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## new paper in GRL confirms link between sun and clouds on global scale

 Quote by Saul Xnn, This is not religious studies where one can appeal to some sacred book that has a higher status or democratic where if 10 people agree with your statement and only 9 agree with what my statement, you win.
Saul;

The problem is that there are a number of quacks around when it comes to science.
The way to avoid being mislead, is to refer to reputable sources and journals that employ the peer review process. It not, then this may just as well be a political or religious belief forum.

I agree with you that the Sun is in an exceptional period which may continue. There has been very few sunspots for the last 2 years. It's about as big a lull and what occurred in 1910 to 1913. This means the solar forcing for the climate is about as low as it was way back then. However, last I checked, global surface and land temps are both near record highs. It's far warmer now than it was back then and I think we both know why.

Here's a link to the latest National Climate Data Center summary:

 *The combined global land and ocean average surface temperature for August 2009 was 0.62°C (1.12°F) above the 20th century average of 15.6°C (60.1°F). This is the second warmest such value on record, behind 1998. August 2009 was the 31st consecutive August with an average global surface temperature above the 20th century average. The last August with global temperatures below the 20th century average occurred in 1978. *The combined global land and ocean average surface temperature for June-August 2009 was the third warmest on record for the season, 0.59°C (1.06°F) above the 20th century average of 15.6°C (60.1°F). *The worldwide ocean surface temperature for August 2009 was the warmest on record for August, 0.57°C (1.03°F) above the 20th century average of 16.4°C (61.4°F). *The seasonal (June-August 2009) worldwide ocean surface temperature was also the warmest on record, 0.58°C (1.04°F) above the 20th century average of 16.4°C (61.5°F). *In the Southern Hemisphere, both the August 2009 average temperature for land areas, and the Hemisphere as a whole (land and ocean surface combined), represented the warmest August on record.
Now, this does not mean we can not discuss the influence of the Sun on the climate. However, I'm not interested in being mislead by outrageous over hyped claims.

Mentor
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 Quote by Saul Science is the analysis of observation data to validate or invalidate hypotheses. There is a significant solar event underway. How has the solar magnetic cycle changed? Are there any unexplained climatic events or changes that correlate with the recent solar changes? Note the mechanism has solar wind bursts removing the ions that are hypothesized to increase planetary cloud cover, therefore the planet will not cool (planetary clouds increased due to high levels of GCR) until the the solar wind bursts abate and then stop. As shown in the solar links below, the solar wind bursts are starting to abate. GCR is 19% higher than any period in the last 40 years. Ocean heat content is starting to trend down. Why? edit: removed link This set of links shows the progress of the solar magnetic cycle. The sun is spotless for this day in 2004 however there is significant magnetic activity. edit: removed links The solar magnetic cycle has not restarted. There continues to be coronal holes in low latitude locations on the sun, however, the affect on the geomagnetic field is less and less as the coronal holes are stripping of the sun's magnetic flux and the solar magnetic cycle has not restarted. (See coronal hole CH382.) Today. (See coronal hole CH382.) edit:deleted links
Saul, those links are not to valid sources. Some even say that they are made by the person from other sources. Since we can't validate every graph that every person puts together, we have to insist on only the original data.

 Quote by Skyhunter OK, Making eyeball guesstimates is not very accurate so let me get more exact numbers. http://www.imcce.fr/Equipes/ASD/inso...line/index.php 65N summer insolation peaked 17,000 years ago. http://www.imcce.fr/tmp/insola/insolaoutKWaaCo The coldest point of the last glaciation was ~25,000 years ago and 65N 360L was about -6Wm2 less than the present. But there are other factors besides orbital forcings and NH summer insolation at any given period. I was not arguing that 65N insolation was the only forcing involved, I was simply pointing out your error. Since your argument was based on bad information, your conclusion is suspect.
 Quote by Skyhunter "Skyhunter 1st Quote:"No it isn't. 20,000 years ago was the coldest part of the last glacial period and insolation at 65N was ~20Wm2 less than it is today.
 "Skyhunter 2nd quote:"65N summer insolation peaked 17,000 years ago. The coldest point of the last glaciation was ~25,000 years ago and 65N 360L was about -6Wm2 less than the present.
Skyhunter,

