Methane And Mini-horses: Fossils Reveal Effects Of Global Warming

Junior's "appeal to authority" doesn't even work.

Ocean warming, sea-level rise and coastal flooding

Warmer temperatures increase melting of mountain glaciers, increase ocean heat content, and cause ocean water to expand. Largely as a result of these effects, global sea level has risen 4 to 10 inches (10-25 cm) over the past 100 years. With additional warming, sea level is projected to rise from half a foot to 3 feet (15-92 cm) more during the next 100 years. On average, 50 to 100 feet (15-30 meters) of beach are lost for every foot (0.3 meters) of sea-level rise. Local land subsidence (sinking) and/or uplift due to geologic forces and coastal development will also affect the rate of coastal land loss.

Hotspot Selection Criteria: The sea-level rise (SLR) data were confirmed by published journal articles. We did not include places where there were tide gauge records of a rising sea level but no information about land inundation consequences (e.g., Buenos Aires, where the shoreline is raised/hardened and thus protected from inundation); places where there was evidence of land erosion but no SLR records (e.g., the island of Geneva and other Caribbean islands); and places where subsidence or other factors (e.g., changes in river sediment deposition) were clearly the dominating influence on land erosion (e.g., New Orleans and Victoria, Egypt). Although the inundation records for the South Pacific islands are based on anecdotal evidence from local residents, we included them because these accounts are often the best and only evidence available in these very vulnerable small island nations.

Glaciers melting

Global Warming May Trigger Ice Sheet Growth

About 150,000 years ago, an anomalous ice age was triggered by an increasingly salty Mediterranean Sea, a development that's occurring today and may start new ice sheet growth in the next few decades, according to a study at the University of Minnesota. Robert Johnson, an adjunct professor of geology and geophysics, will present his study of the glaciation 150,000 years ago and discuss its implications for today's climate on Tuesday, Oct. 29, at the annual meeting of the Geological Society of America in Denver.

Johnson is reluctant to predict exactly how global warming and other climate factors will play out, but he said the increasingly salty Mediterranean is a definite warning that Atlantic circulation patterns will change in ways that favor ice sheet growth.

"Global warming may actually assist new ice sheet growth because growth depends less on cold temperatures than on a strong supply of moisture and very heavy snowfall over northern land masses, said Johnson, who earlier this year published his arguments in a book, "Secrets of the Ice Ages."

The ice age 150,000 years ago was anomalous because it occurred in the face of maximum amounts of summer sunlight striking temperate and tropical latitudes - a phenomenon that the most prominent theory of glaciation can't explain.

"According to the widely accepted Milankovitch theory, when the Northern Hemisphere has a lot of extra solar energy coming in during summer, glacial ice is expected to shrink," said Johnson. "But between 160,000 and 150,000 years ago, solar energy was near a maximum at all latitudes below 65 degrees, yet glaciers grew and combined all across northern Eurasia from Ireland nearly to the Lena River in eastern Siberia. The saltiness of Mediterranean water played a major role in that glaciation, and a similar high salinity could shift climate toward a new ice age in Canada now."

How it works: At the Strait of Gibraltar, deep, salty Mediterranean water flows into the Atlantic and northward as it mixes up into the salty Gulf Stream surface water. Today some of that mixture flows westward into the Labrador Sea Southwest of Greenland, and much of it also flows beyond the Faeroe Islands off Scotland and eventually into the Arctic Ocean. About 160,000 years ago, an ice age was already under way, and the seas east and west of Greenland were very cold. But the salinity of the mixture reaching Labrador made the water dense enough to sink easily when cooled in winter, and the warmer salty replacement mixture kept the seas south of Greenland relatively warm.

"Storms usually track over areas where warm and cold conditions exist side by side," said Johnson. This temperature contrast with the Greenland ice sheet and other cold areas kept eastward-moving storms to the north. This channelled large amounts of moisture over both European and Siberian areas, causing enormous growth of the ice sheets there.

