The Eemian Period

[ilmor]

A recent article in Polar Biology pointed out that 125,000 years ago the earth experienced severe global warming. The oceans were 12 - 18 ft above current levels, trees were growing north of the artic circle, and polar bears were surviving fine, thank you very much.

 

It will be kind of hard for Al gore and his disciples to blame man for that one!!!

 

Here is some additional info:

 

 

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

 

http://www.amnh.org/science/papers/polar_bears.php

[MiniMe]

Scientist have no solid proof that this earth is more than 8,000 years old.

 

 

Al Gore still doesn't have a clue.

 

 

 

.

[Guest markham51]

A recent article in Polar Biology pointed out that 125,000 years ago the earth experienced severe global warming. The oceans were 12 - 18 ft above current levels, trees were growing north of the artic circle, and polar bears were surviving fine, thank you very much.

 

It will be kind of hard for Al gore and his disciples to blame man for that one!!!

 

Here is some additional info:

 

 

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

 

http://www.amnh.org/science/papers/polar_bears.php

 

 

So the Earth has been warm before? We knew that. What does this have to do with our current situation?

[ilmor]

So the Earth has been warm before? We knew that. What does this have to do with our current situation?

 

Everything!

[stump_breaker]

A recent article in Polar Biology pointed out that 125,000 years ago the earth experienced severe global warming.

 

Even though I think current dating methods are severely flawed, to admit that warming is cyclic would be very much an inconvenient truth!

[2007GT]

So the Earth has been warm before? We knew that. What does this have to do with our current situation?

 

There is no "situation". The only evidence that the earth is warming is from old, improperly placed and positioned, ground based thermometers that are mostly in the cities. The cities are "hot zones". One of the thermometers is actually sitting next to an AC condensing unit and regularly measures well over 100 degrees. One of the thermometers is in a parking lot and has actually been paved around. The asphalt sends this thermometer off the charts. Approximately 32 thermometers that were in the countryside where it is cooler, were recently taken off-line, further skewing the temperature averages. Measurements taken with satellites show the earths temperature is the same as it was in 1980. This whole thing is a hoax. That is why they have stopped calling it "Global Warming" and now call it "Climate Change" instead. Gore just spent about 600 million dollars to have "Global Warming" "re-branded" as "Climate change". Why would he do that? Because he is a "Global Warming" pitchman. Gore needs this crisis or his carbon credit company will not make him any money. Dr. Larsen who is Gores chief science guy and the "father" of global warming has had to revise his reports and papers numerous times after other competent scientists pointed out erroneous numbers and fundamental errors in his conclusions. Get the DVD "Global Warming or Global Governance". It is full of competent, credentialed scientists and climatologists who have easily debunked the whole "Global Warming" hoax. It's not even a matter of opinion. The "Global Warming" believers are basing their theory on non-existent data, ginned up data and things that a fourth grade science student could easily refute. The DVD also has prominent people in the political sphere who point out how much the UN and others have to gain both in power and money by pushing this hoax forward and all the laws and regulations and taxes that will go along with it. Al Gore himself stands to make BILLIONS as he owns a carbon credit company.

[David Hawkins]

So the Earth has been warm before? We knew that. What does this have to do with our current situation?

 

This is not the first time for Global Warming......... It is just the First Time it is called Global Warming. It will most likely repeat it self many many many many many Years from now to. It is like a Season, just on a Larger Scale. Just wait for the next "ICE AGE"...........

[DDT]

Living in So. Cal. and I like "Global Warming".................. :D

[69dejavue]

So the Earth has been warm before? We knew that. What does this have to do with our current situation?

 

It shows that the temperature of the earth fluctuates in a cyclic manner. It shows there has been global warming long before auto exhaust and factory emissions, etc. It also shows the earth adapts to changes in temperatures as it has not ended in over 500 billion years. It also tells us that Gore, and the other liberals have an agenda and they are willing to lie to advance their agenda.

