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How Global Warming Really Works

MoonShadowLady said:
there's no such thing as global warming, this planet has been changing for years (it will continue to do so through NO action on our part) and it's high time we stop naming this shit. :rolleyes:
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You know this how?


The antarctic ice core records mean nothing?

Mankind cannot and has never had any regional or even global effects?

I have to disagree.
 
TurdFergeson said:
You know this how?


The antarctic ice core records mean nothing?

Mankind cannot and has never had any regional or even global effects?

I have to disagree.
Click to expand...


[ written as he was flying over the Sahara ]

"It is remarkable to think that these treeless desert lands were, half a million years ago, humid tropical forest lands, with now-extinct primates and a rich diversity of plants and animals— a far cry from the impoverished biota that populates the interior of northwestern Africa today.

If the reader is wondering what happened to the rainforest, the unsurprising answer is... global climate change. It is not a new phenomenon: climate change is the rule, not the exception. And climate change was the rule long before humankind came to dominate our earth or to infuse our atmosphere with greenhouse gases. Climate change, extinction, and speciation have been acting in concert for many millenia. Past climate changes in the climate of northern Africa certainly caused local extinction pulses. These have been well documented by paleontologist Scott Wing, who has written of the Koobi Fora flora and fauna— a now vanished humid tropical world in northern Africa."

Bruce M. Beehler, Ph.D.
"Lost Worlds: Adventures In The Tropical Rainforest"
p. 201
Yale University Press
New Haven, 2008

( Dr. Beehler is vice-president of Conservation International, one of the world's leading authorities on Birds Of Paradise and was a co-leader of the 2006 expedition to the Foja Mountains of Papua that resulted in the discovery of a "Lost World" and several new species )
 
Even if global warming is a farce, or not as important as we are being told, what's wrong with conserving resources and breathing clean air? Carbon based fuels are so 19th century. Let's move on.

Disclaimer: I'm long on solar, wind and battery research companies.
 
A Layman’s Explanation of Why Global Warming Predictions by Climate Models are Wrong
by: Roy W. Spencer, Ph.D.

I occasionally hear the complaint that some of what I write is too technical to understand, which I’m sure is true. The climate system is complex, and discussing the scientific issues associated with global warming (aka “climate change”) can get pretty technical pretty fast.

Fortunately, the most serious problem the climate models have (in my view) is one which is easily understood by the public. So, I’m going to make yet another attempt at explaining why the computerized climate models tracked by the U.N.’s Intergovernmental Panel on Climate Change (IPCC) – all 23 of them – predict too much warming for our future. The basic problem I am talking about has been peer reviewed and published by us, and so cannot be dismissed lightly.

But this time I will use no graphs (!), and I will use only a single number (!!) which I promise will be a small one.

I will do this in three steps. First, I will use the example of a pot of water on the stove to demonstrate why the temperature of things (like the Earth) rises or falls.

Secondly, I will describe why so many climate model “experts” believe that adding CO2 to the atmosphere will cause the climate system to warm by a large, possibly catastrophic amount.

Finally, I will show how Mother Nature has fooled those climate experts into programming climate models to behave incorrectly.

Some of this material can be found scattered through other web pages of mine, but here I have tried to create a logical progression of the most important concepts, and minimized the technical details. It might be edited over time as questions arise and I find better ways of phrasing things.

The Earth’s Climate System Compared to a Pot of Water on the Stove
Before we discuss what can alter the global-average temperature, let’s start with the simple example of a pot of water placed on a stove. Imagine it’s a gas stove, and the flame is set on its lowest setting, so the water will become warm but will not boil. To begin with, the pot does not have a lid.

Obviously, the heat from the flame will warm the water and the pot, but after about 10 minutes the temperature will stop rising. The pot stops warming when it reaches a point of equilibrium where the rate of heat loss by the pot to its cooler surroundings equals the rate of heat gained from the stove. The pot warmed as long as an imbalance in those two flows of energy existed, but once the magnitude of heat loss from the hot pot reached the same magnitude as the heat gain from the stove, the temperature stopped changing.

Now let’s imagine we turn the flame up slightly. This will result in a temporary imbalance once again between the rate of energy gain and energy loss, which will then cause the pot to warm still further. As the pot warms, it loses energy even more rapidly to its surroundings. Finally, a new, higher temperature is reached where the rate of energy loss and energy gain are once again in balance.

