Another possibility is that there was a slowing of thermohaline circulation. The circulation could have been interrupted by the introduction of a large amount of fresh water into the North Atlantic, possibly caused by a period of warming before the Little Ice Age known as the Medieval Warm Period. There is some concern that a shutdown of thermohaline circulation could happen again as a result of the present warming period.
The Little Ice Age (LIA) was a period of cooling that occurred after the Medieval Warm Period (Medieval Climate Optimum). While not a true ice age, the term was introduced into the scientific literature by François E. Matthes in 1939. It is conventionally defined as a period extending from the 16th to the 19th centuries, though climatologists and historians working with local records no longer expect to agree on either the start or end dates of this period, which varied according to local conditions. NASA defines the term as a cold period between 1550 AD and 1850 AD and notes three particularly cold intervals: one beginning about 1650, another about 1770, and the last in 1850, each separated by intervals of slight warming. The Intergovernmental Panel on Climate Change (IPCC) describes areas affected by the LIA:
There is still a very poor understanding of the correlation between low sunspot activity and cooling temperatures. During the period 1645–1715, in the middle of the Little Ice Age, there was a period of low solar activity known as the Maunder Minimum. The Spörer Minimum has also been identified with a significant cooling period between 1460 and 1550. Other indicators of low solar activity during this period are levels of the isotopes carbon-14 and beryllium-10.
Throughout the Little Ice Age, the world experienced heightened volcanic activity. When a volcano erupts, its ash reaches high into the atmosphere and can spread to cover the whole earth. This ash cloud blocks out some of the incoming solar radiation, leading to worldwide cooling that can last up to two years after an eruption. Also emitted by eruptions is sulfur in the form of SO2 gas. When this gas reaches the stratosphere, it turns into sulfuric acid particles, which reflect the sun's rays, further reducing the amount of radiation reaching Earth's surface. The 1815 eruption of Tambora in Indonesia blanketed the atmosphere with ash; the following year, 1816, came to be known as the Year Without a Summer, when frost and snow were reported in June and July in both New England and Northern Europe. Other volcanoes that erupted during the era and may have contributed to the cooling include Billy Mitchell (ca. 1580), Mount Parker (1641), Long Island (Papua New Guinea) (ca. 1660), and Huaynaputina (1600).
Was a change in thermohaline circulation responsible for the Little Ice Age?
Originally posted by Vitchilo
reply to post by CaticusMaximus
it could be enough to displace enough oxygen so that most air breathing creatures die,
Come on. That is NOT possible.
Anyway, some humans would survive... people in closed facilities...edit on 13-12-2011 by Vitchilo because: (no reason given)
"Between AD 1200 to 1300, we see a decrease in stomata and a sharp rise in atmospheric carbon dioxide, due to deforestation we think," says Dr van Hoof, whose findings are published in the journal Palaeogeography, Palaeoclimatology, Palaeoecology.
But after AD 1350, the team found the pattern reversed, suggesting that atmospheric carbon dioxide fell, perhaps due to reforestation following the plague.
The researchers think that this drop in carbon dioxide levels could help to explain a cooling in the climate over the following centuries.
The Black Death is estimated to have killed 30–60 percent of Europe's population, reducing world population from an estimated 450 million to between 350 and 375 million in the 14th century. The aftermath of the plague created a series of religious, social and economic upheavals, which had profound effects on the course of European history. It took 150 years for Europe's population to recover. The plague returned at various times, killing more people, until it left Europe in the 19th century.
The Gulf Stream, so named by Benjamin Franklin in 1762, is a mighty river in the ocean that flows from the Gulf of Mexico around the southern tip of the Florida peninsula and along the East Coast, bending off to the northeast when it reaches the vicinity of Cape Hatteras. It continues on to Iceland,the British Isles, and Norway. In the Straits of Florida the Gulf Stream is about forty miles wide and flows at a speed of about five miles an hour. As it progresses into the North Atlantic, it expands to several hundred miles in width and slows to about three miles an hour.
The first European to recognize the Gulf Stream as a discrete oceanic current was Ponce de Leon, following his landing in 1513 at what is now St. Augustine, Florida, in search of the Fountain of Youth. When he tried to return to Puerto Rico he found the current to be more powerful than the fair wind before which he was sailing, and his ships were driven to the north instead of southward, his intended course.
Originally posted by Melbourne_Militia
reply to post by Erno86
I've said it before and Ill say it again.....the main reason for the Ice melting in Northern latitudes is NOT because of global warming.....the world is actually cooling.
What melts the ice is soot from pollution that our civilisations spews into the air. Soot settles on the ice is is much more heat absorbing then carbon Dioxide is or anything else the propaganda machines try and tell you.
This physical proof of ice melting is what these propagandists use to justify their cry that the world is warming - "surely it must be warming if the ice is melting", which cannot be further for from the truth.
yes, ice is melting, no the world is not warming.....soot is the cause....do your research, there have been great scientists writeups on this. The mainstream media will not discuss this as it goes against the Green Agenda being pounded into everyones head.
Originally posted by Fractured.Facade
reply to post by Melbourne_Militia
If that is all true, what caused the extreme ice melt 55 million years ago, along with a period of catastrophic global warming??
Did we have pollution issues then?
Previous research into this period, called the Palaeocene-Eocene Thermal Maximum, or PETM, estimates the planet's surface temperature blasted upwards by between five and nine degrees Celsius (nine and 16.2 degrees Fahrenheit) in just a few thousand years.
The Arctic Ocean warmed to 23 C (73 F), or about the temperature of a lukewarm bath.
How PETM happened is unclear but climatologists are eager to find out, as this could shed light on aspects of global warming today.
What seems clear is that a huge amount of heat-trapping "greenhouse" gases -- natural, as opposed to man-made -- were disgorged in a very short time.
n 2050, they and their 19-year-old daughter Molly move to New York City by car, passing desperate Texans begging for rides north. One pulls a gun on Molly, but fortunately, others in the car/truck convoy point automatic weapons on the desperate man, who backs down. While the others in the convoy make it to Canada, New York City is a marvel of clean power, clean transit, and community gardening. Josh sets to work building a flood barrier to hold back the ocean,but the CO2 warming unleashes trapped methane in the Arctic, which causes even faster, non-linear warming. An effort to use sulfur dioxide as a last resort to cool the planet is called off when it is found to destroy the ozone layer.Lucy finds and helps quarantine and neutralize a strange new disease, and Molly moves upstate to an agricultural community. During a storm at high tide in 2075, Josh is killed trying to fix a stuck gate, and New York City is flooded. Lucy refuses Molly's offer to live with her, her husband and son. Starving people among the rotting flood damage set the stage for the return of the disease Lucy saw, now called "Caspian Fever."
Originally posted by Fractured.Facade
reply to post by poet1b
There have been much warmer periods on this planet... Methane is a greenhouse gas, so maybe these "eruptions" and global warming are much more related than CO2 emissions from mankind.
Could be at the beginning, middle or end of a millions of years long cycle.
The earth has been warm enough in its distant past to have had the ocean levels 100ft+ higher than now.
How hot can it get?
Does anyone really want the answer to that?