You contradict yourself in the above quotes.
 Quote by Skyhunter No it isn't. 20,000 years ago was the coldest part of the last glacial period and insolation at 65N was ~20Wm2 less than it is today.
This interglacial period began roughly 20,000 years ago. The past six interglacial periods have been around 15,000 years long. The glacial periods are 100,000 years long. Do we agree what has happened before? i.e. I am not stating a theory I am stating the what the paleoclimatic data indicates. i.e. The mechanism must explain what has happened before.

The current interglacial period started about 20,000 years ago. As you note the coldest period of the last glacial period was about 25,000 years ago. Solar insolation in the summer has become progressive less at the 65N. When the interglacial started 20,000 years ago the earth was closest to the sun in June. Now 20,000 years later the earth is closest to the sun in January, which makes summers colder now then they were 20,000 years ago.

We both agree and multi papers state something else besides solar insolation is abruptly forcing the planet's climate. When you look at the peculiar saw shaped glacial/interglacial cycle there is obviously some massive forcing function at work.

Suddenly in the middle the current warming "Holocene interglacial" 12,900 years ago, the planet abruptly returns to glacial cold for a 1000 years. (The abrupt cooling period is called the Younger Dryas cooling period named after an alpine flower that suddenly appears in the fossil record in mid latitudes in Europe.)

My point is the Younger Dryas abrupt cooling event is one of a series of abrupt cooling events in the paleoclimatic record. There are cosmogenic isotope changes that are concurrent with the abrupt cooling events. Cosmogenic isotope changes are caused by interruptions in the solar magnetic cycle and geomagnetic field changes which then causes a massive increase in GCR.

As I said, there is a massive cosmogenic isotope change that is concurrent with a massive 1000 year abrupt cooling event which paleo climatologists have called the "Younger Dryas" cooling event.

http://cio.eldoc.ub.rug.nl/FILES/roo...IntRenssen.pdf

 Reduced solar activity as a trigger for the start of the Younger Dryas? The Younger Dryas (YD, 12.9-11.6 ka cal BP, Alley et al., 1993) was a cold event that interrupted the general warming trend during the last deglaciation. The YD was not unique, as it represents the last of a number of events during the Late Pleistocene, all characterised by rapid and intensive cooling in the North Atlantic region (e.g., Bond et al., 1993; Anderson, 1997). During these events, icebergs were common in the N Atlantic Ocean, as evidenced by ice-rafted sediments found in ocean cores. The most prominent of these episodes with ice rafting are known as Heinrich events (e.g., Bond et al., 1992, 1993; Andrews, 1998). A Heinrich-like event (H-0) was simultaneous with the YD (Andrews et al., 1995). Moreover, the YD seems to be part of a millennial-scale cycle of cool climatic events that extends into the Holocene (Denton and KarleHn, 1973; Harvey, 1980; Magny and Ru!aldi, 1995; O'Brien et al., 1995; Bond et al., 1997). Based on analysis of the 14C record from tree rings, Stuiver and Braziunas (1993) suggested that solar variability could be an important factor a!ecting climate variations during the Holocene (see also Magny, 1993, 1995a), possibly operating together with oceanic forcing.

 Evidence for solar variations in the geological past may be inferred from cosmogenic isotope records (Hoyt and Schatten, 1997). The two most important of these isotopes are carbon-14 (14C) and beryllium-10 (10Be),... Estimates for the increase in 14C at the start of the YD all demonstrate a strong and rapid rise: 40-70 %/% within 300 years (Goslar et al., 1995), 30-60 %/% in 70 years (BjoK rck et al., 1996), 50-80%/% in 200 years (Hughen et al., 1998) and 70%/% in 200 years (Hajdas et al., 1998). This change is apparently the largest increase of atmospheric 14C known from late glacial and Holocene records (Goslar et al., 1995). Hajdas et al. (1998) used this sharp increase of atmospheric 14C at the onset of the YD as a tool for time correlation between sites.
There is evidence is the sun is moving to a complete solar magnetic cycle interruption, not a slow down.