But there’s another way to cause the pot to warm other than to add more heat: We can reduce its ability to cool. If next we place a lid on the pot, the pot will warm still more because the rate of heat loss is then reduced below the rate of heat gain from the stove. In this case, loosely speaking, the increased temperature of the pot is not because more heat is added, but because less heat is being allowed to escape.

Global Warming
The example of what causes a pot of water on a stove to warm is the same fundamental situation that exists with climate change in general, and global warming theory in particular. A change in the energy flows in or out of the climate system will, in general, cause a temperature change. The average temperature of the climate system (atmosphere, ocean, and land) will remain about the same only as long as the rate of energy gain from sunlight equals the rate of heat loss by infrared radiation to outer space...

Again, the average temperature of the Earth (like a pot of water on the stove) will only change when there is an imbalance between the rates of energy gained and energy lost.

What this means is that anything that can change the rates of energy flow illustrated above — in or out of the climate system — can cause global warming or global cooling.

In the case of manmade global warming, the extra carbon dioxide in the atmosphere is believed to be reducing the rate at which the Earth cools to outer space. This already occurs naturally through the so-called “greenhouse effect” of the atmosphere, a process in which water vapor, clouds, carbon dioxide and methane act as a ‘radiative blanket’, insulating the lower atmosphere and the surface, and raising the Earth’s average surface temperature by an average of 33 deg. C (close to 60 deg. F).

The Earth’s natural greenhouse effect is like the lid on our pot of water on the stove. The lid reduces the pot’s ability to cool and so makes the pot of water, on average, warmer than it would be without the lid. (I don’t think you will find the greenhouse effect described elsewhere in terms of an insulator — like a blanket — but I believe that is the most accurate analogy.) Similarly, the Earth’s natural greenhouse effect keeps the lower atmosphere and surface warmer than if there was no greenhouse effect. So, more CO2 in the atmosphere slightly enhances that effect.

And also like the pot of water, the other basic way to cause warming is to increase the rate of energy input — in the case of the Earth, sunlight. Note that this does not necessarily require an increase in the output of the sun. A change in any of the myriad processes that control the Earth’s average cloud cover can also do this. For instance, the IPCC talks about manmade particulate pollution (”aerosols”) causing a change in global cloudiness…but they never mention the possibility that the climate system can change its own cloud cover!

If the amount of cloud cover reflecting sunlight back to space decreases from, say, a change in oceanic and atmospheric circulation patterns, then more sunlight will be absorbed by the ocean. As a result, there will then be an imbalance between the infrared energy lost and solar energy gained by the Earth. The ocean will warm as a result of this imbalance, causing warmer and more humid air masses to form and flow over the continents, which would then cause the land to warm, too.

The $64 Trillion Question: By How Much Will the Earth Warm from More CO2?
Now for a magic number that we will be referring to later, which is how much more energy is lost to outer space as the Earth warms. It can be calculated theoretically that for every 1 deg C the Earth warms, it gives off an average of about 3.3 Watts per square meter more infrared energy to space. Just as you feel more infrared (heat) radiation coming from a hot stove than from a warm stove, the Earth gives off more infrared energy to space the warmer it gets.

This is part of the climate system’s natural cooling mechanism, and all climate scientists agree with this basic fact. What we don’t agree on is how the climate system responds to warming by either enhancing, or reducing, this natural cooling mechanism. The magic number — 3.3 Watts per sq. meter — represents how much extra energy the Earth loses if ONLY the temperature is increased, by 1 deg. C, and nothing else is changed. In the real world, however, we can expect that the rest of the climate system will NOT remain the same in response to a warming tendency.

Thus, the most important debate is global warming research today is the same as it was 20 years ago: How will clouds (and to a lesser extent other elements in the climate system) respond to warming, thereby enhancing or reducing the warming? These indirect changes that further influence temperature are called feedbacks, and they determine whether manmade global warming will be catastrophic, or just lost in the noise of natural climate variability.

Returning to our example of the whole Earth warming by 1 deg. C, if that warming causes an increase in cloud cover, then the 3.3 Watts of extra infrared loss to outer space gets augmented by a reduction in solar heating of the Earth by the sun. The result is a smaller temperature rise. This is called negative feedback...

If negative feedback exists in the real climate system, then manmade global warming will become, for most practical purposes, a non-issue.

But this is not how the IPCC thinks nature works. They believe that cloud cover of the Earth decreases with warming, which would let in more sunlight and cause the Earth to warm to an even higher temperature. (The same is true if the water vapor content of the atmosphere increases with warming, since water vapor is our main greenhouse gas.) This is called positive feedback, and all 23 climate models tracked by the IPCC now exhibit positive cloud and water vapor feedback.

