Guest post by David Archibald
Baby boomers like me have enjoyed the most benign period in human history. The superpower nuclear standoff gave us fifty years of relative peace, we had cheap energy from inherent over-supply of oil, grain supply increased faster than population growth and the climate warmed due to the highest solar activity for 8,000 years. All those trends are now reversing. But it will get much worse than that. The next glaciation will wipe out many countries and nothing will stop that from happening. For example, the UK will end up looking like Lapland. As an indication of just how vicious it is going to get, consider that there are rocks on the beaches of Scotland that got blown over on ice from Norway across a frozen North Sea. As scientists, our task is to predict the onset of the next glaciation.
Onset of interglacials is driven by insolation at 65°N. That is where the landmass is that is either snow-covered all year round or not. It seems that insolation above 510 watts/sq metre will end a glacial period. For an interglacial period to end, the oceans have to lose heat content so that snows will linger through the summer and increase the Earth’s albedo. Thanks to the disposition of the continents, our current ice age might last tens of millions of years yet. From the Milankovitch data, this graph shows insolation at 65°N from 50,000 BC to 50,000 AD:
The green box has the Holocene ending at 3,000 AD – an arbitary choice. Insolation is already low enough to trigger glacial onset. For the last 8,000 years, the Earth has been cooling at 0.25°C per thousand years, so the oceans are losing heat. We just have to get to that trigger point at which snows linger through the northern summer. Solar Cycle 25 might be enough to set it off. By the end of this decade, we will be paying more attention to the Rutgers Global Snow Lab data.
From the source at: http://most-likely.blogspot.com/2012/03/milankovitch-cycles-and-glaciations.html
Model input is obliquity and precession and model output is the inverted δ¹⁸O record, with zero mean during the Pleistocene, from Lisiecki and Raymo 2004 and Huybers 2007. Lisiecki and Raymo use orbital tuning to constrain the age of the benthic records, while Huybers explicitly avoids this, consequently the two datasets are occasionally completely out of phase, but generally in good agreement, especially in the late Pleistocene.
As fitness function we take the product of the sum of squared errors (SSE) between the model and the two reference records from 2580 thousand years before present, with 1000 year timesteps.
For the longer term perspective, this is a combined crop (to make a continuous timeline) of the two fulls panel from the model prediction of the Milankovitch data.
The time period represented is from approximately 450,000 BC to 330,000 AD. The scale on the vertical axis is change in O18 content. There is a very good hind-cast match between the model and past temperature change as shown by the work of Lisiecki et al 2005 and Huybers 2007. The next glaciation is fully developed between 55,000 and 60,000 AD, with the next interglacial 20,000 years after that.
References
Huybers, P., 2007, Glacial variability over the last 2Ma: an extended depth-derived age model, continuous obliquity pacing, and the Pleistocene progression, Quaternary Science Reviews 26, 37-55.
Lisiecki, L. E., and M. E. Raymo, 2005, A Pliocene-Pleistocene stack of 57 globally distributed benthic d18O records Paleoceanography, 20, PA1003, doi:10.1029/2004PA001071.
Source Data: Download the consolidated data, including orbital parameters, insolation calculations, reference data and model output: Milankovitch.xlsx
Too True Tommy.
The Pembina Institute could not have been more wrong – one should NEVER quote the IPCC as an authoritative source – it’s just one more example of (drumroll…..)
“The Law of Warmist BS”
“You can save yourselves a lot of time, and generally be correct, by simply assuming that EVERY SCARY PREDICTION the global warming alarmists express is FALSE.”
http://wattsupwiththat.com/2012/02/28/the-gleick-tragedy/#more-57881
Oh please Lief why are you mangling what I bring up?
Again to point out what David wrote:
“It seems that insolation above 510 watts/sq metre will end a glacial period.”
When I refer to Below Zero insolation (no warming) I meant that it is never on the warming side of 510 watts/sq metere.That is why I keep bringing up what the chart shows that it is NEVER above the 510 level for the next 50,000 years thus it is always on the NEGATIVE (cooling) side of the 510 line.
This means that it will cool more than it warm for the next 50,000 years if the chart is correct as it probably is because there are several papers supporting this.
This Holocene is a long cooling slope since the peak warmth 8,000 or so years ago.I showed you the link to charts which are based on published science paper data that show the undeniable declining temperature trend for thousands of years and been in the NEGATIVE insolation Territory for about 4,000 years yet it had already been cooling for around 1,000 years after the Minoan warm period ended thus it has been a one way cooling slope for 5,000 years now.