The magnetic field strength of newly formed sunspots has been linearly decreasing with time. It is believed sunspots are created at interface of the convection zone and the radiative zone (the tachocline). The sunspot requires a minimum field strength of around 1500 gauss to avoid being torn to pieces as it moves up to the surface of the sun through the turbulent convection zone.

Sunspots from the previous cycle are believed to move back down to tachocline to form the seeds for the next cycle, which explains why there is some periodicity between every second cycle. (The period of the convection motion motion is 22 years.). An interesting and unanswered question is how does the solar magnetic cycle re-start after being interrupted?

http://www.leif.org/EOS/2009EO300001.pdf

 Are Sunspots Different During This Solar Minimum? But something is unusual about the current sunspot cycle. The current solar minimum has been unusually long, and with more than 670 days without sunspots through June 2009, the number of spotless days has not been equaled since 1933 (see http:// users . telenet .be/ j . janssens/ Spotless/ Spotless .html). The solar wind is reported to be in a uniquely low energy state since space measurements began nearly 40 years ago [Fisk and Zhao, 2009]. The same data were later published [Penn and Livingston, 2006], and the observations showed that the magnetic field strength in sunspots were decreasing with time, independent of the sunspot cycle. A simple linear extrapolation of those data suggested that sunspots might completely vanish by 2015.
 Yet although the Sun’s magnetic polarity has reversed and the new solar cycle has been detected, most of the new cycle’s spots have been tiny “pores” without penumbrae (see Figure 1); in fact, nearly all of these features are seen only on flux magnetograms and are difficult to detect on whitelight images.

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The problem with the Younger Dryas is that if you really research it meticulously, checking out a couple of hundred studies on methodology, especially on dating calibration, the cold image crumbles. One example:

Björck et al 2002

 Anomalously mild Younger Dryas summer conditions in southern Greenland abstract The first late-glacial lake sediments found in Greenland were analyzed with respect to a variety of environmental variables. The analyzed sequence covers the time span between 14 400 and 10 500 calendar yr B.P., and the data imply that the conditions in southernmost Greenland during the Younger Dryas stadial, 12 800–11 550 calendar yr B.P., were characterized by an arid climate with cold winters and mild summers, preceded by humid conditions with cooler summers. Climate models imply that such an anomaly may be explained by local climatic phenomenon caused by high insolation and Föhn effects. ... cont'd
Note that model speculations don't count as evidence.

 Quote by Andre The problem with the Younger Dryas is that if you really research it meticulously, checking out a couple of hundred studies on methodology, especially on dating calibration, the cold image crumbles. One example: Björck et al 2002 Note that model speculations don't count as evidence.
Andre,

A melting ice in Greenland during the Younger Dryas does not mean the has not an abrupt cooling climatic climate change during the Younger Dryas that lasted a 1000 years.

If we understood the mechanism then interpreting the paleoclimatic record would be easier.

The Younger Dryas was the strongest climatic event in the Holocene, interglacial period. It was an abrupt climate event, not a gradual cooling. It lasted for 1000 years. During the Younger Dryas the North Atlantic froze each winter to a latitude of around mid-Spain.

There is a 6 fold increase in dust deposited on the Greenland ice sheet during the Younger Dryas cold period which indicates a massive increase in desertification due to abrupt cooling. As noted below the ice sheet dust changes occurs in less than 10 layers of ice. There is cycles of the abrupt increases in the dust deposited on the Greenland ice sheet.

