One possible consequence of the sun going dormant for a time this century might be another little ice age like this one
The Little Ice Age (LIA) was a period of cooling that occurred after the Medieval Warm Period. ...... CO;2-L. Jump up ^ https://web.archive.org/web/
Little Ice Age
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The NASA Earth Observatory notes three particularly cold intervals: one beginning about 1650, another about 1770, and the last in 1850, all separated by intervals of slight warming. The Intergovernmental Panel on Climate Change Third Assessment Report considered the timing and areas affected by the Little Ice Age suggested largely-independent regional climate changes rather than a globally-synchronous increased glaciation. At most, there was modest cooling of the Northern Hemisphere during the period.
Several causes have been proposed: cyclical lows in solar radiation, heightened volcanic activity, changes in the ocean circulation, variations in Earth's orbit and axial tilt (orbital forcing), inherent variability in global climate, and decreases in the human population.
- 1 Areas involved
- 2 Dating
- 3 Northern Hemisphere
- 4 Southern Hemisphere
- 5 Possible causes
- 6 See also
- 7 References
- 8 Further reading
- 9 External links
Areas involvedThe Intergovernmental Panel on Climate Change Third Assessment Report (TAR) of 2001 described the areas affected:
Evidence from mountain glaciers does suggest increased glaciation in a number of widely spread regions outside Europe prior to the twentieth century, including Alaska, New Zealand and Patagonia. However, the timing of maximum glacial advances in these regions differs considerably, suggesting that they may represent largely independent regional climate changes, not a globally-synchronous increased glaciation. Thus current evidence does not support globally synchronous periods of anomalous cold or warmth over this interval, and the conventional terms of "Little Ice Age" and "Medieval Warm Period" appear to have limited utility in describing trends in hemispheric or global mean temperature changes in past centuries.... [Viewed] hemispherically, the "Little Ice Age" can only be considered as a modest cooling of the Northern Hemisphere during this period of less than 1°C relative to late twentieth century levels.The IPCC Fourth Assessment Report (AR4) of 2007 discusses more recent research, giving particular attention to the Medieval Warm Period. It states that "when viewed together, the currently available reconstructions indicate generally greater variability in centennial time scale trends over the last 1 kyr than was apparent in the TAR.... The result is a picture of relatively cool conditions in the seventeenth and early nineteenth centuries and warmth in the eleventh and early fifteenth centuries, but the warmest conditions are apparent in the twentieth century. Given that the confidence levels surrounding all of the reconstructions are wide, virtually all reconstructions are effectively encompassed within the uncertainty previously indicated in the TAR. The major differences between the various proxy reconstructions relate to the magnitude of past cool excursions, principally during the twelfth to fourteenth, seventeenth and nineteenth centuries."
In contrast, a climate reconstruction based on glacial length shows no great variation from 1600 to 1850 but strong retreat thereafter.
Therefore, any of several dates ranging over 400 years may indicate the beginning of the Little Ice Age:
- 1250 for when Atlantic pack ice began to grow; cold period possibly triggered or enhanced by the massive eruption of Samalas volcano in 1257
- 1275 to 1300 based on the radiocarbon dating of plants killed by glaciation
- 1300 for when warm summers stopped being dependable in Northern Europe
- 1315 for the rains and Great Famine of 1315–1317
- 1550 for theorized beginning of worldwide glacial expansion
- 1650 for the first climatic minimum.
Sea ice surrounding Iceland extended for miles in every direction, closing harbors to shipping. The population of Iceland fell by half, but that may have been caused by skeletal fluorosis after the eruption of Laki in 1783. Iceland also suffered failures of cereal crops and people moved away from a grain-based diet. The Norse colonies in Greenland starved and vanished by the early 15th century, as crops failed and livestock could not be maintained through increasingly harsh winters, but Jared Diamond has suggested they had exceeded the agricultural carrying capacity before then. Greenland was largely cut off by ice from 1410 to the 1720s.
The violin maker Antonio Stradivari produced his instruments during the Little Ice Age. The colder climate is proposed to have caused the wood used in his violins to be denser than in warmer periods, contributing to the tone of his instruments. According to the science historian James Burke, the period inspired such novelties in everyday life as the widespread use of buttons and button-holes, knitting of custom-made undergarments to better cover and insulate the body. Fireplace hoods were installed to make more efficient use of fires for indoor heating, and enclosed stoves were developed, with early versions often covered with ceramic tiles.