In fact, the main difference between models that predict only moderate warming versus those that predict strong warming has been traced to the strength of their positive cloud feedbacks.

How Mother Nature Fooled the World’s Top Climate Scientists
Obviously, the question of how clouds in the REAL climate system respond to a warming tendency is of paramount importance, because that guides the development and testing of the climate models. Ultimately, the models must be based upon the observed behavior of the atmosphere.

So, what IS observed when the Earth warms? Do clouds increase or decrease? While the results vary with which years are analyzed, it has often been found that warmer years have less cloud cover, not more.

And this has led to the ’scientific consensus’ that cloud feedbacks in the real climate system are probably positive, although by an uncertain amount. And if cloud feedbacks end up being too strongly positive, then we are in big trouble from manmade global warming.

But at this point an important question needs to be asked that no one asks: When the climate system experiences a warm year, what caused the warming? By definition, cloud feedback can not occur unless the temperature changes…but what if that temperature change was caused by clouds in the first place?

This is important because if decreasing cloud cover caused warming, and this has been mistakenly interpreted as warming causing a decrease in cloud cover, then positive feedback will have been inferred even if the true feedback in the climate system is negative.

As far as I know, this potential mix-up between cause and effect — and the resulting positive bias in diagnosed feedbacks — had never been studied until we demonstrated it in a peer-reviewed paper in the Journal of Climate. Unfortunately, because climate research covers such a wide range of specialties, most climate experts are probably not even aware that our paper exists.

So how do we get around this cause-versus-effect problem when observing natural climate variations in our attempt to identify feedback? Our very latest research, now in peer review for possible publication in the Journal of Geophysical Research, shows that one can separate, at least partially, the effects of clouds-causing-temperature-change (which “looks like” positive feedback) versus temperature-causing-clouds to change (true feedback).

We analyzed 7.5 years of our latest and best NASA satellite data and discovered that, when the effect of clouds-causing-temperature-change is accounted for, cloud feedbacks in the real climate system are strongly negative. The negative feedback was so strong that it more than cancelled out the positive water vapor feedback we also found. It was also consistent with evidence of negative feedback we found in the tropics and published in 2007.

In fact, the resulting net negative feedback was so strong that, if it exists on the long time scales associated with global warming, it would result in only 0.6 deg. C of warming by late in this century.

Natural Cloud Variations: The Missing Piece of the Puzzle?
In this critical issue of cloud feedbacks – one which even the IPCC has admitted is their largest source of uncertainty — it is clear that the effect of natural cloud variations on temperature has been ignored. In simplest of terms, cause and effect have been mixed up. (Even the modelers will have to concede that clouds-causing-temperature change exists because we found clear evidence of it in every one of the IPCC climate models we studied.)

But this brings up another important question: What if global warming itself has been caused by a small, long-term, natural change in global cloud cover? Our observations of global cloud cover have not been long enough or accurate enough to document whether any such cloud changes have happened or not. Some indirect evidence that this has indeed happened is discussed here.

Even though they never say so, the IPCC has simply assumed that the average cloud cover of the Earth does not change, century after century. This is a totally arbitrary assumption, and given the chaotic variations that the ocean and atmosphere circulations are capable of, it is probably wrong. Little more than a 1% change in cloud cover up or down, and sustained over many decades, could cause events such as the Medieval Warm Period or the Little Ice Age.

As far as I know, the IPCC has never discussed their assumption that global average cloud cover always stays the same. The climate change issue is so complex that most experts have probably not even thought about it. But we meteorologists by training have a gut feeling that things like this do indeed happen. In my experience, a majority of meteorologists do not believe that mankind is mostly to blame for global warming. Meteorologists appreciate how complex cloud behavior is, and most tend to believe that climate change is largely natural.

Our research has taken this gut feeling and demonstrated with both satellite data and a simple climate model, in the language that climate modelers speak, how potentially serious this issue is for global warming theory.

And this cause-versus-effect issue is not limited to just clouds. For instance, there are processes that can cause the water vapor content of the atmosphere to change, mainly complex precipitation processes, which will then change global temperatures. Precipitation is what limits how much of our main greenhouse gas, water vapor, is allowed to accumulate in the atmosphere, thus preventing a runaway greenhouse effect. For instance, a small change in wind shear associated with a change in atmospheric circulation patterns, could slightly change the efficiency with which precipitation systems remove water vapor, leading to global warming or global cooling. This has long been known, but again, climate change research covers such a wide range of disciplines that very few of the experts have recognized the importance of obscure published studies like this one.

