What happened during the "Little Ice age" off and on from the 1600 through the 1800s could happen again for about 70 to 100 years starting around 2030 given the present Sun Cycles with declining Sun spots.
How that will affect the present global warming cycle and greenhouse gases is anyone's guess at present. However, Earth's ecosystem will be affected by the Sun's ecosystem and the effect of Solar changes will also affect the Magnetosphere as well both now and into the future.
Little Ice Age
From Wikipedia, the free encyclopedia
For the most recent period much colder than present and with significant glaciation, see
Last glacial period.
The reconstructed depth of the Little Ice Age varies between different
studies (anomalies shown are from the 1950–80 reference period)
The
Little Ice Age (LIA) was a period of cooling that occurred after the
Medieval Warm Period (Medieval Climate Optimum).
[1] While it was not a true
ice age, the term was introduced into the scientific literature by
François E. Matthes in 1939.
[2] It has been conventionally defined as a period extending from the sixteenth to the nineteenth centuries,
[3][4][5] or alternatively, from about 1300
[6] to about 1850,
[7][8][9]
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. The
NASA
Earth Observatory notes three particularly cold intervals: one
beginning about 1650, another about 1770, and the last in 1850, each
separated by intervals of slight warming.
[5] The
Intergovernmental Panel on Climate Change Third Assessment Report
considered the timing and areas affected by the LIA 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.
[10]
Several causes have been proposed:
cyclical lows in solar radiation, heightened
volcanic activity, changes in the
ocean circulation, an inherent variability in global climate, or decreases in the human population.
Areas involved
The
Intergovernmental Panel on Climate Change Third Assessment Report (TAR) of 2001 describes areas affected by the LIA:
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 time frame,
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.[10]
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." Considering confidence limits, "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."
[11]
Dating
The last written records of the
Norse Greenlanders are from a 1408 marriage in the
Church of Hvalsey — today the best-preserved of the Norse ruins.
There is no consensus regarding the time when the Little Ice Age began,
[12][13] although a series of events preceding the known climatic minima has often been referenced. In the thirteenth century,
pack ice began advancing southwards in the
North Atlantic, as did glaciers in
Greenland. Anecdotal evidence suggests expanding
glaciers
almost worldwide. Based on radiocarbon dating of roughly 150 samples of
dead plant material with roots intact, collected from beneath ice caps
on
Baffin Island and
Iceland, Miller
et al. (2012)
[6]
state that cold summers and ice growth began abruptly between AD 1275
and 1300, followed by "a substantial intensification" from 1430 to 1455.
[14]
In contrast, a climate reconstruction based on glacial length
[15][16] shows no great variation from 1600 to 1850, though it shows strong retreat thereafter.
For this reason, 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
- 1275 to 1300 based on 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.
The Little Ice Age ended in the latter half of the nineteenth century or early in the twentieth century.
[17][18][19]
Northern Hemisphere
Europe
The Little Ice Age brought colder winters to parts of
Europe and
North America. Farms and villages in the
Swiss Alps were destroyed by encroaching glaciers during the mid-seventeenth century.
[20] Canals and rivers in
Great Britain and the
Netherlands were frequently frozen deeply enough to support ice skating and winter festivals.
[20] The first
River Thames frost fair was in 1607 and the last in 1814; changes to the bridges and the addition of an
embankment affected the river flow and depth, hence diminishing the possibility of freezes. Freezing of the
Golden Horn and the southern section of the
Bosphorus took place in 1622. In 1658, a Swedish army
marched across the Great Belt to Denmark to attack
Copenhagen. The winter of 1794–1795 was particularly harsh, when the French invasion army under
Pichegru
could march on the frozen rivers of the Netherlands, while the Dutch
fleet was fixed in the ice in Den Helder harbour. Sea ice surrounding
Iceland extended for miles in every direction, closing harbors to shipping.
The population of Iceland fell by half but this was perhaps caused by
fluorosis after the eruption of the volcano
Laki in 1783.
[21] Iceland also suffered failures of cereal crops and people moved away from a grain-based diet.
