Little Ice Age (LIA), climate interval that occurred from the early 14th century through the mid-19th century, when mountain glaciers expanded at several locations, including the European Alps, New Zealand, Alaska, and the southern Andes, and mean annual temperatures across the Northern Hemisphere declined by 0.6 °C (1.1 °F) relative to the average temperature between 1000 and 2000 ce. The term Little Ice Age was introduced to the scientific literature by Dutch-born American geologist F.E. Matthes in 1939. Originally the phrase was used to refer to Earth’s most recent 4,000-year period of mountain-glacier expansion and retreat. Today some scientists use it to distinguish only the period 1500–1850, when mountain glaciers expanded to their greatest extent, but the phrase is more commonly applied to the broader period 1300–1850. The Little Ice Age followed the Medieval Warming Period (roughly 900–1300 ce) and preceded the present period of warming that began in the late 19th and early 20th centuries.
-
Estimates of temperature variations for the Northern Hemisphere and central England from 1000 to …Encyclopædia Britannica, Inc.
Geographic extent
Information obtained from “proxy records” (indirect records of ancient climatic conditions, such as ice cores, cores of lake sediment and coral, and annual growth rings in trees) as well as historical documents dating to the Little Ice Age period indicate that cooler conditions appeared in some regions, but, at the same time, warmer or stable conditions occurred in others. For instance, proxy records collected from western Greenland, Scandinavia, the British Isles, and western North America point to several cool episodes, lasting several decades each, when temperatures dropped 1 to 2 °C (1.8 to 3.6 °F) below the thousand-year averages for those areas. However, these regional temperature declines rarely occurred at the same time. Cooler episodes also materialized in the Southern Hemisphere, initiating the advance of glaciers in Patagonia and New Zealand, but these episodes did not coincide with those occurring in the Northern Hemisphere. Meanwhile, temperatures of other regions of the world, such as eastern China and the Andes, remained relatively stable during the Little Ice Age.
Still other regions experienced extended periods of drought, increased precipitation, or extreme swings in moisture. Many areas of northern Europe, for instance, were subjected to several years of long winters and short, wet summers, whereas parts of southern Europe endured droughts and season-long periods of heavy rainfall. Evidence also exists of multiyear droughts in equatorial Africa and Central and South Asia during the Little Ice Age.
For these reasons the Little Ice Age, though synonymous with cold temperatures, can also be characterized broadly as a period when there was an increase in temperature and precipitation variability across many parts of the globe.
The cause of the Little Ice Age is not known for certain; however, climatologists contend that reduced solar output, changes in atmospheric circulation, and explosive volcanism may have played roles in bringing about and extending the phenomenon.
Variability in solar output
It has long been understood that low sunspot activity is associated with lower solar output and thus less energy available to warm Earth’s surface. Two periods of unusually low sunspot activity are known to have occurred within the Little Ice Age period: the Spörer Minimum (1450–1540) and the Maunder Minimum (1645–1715). Both solar minimums coincided with the coldest years of the Little Ice Age in parts of Europe. Some scientists therefore argue that reduced amounts of available solar radiation caused the Little Ice Age. However, the absence of sunspots has not explained the brief cooling episodes that occurred in other parts of the world during this time. As a result, many scientists argue that reduced solar output cannot be the sole cause of the interval.
Changes in large-scale atmospheric patterns
Many scientists maintain that the Little Ice Age in Europe resulted from a reversal of the North Atlantic Oscillation (NAO), a large-scale atmospheric-circulation pattern over the North Atlantic and adjacent areas. The NAO is believed to have a large influence over winter weather in Europe. During its “positive” phase, characterized by a strong subtropical high-pressure cell over the Azores and a low-pressure cell over Iceland, the track of North Atlantic storms is roughly centred over the British Isles and northern Europe. During the NAO’s “negative” phase, characterized by a weak high-pressure cell over the Azores and a weak low-pressure cell over Iceland, moisture is funneled toward the Mediterranean, and cold Arctic air from Russia moves over northern Europe. Changes in the phases of the NAO may partly explain the variability in climate during the Little Ice Age as well as the known intervals of cooler-than-normal conditions in some European regions.
Tomorrows post is Changes in Winter Weather Statements by the NWS and my first hint at a winter forecast…. heee heee!
Might as well be a bullseye
http://www.cpc.noaa.gov/products/predictions/610day/610temp.new.gif
you can now see these maps on this site under Atmospheric Conditions…
Well John Dee has his winter “guess” out for the upcoming winter.
http://johndee.com//seasonalfcst/2017-18/seasonalforecast.htm
As he states take all winter guesses with a grain of salt.
slim
Yeah, it seems every time he says more snow, or above average snow, we end up with way less. If I was putting money down, I would bet on the rut we have been in for several years continuing through this Winter as well. We’ll probably get a week or two again where it will snow like crazy, then poof, it’s all gone and the mild trend continues.
Very nice information on The Little Ice age. I have to wonder if we are not in a “little warming age” at this time. As So far this fall the coldest it has officially gotten at Grand Rapids is 40° This year is the latest it has gotten in the fall without getting below 40° since 1914! There is a chance that we could set a new latest first sub 40° night this year.
Slim
Or how about “mini blowtorch age”! Ha! Just curious, but what is the date for latest sub 40 to reach the record?
October 25, 1914
Slim