Today, the formation of sea ice and pack ice in the Arctic Ocean depends on the presence of less salty - and therefore less dense - water near the surface. This density gradient arises from inputs of fresh water from rivers flowing into the Arctic Ocean from Canada and Siberia. The salty flow of the Mediterranean and Gulf Stream mixture tends to inhibit the formation of sea ice and pack ice. The rising salinity of the Mediterranean outflow, as measured by European oceanographers over the last 40 years, tends to increase the Arctic Ocean salinity, reduce the density gradient, and melt the pack ice there - a process doubtless helped by global warming, Johnson said.

The pack ice has thinned by about 40 percent in the last 30 years and may be nearly gone in a few decades, said Johnson. As it melts, the pack ice supplies fresh water to the Arctic Ocean, but this fresh water will be lost once the pack ice is all gone. The result will be a sudden increase in salinity of the Arctic Ocean, with profound effects west of Greenland in Baffin Bay, which is now covered with heavy sea ice almost eight months of the year.

Arctic Ocean water enters the north end of Baffin Bay through small inter-island channels. As this water gets saltier and denser, the expected effect is that in winter, surface water in the bay will cool and sink. This already happens in winter to saltier water east of Greenland, Johnson said. But the sinking water would be replaced by salty water from the wide mouth of the bay to the south. All Baffin Bay water would then remain unfrozen in winter, and the contrast between the warmer ice-free water and the cold land of Baffin Island and Greenland would draw storms from the warmer Labrador Sea into the Baffin area. The result: Northern Quebec and Baffin Island would experience extremely heavy snows. This, said Johnson, is the inferred process that started the last ice age and that may initiate similarly rapid ice sheet growth in a few decades with relatively warm seas near Labrador.

The cause of the increase in Mediterranean saltiness 150,000 years ago is believed to have been a decrease in the tilt of Earth's axis, said Johnson. This weakened the African monsoons by reducing the difference in temperature between the Sahara Desert and areas south of the equator. The monsoons are driven by this temperature difference, and weaker monsoons 150,000 years ago caused extreme aridity in northern Africa and the Mediterranean regions, resulting in a saltier Mediterranean and stronger outflow at Gibraltar than today. Today, the climate of the Sahara and the Mediterranean is also arid, and much water from the Nile and other major rivers has been diverted for irrigation. These losses increase the salt content of the Mediterranean, a process helped by evaporation losses due to global warming.

"If an increase in salt from the Mediterranean should start the growth of glacial ice sheets in this century, some of the damage caused by global warming might be mitigated," Johnson said. First, if additional salty water cools and sinks in Baffin Bay, it will carry with it carbon dioxide dissolved from air. This should reduce the net annual addition of carbon dioxide to the atmosphere because, while the sinking water is balanced by water surfacing elsewhere, the water surfacing today sank many hundreds of years ago, when the atmospheric carbon dioxide was less. Second, there is widespread concern that the Greenland ice sheet may melt in the near future, and cooling due to new glaciation in Canada may prevent it. Third, the new glaciation would draw water from the sea, which would counteract the damaging sea level rise that is occurring today.

"The evidence shows that temperature is not the only factor in determining ice ages," he said. "The conventional Milankovitch theory doesn't account for shifts in precipitation - which is, after all, the source of ice sheets."

The ice age 150,000 years ago was anomalous because it occurred in the face of maximum amounts of summer sunlight striking temperate and tropical latitudes

Anomalous?? Hardly, such also occured 250krys, 350kyrs ... ago, as a consequence of the earth's orbit moving out of the path of cometary debris of the mean solar plane. High statospheric dust causes noctilucent cloud layers reflecting sun light from the earthes surface reducing earth's temperature at all latitudes maintaining ice age climates.

- a phenomenon that the most prominent theory of glaciation can't explain.

True as Milankovitch did not account for precession of the earth's orbit, He looked only at changes in orbital eccentricity(shape) and earth's polar precession. Eccentricity is insufficient to account for the required changes of insolation to account for warming into interglacial periods, and its periodicity( ~100kyrs) and phasing is not correct for the observed periodicity and inception of ice ages.

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

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

"The conventional Milankovitch theory doesn't account for shifts in precipitation - which is, after all, the source of ice sheets."

The conventional Milankovitch theory is insufficient to account for ever leaving ice ages, much less shifts in precipitation during ice ages.