[22]
The
Norse colonies in
Greenland
starved and vanished by the early fifteenth century, as crops failed
and livestock could not be maintained through increasingly harsh
winters, though
Jared Diamond
suggested they had exceeded the agricultural carrying capacity before
then. Greenland was largely cut off by ice from 1410 to the 1720s.
[23]
In
Lisbon, Portugal, snowstorms were much more frequent than today. One winter in the 17th century experienced eight snowstorms.
[24]
Winter skating on the main canal of Pompenburg,
Rotterdam in 1825, shortly before the minimum, by Bartholomeus Johannes van Hove
Hubert Lamb
said that in many years, "snowfall was much heavier than recorded
before or since, and the snow lay on the ground for many months longer
than it does today."
[25]
Many springs and summers were cold and wet but with great variability
between years and groups of years. Crop practices throughout Europe had
to be altered to adapt to the shortened, less reliable growing season
and there were many years of dearth and famine (such as the
Great Famine of 1315–1317, although this may have been before the LIA proper).
[26] According to Elizabeth Ewan and Janay Nugent, "
Famines
in France 1693–94, Norway 1695–96 and Sweden 1696–97 claimed roughly 10
percent of the population of each country. In Estonia and Finland in
1696–97, losses have been estimated at a fifth and a third of the
national populations, respectively."
[27] Viticulture
disappeared from some northern regions and storms caused serious
flooding and loss of life. Some of these resulted in permanent loss of
large areas of land from the Danish, German and Dutch coasts.
[25]
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 Stradivari's
instruments.
[28] 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 and installation of fireplace
hoods to make more efficient use of fires for indoor heating, as well as
the development of the enclosed
stove, in early versions often covered with
ceramic tiles.
[29]
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 seventeenth century, writes Fagan, agriculture
had dropped off so dramatically, "Alpine villagers lived on bread made
from ground nutshells mixed with barley and oat flour."
[30] Historian
Wolfgang Behringer has linked intensive
witch-hunting episodes in Europe to agricultural failures during the Little Ice Age.
[31]
Depictions of winter in European painting
William James Burroughs analyses the depiction of winter in paintings, as does
Hans Neuberger.
[32]
Burroughs asserts that this occurred almost entirely from 1565 to 1665
and was associated with the climatic decline from 1550 onwards.
Burroughs claims that before this, there were almost no depictions of
winter in art, and "hypothesizes that the unusually harsh winter of 1565
inspired great artists to depict highly original images and that the
decline in such paintings was a combination of the "theme" having been
fully explored and mild winters interrupting the flow of painting".
[33]
Wintry scenes, which have technical difficulties in painting, had been
regularly and very well handled since the early fifteenth century by
artists in
illuminated manuscript cycles showing the
Labours of the Months, typically placed on the calendar pages of
books of hours. January and February are typically shown as snowy, as in
February in the famous cycle in the
Les Très Riches Heures du duc de Berry,
painted 1412-1416 and illustrated below. At this period independent
landscape subjects had not developed as a genre in art, so the absence
of other winter scenes is not remarkable.
The famous winter
landscape paintings by
Pieter Brueghel the Elder, such as
The Hunters in the Snow, are all thought to have been painted in 1565. His son
Pieter Brueghel the Younger
(1564-1638) also painted many snowy landscapes, though according to
Burroughs he "slavishly copied his father's designs. The derivative
nature of so much of this work makes it difficult to draw any definite
conclusions about the influence of the winters between 1570 and
1600...".
[34]
Burroughs say that snowy subjects return to
Dutch Golden Age painting with works by
Hendrick Avercamp
from 1609 onwards. There is then a hiatus between 1627 and 1640, before
the main period of such subjects from the 1640s to the 1660s, which
relates well with climate records for this later period. The subjects
are less popular after about 1660, but this does not match any recorded
reduction in severity of winters, and may just reflect changes in taste
or fashion. In the later period between the 1780s and 1810s, snowy
subjects again become popular.
