[ancient_geezer]

FOR most of the Earth's history, the planet has been either very cold, by our standards, or very hot. Fifty million years ago there was no ice on the poles and crocodiles lived in Wyoming. Eighteen thousand years ago there was ice two miles thick in Scotland and, because of the size of the ice sheets, the sea level was 130m lower. Ice-core studies show that in some places dramatic changes happened remarkably swiftly: temperatures rose by as much as 20°C in a decade. Then, 10,000 years ago, the wild fluctuations stopped, and the climate settled down to the balmy, stable state that the world has enjoyed since then. At about that time, perhaps coincidentally, perhaps not, mankind started to progress.

I rather doubt that, unless of course you figure the earth is no longer in the same orbit it entered and has sustained for the last three million years.

 

 

Ice Ages & Astronomical Causes
Brief Introduction to the History of Climate
by Richard A. Muller

Origin of the 100 kyr Glacial Cycle

Figure 1-1 Global warming

Figure 1-2 Climate of the last 2400 years

 

Figure 1-3 Climate of the last 12,000 years

Figure 1-4 Climate of the last 100,000 years

Figure 1-5 Climate for the last 420 kyr, from Vostok ice

 

 

In Figure 1-6, the 10 kyr years of agriculture and civilization appear as a sudden rise in temperature barely visible squeezed against the left hand axis of the plot. The temperature of 1950 is indicated by the horizontal line. As is evident from the data, civilization was created in an unusual time.

There are several important features to notice in these data, all of which will be discussed further in the remainder of the book. For the last million years or so (the left most third of the plot) the oscillations have had a cycle of about 100 kyr (thousand years). That is, the enduring period of ice is broken, roughly every 100 kyr, by a brief interglacial. During this time, the terminations of the ice ages appear to be particularly abrupt, as you can see from the sudden jumps that took place near 0, 120, 320, 450, and 650 thousand years ago. This has led scientists to characterize the data as shaped like a "sawtooth," although the pattern is not perfectly regular.

Figure 1-6 Climate of the last 3 million years

But as we look back beyond a 1000 kyr (1 million years), the character changes completely. The cycle is much shorter (it averages 41 kyr), the amplitude is reduced, the average value is higher (indicating that the ice ages were not as intense) and there is no evidence for the sawtooth shape. These are the features that ice age theories endeavor to explain. Why did the transition take place? What are the meanings of the frequencies? (We will show that they are well-known astronomical frequencies.) In the period immediately preceding the data shown here, older than 3 million years, the temperature didn’t drop below the 1950 value, and we believe that large glaciers didn’t form – perhaps only small ones, such as we have today in Greenland and Antarctica.

 

Spectrum of 100-kyr glacial cycle: Orbital inclination, not eccentricity
Richard A. Muller^* and Gordon J. MacDonald

Origin of the 100 kyr Glacial Cycle
by Richard A. Muller

Figure 2. Spectral fingerprints in the vicinity of the 100 kyr peak: (a) for data from Site 607; (b) for data of the SPECMAP stack; (c) for a model with linear response to eccentricity, calculated from the results of Quinn et al. (ref 6); (d) for the nonlinear ice-sheet model of Imbrie and Imbrie (ref 22); and (e) for a model with linear response to the inclination of the Earth's orbit (measured with respect to the invariable plane). All calculations are for the period 0-600 ka. The 100 kyr peak in the data in (a) and (b) do not fit the fingerprints from the theories (c) and (d), but are a good match to the prediction from inclination in (e). return to beginning


Far more important to our present analysis, however, is the fact that the predicted 100 kyr "eccentricity line" is actually split into 95 and 125 kyr components, in serious conflict with the single narrow line seen in the climate data. The splitting of this peak into a doublet is well known theoretically (see, e.g., ref 5), but in comparisons with data the two peaks in the eccentricity were merged into a single broad peak by the poor resolution of the Blackman-Tukey algorithm (as was done, for example, in ref 8). The single narrow peak in the climate data was likewise broadened, and it appeared to match the broad eccentricity feature.

***

Figure 3. Variations of the inclination vector of the Earth's orbit. The inclination i is the angle between this vector and the vector of the reference frame; Omega is the azimuthal angle = the angle of the ascending node (in astronomical jargon).. In (A), (B), and (C) the measurements are made with respect to the zodiacal (or ecliptic) frame, i.e. the frame of the current orbit of the Earth. In (D), (E), and (F) the motion has been trasformed to the invariable frame, i.e. the frame of the total angular momentum of the solar system. Note that the primary period of oscillation in the zodiacal frame (A) is 70 kyr, but in the invariable plane (D) it is 100 kyr.

