‘Little Ice Age’ maxima and glacier retreat in northern Troms and western Finnmark, northern Norway

2020 ◽  
Author(s):  
Joshua Leigh ◽  
Chris Stokes ◽  
David Evans ◽  
Rachel Carr ◽  
Liss Andreassen
Keyword(s):  
Little Ice Age ◽  
Ice Age ◽  
Early 20Th Century ◽  
Main Study ◽  
Remotely Sensed Data ◽  
Mountain Glacier ◽  
Northern Norway ◽  
Glacier Recession ◽  
Proglacial Lakes ◽  
Main Study Area

<p>Glaciers are important indicators of climate change and observations worldwide document increasing rates of mountain glacier recession. Here we present ~200 years of change in mountain glacier extent in northern Troms and western Finnmark. This was achieved through: (1) mapping recent (post-1980s) changes in ice extent from remotely sensed data and (2) lichenometric dating and mapping of major moraine systems within a sub-set of the main study area (the Rotsund Valley). Lichenometric dating reveals that the Little Ice Age (LIA) maximum occurred as early as AD 1814 (±41 years), which is before the early-20th century LIA maximum proposed on the nearby Lyngen Peninsula, but younger than the LIA maximum limits in southern and central Norway (ca. AD 1740-50). Between LIA maximum and AD 1989, the reconstructed glaciers (n = 15) shrank by 3.9 km<sup>2</sup> (39%), with those that shrank by >50% fronted by proglacial lakes. Between AD 1989 and 2018, the total area of glaciers within the study area (n = 219 in AD 1989) shrank by ~35 km<sup>2</sup>. Very small glaciers (<0.5 km<sup>2</sup> in AD 1989) show the highest relative rates of shrinkage, and 90% of mapped glaciers within the study area are <0.5 km<sup>2</sup> as of AD 2018.</p>

scholarly journals Skaftafellsjökull, Iceland: glacial geomorphology recording glacier recession since the Little Ice Age

2017 ◽  
Vol 13 (2) ◽  
pp. 358-368 ◽  
Author(s):  
David J. A. Evans ◽  
Marek Ewertowski ◽  
Chris Orton
Keyword(s):  
Little Ice Age ◽  
Ice Age ◽  
Glacial Geomorphology ◽  
Glacier Recession

Recent, rapid and profound changes to glacier morphology and dynamics, Juneau Icefield, Alaska

2021 ◽  
Author(s):  
Bethan Davies ◽  
Jacob Bendle ◽  
Robert McNabb ◽  
Jonathan Carrivick ◽  
Christopher McNeil ◽  
...  
Keyword(s):  
Little Ice Age ◽  
Ice Age ◽  
Aerial Photographs ◽  
Equilibrium Line Altitude ◽  
Regional Warming ◽  
Geomorphological Mapping ◽  
Glacier Recession ◽  
Digital Elevation ◽  
High Resolution Satellite Imagery ◽  
Global Sea Level

<p>The Alaskan region (comprising glaciers in Alaska, British Columbia and Yukon) contains the third largest ice volume outside of the Greenland and Antarctic ice sheets, and contributes more to global sea level rise than any other glacierised region defined by the Randolph Glacier Inventory. However, ice loss in this area is not linear, but in part controlled by glacier hypsometry as valley and outlet glaciers are at risk of becoming detached from their accumulation areas during thinning. Plateau icefields, such as Juneau Icefield in Alaska, are very sensitive to changes in Equilibrium Line Altitude (ELA) as this can result in rapidly shrinking accumulation areas. Here, we present detailed geomorphological mapping around Juneau Icefield and use this data to reconstruct the icefield during the “Little Ice Age”. We use topographic maps, archival aerial photographs, high-resolution satellite imagery and digital elevation models to map glacier lake and glacier area and volume change from the Little Ice Age to the present day (1770, 1948, 1979, 1990, 2005, 2015 and 2019 AD). Structural glaciological mapping (1979 and 2019) highlights structural and topographic controls on non-linear glacier recession.  Our data shows pronounced glacier thinning and recession in response to widespread detachment of outlet glaciers from their plateau accumulation areas. Glacier detachments became common after 2005, and occurred with increasing frequency since then. Total summed rates of area change increased eightfold from 1770-1948 (-6.14 km<sup>2</sup> a<sup>-1</sup>) to 2015-2019 (-45.23 km<sup>2</sup> a<sup>-1</sup>). Total rates of recession were consistent from 1770 to 1990 AD, and grew increasingly rapid after 2005, in line with regional warming.</p>