Due to insolation, summers should have been warmer 12,900 years ago than now. Melt water in the Greenland region during the summer does not disprove an abrupt climatic cooling event occurred.

http://www.agu.org/revgeophys/mayews01/node6.html

 The Younger Dryas (YD) was the most significant rapid climate change event that occurred during the last deglaciation of the North Atlantic region. Previous ice core studies have focused on the abrupt termination of this event [ Dansgaard et al., 1989] because this transition marks the end of the last major climate reorganization during the deglaciation. Most recently the YD has been redated--using precision, subannually resolved, multivariate measurements from the GISP2 core--as an event of 1300 70 years duration that terminated abruptly, as evidenced by an 7 C rise in temperature and a twofold increase in accumulation rate, at 11.64 kyr BP [ Alley et al., 1993] (Figure 2). The transition into the Preboreal (PB), the PB/YD transition, and the YD/Holocene transition were all remarkably fast, each occurring over a period of a decade or so [ Alley et al., 1993]. Fluctuations in the electrical conductivity of GISP2 ice on the scale of <5-20 years have been used to reveal rapid changes in the dust content of the atmosphere during the same periods and throughout the last glacial [ Taylor et al., 1993b]. These rapid changes appear to reflect a type of flickering'' between preferred states of the atmosphere [ Taylor et al., 1993b], which provides a new view of climate change. Holocene climates are by comparison stable and warm.
 High resolution (mean: 3.48 years/sample), continuous measurements of GISP2 major anions (chloride, sulfate and nitrate) and cations (sodium, magnesium, potassium, calcium and ammonium) were used to reconstruct the paleoenvironment during the YD because these series record the history of the major soluble constituents transported in the atmosphere and deposited over central Greenland [ Mayewski et al., 1993c]. These multivariate glaciochemical records provide a robust indication of changes in the characteristics of the sources of these soluble components or changes in their transport paths, in response to climate change. A dramatic example is provided by the calcium series (Figure 2) covering the last 10-18 kyr BP. Prominent periods of increased dustiness have been observed in the record, peaking approximately every 500 years (see figures in Mayewski et al. [1993c]): during the early PB at 11.4 kyr BP; throughout the YD at 11.81, 12.22 and 12.64 kyr BP; during the Bolling/Allerod (B/A) at 13.18, 13.65, and 14.02 kyr BP; and during much of the Glacial. Such events have been attributed by Mayewski et al. [1993c] to changes in the size of the polar atmospheric cell and in source regions (e.g., growth and decay of continental biogenic and terrestrial source regions). The climate change that accompanied the YD was not restricted to Greenland. The record of variations in the CH concentration of trapped gases in the GRIP ice core [ Chappellaz et al., 1993] shows that tropical and subtropical climates were colder and drier during the YD and also earlier cold events. The major natural source region of CH is low-latitude wetlands [ Chappellaz et al., 1993]; higher atmospheric concentrations are presumably due to the greater areal extent of tropical and subtropical wetlands [ Chappellaz et al., 1993].

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No Saul, the Bjorck et al paper is just an example.

Another example, starting with the A:

http://esp.cr.usgs.gov/research/alas...Ager2003QR.pdf

 ..A brief invasion of Populus (poplar, aspen) occurred ca.11,000–9500 14C yr B.P., overlapping with the Younger Dryas interval of dry, cooler(?) climate...
and in the discussion:

 ...At Zagoskin Lake, the time interval for the Populus-Salix assemblage overlaps with the Younger Dryas interval of colder, drier climate that has been documented in several areas of Alaska (e.g., Peteet and Mann, 1994). It is unclear why an interval of apparently colder, drier climate might favor the expansion of Populus and Salix populations, even into areas beyond the present day range of Populus trees...
How many more shall I present?

 Quote by Andre No Saul, the Bjorck et al paper is just an example. Another example, starting with the A: http://esp.cr.usgs.gov/research/alas...Ager2003QR.pdf and in the discussion: How many more shall I present?
Andre,

I am not sure what your point or mechanism is. The paper you quote above discusses a microclimatic region (Bering Straight) where the Pacific Ocean significantly moderates the climate. i.e. That area and similar microclimate regions could be less cold than the Northern Hemisphere as a whole.

The Younger Dryas Greenland Ice sheet cooling occurred in less than a decade. Your paper does challenge the observation of rapid and extreme cooling on the Greenland Ice sheet.

The Greenland Ice Sheet temperatures dropped -15C as compared today. The Northern Atlantic ocean froze to the latitude of mid Spain. Why? What planetary or external change caused the planet to change.