[gtss]

While i recognize that blatant toxic polution of the earth is a bad thing, so many of these enviromental movements are based on "theory" and then blown out of proportion. You are correct warming, and cooling for that matter, are cyclic. The whole in the ozone cycles and has been there for as long as science can track it. Ironically it was larger before the industrial revolution...hmmm

depending of course on who you listen too, and what day it is (haha)

 

What happens if we stop global warming so the earth does not reach its peak temperature, and then it cools again, does that mean that the next ice age will be far more severe and all life forms will cease to exist.

 

P.S. I live in Canada, and welcome global warming because I could then drive my Shelby more

gtss

[JeffIsHereToo]

Interesting you talk about the Eemian period but I'm not aware of any changes in the earths orbital parameters that may be the cause of the climate changes we see today and that are predicted. Did I miss that news flash?

[69dejavue]

Interesting you talk about the Eemian period but I'm not aware of any changes in the earths orbital parameters that may be the cause of the climate changes we see today and that are predicted. Did I miss that news flash?

 

Jeff, NEWS FLASH; the eccentric orbit of the earth has contributed to the earth's temperature forever. The orbit of the earth is not perfectly round but rather eccentric. When the earth is closer to the sun the temperature increases.

[JeffIsHereToo]

Jeff, NEWS FLASH; the eccentric orbit of the earth has contributed to the earth's temperature forever. The orbit of the earth is not perfectly round but rather eccentric. When the earth is closer to the sun the temperature increases.

 

 

I think you should read this Scientific American article:

 

http://www.sciam.com/article.cfm?id=earths...mate-changes-in

 

"Earth's orbit oscillates between an elliptical and circular path on a roughly 400,000-year cycle--the researchers found that patterns of glaciation and ice retreat followed the eccentricity of our planet's orbit"

 

The point being you are citing a period 125,000 years ago during that transitional period and claiming that the changes we've seen in the last 100 years are somehow related. I will just say again that the earth's orbit has not change so much in the last 100 years to account for what you're claiming it does.

 

BTW: Didn't you watch the last episode of Battlestar Galactica? It really wasn't so bad back then! :happy feet:

[69dejavue]

Jeff, you are correct that the orbit has not changed that much over the last 100 years. However, you fail to understand the totality of many issues that contribute to climate change. It is not just the eccentricity of the earth's orbit. There are changes in ocean currents, volcanoes, under sea volcanoes, changes in the continents (tectonic plates movement). All of which contribute to climate change.

 

Remember that approximately 500 years ago England had a climate similar to Italy. Warm enough to grow fine grapes for wine. There was no auto emissions or smoke stacks.

 

Yes I am sure that CO2 production is also a factor. As are sun spots, CCF.s etc.

[JeffIsHereToo]

Jeff, you are correct that the orbit has not changed that much over the last 100 years. However, you fail to understand the totality of many issues that contribute to climate change. It is not just the eccentricity of the earth's orbit. There are changes in ocean currents, volcanoes, under sea volcanoes, changes in the continents (tectonic plates movement). All of which contribute to climate change.

 

Remember that approximately 500 years ago England had a climate similar to Italy. Warm enough to grow fine grapes for wine. There was no auto emissions or smoke stacks.

 

Yes I am sure that CO2 production is also a factor. As are sun spots, CCF.s etc.

 

Then we agree! I know I don't know what is real science, truth, or conjecture, at least I think I'm smart enough to know what I don't know!

 

I agree that what ever it is that people think they see as far as climate change I suspect is probably related to a whole host of things; some natural, some man made, some animal and vegetation even! Regardless, I do believe we should be working to understand better how all of these contribute to what we're seeing, and if required, make any adjustments to our side of the equation we think needed.

 

I'm pretty sure changing the earth's orbit is out of the question.

[69dejavue]

News Flash, the earth's orbit is eccentric and it also effects the axis of the planet. The earth is supposed to continue to warm for another 50,000 years. Give or take a couple of months.