The Little Ice Age, by anthropology professor Brian Fagan of the University of California at Santa Barbara, tells of the plight of European peasants during the 1300 to 1850 chill: famines, hypothermia, bread riots and the rise of despotic leaders brutalizing an increasingly dispirited peasantry. In the late 17th century, agriculture had dropped off dramatically: "Alpine villagers lived on bread made from ground nutshells mixed with barley and oat flour."  Historian Wolfgang Behringer has linked intensive witch-hunting episodes in Europe to agricultural failures during the Little Ice Age.
Depictions of winter in European painting
Neuberger analysed 12,000 paintings, held in American and European museums and dated between 1400 and 1967, for cloudiness and darkness. His 1970 publication shows an increase in such depictions that corresponds to the Little Ice Age, peaking between 1600 and 1649.
Paintings and contemporary records in Scotland demonstrate that curling and ice skating were popular outdoor winter sports, with curling dating back to the 16th century and becoming widely popular in the mid-19th century. As an example, an outdoor curling pond constructed in Gourock in the 1860s remained in use for almost a century, but increasing use of indoor facilities, problems of vandalism, and milder winters led to the pond being abandoned in 1963.
The extent of mountain glaciers had been mapped by the late 19th century. In the north and the south temperate zones, snowlines (the boundaries separating zones of net accumulation from those of net ablation) were about 100 metres (330 ft) lower than they were in 1975. In Glacier National Park, the last episode of glacier advance came in the late 18th and the early 19th centuries. In Chesapeake Bay, Maryland, large temperature excursions were possibly related to changes in the strength of North Atlantic thermohaline circulation.
MesoamericaAn analysis of several proxies undertaken in Mexico's Yucatan Peninsula, linked by its authors to Maya and Aztec chronicles relating periods of cold and drought, supports the existence of the Little Ice Age in the region.
Atlantic OceanIn the North Atlantic, sediments accumulated since the end of the last ice age, nearly 12,000 years ago, show regular increases in the amount of coarse sediment grains deposited from icebergs melting in the now open ocean, indicating a series of 1–2 °C (2–4 °F) cooling events recurring every 1,500 years or so. The most recent of these cooling events was the Little Ice Age. These same cooling events are detected in sediments accumulating off Africa, but the cooling events appear to be larger, ranging between 3–8 °C (6–14 °F).
AsiaAlthough the original designation of a Little Ice Age referred to reduced temperature of Europe and North America, there is some evidence of extended periods of cooling outside this region, but it is not clear whether they are related or independent events. Mann states:
While there is evidence that many other regions outside Europe exhibited periods of cooler conditions, expanded glaciation, and significantly altered climate conditions, the timing and nature of these variations are highly variable from region to region, and the notion of the Little Ice Age as a globally synchronous cold period has all but been dismissed.In China, warm-weather crops such as oranges were abandoned in Jiangxi Province, where they had been grown for centuries. Also, the two periods of most frequent typhoon strikes in Guangdong coincide with two of the coldest and driest periods in northern and central China (1660–1680, 1850–1880).
In Pakistan, the Balochistan province became colder and the native Baloch people started mass migration and settled along the Indus River in Sindh and Punjab provinces.
Southern HemisphereScientific works point out cold spells and climate changes in areas of the Southern Hemisphere and their correlation to the Little Ice Age.
AfricaIn Ethiopia and Mauritania, permanent snow was reported on mountain peaks at levels where it does not occur today. Timbuktu, an important city on the trans-Saharan caravan route, was flooded at least 13 times by the Niger River; there are no records of similar flooding before or since.
In Southern Africa, sediment cores retrieved from Lake Malawi show colder conditions between 1570 and 1820, suggesting the Lake Malawi records "further support, and extend, the global expanse of the Little Ice Age." A novel 3,000-year temperature reconstruction method, based on the rate of stalagmite growth in a cold cave in South Africa, further suggests a cold period from 1500 to 1800 "characterizing the South African Little Ice age." Periglacial features in the eastern Lesotho Highlands might have been reactivated by the Little Ice Age.