While there are a number of other potentially serious problems with climate model predictions, the mix-up between cause and effect when studying cloud behavior, by itself, has the potential to mostly deflate all predictions of substantial global warming. It is only a matter of time before others in the climate research community realize this, too.
 
this
is my model
it's based on theory
observation
and experiment

like all models
it's unsound and subject to change

nothing is sacrosanct
 
Atmospheric Temperature and Carbon Dioxide: Feedback or Equilibrium?
R. Taylor

For several years, the suggestion that there is positive feedback between atmospheric temperature (T) and carbon-dioxide concentration (CO2) has dominated the scientific literature, and has become a fundamental assumption of climate science. Alternatively, the relationship between T and CO2 might be one of equilibrium. We can test models of each type by comparison with the Vostok record, first published by Petit, et al. (1999). The Vostok record contains about 3,300 determinations of T and 280 determinations of CO2, spanning the last 420,000 years.

Figure 1 shows the Vostok record; for clarity, the dates and measurements of T have been averaged in groups of 10, and those after 0 BCE are not shown (cf. Figure 4).

http://wattsupwiththat.files.wordpress.com/2009/08/rtaylorfig11.png
Figure 1: Temperature and Carbon Dioxide Inferred from the Vostok Ice-core.

T ranges through about 13 °C in the record, and CO2 ranges through about 120 ppm. There are peaks and valleys of various amplitudes and durations, and changes in T precede corresponding changes in CO2 (Mudelsee, 2001). The resolution of the record improves as measurements become more recent.

The first quantitative model comparable to the Vostok record with feedback between T and CO2 seems to be that of Hogg (2008). Hogg simulated insolation and other factors over a given interval of 500,000 years to predict values of T and CO2. Figure 2 is rescaled from Hogg’s figure 2a, so T and CO2 have approximately equal amplitude.

http://wattsupwiththat.files.wordpress.com/2009/08/rtaylorfig2.png
Figure 2: Temperature and Carbon Dioxide from Hogg’s Feedback-Model.

Feedback systems typically have characteristic amplitude and period. For this model, 1.7 °C is the characteristic amplitude of T, and 100,000 years is about the characteristic period. Adjusting the parameters of the model will change its amplitude and period, but these will be characteristic for any given set of parameters: Other amplitudes and periods will be suppressed.

Since the model assumes that CO2 has a significant effect on T, changes in CO2 happen before corresponding changes in T through a substantial portion of its cycle, viz. the latter portion of the rises to the peaks (cf. Hogg) and through essentially all of the subsequent declines. As previously mentioned, however, the Vostok record shows that changes in CO2 happen after corresponding changes in T. This lag is shown most clearly by large-amplitude features in the more recent portion of the record: CO2 rises hundreds of years after T rises, and falls thousands of years after T falls.

The substantially inverted lag of this feedback model confirms what is self-evident in an equilibrium model: A lagging entity can have no significant effect on a leading entity. For example, CO2 at a given time cannot affect the level of T that existed hundreds-to-thousands of years earlier.

A model of equilibrium between T and CO2 can be based on balance between temperature dependent processes that (i) release CO2 into the atmosphere and (ii) absorb it into the surface of the earth. If the temperature dependency is simply linear, we can express our model as:

CO2(t+l) = mT(t) + b

where t is time, l is the length of time required for CO2 to regain equilibrium after a change in T, m is the number of units that CO2 changes for a unit change in T, and b is the constant offset between units of CO2 and units of T.

Using this equation, we can predict a value for CO2 at some time in the future from each value of T. If we give l a value of 50 years after a rise in temperature and 8000 years after a fall in temperature, m a value of 10 and b a value of 270, and average the times and predicted values of CO2 in groups of 10, we obtain the predicted values shown in figure 3. The figure also shows the measured values of CO2 for comparison.

http://wattsupwiththat.files.wordpress.com/2009/08/rtaylorfig3.png
Figure 3: Carbon Dioxide, Measured and Predicted by Lagged Temperature.

The output of the equilibrium model is consistent with the lag, spectrum and amplitudes of the record. The correspondence between predicted and measured values of CO2 indicates that CO2 is in temperature-dependent time-lagged equilibrium, and that the temperature dependence of CO2 is essentially linear through the Vostok range.