As I note there are cosmogenic isotope changes that are concurrent to the planetary temperature changes.

There is a cycle of warming and abrupt cooling periods throughout the glacial and interglacial period which show evidences of an external forcing function. The forcing occurs regardless of surface events. Its effect (the external forcing function) depends on surface events at the time of the occurrence.

http://en.wikipedia.org/wiki/Milankovitch_cycles

People have been silent on the list of paradoxes concerning Milankovitch's theory.

Milankovitch's theory does not explain the observations. There is evidence of abrupt warmings and coolings that do not correlate with any surface events.

 The 100,000 year problem The 100,000-year problem is that the eccentricity variations have a significantly smaller impact on solar forcing than precession or obliquity and hence might be expected to produce the weakest effects. However, observations show that during the last 1 million years, the strongest climate signal is the 100,000-year cycle. In addition, despite the relatively large 100,000-year cycle, some have argued that the length of the climate record is insufficient to establish a statistically significant relationship between climate and eccentricity variations.[6] Some models can however reproduce the 100,000 year cycles as a result of non-linear interactions between small changes in the Earth's orbit and internal oscillations of the climate system.[7][8]
 The 400,000 year problem The 400,000-year problem is that the eccentricity variations have a strong 400,000-year cycle. That cycle is only clearly present in climate records older than the last million years. If the 100 ka variations are having such a strong effect, the 400 ka variations might also be expected to be apparent. This is also known as the stage 11 problem, after the interglacial in marine isotopic stage 11 which would be unexpected if the 400,000-year cycle has an impact on climate. The relative absence of this periodicity in the marine isotopic record may be due, at least in part, to the response times of the climate system components involved — in particular, the carbon cycle.
 The Stage 5 Problem The stage 5 problem refers to the timing of the penultimate interglacial (in marine isotopic stage 5) which appears to have begun 10 thousand years in advance of the solar forcing hypothesized to have been causing it. This is also referred to as the causality problem. Effect exceeds cause 420,000 years of ice core data from Vostok, Antarctica research station. The effects of these variations are primarily believed to be due to variations in the intensity of solar radiation upon various parts of the globe. Observations show climate behaviour is much more intense than the calculated variations. Various internal characteristics of climate systems are believed to be sensitive to the insolation changes, causing amplification (positive feedback) and damping responses (negative feedback).
 The unsplit peak problem The unsplit peak problem refers to the fact that eccentricity has cleanly resolved variations at both the 95 and 125 ka periods. A sufficiently long, well-dated record of climate change should be able to resolve both frequencies [5], but some researchers interpret climate records of the last million years as showing only a single spectral peak at 100 ka periodicity. It is debatable whether the quality of existing data ought to be sufficient to resolve both frequencies over the last million years.
 The transition problem The transition problem refers to the change in the frequency of climate variations 1 million years ago. From 1-3 million years, climate had a dominant mode matching the 41 ka cycle in obliquity. After 1 million years ago, this changed to a 100 ka variation matching eccentricity. No reason for this change has been established.

The following is additional evidence that indicates Milankovitch's theory is not correct and there is an external mechanism that is forcing the planet's temperature.

http://earthobservatory.nasa.gov/New...w.php?id=24476

 Glacial Records Depict Ice Age Climate In Synch Worldwide An answer to the long-standing riddle of whether the Earth's ice ages occurred simultaneously in both the Southern and Northern hemispheres is emerging from the glacial deposits found in the high desert east of the Andes. "The results are significant because they indicate that the whole Earth experiences major ice age cold periods at the same time, and thus, some climate forcing mechanism must homogenize the Earth's climate system during ice ages and, by inference, other periods," says Michael R. Kaplan, a postdoctoral fellow at the University of Edinburgh who conducted the work in a postdoctoral position at UW-Madison "During the last two times in Earth's history when glaciation occurred in North America, the Andes also had major glacial periods," says Kaplan. "Because the Earth is oriented in space in such a way that the hemispheres are out of phase in terms of the amount of solar radiation they receive, it is surprising to find that the climate in the Southern Hemisphere cooled off repeatedly during a period when it received its largest dose of solar radiation," says Singer. "Moreover, this rapid synchronization of atmospheric temperature between the polar hemispheres appears to have occurred during both of the last major ice ages that gripped the Earth."
This is evidence that the short term planetary temperature changes in this interglacial period are global and synchronous. The synchronicity rules out ocean current as a possible mechanism as the time for ocean currents changes in the Northern Hemisphere to affect the Southern Hemisphere is theoretically around 1000 years.

