Little Ice Age facts for kids

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 after a warmer era (time) that is known as the Medieval Warm Period.

Climatologists (people who study climate) and historians find it difficult to agree on either the start or end dates of this period. Some say the Little Ice Age started about the 16th century and continued to the mid 19th century. It is generally agreed that there were three minima, one beginning about 1650, one about 1770, the last one about 1850. Each time was separated by slight warming intervals. At first, it was believed that the LIA was all over the world. Now it is not clear if this is true.

Solar activity

Solar activity events recorded in radiocarbon.

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 physical link between low sunspot activity and cooling temperatures has not been established, but the coincidence of the Maunder Minimum with the deepest trough of the Little Ice Age is suggestive of such a connection. The Spörer Minimum has also been identified with a significant cooling period near the beginning of the Little Ice Age. Other indicators of low solar activity during this period are levels of the isotopes carbon-14 and beryllium-10.

Volcanic activity

Throughout the Little Ice Age, the world also experienced heightened volcanic activity. When a volcano erupts, its ash reaches high into the atmosphere and can spread to cover the whole of 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.

Ocean conveyor shutdown

Another possibility is that there was a shutdown or slowing of Thermohaline circulation, also known as the "great ocean conveyor" or "meridional overturning circulation". The Gulf Stream could have been interrupted by the introduction of a large amount of fresh water to the North Atlantic, possibly caused by a period of warming before the little ice age. There is some concern that shutdown of thermohaline circulation could happen again as a result of global warming.

End of Little Ice Age

Beginning around 1850, the climate began warming and the Little Ice Age ended. Some global warming critics believe that Earth's climate is still recovering from the Little Ice Age and that human activity is not the decisive factor in present temperature trends, but this idea is not widely accepted.

• IPCC on Was there a Little Ice Age and a Medieval Warm Period?

Images for kids

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  The last written records of the Norse Greenlanders are from a 1408 marriage at Hvalsey Church, which is now the best-preserved Norse ruin.

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  The Frozen Thames, 1677

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  Winter skating on the main canal of Pompenburg, Rotterdam in 1825, shortly before the minimum, by Bartholomeus Johannes van Hove

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  The Reverend Robert Walker Skating on Duddingston Loch, attributed to Henry Raeburn, 1790s

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  The Hunters in the Snow by Pieter Brueghel the Elder, 1565

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  Winter landscape with iceskaters, c. 1608, Hendrick Avercamp

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  Patterdale Landscape with Cattle (1833) by John Glover depicts agricultural practices like pastoralism, which contributed to the aridification of Australia's late Little Ice Age.

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  Seasonal values of Central England Temperatures. The top panel shows group sunspot numbers: the grey area shows the annual values from telescopic observations, the mauve line its 11-year running means, and the green line the values deduced from the abundance of the Carbon-14 cosmogenic isotope in tree trunks. The second panel shows the winter values of Central England Temperature, being the mean for December, January and February. The third panel shows the summer values, being the mean for June, July and August. The bottom panel gives the aerosal optical depth, showing volcanic dust levels, from ice sheet cores. The vertical mauve lines are years in which frost fairs were held on the Thames in London and the vertical orange lines are the years when the ice there was reported as thick enough to walk on. The first cyan line is the date of the removal of the old London Bridge and wier and the second is the completion of the embankments: both riverine developments that increased the flow and ended Thames freezing events. All data sources are given in reference

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  The Maunder Minimum in a 400-year history of sunspot numbers

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  Sunspot number compared with Northern Hemisphere (NH) temperature anomaly. The upper panel shows 11-year smoothed group sunspot numbers from telescopic observations and the sunspot number derived from Carbon-14 cosmogenic isotope abundances in tree trunks. The lower panel shows the northern hemisphere (NH) temperature anomaly (relative to the 1990 level) from a wide variety of paleoclimate proxies: the black line is the mean value, and the colours give the uncertainty probability distribution. The blue dots are the instrumental record. The dashed lines mark the start and end of thae Little Ice Age (LIA) defined by the (NH) temperature anomaly level -0.16 degrees Celsius. All data sources are described in references and

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  Thermohaline circulation or Oceanic conveyor belt illustrated

See also

In Spanish: Pequeña Edad de Hielo para niños