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Milankovitch cycles
#1
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EXCERPT:

Milankovitch theory describes the collective effects of changes in the Earth's movements upon its climate, named after Serbian civil engineer and mathematician Milutin Milanković, who worked on it during First World War internment. Milanković mathematically theorized that variations in eccentricity, axial tilt, and precession of the Earth's orbit determined climatic patterns on Earth through orbital forcing.

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. The combined effect of the two precessions leads to a 21,000-year period between the seasons and the orbit. In addition, 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.

Other astronomical 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)[1] did the theory attain its present state.

LINK
It is our attitude toward free thought and free expression that will determine our fate. There must be no limit on the range of temperate discussion, no limits on thought. No subject must be taboo. No censor must preside at our assemblies.

–William O. Douglas, U.S. Supreme Court Justice, 1952
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#2
Thanks tommy, I'll read that later. What I want to know is where are we in the current Milankovitch states and what does this say about the onset of the next ice-age. It is a question of when, not if, and we REALLY need to know the when.
Is this study the right one? :- "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."[18]"

Or this one?? :-

More recent work by Berger and Loutre suggests that the current warm climate may last another 50,000 years.[19
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#3
One logic I've never seen addressed by warmers:

They keep saying that increasing CO2 will cause a runaway greenhousing effect, by what ever mechanism they are pushing this week. But we are at historic lows for CO2. We had iceages even with considerably more CO2 in the atmosphere. If slightly more CO2 causes an unstoppable effect then what stopped it when CO2 was greater?
“We do not believe any group of men adequate enough or wise enough to operate without scrutiny or without criticism. We know that the only way to avoid error is to detect it, that the only way to detect it is to be free to inquire. We know that in secrecy error undetected will flourish and subvert”.J Robert Oppenheimer.
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#4
The alleged "runaway" mechanism is that warming by CO2 will cause more evaporation of water and cause the oceans to release more CO2 which evaporates more water vapour etc, thus causing warming in a runaway feedback cycle.

This is plainly nonsense as it would imply that the earth's climate system is inherently unstable, tending towards runaway at any cause of increased temperature. If this were the case then just increasing the earth's temp, by an El Nino or solar activity would be enough to trigger a runaway warming. As this has never happened, despite past climates being up to 7 or 8 degrees C warmer than at present then we can discount this theory as fantasy.
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#5
(07-30-2011, 09:17 AM)Climate Realist Wrote: Thanks tommy, I'll read that later. What I want to know is where are we in the current Milankovitch states and what does this say about the onset of the next ice-age. It is a question of when, not if, and we REALLY need to know the when.
Is this study the right one? :- "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."[18]"

Or this one?? :-

More recent work by Berger and Loutre suggests that the current warm climate may last another 50,000 years.[19

I favor the Imbrie paper.Because it is undeniable that the world have been in an over all cooling trend for at least 5,000 years.

LINK

The warmest climate time was near the beginning of this current and decaying interglacial period.
It is our attitude toward free thought and free expression that will determine our fate. There must be no limit on the range of temperate discussion, no limits on thought. No subject must be taboo. No censor must preside at our assemblies.

–William O. Douglas, U.S. Supreme Court Justice, 1952
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#6
(07-30-2011, 10:15 AM)Scpg02. Wrote: One logic I've never seen addressed by warmers:

They keep saying that increasing CO2 will cause a runaway greenhousing effect, by what ever mechanism they are pushing this week. But we are at historic lows for CO2. We had iceages even with considerably more CO2 in the atmosphere. If slightly more CO2 causes an unstoppable effect then what stopped it when CO2 was greater?

They are not rational beings.Therefore they will fail to see the absurdity of their claim of a run away warming trend.
It is our attitude toward free thought and free expression that will determine our fate. There must be no limit on the range of temperate discussion, no limits on thought. No subject must be taboo. No censor must preside at our assemblies.

–William O. Douglas, U.S. Supreme Court Justice, 1952
Reply
#7
(07-30-2011, 10:15 AM)Scpg02. Wrote: One logic I've never seen addressed by warmers:

They keep saying that increasing CO2 will cause a runaway greenhousing effect, by what ever mechanism they are pushing this week. But we are at historic lows for CO2. We had iceages even with considerably more CO2 in the atmosphere. If slightly more CO2 causes an unstoppable effect then what stopped it when CO2 was greater?

From what I have been learning about this topic.CO2 is a nobody against the power of the Insolation changes in an interglacial age and also the glacial age.

It does not matter whether CO2 levels are 300 or 3,000 ppm.It contributes so little additional w/m2 to the total w/m2 to matter.

We are midway into Climate Autumn.There is nothing to stop it from going into the next glacial period.

It is our attitude toward free thought and free expression that will determine our fate. There must be no limit on the range of temperate discussion, no limits on thought. No subject must be taboo. No censor must preside at our assemblies.

–William O. Douglas, U.S. Supreme Court Justice, 1952
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