 

 

 

Milankovitch cycles

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Milankovitch Theory are the collective effect of changes in the Earth's movements upon its climate, named after Serbian civil engineer and mathematician Milutin Milanković. The eccentricity, axial tilt, and precession of the Earth's orbit vary in several patterns, resulting in 100,000-year ice age cycles of the Quaternary glaciation over the last few million years. The Earth's axis completes one full cycle of precession approximately every 26,000 years. At the same time, the elliptical orbit rotates, more slowly, leading to a 21,000-year cycle between the seasons and the orbit. In addition, the angle between Earth's rotational axis and the normal to the plane of its orbit moves from 22.1 degrees to 24.5 degrees and back again on a 41,000-year cycle. Currently, this angle is 23.44 degrees and is decreasing.

 

The Milankovitch theory of climate change is not perfectly worked out; in particular, the largest observed response is at the 100,000-year timescale, but the forcing is apparently small at this scale, in regard to the ice ages.[1] Various feedbacks (from carbon dioxide, or from ice sheet dynamics) are invoked to explain this discrepancy.

 

Milankovitch-like theories were advanced by Joseph Adhemar, James Croll and others, but verification was difficult due to the absence of reliably dated evidence and doubts as to exactly which periods were important. Not until the advent of deep-ocean cores and a seminal paper by Hays, Imbrie and Shackleton, "Variations in the Earth's Orbit: Pacemaker of the Ice Ages", in Science, 1976,[2] did the theory attain its present state.

 

Contents [hide]

1 Earth’s movements

1.1 Orbital shape (eccentricity)

1.2 Axial tilt (obliquity)

1.3 Precession (axial rotation)

1.4 Orbital inclination

2 Problems

2.1 100,000-year problem

2.2 400,000-year problem

2.3 Stage 5 problem

2.4 Effect exceeds cause

2.5 The unsplit peak problem

2.6 The transition problem

3 Present conditions

4 The future

5 See also

6 References

7 Further reading

8 External links

 

 

 

[edit] Earth’s movements

As the Earth spins around its axis and orbits around the Sun, several quasi-periodic variations occur. Although the curves have a large number of sinusoidal components, a few components are dominant. Milankovitch studied changes in the orbital eccentricity, obliquity, and precession (astronomy) of Earth's movements. Such changes in movement and orientation change the amount and location of solar radiation reaching the Earth. This is known as solar forcing (an example of radiative forcing). Changes near the north polar area are considered important due to the large amount of land, which reacts to such changes more quickly than the oceans do.

 

 

 

[edit] Orbital shape (eccentricity)

 

Circular orbit, no eccentricity.

Orbit with 0.5 eccentricity.The Earth's orbit is an ellipse. The eccentricity is a measure of the departure of this ellipse from circularity. The shape of the Earth's orbit varies from being nearly circular (low eccentricity of 0.005) to being mildly elliptical (high eccentricity of 0.058) and has a mean eccentricity of 0.028 (or 0.017 which is current value, if we take geometric mean, because phenomena in a gravitational field of Lobachevskian pseudosphere as used by Einstein behave logarithmically). The major component of these variations occurs on a period of 413,000 years (eccentricity variation of ±0.012). A number of other terms vary between 95,000 and 136,000 years, and loosely combine into a 100,000-year cycle (variation of −0.03 to +0.02). The present eccentricity is 0.017.

 

If the Earth were the only planet orbiting our Sun, the eccentricity of its orbit would not vary over time. The Earth's eccentricity varies primarily due to interactions with the gravitational fields of Jupiter and Saturn. As the eccentricity of the orbit evolves, the semi-major axis of the orbital ellipse remains unchanged. From the perspective of the perturbation theory used in celestial mechanics to compute the evolution of the orbit, the semi-major axis is an adiabatic invariant. According to Kepler's third law the period of the orbit is determined by the semi-major axis. It follows that the Earth's orbital period, the length of a sidereal year, also remains unchanged as the orbit evolves.