 

 

There is evidence from the Infrared Astronomical Satellite (ref 39) of a narrow dust band extending only two degrees from the invariable plane. The precise location of these bands is uncertain; they may be orbiting in resonant lock with the Earth (ref 40, 41). It is not clear that these bands contain sufficient material to cause the observed climate effects. We note, however, that even small levels of accretion can scavenge greenhouse gases from the stratosphere, and cool the Earth's climate through the mechanism proposed by Hoyle (ref 30). The dust could also affect climate by seeding the formation of much larger ice crystals. The accreting material could be meteoric, originating as particles too large to give detectable infrared radiation.

Data on noctilucent clouds (mesospheric clouds strongly associated with the effects of high meteors and high altitude dust) supports the hypothesis that accretion increase significantly when the Earth passes through the invariable plane. As shown in Figure 6, a strong peak in the number of observed noctilucent clouds occurs on about July 9 in the northern hemisphere (ref 41, 42) within about a day of the date when the Earth passes through the invariable plane (indicated with an arrow). In the southern hemisphere the peak is approximately on January 9, also consistent with the invariable plane passage, but the data are sparse. The coincidence of the peaks of the clouds with the passage through the invariable plane had not previously been noticed, and it supports the contention that there is a peak in accretion at these times. On about the same date there is a similarly narrow peak is observed in the number of polar mesospheric clouds (ref43) and there is a broad peak in total meteoric flux (ref 44). It is therefore possible that it is the trail of meteors in the upper atmosphere, rather than dust, that is responsible for the climate effects.


Fig 6. Frequency of noctilucent clouds vs. day of year, in (A) the northern hemisphere, and in (B) the sourthern hemisphere (ref 41, 42). The arrows indicate the dates when the earth passes through the invariable plane. The coincidence of these dates with the maxima in the noctilucent clouds suggests the presence of a thin ring around the sun. Peaks on the same dates are seen in Polar mesospheric clouds (ref 44) and in radar counts of meteors.

 

 

http://newton.ex.ac.uk/aip/physnews.252.html#1

INTERPLANETARY DUST PARTICLES (IDPs) are deposited on the Earth at the rate of about 10,000 tons per year. Does this have any effect on climate? Scientists at Caltech have found that ancient samples of helium-3 (coming mostly from IDPs) in oceanic sediments exhibit a 100,000-year periodicity. The researchers assert that their data, taken along the Mid-Atlantic Ridge, support a recently enunciated idea that Earth's orbital inclination varies with a 100-kyr period; this notion in turn had been broached as an explanation for a similar periodicity in the succession of ice ages. (K.A. Farley and D.B. Patterson, Nature, 7 December 1995.)
Farley & Patterson 1998, http://www.elsevier.com/gej-ng/10/20/36/33/37/32/abstract.html
Farley http://www.gps.caltech.edu/~farley/
Farley http://www.elsevier.nl/gej-ng/10/18/23/54/21/49/abstract.html

 

http://www.publicaffairs.noaa.gov/pr96/dec96/noaa96-78.html

ABRUPT CLIMATE CHANGE DURING LAST GLACIAL PERIOD COULD BE TIED TO DUST-INDUCED REGIONAL WARMING

Preliminary new evidence suggests that periodic increases in atmospheric dust concentrations during the glacial periods of the last 100,000 years may have resulted in significant regional warming, and that this warming may have triggered the abrupt climatic changes observed in paleoclimate records, according to a scientist at the Commerce Department's National Oceanic and Atmospheric Administration. Current scientific thinking is that the dust concentrations contributed to global cooling.

 

 

http://www.newscientistspace.com/article/dn9228-mysterious-glowing-clouds-targeted-by-nasa.html

Mysterious glowing clouds targeted by NASA
26 May, 2006

High-altitude noctilucent clouds have been mysteriously spreading around the world in recent years (Image: NASA/JSC/ES and IA)

[Revolutionary]

Excellent information! Even I learned something. The real question is: Since the world gets hotter and colder all the time, what is the most desirable temperature? A little hotter? A little colder? My wife wants it a little hotter! For those that want it a little colder, a satellite at L-1 would do the trick. The climate is very sensitive to the intensity of the sun. Currently, I ascribe to the theory that methane has moderated the wild swings in temperature. So actually, man has made the climate better for man. If the world started getting colder in the future, how could we keep my wife happy and turn up the temperature? Good question! Nope, increasing CO2 wouldn't do it. Increasing the reflectivity of the moon might be an interesting though experiment.

Next time that you meet a rabid "the ice caps are melting" liberal, make a little money. Put ice and water in a glass and fill it right up to the brim. This is your very own North Pole ice cap. Bet them that when the ice melts, it will not overflow. (Unconfined ice displaces the exact amount of water as it would if it was liquid.)

[brityank]

Bookmark Bump.

Good info; thanks.