Let us turn our attention to the last 11,000 years, during which humans have disturbed the equilibrium between T and CO2. The most recent CO2 determination from the ice-core has a date of about 340 BCE. We can add an early-industrial-era value of 290 ppm at 1800 CE and a value of 365 ppm at 2000 CE to provide figure 4. The scaling in the figure is consistent with the
equilibrium model that fits the overall Vostok record, where a change of 1 °C in T causes a change of 10 ppm in CO2.

http://wattsupwiththat.files.wordpress.com/2009/08/rtaylorfig4.png
Figure 4: Temperature and Carbon Dioxide since 9,000 BCE.

T and CO2 appear to have been in equilibrium until about 3,000 BCE. Over the 5,000 years since then, CO2 has risen increasingly above its natural equilibrium. By 1,800 CE, CO2 had risen to a level comparable to the highest in the Vostok record. During this time, T declined at a rate of 0.1 °C per thousand years, indicating again that CO2 has no apparent effect on T. The trends of this 5,000-year interval of excess CO2 are consistent with the equilibrium model, in which T is independent of CO2.

The last 5,000 years are trivial compared to the 420,000 years of the Vostok record; of even less significance are the last 1,200 years. However, climate science has put great emphasis on the features of this interval, even though they fit within the noise-envelope. The “medieval warm period” spanned 800 CE to 1,200 CE; Vostok shows it wasn’t really warm, but wasn’t really cold either. The “little ice age” followed (although average T was barely lower), and ended after the low of -1.84 °C around 1,770 CE. By the early 1800s, T was higher than it is at present, and it has fluctuated within levels typical of the last 11,000 years since then. It is remarkable that climate hysteria should be based on noise-level changes in T over the last 200 years, which is an eye-blink in the Vostok record. It seems to be the superstition of our time.

In summary, the Vostok record indicates that CO2 is in lagged equilibrium with T and that, for the range of T in Vostok, the dependency of CO2 on T is essentially linear. Unnaturally high CO2 for the last 5,000 years has had no apparent effect on T. This empirical evidence supports a conclusion that there cannot be any significant feedback between CO2 and T. Such feedback would cause predicted T and CO2 to show fundamental disagreement with the lag, spectrum and amplitudes evident in the Vostok record.

It is impossible to say how enduring the feedback fallacy will be. However, any such model proposed in the future can be regarded as qualitative if it does not specify lag, characteristic amplitude and period, and as speculative if it cannot be compared to the Vostok record. Accordingly, any such model can be ignored.

If we may depart for a moment from objectivity, any such model should be ignored if its proponents declare that it shows polar bears are in peril, and you can save them by painting your roof white and burning nuts and corn in your car.

References
Hogg, A.M., 2008, Glacial cycles and carbon dioxide: A conceptual model. Geophysical Research Letters, 35, L01701 (5 pp.).

Mudelsee, M., 2001, The phase relations among atmospheric CO2 content, temperature and global ice volume over the past 420 ka. Quaternary Science Reviews, 20, 583-589. Petit, J.R., Jouzel, J., Raynaud, D., Barkov, N.I., Barnola, J.-M., Basile, I., Bender, M., Chappellaz, J., Davis, M., Delaygue, G., Delmotte, M., Kotlyakov, V.M., Legrand, M., Lipenkov, V.Y., Lorius, C., Pépin, L., Ritz, C., Saltzman, E. and Stievenard, M., 1999, Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica. Nature, 399, 429-436. http://www.ncdc.noaa.gov/paleo/icecore/antarctica/vostok/vostok_data.html provides on-line data.
 
climate change:

how much is down to Earth's axis wobble
how much is down to tectonic plate movement and accompanying creation of mountain ranges/new seas/swallowed and newly created landmasses

and how much is down to our way of living?

It's all relative, and all in the fields of speculation, but with so many people consuming so much fossil fuel - something relatively new to our climate - I believe it is negligent to waive any concerns about human impact on our surroundings. Even beavers building dams influence their environment.
 
chipbutty said:
climate change:

how much is down to Earth's axis wobble
how much is down to tectonic plate movement and accompanying creation of mountain ranges/new seas/swallowed and newly created landmasses

and how much is down to our way of living?

It's all relative, and all in the fields of speculation, but with so many people consuming so much fossil fuel - something relatively new to our climate - I believe it is negligent to waive any concerns about human impact on our surroundings. Even beavers building dams influence their environment.
Click to expand...