 

Currently the difference between closest approach to the Sun (perihelion) and furthest distance (aphelion) is only 3.4% (5.1 million km). This difference is equivalent to about a 6.8% change in incoming solar radiation. Perihelion presently occurs around January 3, while aphelion is around July 4. When the orbit is at its most elliptical, the amount of solar radiation at perihelion is about 23% greater than at aphelion. This difference is roughly 4 times the value of the eccentricity.

 

Season (Northern Hemisphere) Durations

data from United States Naval Observatory

Year Date: GMT Season Duration

2005 Winter Solstice 12/21/2005 18:35 88.99 days

2006 Spring Equinox 3/20/2006 18:26 92.75 days

2006 Summer Solstice 6/21/2006 12:26 93.65 days

2006 Autumn Equinox 9/23/2006 4:03 89.85 days

2006 Winter Solstice 12/22/2006 0:22 88.99 days

2007 Spring Equinox 3/21/2007 0:07 92.75 days

2007 Summer Solstice 6/21/2007 18:06 93.66 days

2007 Autumn Equinox 9/23/2007 9:51 89.85 days

2007 Winter Solstice 12/22/2007 06:08

 

 

Orbital mechanics require that the length of the seasons be proportional to the areas of the seasonal quadrants, so when the eccentricity is extreme, the seasons on the far side of the orbit can be substantially longer in duration. When autumn and winter occur at closest approach, as is the case currently in the northern hemisphere, the earth is moving at its maximum velocity and therefore autumn and winter are slightly shorter than spring and summer. Thus, summer in the northern hemisphere is 4.66 days longer than winter and spring is 2.9 days longer than autumn.

 

 

 

[edit] Axial tilt (obliquity)

Main article: Axial tilt

 

22.1-24.5° range of Earth's obliquity.The angle of the Earth's axial tilt (obliquity) varies with respect to the plane of the Earth's orbit. These slow 2.4° obliquity variations are roughly periodic, taking approximately 41,000 years to shift between a tilt of 22.1° and 24.5° and back again. When the obliquity increases, the amplitude of the seasonal cycle in insolation (INcident SOLar radiATION) increases, with summers in both hemispheres receiving more radiative flux from the Sun, and the winters less radiative flux. As a result, it is assumed that the winters become colder and summers warmer.

 

But these changes of opposite sign in the summer and winter are not of the same magnitude. The annual mean insolation increases in high latitudes with increasing obliquity, while lower latitudes experience a reduction in insolation. Cooler summers are suspected of encouraging the start of an ice age by melting less of the previous winter's ice and snow. So it can be argued that lower obliquity favors ice ages both because of the mean insolation reduction in high latitudes as well as the additional reduction in summer insolation.

 

Currently the Earth is tilted at 23.44 degrees from its orbital plane, roughly half way between its extreme values. The tilt is in the decreasing phase of its cycle, and will reach its minimum value around the year 10,000 AD.

 

 

 

 

 

[edit] Precession (axial rotation)

Main article: Precession (astronomy)

 

Precessional movement.Precession is the change in the direction of the Earth's axis of rotation relative to the fixed stars, with a period of roughly 26,000 years. This gyroscopic motion is due to the tidal forces exerted by the sun and the moon on the solid Earth, associated with the fact that the Earth is not a perfect sphere but has an equatorial bulge. The sun and moon contribute roughly equally to this effect. In addition, the orbital ellipse itself precesses in space (anomalistic precession), primarily as a result of interactions with Jupiter and Saturn. This orbital precession is in the opposite sense to the gyroscopic motion of the axis of rotation, shortening the period of the precession of the equinoxes with respect to the perihelion from 25,771.5 to ~21,636 years.

 

When the axis is aligned so it points toward the Sun during perihelion, one polar hemisphere will have a greater difference between the seasons while the other hemisphere will have milder seasons. The hemisphere which is in summer at perihelion will receive much of the corresponding increase in solar radiation, but that same hemisphere will be in winter at aphelion and have a colder winter. The other hemisphere will have a relatively warmer winter and cooler summer.