A second as serious issue with the ocean current mechanism (likely a show stopper) is the recently confirmed finding that the deep ocean conveyor does not exist. There is therefore no ocean current mechanism to teleconnect the two hemispheres even with a time delay.

http://geology.geoscienceworld.org/c...tract/33/3/237

 Evidence of early Holocene glacial advances in southern South America from cosmogenic surface-exposure dating Cosmogenic nuclide surface-exposure dating reveals that glaciers in southern South America (46°S) advanced ca. 8.5 and 6.2 ka, likely as a result of a northward migration of the Southern Westerlies that caused an increase in precipitation and/or a decrease in temperature at this latitude. The older advance precedes the currently accepted initiation of Holocene glacial activity in southern South America by 3000 yr. Both of these advances are temporally synchronous with Holocene climate oscillations that occurred in Greenland and the rest of the world. If there are causal links between these events, then rapid climate changes appear to be either externally forced (e.g., solar variability) or are rapidly propagated around the globe (e.g., atmospheric processes).

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 Quote by Saul Andre, I am not sure what your point or mechanism is. The paper you quote above discusses a microclimatic region (Bering Straight) where the Pacific Ocean significantly moderates the climate. i.e. That area and similar microclimate regions could be less cold than the Northern Hemisphere as a whole. The Younger Dryas Greenland Ice sheet cooling occurred in less than a decade. Your paper does challenge the observation of rapid and extreme cooling on the Greenland Ice sheet. The Greenland Ice Sheet temperatures dropped -15C as compared today. The Northern Atlantic ocean froze to the latitude of mid Spain. Why? What planetary or external change caused the planet to change. As I note there are cosmogenic isotope changes that are concurrent to the planetary temperature changes. There is a cycle of warming and abrupt cooling periods throughout the glacial and interglacial period which show evidences of an external forcing function. The forcing occurs regardless of surface events. Its effect (the external forcing function) depends on surface events at the time of the occurrence.
I know, it's a bit weird to challenge the cold of the Younger Dryas and oppose all parties in the climatology, "warmers" and "deniers", but it's just the outcome of my years of research into that direction as I shall prove. There is no other option than to be absolutely accurate about the data before the suppositions can start and we are far away from that.

So, I'm afraid, it's all a bit different. and I still have dozens of "micro" climates on my sleeve. After the B of Bjorck, we now have the C for Columbia.

Van’t Veer R., G.A. Islebe, H. Hooghiemstra, 2000; Climate change during the Younger Dryas chron in Northern South America: a test of the evidence. Quartenary Science Review Vol 19 (2000) pp 1821 - 1835

 Abstract New AMS and palynological data are presented from the Colombian Andes to assess vegetational and climatic change during the Lateglacial-Holocene transition, with special emphasis on the Younger Dryas (YD) chronozone. ....From ca. 11,000 to ca. 10,500 14C yr BP there is a sharp increase of subparamo and paramo pollen, reflecting a relatively cool phase during the YD chronozone (zone Y1). After ca. 10,500 14C yr BP, a slight increase of arboreal pollen and the presence of Cactaceae (zone Z1) point toward a relatively milder but drier phase extending to ca. 9000 14C yr BP in the earliest Holocene....
The sharp boundary at 11,000 and 10,500 year 14C BP, carbon dated, convert to 12,920 and 12,600 calendar years BP using the INTCAL04 calibration table so that cooling period is mosty before the beginning of the Younger Dryas that started about 12680 "varve" counted years ago (Lucke and Bauer 2004)

So the warm period after 10,500 carbon years is actually in the middle of the Younger Dryas. Furthermore, peek at Lucke and Brauer again:

 High lacustrine primary production was further favored by relatively warm YD summer temperatures.
so we have yet another micro climate here, but now in Germany, Europe.