We created artificial radiation belts in the ionosphere that span the globe -

decades ago - and they still exist to this day.

The "Great Dust Bowl" in the US was created by improper farm land managament.

The Amazon rainforests are shrinking every year due to slash and burn activities on massive scales.

The Soviets have nearly drained the entire Aral Sea. In the US we have created the Salton Sea.

Desertification and deforestation are globally overtaking reforestation or greening at a rapid pace.

I strongly believe we have already begun to implement powerful climate change mitigation techniques.

To wit:

"It has been suggested that large-scale climate changes, mostly due to atmospheric injection of
"greenhouse gases" connected with fossil-fired energy production, should be forestalled by
internationally-agreed reductions in, e.g., electricity generation. The potential economic impacts of
such limitations are obviously large: ³$1011/year. We propose that for far smaller — <1% —
costs, the mean thermal effects of "greenhouse gases" may be obviated in any of several distinct
ways, some of them novel. These suggestions are all based on scatterers that prevent a small
fraction of solar radiation from reaching all or part of the Earth. We propose research directed to
quite near-term realization of one or more of these inexpensive approaches to cancel the effects of
the "greenhouse gas" injection.
While the magnitude of the climatic impact of "greenhouse gases" is currently uncertain, the
prospect of severe failure of the climate, for instance at the onset of the next Ice Age, is undeniable.
The proposals in this paper may lead to quite practical methods to reduce or eliminate all climate
failures."

http://www.osti.gov/accomplishments/documents/fullText/ACC0229.pdf
 
Last edited:
TurdFergeson said:
We created artificial radiation belts in the ionosphere that span the globe -

decades ago - and they still exist to this day...
Click to expand...

Right. Next.


CORVALLIS, Ore. – A team of researchers says it has largely put to rest a long debate on the underlying mechanism that has caused periodic ice ages on Earth for the past 2.5 million years – they are ultimately linked to slight shifts in solar radiation caused by predictable changes in Earth’s rotation and axis.

In a publication to be released Friday in the journal Science, researchers from Oregon State University and other institutions conclude that the known wobbles in Earth’s rotation caused global ice levels to reach their peak about 26,000 years ago, stabilize for 7,000 years and then begin melting 19,000 years ago, eventually bringing to an end the last ice age.

The melting was first caused by more solar radiation, not changes in carbon dioxide levels or ocean temperatures, as some scientists have suggested in recent years.
“Solar radiation was the trigger that started the ice melting, that’s now pretty certain,” said Peter Clark, a professor of geosciences at OSU. “There were also changes in atmospheric carbon dioxide levels and ocean circulation, but those happened later and amplified a process that had already begun.”

The findings are important, the scientists said, because they will give researchers a more precise understanding of how ice sheets melt in response to radiative forcing mechanisms. And even though the changes that occurred 19,000 years ago were due to increased solar radiation, that amount of heating can be translated into what is expected from current increases in greenhouse gas levels, and help scientists more accurately project how Earth’s existing ice sheets will react in the future.

“We now know with much more certainty how ancient ice sheets responded to solar radiation, and that will be very useful in better understanding what the future holds,” Clark said. “It’s good to get this pinned down.”

The researchers used an analysis of 6,000 dates and locations of ice sheets to define, with a high level of accuracy, when they started to melt. In doing this, they confirmed a theory that was first developed more than 50 years ago that pointed to small but definable changes in Earth’s rotation as the trigger for ice ages.

“We can calculate changes in the Earth’s axis and rotation that go back 50 million years,” Clark said. “These are caused primarily by the gravitational influences of the larger planets, such as Jupiter and Saturn, which pull and tug on the Earth in slightly different ways over periods of thousands of years.”

That, in turn, can change the Earth’s axis – the way it tilts towards the sun – about two degrees over long periods of time, which changes the way sunlight strikes the planet. And those small shifts in solar radiation were all it took to cause multiple ice ages during about the past 2.5 million years on Earth, which reach their extremes every 100,000 years or so.

Sometime around now, scientists say, the Earth should be changing from a long interglacial period that has lasted the past 10,000 years and shifting back towards conditions that will ultimately lead to another ice age – unless some other forces stop or slow it. But these are processes that literally move with glacial slowness, and due to greenhouse gas emissions the Earth has already warmed as much in about the past 200 years as it ordinarily might in several thousand years, Clark said.

“One of the biggest concerns right now is how the Greenland and Antarctic ice sheets will respond to global warming and contribute to sea level rise,” Clark said. “This study will help us better understand that process, and improve the validity of our models.”