 

When the Earth's axis is aligned such that aphelion and perihelion occur near the equinoxes, the Northern and Southern Hemispheres will have similar contrasts in the seasons.

 

At present, perihelion occurs during the Southern Hemisphere's summer, and aphelion is reached during the southern winter. Thus the Southern Hemisphere seasons are somewhat more extreme than the Northern Hemisphere seasons, when other factors are equal.

 

 

[edit] Orbital inclination

The inclination of Earth's orbit drifts up and down relative to its present orbit with a cycle having a period of about 70,000 years. Milankovitch did not study this three-dimensional movement.

 

More recent researchers noted this drift and that the orbit also moves relative to the orbits of the other planets. The invariable plane, the plane that represents the angular momentum of the solar system, is approximately the orbital plane of Jupiter. The inclination of the Earth's orbit has a 100,000 year cycle relative to the invariable plane. This 100,000-year cycle closely matches the 100,000-year pattern of ice ages.

 

It has been proposed that a disk of dust and other debris is in the invariable plane, and this affects the Earth's climate through several possible means. The Earth presently moves through this plane around January 9 and July 9, when there is an increase in radar-detected meteors and meteor-related noctilucent clouds.[3][4]

 

A study of the chronology of Antarctic ice cores using oxygen to nitrogen ratios in air bubbles trapped in the ice, which appear to respond directly to the local insolation, concluded that the climatic response documented in the ice cores was driven by Northern Hemisphere insolation as proposed by the Milankovitch hypothesis (Kawamura et al, Nature, 23 August 2007, vol 448, p912-917). This is an additional validation of the Milankovitch hypothesis by a relatively novel method, and is inconsistent with the "inclination" theory of the 100,000-year cycle.

 

 

[edit] Problems

 

The nature of sediments can vary in a cyclic fashion, and these cycles can be displayed in the sedimentary record. Here, cycles can be observed in the colouration and resistance of different strataBecause the observed periodicities of climate fit so well with the orbital periods, the orbital theory has overwhelming support. Nonetheless, there are several difficulties in reconciling theory with observations.

 

 

[edit] 100,000-year problem

Main article: 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.[5] 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.[6][7]

 

 

[edit] 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.

 

 

[edit] 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.

 

 

[edit] 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).

 

 

[edit] 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, 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.

 

 

[edit] 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.

 

 

[edit] Present conditions

The amount of solar radiation (insolation) in the Northern Hemisphere at 65° N seems to be related to occurrence of an ice age. Astronomical calculations show that 65° N summer insolation should increase gradually over the next 25,000 years, and that no declines in 65° N summer insolation sufficient to cause an ice age are expected in the next 50,000 to 100,000 years.

 

As mentioned above, at present perihelion occurs during the Southern Hemisphere's summer, and aphelion during the southern winter. Thus the Southern Hemisphere seasons should tend to be somewhat more extreme than the Northern Hemisphere seasons. The relatively low eccentricity of the present orbit results in a 6.8% difference in the amount of solar radiation during summer in the two hemispheres.

 

 

[edit] The future

Since orbital variations are predictable[8], if one has a model that relates orbital variations to climate, it is possible to run such a model forward to "predict" future climate. Two caveats are necessary: that anthropogenic effects and that the mechanism by which orbital forcing influences climate is not well understood.

 

An often-cited 1980 study by Imbrie and 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 which began some 6,000 years ago will continue for the next 23,000 years."[9]

 

More recent work by Berger and Loutre suggests that the current warm climate may last another 50,000 years.[10]

[JeffIsHereToo]

My head hurts!

[69dejavue]

Facts often have that effect on liberals.

 

Sorry Jeff, couldn't resist! You left yourself open for that one.

[ingram4868]

So if the Earth is going to continue to warm for the next 50,000 years should I be using something better than Zaino?

[JeffIsHereToo]

My head hurts!

 

 

Touche!

 

No worries! This Republican Congressman, unfortunately from my state, thinks he has the answer!

 

http://forcechange.com/2009/04/04/congress...earth-will-end/

 

Ugh...