Here is a chart comparing the last two interglacial’s:
http://theinconvenientskeptic.com/wp-content/uploads/2012/01/Chap_8-Illustration_63-550×524.png
The interglacial we are in is running longer than the previous one because of the slower insolation changes.
This one shows the ZERO insolation line for the two interglacial’s
http://theinconvenientskeptic.com/wp-content/uploads/2012/01/Chap_8-Illustration_64-550×393.png
We ARE sliding into a new climate winter,it may not be as cold and icy as the last one but will last around 90,000 years.
lgl says:
September 27, 2012 at 12:55 pm
“The insolation is, obviously, NEVER below zero”
Slide 20 and 25.
Shows that the average insolation is always above 50. At night the insolation is zero. Never is it below zero.
http://en.wikipedia.org/wiki/Insolation
“Insolation is a measure of solar radiation energy received on a given surface area and recorded during a given time”
sunsettommy says:
September 27, 2012 at 6:24 pm
Again to point out what David wrote:
“It seems that insolation above 510 watts/sq metre will end a glacial period.”
Since when is what David writes valid?
We ARE sliding into a new climate winter,it may not be as cold and icy as the last one but will last around 90,000 years.
Of course we are as I’ve been saying. The next glaciation will be about 63,000 years from now. So the ‘slide’ is VERY slow, and will in the beginning [until 35,000 years] actually be a warming. I.e. the current interglacial will be longer than usual. The topic of this post is whether we are entering a glaciation [mile thick ice above, say New York] in our lifetime. And we are not.
Leif
In a system with an oscillating forcing and large heat capacity the temperature will continue to drop even after the forcing has started to climb again, a little less than 1/4 cycle lag. I have given you numerous examples of this from diurnal to now glacial time frames (last from your own link) but still you are desperately trying not to understand this very basic physics, why?
lgl says:
September 28, 2012 at 7:39 am
In a system with an oscillating forcing and large heat capacity the temperature will continue to drop even after the forcing has started to climb again, a little less than 1/4 cycle lag.
There is no 25,000 year lag on the 100,000 year cycle.
That’s because there is no 100 kyr cycle. There is a n*40 kyr cycle. It used to be 1*40, then a few 2*40 and the last two 3*40 kyr. Remember the forcing is a combination of the ~40 kyr obliquity and the ~20 kyr precession, and Roe found the lag to be 6-8 kyr, right on spot.
lgl says:
September 29, 2012 at 7:25 am
That’s because there is no 100 kyr cycle.
Looking back at the comments of this thread, one is struck with the diversity of pseudo-facts peddled by various people. Roe found “that the available records support a direct, zero-lag, antiphased relationship between the rate of change of global ice volume and summertime insolation in the northern high latitudes.”
The 100 kyr cycle is demonstrated by spectral analysis: http://muller.lbl.gov/papers/nature.html#anchor354569
The clear conclusion is that we are not entering a new glaciation any time soon as the insolation is going up the next 35.000 years. The integrated ice volume is thus going down.
Leif is struck with the pseudo-facts peddled by various people.
Who was peddling the importance of eccentricity? The same person who now links to a webpage named “eccentricity is ruled out”.
Who claimed “and as soon as the insolation goes up again, the temperature will follow.”?
The same person who finally descovers that “the available records support a direct, zero-lag, antiphased relationship between the rate of change of global ice volume and summertime insolation” which implies a relationship between ice volume (and thereby temperature) and the integral of summertime insolation. And the lag between insolation and temperature will according to Roe be 6-8 kyr because “the maximum correlation occurs when the ice volume lags the June 65N insolation curve.The lag is 6 kyr in the SPECMAP record and 8 kyr in the HW04 record”
And who said “There is no 25,000 year lag on the 100,000 year cycle”?
The same person who now links to “The best fit was obtained with a lag of 33 +/-3 kyr. This is a plausible result; for example, if low inclination causes cooling, it might affect the rate of ice buildup, and glaciation would lag 1/4 cycle ~ 25 kyr. Additional delay of 10 to 20 kyr could result from mechanisms discussed by Weertman24”
Right, there is no 25,000 year lag, it’s 33,000 years.
Leif, stop digging.
lgl says:
September 30, 2012 at 12:23 pm
it might affect…could result
The next 35,000 insolation is going up, so no glaciation in the near future, is all. I think you have lost the overall picture.