The research was done in collaboration with scientists from the Geological Survey of Canada, University of Wisconsin, Stockholm University, Harvard University, the U.S. Geological Survey and University of Ulster. It was supported by the National Science Foundation and other agencies.

Science 7 August 2009:
Vol. 325. no. 5941, pp. 710 – 714
DOI: 10.1126/science.1172873

The Last Glacial Maximum

Peter U. Clark,1,* Arthur S. Dyke,2 Jeremy D. Shakun,1 Anders E. Carlson,3 Jorie Clark,1 Barbara Wohlfarth,4 Jerry X. Mitrovica,5 Steven W. Hostetler,6 A. Marshall McCabe7

We used 5704 14C, 10Be, and 3He ages that span the interval from 10,000 to 50,000 years ago (10 to 50 ka) to constrain the timing of the Last Glacial Maximum (LGM) in terms of global ice-sheet and mountain-glacier extent. Growth of the ice sheets to their maximum positions occurred between 33.0 and 26.5 ka in response to climate forcing from decreases in northern summer insolation, tropical Pacific sea surface temperatures, and atmospheric CO2. Nearly all ice sheets were at their LGM positions from 26.5 ka to 19 to 20 ka, corresponding to minima in these forcings. The onset of Northern Hemisphere deglaciation 19 to 20 ka was induced by an increase in northern summer insolation, providing the source for an abrupt rise in sea level. The onset of deglaciation of the West Antarctic Ice Sheet occurred between 14 and 15 ka, consistent with evidence that this was the primary source for an abrupt rise in sea level ~14.5 ka.
1 Department of Geosciences, Oregon State University, Corvallis, OR 97331, USA.
2 Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A 0E8, Canada.
3 Department of Geology and Geophysics, University of Wisconsin, Madison, WI 53706, USA.
4 Department of Geology and Geochemistry, Stockholm University, SE-10691, Stockholm, Sweden.
5 Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, USA.
6 U.S. Geological Survey, Department of Geosciences, Oregon State University, Corvallis, OR 97331, USA.
7 School of Environmental Science, University of Ulster, Coleraine, County Londonderry, BT52 1SA, UK.



WHAT TURNS ICE AGES ON. . . and OFF ?

Research has shown that the amount of sunlight shining on the polar region determines when ice ages occur. Less sunlight shining on the northern polar region has been linked to the last four ice ages. Interglacial periods (time between glacial epochs) occur when the area receives more sunlight. Why? I knew you were going to ask! The amount of sunlight changes due to the orbit of Earth about the sun and the tilt of Earth (23.5 degrees) on its imaginary axis. (It's important to remember these important factors as you read on.) These orbit and tilt variations are due to interactions between Earth, Sun, the moon, and other planets. Scientists refer to this as astronomical forcing.

It is the tilt of Earth's axial rotation that creates seasons. During the summer (warm) season in the Northern Hemisphere, the North Pole is tilted toward the sun and the sun is high in the sky at noon. This allows the sun's rays to come in more perpendicular to the ground on the Northern Hemisphere. During the winter (cold) season in the Northern Hemisphere, the North Pole is tilted away from the sun. The sun stays close to the horizon, and days are short. In the Southern hemisphere, the sun is high in the sky at noon, and days are longer. This is why the seasons are reverse in the two hemispheres. While those of us living in the Northern Hemisphere enjoy summer, our neighbors in the Southern Hemisphere are experiencing winter.

http://oceanworld.tamu.edu/students/iceage/images/precession_2.jpg
Precession of the rotational axis.
(©1997 Wadsworth Publishing Company/ITP)

Earth wobbles slightly on its axis of rotation, giving rise to a precession, or wobble, with a time period of about 23,000 to 26,000 years. Because Earth "wobbles" (like a spinning top) in space, its tilt changes between 22 and 25 degrees on a cycle of about 41,000 years. That's a long time just to get back to where you started! It's during the periods of less tilt (cooler summers) that scientist believe snow and ice in the high latitudes tend to last (without melting) from year to year. The build-up of this snow and ice from year to year creates massive ice sheets.