However, precession of earth's orbit out of the mean solar system plane removing dust arising from cometary debris, (which Milankovitch ignores), can account for the observed history of 10kyr interglacial periods between ice ages.

Origin of the 100 kyr Glacial Cycle

Introduction

For over a century it has been argued that changes in the Earth's orbital eccentricity were responsible for the primary cycle of the ice ages (ref 1-4). Although the eccentricity changes were small (between 0.01 and 0.05), they can be calculated with good accuracy back at least several million years (ref 5, 6) and they show quasi-periodic behavior with a period of about 100 kyr. Milankovitch (ref 2) proposed that the eccentricity affected the climate through its effect on insolation, the average solar energy reaching the earth. The discovery (ref 3) of a strong quasi-periodic 100 kyr cycle in the climate data, in approximate phase coherence with the eccentricity, gave strong support to the theory. But the calculated insolation changes from eccentricity were too small to account for the strong 100 kyr cycle (ref 7). Moreover a second expected eccentricity period near 400 kyr is absent in most climate records, leading to specific disagreements between eccentricity and glacial data at both 400 ka and the present. Dozens of proposed explanations for the discrepancies have been proposed; in a recent review, Imbrie et al. (ref 8) give a "short list" consisting of seven different groups of models. Many involve resonant or nonlinear behavior of the ice-ocean-atmosphere system; some derive the 100 kyr period from the envelope of the variation in the precession parameter.

As dating has become more accurate, another possible problem with the Milankovitch insolation mechanism has developed: several recent experiments suggested that the abrupt terminations of the ice ages preceded the warming from insolation (ref 9, 10), an effect we refer to as the "causality problem." The interpretation of these results has been debated (ref 11, 12, 13). Imbrie et al. (ref 11) argued that a true test of the Milankovitch theory must be performed in the frequency domain, not the time domain. However we will show that the Milankovitch theory also has a previously unrecognized and serious problem in the frequency domain.

***
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.

***
Summary

The narrow width of the 100 kyr glacial cycles strongly supports an astronomical origin. It also argues that the orbitally-tuned paleontological time scales (those obtained by fitting the data to obliquity and precession cycles) are basically correct, at least to within a time delay and overall rate. However we know of no model, linear or nonlinear, that can reconcile the of eccentricity with the observed narrow 100 kyr glacial cycle. This is a severe and possibly fatal problem for the conventional Milankovitch mechanism of insolation, although insolation variations might account for the weaker 41 and 23-19 kyr cycles. Time scales which were tuned to a 100 kyr cycle derived from eccentricity (e.g. which use nonlinear ice models as a target) may have serious systematic errors.

We are not arguing that eccentricity cannot have an effect on glaciation. Perhaps we should be reassured that the insolation calculations, which always predicted a very small eccentricity effect, have been verified. If eccentricity does affect climate, the best way to look for it would be at the strongest expected frequency: that of the 400 kyr cycle.

In contrast, the inclination of the Earth's orbit matches both the spectral and the bispectral fingerprints of the climate data, and accounts for the absence of the 400 kyr cycle (the stage-1 and stage-11 problems). It also gives a natural solution to the controversial causality problem. The precession of the inclination vector also gives a natural source for the 70 kyr "anomalous" line of MacDonald (ref 43).

The only plausible mechanism that we have found that could link orbital inclination to climate is extraterrestrial accretion of dust or meteoroids. Although there is circumstantial evidence supporting this picture (e.g., the maximum in noctilucent clouds when the earth passes through the invariable plane, and the low present iridium levels), the weakest part of the proposed mechanism is the absence of a clearly identifiable band of meteoroids or dust responsible for it. Meteor streams are virtually impossible to find unless the earth passes through them. Dust bands may have been missed in past surveys, which require three-dimensional modeling in order to separate physical structures from the data. It is also possible that a totally different mechanism (other than accretion) links climate to inclination. A definitive test of the accretion model can be made by studying iridium and He-3 variations in sediment and ice.

AG, thanks for the chart and info. Junior look at 160,000 years ago and look at the temperature now using figure 1-5.