[33]
Neuberger analysed 12,000 paintings, held in American and European
museums and dated between 1400 and 1967, for cloudiness and darkness.
[32] His 1970 publication shows an increase in such depictions that corresponds to the LIA,
[32] peaking between 1600 and 1649.
[35]
Paintings and contemporary records in Scotland demonstrate that
curling and
ice skating
were popular outdoor winter sports, with curling dating back to the
sixteenth century and becoming widely popular in the mid-nineteenth
century.
[36] 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.
[37]
North America
In North America, American Natives formed leagues in response to food shortages.
[23]
The early European explorers and settlers of North America reported
exceptionally severe winters. For example, according to Lamb,
Samuel Champlain reported bearing ice along the shores of
Lake Superior in June 1608; both Europeans and indigenous peoples suffered excess mortality in
Maine during the winter of 1607–1608 and extreme frost was reported in the
Jamestown, Virginia settlement at the same time.
[25] The journal of
Pierre de Troyes, Chevalier de Troyes, who led an expedition to
James Bay
in 1686, recorded that the bay was still littered with so much floating
ice that he could hide behind it in his canoe on 1 July.
[38]
In the winter of 1780,
New York Harbor froze, allowing people to walk from
Manhattan to
Staten Island.
The extent of mountain glaciers had been mapped by the late
nineteenth 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.
[39] In
Glacier National Park, the last episode of glacier advance came in the late 18th and early 19th centuries.
[40] In
Chesapeake Bay,
Maryland, large temperature excursions were possibly related to changes in the strength of North Atlantic
thermohaline circulation.
[41]
Atlantic Ocean
In 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.
[42]
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).
[43]
Outside of Europe and North America
Although 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, although it is not
clear whether these are the related or independent events. Mann states:
[3]
"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."
China
In China, warm-weather crops such as oranges were abandoned in
Jiangxi Province, where they had been grown for centuries.
[44] Also, two periods of most frequent
typhoon strikes in
Guangdong coincide with two of the coldest and driest periods in northern and central China (AD 1660-1680, 1850–1880).
[45]
Mesoamerica
An analysis of several proxies undertaken in Mexico's
Yucatan Peninsula, linked by its authors to
Mayan and
Aztec chronicles relating periods of cold and drought, supports the existence of the Little Ice Age in the region.
[46]
Africa
In Ethiopia and Mauritania, permanent snow was reported on mountain peaks at levels where it does not occur today.
[44] 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.
[44]
Southern Hemisphere
Scientific works point out cold spells and climate changes in areas
of the Southern Hemisphere and their correlation to the Little Ice Age.
Africa
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."
[47]
A novel 3,000-year temperature reconstruction method based on the rate of
stalagmite growth in a cold cave in
South Africa suggests a cold period from 1500 to 1800 "characterizing the South African Little Ice age."
[48]
Antarctica
Kreutz et al. (1997) compared results from studies of West Antarctic
ice cores with the Greenland Ice Sheet Project Two (GISP2) and suggested
a synchronous global Little Ice Age.
[49] An ocean sediment core from the eastern Bransfield Basin in the
Antarctic Peninsula shows centennial events that the authors link to the Little Ice Age and Medieval Warm Period.
[50]
The authors note "other unexplained climatic events comparable in
duration and amplitude to the LIA and MWP events also appear."
CO2 mixing ratios at Law Dome
The
Siple Dome
(SD) had a climate event with an onset time that is coincident with
that of the LIA in the North Atlantic based on a correlation with the
GISP2 record. This event is the most dramatic climate event in the SD
Holocene glaciochemical record.
[51]
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.
[52]
Law Dome ice cores show lower levels of CO
2 mixing ratios during 1550–1800 AD, leading Etheridge and Steele to conjecture "probably as a result of colder global climate."
[53]
Sediment cores in Bransfield Basin, Antarctic Peninsula, have neoglacial indicators by
diatom and sea-ice taxa variations during the period of the LIA.
[54]
The MES stable isotope record suggests that the Ross Sea region
experienced 1.6 ± 1.4 °C cooler average temperatures during the LIA in
comparison to the last 150 years.