Equinox is another term you'll need to be familiar with before you can fully understand present theories on the occurrence of ice ages. An equinox is the time when the sun crosses the equator, making night and day of equal length in all parts of Earth. In the Northern Hemisphere, the vernal (spring) equinox occurs about March 21 and the autumnal (autumn) equinox occurs about September 22. It is during the vernal and autumnal equinoxes that the sun is overhead at the equator throughout the day. In other words, the angle of incidence of the sun's rays to Earth's surface at noon on the equator is 90 degrees. The sun's rays at the equator at noon are perpendicular to Earth's surface.

http://oceanworld.tamu.edu/students/iceage/images/axis_wobble_2.jpg
The tilt of the Earth's rotational axis changes over a period of time.

Changes in the degree of Earth's tilt can cause the seasons to become more or less severe. More tilt would result in colder winters and hotter summers, while less tilt would result in cooler summers and milder winters. Other processes are also important. During ice ages, snow and ice bulid up on the land close to the poles.

Because of this build-up, more of Earth is covered with ice and snow giving it more albedo. In simpler terms, the whiteness of the snow and ice reflects the sun's energy back into space. Thus, more cooling takes place. As the ice sheets continue to grow, scientists also believe less carbon dioxide is in the atmosphere. This adds to the cooling process.

http://oceanworld.tamu.edu/students/iceage/images/orbit_eccentricity_2.jpg
The above image shows how much the Earth's orbit can vary in shape.
This process in a slow one, taking roughly 100,000 years to cycle.

Earth's orbit (path around the sun) is slightly elliptical (oval-shaped). This means that Earth is slightly closer to the sun during some parts of its year-long orbit and further away at other times. The closest approach of Earth to the sun is called perihelion, and it now occurs in January, making Northern Hemisphere winters slightly warmer. Eleven thousand years ago, perihelion occurred in July, making the summer slightly warmer in the Arctic.

Periodic changes in the "roundness" of Earth's orbit varies in cycles of 100,000 to 400,000 years. This affects how important "timing of the perihelion" is to the strength of the seasons. The growth and retreat of ice sheets are thought to be controlled by the combination of:

the tilt cycle which takes 41,000 years from onset to completion

the year precession cycle which is 26,000 years, and

the perhaps smaller effect of Earth's orbit eccentricities (non-circular and elliptical) cycle which can take 100,000 to 400,000 years for completion.

This seems reasonable as each of these cycles has a definite effect on the severity of the summer and winter seasons.

Ice cores obtained by boring deep into Earth's ice sheets provide scientists with information of Earth's paleoclimate. Two ice cores through the Greenland ice sheet have provided a continuous record of atmospheric conditions over Greenland from abut 100,000 years ago to present time. The ice cores show remarkable temperature variability (changes) over the past 100,000 years with rapid warming and cooling of the northern hemisphere, sometimes within decades (tens of years).

http://oceanworld.tamu.edu/students/iceage/iceage2.htm
 
in a hurry but thanks, trysail, for some of these points:

"Sometime around now, scientists say, the Earth should be changing from a long interglacial period that has lasted the past 10,000 years and shifting back towards conditions that will ultimately lead to another ice age – unless some other forces stop or slow it. But these are processes that literally move with glacial slowness, and due to greenhouse gas emissions the Earth has already warmed as much in about the past 200 years as it ordinarily might in several thousand years, Clark said."

...

"We used 5704 14C, 10Be, and 3He ages that span the interval from 10,000 to 50,000 years ago (10 to 50 ka) to constrain the timing of the Last Glacial Maximum (LGM) in terms of global ice-sheet and mountain-glacier extent. Growth of the ice sheets to their maximum positions occurred between 33.0 and 26.5 ka in response to climate forcing from decreases in northern summer insolation, tropical Pacific sea surface temperatures, and atmospheric CO2. Nearly all ice sheets were at their LGM positions from 26.5 ka to 19 to 20 ka, corresponding to minima in these forcings. The onset of Northern Hemisphere deglaciation 19 to 20 ka was induced by an increase in northern summer insolation, providing the source for an abrupt rise in sea level. The onset of deglaciation of the West Antarctic Ice Sheet occurred between 14 and 15 ka, consistent with evidence that this was the primary source for an abrupt rise in sea level ~14.5 ka. "

Which give us basis for the 'flood' stories reaching way back. People worked out a lot more than we give them credit for.
 
And I just noticed AJ's original c+p was from the Cato institute. Nuff said.
 
TurdFergeson said:
Other countries are harvesting their timber resources.
Click to expand...

So, what exactly is it that you trying to tell us?

Are you saying the U.S. ought to send the Marine Corps into Brazil to impose your will?

Fact: There are more trees in the United States today than there were in 1800.


 
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