Holocene Glacial and Tree-Line Variations in the White River Valley and Skolai Pass, Alaska and Yukon Territory

1977 ◽  
Vol 7 (1) ◽  
pp. 63-111 ◽  
Author(s):  
George H. Denton ◽  
Wibjörn Karlén
Keyword(s):  
20Th Century ◽  
Little Ice Age ◽  
Yukon Territory ◽  
Summer Temperature ◽  
River Valley ◽  
Ice Age ◽  
The Arctic ◽  
Tree Line ◽  
White River ◽  
Glacier Recession

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.

Pattern and Forcing of Northern Hemisphere Glacier Variations During the Last Millennium

1986 ◽  
Vol 26 (1) ◽  
pp. 27-48 ◽  
Author(s):  
Stephen C. Porter
Keyword(s):  
Northern Hemisphere ◽  
Little Ice Age ◽  
Ice Core ◽  
Volcanic Eruptions ◽  
Ice Age ◽  
Phase Lag ◽  
Mountain Glacier ◽  
Radiocarbon Dates ◽  
Glacier Fluctuations ◽  
Decadal Scale

Time series depicting mountain glacier fluctuations in the Alps display generally similar patterns over the last two centuries, as do chronologies of glacier variations for the same interval from elsewhere in the Northern Hemisphere. Episodes of glacier advance consistently are associated with intervals of high average volcanic aerosol production, as inferred from acidity variations in a Greenland ice core. Advances occur whenever acidity levels rise sharply from background values to reach concentrations ≥1.2 μequiv H+/kg above background. A phase lag of about 10–15 yr, equivalent to reported response lags of Alpine glacier termini, separates the beginning of acidity increases from the beginning of subsequent ice advances. A similar relationship, but based on limited and less-reliable historical data and on lichenometric ages, is found for the preceding 2 centuries. Calibrated radiocarbon dates related to advances of non-calving and non-surging glaciers during the earlier part of the Little Ice Age display a comparable consistent pattern. An interval of reduced acidity values between about 1090 and 1230 A.D. correlates with a time of inferred glacier contraction during the Medieval Optimum. The observed close relation between Noothern Hemisphere glacier fluctuations and variations in Greenland ice-core acidity suggests that sulfur-rich aerosols generated by volcanic eruptions are a primary forcing mechanism of glacier fluctuations, and therefore of climate, on a decadal scale. The amount of surface cooling attributable to individual large eruptions or to episodes of eruptions is simlar to the probable average temperature reduction during culminations of Little Ice Age alacier advances (ca. 0.5°–1.2°C), as inferred from depression of equilibrium-line altitudes.

The status of research on glaciers and global glacier recession: a review

2006 ◽  
Vol 30 (3) ◽  
pp. 285-306 ◽  
Author(s):  
Roger G. Barry
Keyword(s):  
Global Climate ◽  
Ice Age ◽  
Remotely Sensed Data ◽  
New Techniques ◽  
Mountain Glaciers ◽  
Glacier Recession ◽  
The Status ◽  
Global Sea Level ◽  
Key Indicators

Mountain glaciers are key indicators of climate change, although the climatic variables involved differ regionally and temporally. Nevertheless, there has been substantial glacier retreat since the Little Ice Age and this has accelerated over the last two to three decades. Documenting these changes is hampered by the paucity of observational data. This review outlines the measurements that are available, new techniques that incorporate remotely sensed data, and major findings around the world. The focus is on changes in glacier area, rather than estimates of mass balance and volume changes that address the role of glacier melt in global sea-level rise. The glacier observations needed for global climate monitoring are also outlined.