So if you find all these discrepancies, are these all micro climates? or is something more seriously wrong with our interpretations?

 Quote by Saul Skyhunter, You contradict yourself in the above quotes.
What part of:

 OK, Making eyeball guesstimates is not very accurate so let me get more exact numbers.
didn't you understand?

Since my second post was specifically to offer more precise numbers... why are you accusing me of contradicting myself?

 This interglacial period began roughly 20,000 years ago. The past six interglacial periods have been around 15,000 years long. The glacial periods are 100,000 years long. Do we agree what has happened before? i.e. I am not stating a theory I am stating the what the paleoclimatic data indicates. i.e. The mechanism must explain what has happened before. The current interglacial period started about 20,000 years ago. As you note the coldest period of the last glacial period was about 25,000 years ago. Solar insolation in the summer has become progressive less at the 65N. When the interglacial started 20,000 years ago the earth was closest to the sun in June. Now 20,000 years later the earth is closest to the sun in January, which makes summers colder now then they were 20,000 years ago.
The current interglacial is known as the Holocene and it began ~10,000 years ago, not 20,000.

 We both agree and multi papers state something else besides solar insolation is abruptly forcing the planet's climate. When you look at the peculiar saw shaped glacial/interglacial cycle there is obviously some massive forcing function at work. Suddenly in the middle the current warming "Holocene interglacial" 12,900 years ago, the planet abruptly returns to glacial cold for a 1000 years. (The abrupt cooling period is called the Younger Dryas cooling period named after an alpine flower that suddenly appears in the fossil record in mid latitudes in Europe.) My point is the Younger Dryas abrupt cooling event is one of a series of abrupt cooling events in the paleoclimatic record. There are cosmogenic isotope changes that are concurrent with the abrupt cooling events. Cosmogenic isotope changes are caused by interruptions in the solar magnetic cycle and geomagnetic field changes which then causes a massive increase in GCR.
The Younger-Dryas preceded the Holocene. One theory is that a comet struck the Laurentide ice sheet and caused the abrupt cooling, but the more likely cause was a Dansgaard/Oeschger event. Here are two recent papers that synchronize the Antarctic and Greenland ice cores.

Do you have a link showing the cosmogenic isotope proxies that coincide with the 100,000 year glaciations?

It is my understanding that they isotope proxies reveal a 2500 year cycle.

How does the GCR theory explain the tropical Earth and snowball Earth events?

How do you explain the anti-correlation with low clouds and medium altitude clouds?

 Here is a comparison of the Delta 18O ice core records. The Y-D event was not globally synchronous.

 Quote by Skyhunter Here is a comparison of the Delta 18O ice core records. The Y-D event was not globally synchronous.
Skyhunter if you look at this graph there is abrupt interglacial warming that began 15,000 years ago, not 10,000 years ago. The start of the warming is the start of the interglacial. Your comment is correct, the Holocene period is defined as the warming that occurs after the Younger Dryas event. Interglacial periods are typically 15,000 years long.

The Younger Dyras cooling affected the tropics in addition to the Northern Hemisphere. I believe there was cooling in the Southern Hemisphere however not a 1000 year cooling period as occurred in the Northern Hemisphere.

What is key (to explain in terms of mechanism) about the Younger Dryas event is the rapidity and magnitude of cooling event. Also note the North Hemisphere was cold for a 1000 years. Impacts to the planet or volcanic eruptions cool the planet for a few years. Those how appeal to impacts and volcanic eruptions cannot explain the duration of the cooling event. Insolation at 65N is at maximum during the Younger Dryas cooling event, the oceans will retain there heat and will not cool based on increased cloud cover for a couple of years.

Thinking in terms of mechanism what is required is a mechanism that can abrupt cool one hemisphere and regions in a hemisphere more than others in addition to a mechanism that can cool the entire planet.