The Siple Dome (SD) had a climate event with an onset time that is coincident with that of the Little Ice Age in the North Atlantic based on a correlation with the GISP2 record. The event is the most dramatic climate event in the SD Holocene glaciochemical record. The Siple Dome ice core also contained its highest rate of melt layers (up to 8%) between 1550 and 1700, most likely because of warm summers. Law Dome ice cores show lower levels of CO2 mixing ratios from 1550 to 1800, which Etheridge and Steele conjecture are "probably as a result of colder global climate."
Sediment cores in Bransfield Basin, Antarctic Peninsula, have neoglacial indicators by diatom and sea-ice taxa variations during the Little Ice Age. The MES stable isotope record suggests that the Ross Sea region experienced 1.6 ± 1.4 °C cooler average temperatures during the Little Ice Age, compared to the last 150 years to now.
Australia and New ZealandLimited evidence describes conditions in Australia. Lake records in Victoria suggest that conditions, at least in the south of the state, were wet and/or unusually cool. In the north, evidence suggests fairly dry conditions, but coral cores from the Great Barrier Reef show similar rainfall as today but with less variability. A study that analyzed isotopes in Great Barrier Reef corals suggested that increased water vapor transport from southern tropical oceans to the poles contributed to the Little Ice Age. Borehole reconstructions from Australia suggest that over the last 500 years, the 17th century was the coldest on the continent, but the borehole temperature reconstruction method does not show good agreement between the Northern and Southern Hemispheres.
On the west coast of the Southern Alps of New Zealand, the Franz Josef glacier advanced rapidly during the Little Ice Age and reached its maximum extent in the early 18th century, in one of the few cases of a glacier thrusting into a rain forest. Based on dating of a yellow-green lichen of the Rhizocarpon subgenus, the Mueller Glacier, on the eastern flank of the Southern Alps within Aoraki/Mount Cook National Park, is considered to have been at its maximum extent between 1725 and 1730.
Pacific IslandsSea-level data for the Pacific Islands suggest that sea level in the region fell, possibly in two stages, between 1270 and 1475. This was associated with a 1.5 °C fall in temperature (determined from oxygen-isotope analysis) and an observed increase in El Niño frequency. Tropical Pacific coral records indicate the most frequent, intense El Niño-Southern Oscillation activity in the mid-seventeenth century.
South AmericaTree-ring data from Patagonia show cold episodes between 1270 and 1380 and from 1520 to 1670, contemporary with the events in the Northern Hemisphere. Eight sediment cores taken from Puyehue Lake have been interpreted as showing a humid period from 1470 to 1700, which the authors describe as a regional marker of the onset of the Little Ice Age. A 2009 paper details cooler and wetter conditions in southeastern South America between 1550 and 1800, citing evidence obtained via several proxies and models. 18O records from three Andean ice cores show a cool period from 1600–1800 
Although only anecdotal evidence, in 1675 the Spanish explorer Antonio de Vea entered San Rafael Lagoon through Río Témpanos (Spanish for "Ice Floe River") without mentioning any ice floe but stating that the San Rafael Glacier did not reach far into the lagoon. In 1766, another expedition noticed that the glacier reached the lagoon and calved into large icebergs. Hans Steffen visited the area in 1898, noticing that the glacier penetrated far into the lagoon. Such historical records indicate a general cooling in the area between 1675 and 1898: "The recognition of the LIA in northern Patagonia, through the use of documentary sources, provides important, independent evidence for the occurrence of this phenomenon in the region." As of 2001, the border of the glacier had significantly retreated as compared to the borders of 1675.
Possible causesScientists have tentatively identified these possible causes of the Little Ice Age: orbital cycles, decreased solar activity, increased volcanic activity, altered ocean current flows, the inherent variability of global climate, and reforestation following decreases in the human population.
Orbital cyclesOrbital forcing from cycles in the earth's orbit around the sun has, for the past 2,000 years, caused a long-term northern hemisphere cooling trend that continued through the Middle Ages and the Little Ice Age. The rate of Arctic cooling is roughly 0.02 °C per century. This trend could be extrapolated to continue into the future, possibly leading to a full ice age, but the twentieth-century instrumental temperature record shows a sudden reversal of this trend, with a rise in global temperatures attributed to greenhouse gas emissions.
Volcanic activityIn a 2012 paper, Miller et al. link the Little Ice Age to an "unusual 50-year-long episode with four large sulfur-rich explosive eruptions, each with global sulfate loading >60 Tg" and notes that "large changes in solar irradiance are not required."
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. The 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 sulfur dioxide gas. When it 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.