scholarly journals Timing of Little Ice Age maxima and subsequent glacier retreat in northern Troms and western Finnmark, northern Norway

2020 ◽  
Vol 52 (1) ◽  
pp. 281-311
Author(s):  
J. R. Leigh ◽  
C. R. Stokes ◽  
D. J. A. Evans ◽  
R. J. Carr ◽  
L. M. Andreassen
Keyword(s):  
Little Ice Age ◽  
Glacier Retreat ◽  
Ice Age ◽  
Northern Norway

scholarly journals Neoglaciation in the Southern Kenai Mountains, Alaska

1990 ◽  
Vol 14 ◽  
pp. 319-322 ◽  
Author(s):  
Gregory C. Wiles ◽  
Parker E. Calkin
Keyword(s):  
Little Ice Age ◽  
Late Holocene ◽  
Ice Age ◽  
Past Century ◽  
Partial Control ◽  
The Past ◽  
Proglacial Lakes ◽  
Glacial Chronology ◽  
Historical Accounts ◽  
Ice Complex

A preliminary late-Holocene glacial chronology from the west flank of the southern Kenai Mountains, Alaska, is characterized by two major episodes of advance. Outlet glaciers of both the Harding Icefield and the Grewingk-Yalik ice complex were expanding across their present positions at 545 A.D. and again during the Little Ice Age, about 1500 A.D. The earliest of these Neoglacial advances is dated by radiocarbon ages from the outer rings of tree trunks rooted near the margins of Grewingk and Dinglestadt glaciers. Subsequently, ice margins retreated some distance behind their present positions allowing marked soil development before the last readvance through mature forest. Wood preserved in lateral moraines at Grewingk Glacier and from an uprooted stump at Tustemena Glacier date this later ice advance. Tree-ring ages, correlated with lichen diameters, suggest that this last advance was widespread and culminated in its Neoglacial maximum about 1800 A.D.. Since this time, glacier retreat has dominated in the area, punctuated by at least two pauses. Historical accounts and photographs document a mean rate of retreat of 27 m a−1 for the past century with partial control exerted by calving of ice margins into proglacial lakes.

Climatic variation and runoff in mountain basins with differing proportions of glacier cover*

2006 ◽  
Vol 37 (4-5) ◽  
pp. 315-326 ◽  
Author(s):  
David N. Collins
Keyword(s):  
Air Temperature ◽  
Little Ice Age ◽  
Climatic Variation ◽  
Ice Age ◽  
Precipitation Data ◽  
Climatic Fluctuation ◽  
Temperature And Precipitation ◽  
Glacier Recession ◽  
Mountain Basins ◽  
High Elevations

Records of discharge from partially-glacierised basins in the upper Rhône catchment, Switzerland, were examined together with air temperature and precipitation data in order to assess impacts of climatic fluctuation and percentage glacierisation of basin on runoff, as glaciers declined from dimensions attained during the Little Ice Age. Above 60% glacierisation, year-to-year variations in runoff mimicked mean May–September air temperature, rising in the warm 1940s, declining in the cool 1970s, before increasing (by 50%) into the warm dry 1990s/2000s but not reaching 1940s maxima. In basins with between 35–60% glacierisation, flow also increased into the 1980s but waned through the 1990s. With less than 2% glacierisation, the pattern of runoff was broadly the inverse of that of temperature and followed precipitation, dipping in the 1940s, rising in the cool wet late 1960s, and declining into the 1990s/2000s, with glacier melt in warm years being insufficient to offset lack of precipitation. On mid-sized glaciers at relatively low elevations and with limited vertical extent, in warmer years, the transient snow line was above the highest point of the glacier. Only on large glaciers descending from high elevations can rising transient snowlines continue to expose more ice to melt. Runoff from such large glaciers was enhanced in warm summers but reduction of overall ice area through glacier recession led to runoff in the warmest summer (2003) being lower than the previous peak discharge recorded in the second warmest year (1947).

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