'Little Ice Age' summer temperature variations: their nature and relevance to recent global warming trends

The Holocene ◽  
1993 ◽  
Vol 3 (4) ◽  
pp. 367-376 ◽  
Author(s):  
Raymond S. Bradley ◽  
Philip D. Jonest
1992 ◽  
Vol 16 ◽  
pp. 11-16 ◽  
Author(s):  
Liu Chaohai ◽  
Han Tianding

Since the Little Ice Age, most glaciers in the Tien Shan mountains have been retreating. Owing to an increase in precipitation in most parts of the mountains during the late 1950s to early 1970s, the percentage of receding glaciers and the speed of retreat have tended to decrease in the 1970s. However, the general trend of continuous glacier retreat remains unchanged, in part because the summer air temperature shows no tendency to decrease.In the Tien Shan mountains, as the degree of climatic continentality increases the mass balance becomes more dependent on summer temperature, and accumulation and ablation tend to be lower. Therefore, the responses of glaciers to climatic fluctuations in more continental areas are not synchronous with those in less continental areas, and the amplitude of the glacier variations becomes smaller.


1977 ◽  
Vol 7 (1) ◽  
pp. 63-111 ◽  
Author(s):  
George H. Denton ◽  
Wibjörn Karlén

Complex glacier and tree-line fluctuations in the White River valley on the northern flank of the St. Elias and Wrangell Mountains in southern Alaska and Yukon Territory are recognized by detailed moraine maps and drift stratigraphy, and are dated by dendrochronology, lichenometry,14C ages, and stratigraphic relations of drift to the eastern (123014C yr BP) and northern (198014C yr BP) lobes of the White River Ash. The results show two major intervals of expansion, one concurrent with the well-known and widespread Little Ice Age and the other dated between 2900 and 210014C yr BP, with a culmination about 2600 and 280014C yr BP. Here, the ages of Little Ice Age moraines suggest fluctuating glacier expansion between ad 1500 and the early 20th century. Much of the 20th century has experienced glacier recession, but probably it would be premature to declare the Little Ice Age over. The complex moraine systems of the older expansion interval lie immediately downvalley from Little Ice Age moraines, suggesting that the two expansion intervals represent similar events in the Holocene, and hence that the Little Ice Age is not unique. Another very short-lived advance occurred about 1230 to 105014C yr BP. Spruce immigrated into the valley to a minimum altitude of 3500 ft (1067 m), about 600 ft (183 m) below the current spruce tree line of 4100 ft (1250 m), at least by 802014C yr BP. Subsequent intervals of high tree line were in accord with glacier recession; in fact, several spruce-wood deposits above current tree line occur bedded between Holocene tills. High deposits of fossil wood range up to 76 m above present tree line and are dated at about 5250, 3600 to 3000, and 2100 to 123014C yr BP. St. Elias glacial and tree-line fluctuations, which probably are controlled predominantly by summer temperature and by length of the growing and ablation seasons, correlate closely with a detailed Holocene tree-ring curve from California, suggesting a degree of synchronism of Holocene summer-temperature changes between the two areas. This synchronism is strengthened by comparison with the glacier record from British Columbia and Mt. Rainier. Likewise, broad synchronism of Holocene events exists across the Arctic between the St. Elias Mountains and Swedish Lappland. Finally, two sequences from the Southern Hemisphere show similar records, in so far as dating allows. Hence, we believe that a preliminary case can be made for broad synchronism of Holocene climatic fluctuations in several regions, although further data are needed and several areas, particularly Colorado and Baffin Island, show major differences in the regional pattern.


2001 ◽  
Vol 80 (5) ◽  
pp. 160
Author(s):  
Richard N. Cooper ◽  
Brian Fagan

2009 ◽  
Vol 66 (7) ◽  
pp. 1508-1514 ◽  
Author(s):  
Arturo Sousa ◽  
Pablo García-Murillo ◽  
Julia Morales ◽  
Leoncio García-Barrón

Abstract Sousa, A., García-Murillo, P., Morales, J., and García-Barrón, L. 2009. Anthropogenic and natural effects on the coastal lagoons in the southwest of Spain (Doñana National Park). – ICES Journal of Marine Science, 66: 1508–1514. The Doñana peridunal lagoons, located in the southwest of Spain, have been well studied, because their conservation is of great interest. Since 1965, they have also been affected by the extraction of underground water for local coastal tourist resorts. A reconstruction of the evolution of this series of coastal lagoons reveals that, along with the anthropogenic effect, there was a natural effect resulting from the reactivation of mobile dune fronts that have blocked and filled the original lagoon complex—in the period 1920–1987, the lagoons were reduced by 70.7%. These fronts might have been fed by deposits of marine sand during the climatically driest phases of the Little Ice Age in Andalusia, Spain. Therefore, if the frequency and duration of dry periods increase, as well as droughts as a whole, because of global warming, the desiccation and disappearance of the lagoons could become more widespread, not only at this site in southwestern Europe, but in other Mediterranean coastal ecosystems as well.


2020 ◽  
Vol 66 (259) ◽  
pp. 777-789
Author(s):  
Grégoire Guillet ◽  
Ludovic Ravanel

AbstractDeglaciation of high mountain rockwalls alters slope stability as rockwalls become more sensitive to modifications in environmental factors (e.g. seasonal temperature variations). In the past decades, increasing efforts focused on studying deglaciated Alpine rockwalls. Yet, currently deglaciating rockfaces remain unstudied. Here, we quantify surface area variations of massive ice bodies lying on high mountain rockwalls (ice aprons) in the French sector of the Mont Blanc massif between the end of the Little Ice Age (LIA) and 2018. Surface area estimates are computed from terrestrial and aerial oblique photographs via photogrammetry. This technique allows using photographs taken without scientific intent, and to tap into diverse historical or recent photographic catalogs. We derive an ice apron surface area model from precipitation records and the positive degree-days. The studied ice aprons shrank from 1854 to the 1950s, before expanding until the end of the 1990s. The beginning of the 21st century shows a decrease in surface area, leading to the complete melt of one of the studied ice aprons in 2017. Observed variations correlate with modeled surface area, suggesting strong sensitivity of ice aprons to changes in climatic variables. By studying site-specific correlations, we explore the importance of local drivers over the balance of ice aprons.


2005 ◽  
Vol 1 (2) ◽  
pp. 155-168 ◽  
Author(s):  
S. Hou ◽  
J. Chappellaz ◽  
J. Jouzel ◽  
P. C. Chu ◽  
V. Masson-Delmotte ◽  
...  

Abstract. Two Himalayan ice cores display a factor-two decreasing trend of air content over the past two millennia, in contrast to the relatively stable values in Greenland and Antarctica ice cores over the same period. Because the air content can be related with the relative frequency and intensity of melt phenomena, its variations along the Himalayan ice cores provide an indication of summer temperature trend. Our reconstruction point toward an unprecedented warming trend in the 20th century but does not depict the usual trends associated with "Medieval Warm Period" (MWP), or "Little Ice Age" (LIA).


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