com/2015/09/01/the-arctic-iris-effect-dansgaard-oeschger-events-and-climate-model-shortcomings-lesson-from-climate-past-part-1/
Humans are estimated to have arrived in Australia about – 50,000 years ago – However, the extinctions of the megafauna being wiped out by this was actually a hypothesis of Tim Flannery – the ex- climate change commissioner – effectively knocked off his post by Tony Abott (yeah cheers finally) . Thus he even got his own science wrong – all scientists who still work in the field Tim Flannery abandoned for his new opportunistic field – now agree that for the 1st 25,000 years the indigenous Australians lived alongside the megafauna – and believe it not – how ironic – it is now theorised (thus evidence to support it) that the Australian megafauna were wiped out by – yes you guessed it – climate change!!!
Sirocko and Seelos, 2005, A late Eemian aridity pulse in central Europe during the last glacial inception, nature, vol. 436, 11 August 2005, doi:10.1038/nature03905, pp 833-836, state:
“Investigating the processes that led to the end of the last interglacial period is relevant for understanding how our ongoing interglacial will end, which has been a matter of much debate…..
“The onset of the LEAP occurred within less than two decades, demonstrating the existence of a sharp threshold, which must be near 416 Wm2, which is the 65oN July insolation for 118 kyr BP (ref. 9). This value is only slightly below today’s value of 428 Wm2. Insolation will remain at this level slightly above the [glacial] inception for the next 4,000 years before it then increases again.”
http://www.climate.unibe.ch/~born/share/papers/eemian_and_lgi/sirocko_seelos05.nat.pdf
“The possible explanation as to why we are still in an interglacial relates to the early anthropogenic hypothesis of Ruddiman (2003, 2005). According to that hypothesis, the anomalous increase of CO2 and CH4 concentrations in the atmosphere as observed in mid- to late Holocene ice-cores results from anthropogenic deforestation and rice irrigation, which started in the early Neolithic at 8000 and 5000 yr BP, respectively. Ruddiman proposes that these early human greenhouse gas emissions prevented the inception of an overdue glacial that otherwise would have already started.”
conclude Muller and Pross (2007)
https://www.researchgate.net/profile/Ulrich_Mueller7/publication/222561971_Lesson_from_the_past_present_insolation_minimum_holds_potential_for_glacial_inception/links/0c96051e593f3a593d000000.pdf
“Here, we study the questions why we still live in an interglacial world and when we should expect the end of the Holocene under natural conditions (no anthropogenic influence) or under anthropogenic perturbations (also referred to as “Anthropocene”), questions which attracted considerable interest in recent years. It was argued that without earlier anthropogenic activity we would live already in glacial world (Ruddiman’s hypothesis). Tzedakis et al. (Nature Geoscience, 2012), using MIS 19 as the best analogy in terms of the orbital parameters for the Holocene, suggested that the new glacial inception would start within the next 1500 years, assuming natural CO2 level of 240 ppm. However, 240 ppm is much lower than preindustrial CO2 level and CO2 concentrations during several most recent interglacials (starting from MIS 11). Here, using the comprehensive Earth system model of intermediate complexity CLIMBER-2, carefully calibrated for the simulations of the past eight glacial cycles, we show that (i) although climate conditions during late Holocene were very close to the bifurcation transition to the glacial climate state (Calov and Ganopolski, Geophys. Res. Lett., 2005), it is very unlikely that under pre-industrial CO2 level (280 ppm) glacial inception would occur within the next several thousand years; (ii) it is likely that the current interglacial, even without anthropogenic CO2 emission, would be the longest interglacial during the past million years; (iii) current CO2 level makes new glacial inception virtually impossible within the next 50,000 years; (iv) in agreement with earlier result of Archer and Ganopolski (Geochem. Geophys. Geosyst., 2007) based on a conceptual model of glacial cycles, we found that consumption of a large portion of available fossil fuel could postpone the next glacial inception by hundreds of thousand years.”
http://adsabs.harvard.edu/abs/2013EGUGA..15.1666G
I am aware of those studies. They are proposing that the current interglacial will be unprecedentedly long based on certain assumptions.
Ruddiman’s hypothesis is highly controversial and heavily contested by many of the experts in carbon stores and methane sources. It has captivated the press and the public but failed to make a similar impact in the scientific community. He has done some serious cherry picking of data that leads to questions about his integrity in acknowledging his hypothesis’ weaknesses.
The CO2 hypothesis of a delayed glacial start relies on two unproven assumptions, a high climate sensitivity for CO2 and a very long residence time for CO2. There is evidence that both assumptions are incorrect.
The insolation hypothesis relies on the hypothesis that glaciations main determinant is northern summer insolation and on the assumption that current levels are enough to prevent a glacial inception. while the first is under discussion and without agreement, the second is clearly false. Proponents of this hypothesis have failed to do their homework as there have been previous glacial inceptions with current insolation levels, for example MIS19.
While northern summer insolation is going to remain the same for the next few thousands of years, obliquity is going down at its fastest rate, which is going to make both poles colder with time, and the colder the poles the more heat that the Earth loses, independently of insolation. Failure to see this important fact is leading these people to the incorrect assumption that we are going to have an unprecedented interglacial. Luckily for us all we are not going to be around to see the failure of that prediction.
Really nice chart showing 65N summer solar insolation for the past 200,000 years and then going out for the next 135,000 years. [Note that this modelling can be very accurate for +/- 5 million years and outside of this large boundary, the uncertainties get too large].
Basically we are already at the end of a low cycle right now and the next low cycle is 52,000 years out. But I don’t think a 15 W/m2 drop at that time versus today is enough to put us into an ice age. The next big drop is 130,000 years from now which itself may not be enough for ice age as well (probably close though).
“Basically we are already at the end of a low cycle right now”
End of a low cycle in northern summer insolation. The end of a low cycle in obliquity is 10,000 years away. Both poles are going to continue cooling until then, and the rest of the planet likely too.
The last referenced paper disappeared recently here: http://adsabs.harvard.edu/abs/2013EGUGA..15.1666G
This is the best post ever! Sorry I missed it as I was travelling. Thanks Javier, I am impressed by your understanding of Milankovitch cycles.
I have often wondered if one of the important triggers for glaciation might actually be the moisture content of the arctic air masses rather than the temperature, especially in the Canadian archipelago region. The region is fairly dry today, and its difficult to imagine enough snowfall in this region to initiate glaciation no matter how cold it is. Is there a possible mechanism where influx of warmer water into the arctic periodically shifts the climate to a much greater maritime influence, transforming it from a relatively dry climate to one of heavy snowfall? Ive always wondered if it really needed to be much colder to initiate glaciation, or even if glacier formation could be starved of snowfall to bring about the beginnings of interglacial.
Thanks again for a great post and great comments.