[55]
Australia and New Zealand
Limited 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, while 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
LIA.
[56]
Borehole reconstructions from Australia suggest that, over the last 500
years, the seventeenth century was the coldest on that continent,
although the borehole temperature reconstruction method does not show
good agreement between the Northern and Southern Hemispheres.
[57]
On the west coast of the
Southern Alps of
New Zealand, the
Franz Josef glacier
advanced rapidly during the Little Ice Age, reaching its maximum extent
in the early eighteenth century, in one of the few places where a
glacier thrust into a
rain forest.
[30] 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.
[58]
Pacific Islands
Sea-level data for the Pacific Islands suggest that sea level in the
region fell, possibly in two stages, between AD 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.
[59]
South America
Tree-ring data from
Patagonia
show cold episodes between 1270 and 1380 and from 1520 to 1670, periods
contemporary with LIA events in the Northern Hemisphere.
[60][61] 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 LIA onset.
[62]
A 2009 paper details cooler and wetter conditions in southeastern South
America between 1550 and 1800 AD, citing evidence obtained via several
proxies and models.
[63]
18O records from three Andean ice cores show a cool period from 1600-1800
[64]
Although it only provides 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 and stated that the
San Rafael Glacier did not reach far into the lagoon. In 1766, another expedition noticed that the glacier did reach 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, and "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."
[65] As of 2001, the border of the glacier had significantly retreated compared to the borders of 1675.
[65]
Possible causes
Scientists have tentatively identified these possible causes of the Little Ice Age:
orbital cycles; decreased
solar activity; increased volcanic activity; altered
ocean current flows;
[66] the inherent variability of global climate; and reforestation following decreases in the human population.
Orbital cycles
Orbital forcing
due to 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 Medieval period and the Little Ice Age. The rate
of
Arctic cooling is roughly 0.02 degrees Celsius per century.
[67] 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.
[67]
The Maunder minimum in a 400-year history of sunspot numbers
Solar activity events recorded in radiocarbon
Solar activity
There is still a very poor understanding of the correlation between low
sunspot activity and cooling temperatures.
[68][69] 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.
[70] Other indicators of low solar activity during this period are levels of the isotopes
carbon-14 and
beryllium-10.
[71]
Volcanic activity
In 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."
[6]
Throughout the Little Ice Age, the world experienced heightened volcanic activity.
[72] 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
sulfur dioxide 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.
A recent study found that an especially massive tropical volcanic eruption in 1258, possibly of
Mount Rinjani,
followed by three smaller eruptions in 1268, 1275, and 1284 that did
not allow the climate to recover, may have caused the initial cooling,
and that the 1452–53 eruption of
Kuwae in Vanuatu triggered a second pulse of cooling.
[6][14] 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).
[20]
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.
Ocean Circulation
Thermohaline circulation or Oceanic conveyor belt illustrated
Another possibility is that there was a slowing of
thermohaline circulation.
[39][66][73][74]
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.
[30][75][76] There is some concern that a
shutdown of thermohaline circulation could happen again as a result of the present warming period.
[77][78]
Decreased human populations
Some 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.
[79][80] Faust, Gnecco, Mannstein and Stamm (2005)
[81] and Nevle (2011)
[82]
supported depopulation in the Americas as a factor, asserting that
humans had cleared considerable amounts of forests 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.
[83] The depopulation is linked to a drop in carbon dioxide levels observed at
Law Dome,
Antarctica.
[81]
Inherent variability of climate
Spontaneous 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; and their magnitude may not be known either. One
approach to evaluating internal variability is to use long integrations
of coupled ocean-atmosphere
global climate models.
These have the advantage that the external forcing is known to be zero;
but the disadvantage is that they may not fully reflect reality. These
variations may result from
chaos-driven changes in the oceans, the atmosphere, or interactions between the two.
[84] Two studies have concluded that the demonstrated inherent variability is not great enough to account for the Little Ice Age.
[84][85]
See also
References
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