Junior over looks the fact of the periodic nature of the interglacial periods like we now enjoy closely linked to "predictable" astonomical events. Nor do his theories account for the long term downward trend in global temperature that has been sustained over the last 2400 years, with occasional excursions up and down in excess of the current so called "global warming" of the last 100yrs:

supposedly induced by the activities of mankind.

The real kicker comes down to the fact that:

Mankind's impact is only 0.28% of Total Greenhouse effect

" There is no dispute at all about the fact that even if punctiliously observed, (the Kyoto Protocol) would have an imperceptible effect on future temperatures -- one-twentieth of a degree by 2050. "

Dr. S. Fred Singer, atmospheric physicist
Professor Emeritus of Environmental Sciences at the University of Virginia,
and former director of the US Weather Satellite Service;
in a Sept. 10, 2001 Letter to Editor, Wall Street Journal

That "global warming", is nothing more than the natural variation in earth's climate from factors generally outside the control of mankind.

Of course if junior is really worried about "Global Warming", Nuclear winter will nullify it , seeing as we are due to return back to the usual state of an Ice Age, a little nuclear war should precipitate the event in short order.

The Discovery channel had a program where I first heard about the Great conveyor and the current moderate global temperature. It mentioned the catastrophic release of fresh water from the collapse of Lake Agassiz that might have something to do with the Great conveyor. This event happened around 12,000 years ago and coincides with the "flat smooth" area of figure 1-5. Here is a link that mentions that scenario. Chaotic Climate

. Be aware that some people will ridicule the link, however, the source is Sciam and this is a corroboration of a Discovery channel program. Interesting reading in any case.

I did not link global warming to man. Global warming happens; whether the cause is astronomical or not.

I did not link global warming to man.

That's a relief.

Now precisely what "global warming" is going on that we need to be concerned about?

Seems the peak as far as we are concerned happened several thousand years ago. We have been in a slow downtrend ever since looking for the downward fall back to normal earth temperatures associated with an ice age.

Climate of the last 12,000 years

Knowing that mankind has have little effect upon the global climate trends, and the current historical trend in global temperatures is downward, (i.e. no global warming just weather) What is the point of your post?

I refer you to the articles you posted:

"In today's Earth, additional warming could set off a methane release that would bump the Earth's temperature up by several degrees---enough to melt polar ice and raise sea level and cause many other problems that would be difficult to survive."

That has already happen, around 9,500 BC to be precise.

"That's what makes the temperature rises we're measuring now more worrisome than those that occurred in the past."

With the multi-point rise from earth's nominal ice age temperatures well in the past, the current temporary temperatures at midpoint of the inter-glacial high on a decaying trend, and with an astronomically induced return towards Ice Age conditions on the near geological horizon.

Just what is "worrisome" about a hypothetical "global warming" now? The astronomical factors that will force us back to ice age conditions are in place regardless of any of the hypothetical "global warming" scenarios of either of the articles you have provided. At most they can explain the events that occur as an effect of astronomical forcings.

Looking them over, the most they really say is we can expect more weather, and that at some indefinite point in the future, we will be entering another ice age. Which is something we already know and is as certain as orbital mechanics having nothing at all to do with any that mankind may be doing or could in anyway prevent or affect.

Were doomed...

"Believe it or not, heavy glaciation and the resultant drop in sea levels is associated with global warming."

But the ice caps melted . . .

For as long as I can remember we have been told that man crossed the land bridge between Asia and North America during the last ice age, more or less 14,000 years ago. The land bridge formed because of the drop in sea level due to heavy glaciation. Fine.

Now we are being told that +- 52 MYA the ice caps melted and animals crossed the resulting land bridge. If the ice caps melted, indeed the ice caps have melted and re-formed many, many times, sea levels would rise and there would be LESS land, not more.

If what you say is true and global warming trends, tend to produce large-scale glaciers, then why are glaciers shrinking world-wide?

On the other hand if glaciers do indeed increase in size and number during periodic warming events this would bolster the argument of the existance of positive and negative feedback loops in the global weather system. As graciation increases more of the Sun's energy is reflected back into space lowering over-all global temps.

Note: this topic is from March 4, 2003.

the past offers clues, say scientists who are studying a period of warming that occurred about 55 million years ago.




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