A recent study found that an especially massive tropical volcanic eruption in 1257, possibly of the now-extinct Mount Samalas near Mount Rinjani, both in Lombok, Indonesia, followed by three smaller eruptions in 1268, 1275, and 1284 did not allow the climate to recover. This may have caused the initial cooling, and the 1452–53 eruption of Kuwae in Vanuatu triggered a second pulse of cooling. The cold summers can be maintained by sea-ice/ocean feedbacks long after volcanic aerosols are removed.
Other volcanoes that erupted during the era and may have contributed to the cooling include Billy Mitchell (ca. 1580), Huaynaputina (1600), Mount Parker (1641), Long Island (Papua New Guinea) (ca. 1660), and Laki (1783). The 1815 eruption of Tambora, also 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.
Decreased human populationsSome researchers have proposed that human influences on climate began earlier than is normally supposed (see Early anthropocene for more details) and that major population declines in Eurasia and the Americas reduced this impact, leading to a cooling trend. William Ruddiman has proposed that somewhat reduced populations of Europe, East Asia, and the Middle East during and after the Black Death caused a decrease in agricultural activity. He suggests reforestation took place, allowing more carbon dioxide uptake from the atmosphere, which may have been a factor in the cooling noted during the Little Ice Age. Ruddiman further hypothesizes that a reduced population in the Americas after European contact in the early sixteenth century could have had a similar effect. Faust, Gnecco, Mannstein and Stamm (2005) and Nevle (2011) supported depopulation in the Americas as a factor, asserting that humans had cleared considerable amounts of forest to support agriculture in the Americas before the arrival of Europeans brought on a population collapse. A 2008 study of sediment cores and soil samples further suggests that carbon dioxide uptake via reforestation in the Americas could have contributed to the Little Ice Age. The depopulation is linked to a drop in carbon dioxide levels observed at Law Dome, Antarctica.
Increased human populationsIt has been speculated that increased human populations living at high latitudes caused the Little Ice Age through deforestation. The increased albedo due to this deforestation (more reflection of solar rays from snow-covered ground than dark, tree-covered area) could have had a profound effect on global temperatures.
Inherent variability of climateSpontaneous fluctuations in global climate might explain past variability. It is very difficult to know what the true level of variability from only internal causes might be since other forcings, as noted above, exist whose magnitude may not be known either. One approach to evaluating internal variability is to use long integrations of coupled ocean-atmosphere global climate models. They have the advantage that the external forcing is known to be zero, but the disadvantage is that they may not fully reflect reality. The variations may result from chaos-driven changes in the oceans, the atmosphere, or interactions between the two. Two studies have concluded that the demonstrated inherent variability is not great enough to account for the Little Ice Age.
- Fagan, Brian M. (2001). The Little Ice Age: How Climate Made History, 1300–1850. Basic Books. ISBN 0-465-02272-3.
|Wikimedia Commons has media related to Little Ice Age.|
- Abrupt Climate Change Information from the Ocean & Climate Change Institute, links to Woods Hole Oceanographic Institution articles
- "The Next Ice Age". Discover. September 2002. (discussion of Woods Hole research)
- "Huascaran (Peru) Ice Core Data". NOAA/NGDC Paleoclimatology Program. 1995.
- Dansgaard cycles and the Little Ice Age (LIA) (It is not easy to see a LIA in the graphs.)
- Tyson, P.D.; Karlen, W.; Holmgren, K.; Heiss, G.A. (2000). "The Little Ice Age and Medieval Warming in South Africa" (PDF). South African Journal of Science. 96 (3): 121–6.
- Was El Niño unaffected by the Little Ice Age? (2002)
- Evidence for the Little Ice Age in Spain, circa 2003
- The Little Ice Age in Europe, updated 2009
- "The Little Ice Age, Ca. 1300–1870". Timeline of European Environmental History. undated review article
- What's wrong with the sun? (Nothing) (2008)
- HistoricalClimatology.com, further links, resources, and relevant news, updated 2016
- Climate History Network, association of historical climatologists and climate historians, updated 2016
"Arctic Warming Overtakes 2,000 Years of Natural Cooling". UCAR. 3 September 2009. Archived from the original on 27 April 2011. Retrieved 19 May 2011.
Bello, David (4 September 2009). "Global Warming Reverses Long-Term Arctic Cooling". Scientific American. Retrieved 19 May 2011.