The were other cooling events, as per my comments in links, that concurrently effected both hemispheres. Including the long term cooling glacial cycle for the last two glacial cycles.

The problem of course with the finding of long term glacial cooling occurring in both hemispheres at the same time is insolation can only cool one hemisphere based on insolation at 65 degree latitude. The other hemisphere is 180 degrees out of phase and will be receiving maximum insolation in the summer. If both hemispheres abruptly cool something else is forcing the planet's climate.

Everyone that is interested in Milankovitch's theory look closely at this link that shows how the planet's temperature has changed vs insolation for the last 800,000 years.

Look closely at this comparison of insolation at 65N Vs planetary temperature. Skyhunter, how do explain the planet becoming colder and colder over 100,000 years and then 15,000 years ago abruptly warming? Also if you look at insolation at 65N compared to past glacial/interglacial cycles, there is a lack of proportional change. Insolation is has become less and less in the last 15,000 years.

This also is interesting. Using ocean floor sediments this graph shows how planetary temperature has changed over the last 5 million years. You can see the evidence of the abrupt forcing function in the plot. What is confusing the researchers is they initially selected the incorrect mechanism.

As Jasper Kirkby notes in his review paper, the geomagnetic field intensity now peaks during the interglacial and is stronger in intensity than during normal periods. There is also a cycle of 41 kyrs in the geomagnetic field.

 Quote by Skyhunter What part of: Do you have a link showing the cosmogenic isotope proxies that coincide with the 100,000 year glaciations?
This is the paper that shows there is 100,000 period for geomagnetic field intensity changes. (The geomagnetic field intensity is 5 to 6 times greater during the interglacial period. For the last 40 kyr lava flows can be used to determine geomagnetic field intensity quite precisely. All accept that the geomagnetic field intensity has increased 5 to 6 times from the cold glacial period to the warm interglacial period. Jasper Kirkby discusses the correlation of geomagnetic field intensity with planetary climate.) The GCR is modulate by the geomagnetic intensity in terms of the intensity of the GCR that strikes the planet and the latitudes the GCR can reach.

The 100kyr magnetic cycle paper's hypothesized mechanism for what is modulating the geomagnetic field intensity is not correct. The eccentricity of the planet's orbit changes how the periodic solar event affects the planet. The effect is greater when the orbital eccentricity is greater. The effect is also greater when the orbital tilt is greater. Based on the timing of abrupt cooling event the solar event occurs with periodicity of roughly 8000 to 12,000 years.

So if you have a solar event that is semi periodic and its effect on the geomagnetic field depends on the planetary orbital changes (tilt, timing of aphelion, and orbital eccentricity) and also on the amount of the planet's surface that is covered with ice sheets, a person is not going to understand what is happening (the observations) without a correct strawman mechanism. Picking an incorrect mechanism will force other assumptions to be incorrect in an attempt to try to match the paleo record. (Look at the paleo record of temperatures for the last 5 million years.)

http://www.geo.uu.nl/~forth/people/H.../Hiro2002a.pdf

 Orbital Influence on Earth’s Magnetic Field: 100,000-Year Periodicity in Inclination A continuous record of the inclination and intensity of Earth’s magnetic field, during the past 2.25 million years, was obtained from a marine sediment core of 42 meters in length. This record reveals the presence of 100,000-year periodicity in inclination and intensity, which suggests that the magnetic field is modulated by orbital eccentricity. The correlation between inclination and intensity shifted from antiphase to in-phase, corresponding to a magnetic polarity change from reversed to normal. To explain the observation, we propose a model in which the strength of the geocentric axial dipole field varies with 100,000-year periodicity, whereas persistent nondipole components do not.

 Thanks I will try and read it today.
 I could find no validation for the intensity of the magnetic field intensity being 5-6 times stronger than during the last glaciation. In fact what I read offered evidence that overall it remains fairly constant over time, weakening during reversals. http://www.terrapub.co.jp/e-library/ecp/pdf/EC0075.PDF