Some alarmists for example seem that the melting of glacial ice in the last few decades is some disastrous unprecedented event and as evidence for man-caused climate change - yet this current interglacial period has been a continuing event for the last 10,000 - 13,000 years.
I am a heretic as far as this new age religion of global climate change is concerned. No one disputes Global Climate change. The dispute is what the causes are. That I and many other scientists see natural processes as the main driving force rather than man as some perceived culprit in some conspiracy to warm up the earth. I hate to be the bearer of bad news for the alarmists but we have been here many times before.
We are currently in the midst of an interglacial period since the end of the last glacial period near the end of the Pleistocene (roughly 10,000-13,000 years ago). There have been three major continental glacial advances and interglacials (aka "Global Warmings") during the last 70,000 years. We are in the midst of the third "interglacial" which now is being termed "global warming" or "global climate change".
Those who are familiar with short (i.e. coronal mass ejections, el Nino/la Nina, volcanis/bollide ejecta, etc.) and long term cycles (i.e. earth's orbital variations such as the 23,000 year Milankovich cycle) that affect global climate change are quite familiar with the reasons for the current warming period. Meteorologists on the IPCC panel and in the current debate are not geologists nor are they necessarily familiar with paleo-climatology so many of us in the scientific community will excuse them of their ignorance.
Image: Extent of all glaciation over the last three million years superimposed on each other. The stars are three estimated center-points of glaciation over the last 60,000 years. "X" is the current location of the magnetic north pole.
Interesting to note that the Antarctic Ice Sheet is actually expanding both laterally and by thickness, but gets little media coverage because it just isn't as sexy as a shrinking ice sheet.
In North America:
Wisconsin glaciation, in North America
Glacial Ice Sheet typical of current continental glaciation and of past "glacials".
The Wisconsin or Wisconsinian was the last major advance of continental glaciers in North America. This glaciation is made of three glacial maximums (commonly called ice ages) separated by interglacial periods (such as the one we are living in). These ice ages are called (from oldest to youngest); Tahoe, Tenaya and Tioga. The Tahoe reached its maximum extent perhaps about 70,000 years ago while little is known about the Tenaya. The Tioga was the least severe and last of the Wisconsinan group and reached its greatest advance 20,000 years ago and ended about 10,000 years before present (it started 30,000 years ago). At the height of glaciation the Bering land bridge permitted migration of mammals and humans to North America from Siberia.
It radically altered the geography of North America north of the Ohio River. At the height of the Wisconsin glaciation, ice covered most of Canada, the Upper Midwest, and New England, as well as parts of Montana and Washington. On Kelleys Island in Lake Erie or in New York's Central Park, the grooves left by these glaciers can be easily observed. In southwestern Saskatchewan and southeastern Alberta a suture zone between the Laurentide and Cordilleran ice sheets formed the Cypress Hills, which is the northernmost point in North America that remained south of the continental ice sheets.
The Great Lakes are the result of glacial scour and pooling of melt water at the rim of the receding ice. When the enormous mass of the continental ice sheet retreated, the Great Lakes began gradually moving south due to isostatic rebound of the north shore. Niagara Falls is also a product of the glaciation, as is the course of the Ohio River, which largely supplanted the prior Teays River.
In its retreat, the Wisconsin glaciation left terminal moraines that form Long Island, Nantucket and Cape Cod, and the Oak Ridges Moraine in south central Ontario, Canada. The drumlins and eskers formed at its melting edge are landmarks of the Lower Connecticut River Valley.
Alpine Glacier typical of mountain glaciers past and present.
The Pinedale glaciation was the last of the major ice ages to appear in the Rocky Mountains in the United States. The Pinedale lasted from approximately 30,000 to 10,000 years ago and was at its greatest extent between 23,500 and 21,000 years ago. This glaciation was somewhat distinct from the main Wisconsin glaciation as it was unrelated to the giant ice sheets and was instead composed of mountain glaciers. The Pinedale and the main ice sheets of the Wisconsin produced features such as glacial Lake Missoula, which would break free from its ice dam causing the massive Missoula floods. Geologists estimate that the cycle of flooding and reformation of the lake lasted on average of 55 years and that the floods occurred approximately 40 times over the 2,000 year period between 15,000 and 13,000 years ago. Glacial lake outburst floods such as these are not uncommon today in Iceland and other places.
Time equivalent Glaciations:
Other time equivalent glaciations (ice ages) and interglacials (global warmings) were in force at the same time around the world. The Wisconsin (in North America), Weichsel (in Scandinavia), Devensian (in the British Isles), Midlandian (in Ireland) and Wrm glaciation (in the Alps) are the most recent glaciations of the Pleistocene epoch, which ended around 10,000 BCE. The general glacial advance began about 70,000 BCE, and reached its maximum extent about 18,000 BCE. In Europe, the ice sheet reached northern Germany.
Milankovitch cycles also known as Wobble, are the collective effect of changes in the Earth's movements upon its climate, named after Serbian civil engineer and mathematician Milutin Milankovi. 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
We are at about the midpoint of the current interglacial ("global warming") period +3,000 years given what we know about the periodicity of ice ages and interglacials and the corresponding Milankovich Cycle. Periodic variations in the earth's position relative to the sun as the earth orbits, affecting the distribution of the solar radiation reaching the earth and causing climatic changes that have profound impacts on the abundance and distribution of organisms, best seen in the fossil record of the Quaternary Period (the last 1.6 million years). Climate patterns are dictated by the orbital path of the earth around the sun (apogee/perigee). During the warmest periods (like now) the earth's orbit is more elliptically exaggerated with close passes to the sun during the mid-cycle.
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 22,000-year cycle in the equinoxes. In addition, the angle between Earth's rotational axis and the normal to the plane of its orbit changes from 21.5 degrees to 24.5 degrees and back again on a 41,000-year cycle. Presently, this angle is 23.44 degrees. But I digress.
Before I get too complicated for some and begin to go into a raging description involving astrophysics (another past endeavor of research and academia) and really lose the reader, I will end it here. The simple fact is that man has little if any overall impact on the climate of the earth. The processes of "global climate change" are largely natural processes. I am aware that many of the new-age religion will balk and call me a denialist. Be that as it may, I will proudly wear the label of "heretic". Many a great scientist has had that label thrust upon him/her from time to time.
Simply put, this is well known among earth scientists. To claim that the debate is over and there is now definitive proof based on competing computer models based on "what ifs" and "extreme scenarios" is ludicrous. There is always scientific debate. There can be no "consensus". Politics is done by "consensus", Research and scientific studies are never done "by consensus" - sorry, but just isn't that simple - science does not work that way.
Yes, it is true that ice melts when the temperature rises above 32F. Personally I wish it were "proven" that man were the cause of global warming because there would be a major push toward clean-burning Natural Gas and Nuclear Power from which I would benefit nicely with huge financial gains from my investments. But alas, the whole argument of anthropogenic global warming is nothing more than an unproven theory based on emotion rather than science fact.
- Black Blade
The meek shall inherit the Earth, but not the mineral rights!