Figure 5 - uploaded by Nicole K Davi
Content may be subject to copyright.
Location map of Nabesna Glacier. Base map from the U.S. Geological Survey 1:63 360 series, Nabesna C-4 sheet. Ice margin shown by shading is the 1957 position.
Similar publications
Citations
... Another possibility is that the T3 till includes the deposits of the two short but large-scale advances occurred between AD 7th and 9th centuries. This interval (AD 600-900) was also identified as a period of advances in Alaska and Coastal Ranges of Canada (Barclay et al., 2013;Reyes et al., 2006;Wiles et al., 2002Wiles et al., , 2004Young et al., 2009). ...
Three paleosols buried in the left lateral moraines of the Greater Azau Glacier (Northern Caucasus) were identified in an excavated outcrop (43.2658 N, 42.4766 E, 2370 m a.s.l.). When the glacier was overlying the surface of the lateral moraines at this site, the thickness of the ice was 50 m and more above the valley floor. Fragments of charcoal from the uppermost soil (S1) buried 0.6 m below the surface yielded the radiocarbon date 130 ± 20 yr BP (IGAN AMS -6826) (AD 1680–1939). The middle soil (S2), buried at the depth of 13 m yielded two ¹⁴ C dates 320 ± 20 yr BP (IGAN AMS -8127) (bark of birch) (AD 1496–1641) and 1190 ± 20 yr BP (IGAN AMS -8126) (AD 774–889) (charcoal). We suggest that the soil S2 has been formed between these dates during the Medieval Warm Period and in the early Little Ice Age. The lowermost (S3) unit lying 15 m below the surface is the thickest (0.4–0.6 m), well-developed paleosol. Charcoal collected at the top of S3, yielded the date 1300 ± 20 yr BP (IGAN AMS -6826) (AD 663–773), indicating a prominent glacier advance occurred shortly before this date. Two dates from the charcoal buried at the bottom of S3 (2855 ± 20 yr BP (IGAN AMS -8125) and 2880 ± 20 yr BP (IGAN AMS -6827) mark the beginning of a long episode of restricted glacier extent that lasted for about 1600 years. The dates at the bottom of the S3 paleosol constrain the end of glacier advance that occurred before 2800–2900 ¹⁴ C yr BP. The timing of most prominent advances of the Greater Azau Glacier in the past 3500 years is in general agreement with the Late-Holocene glacial chronologies in the European Alps, Scandinavia and other regions of the Northern Hemisphere.
... The issue of high-elevation warming is particularly important in the North Pacific because over 80,000 km 2 of alpine glaciers in this region are vulnerable to mass loss from warming temperatures (Arendt et al., 2002(Arendt et al., , 2009Berthier et al., 2010;Meier et al., 2007). Evidence suggests that the principal driver of glacial mass balance in much of this region is summer temperature (Arendt et al., 2009;Criscitiello et al., 2010;Josberger et al., 2007;Molnia, 2007;Wiles et al., 2002Wiles et al., , 2004, which has been increasing regionally during the last 50 years (Stafford et al., 2000;Wendler & Shulski, 2009). In response, North Pacific alpine glaciers have been rapidly receding, contributing as much as 0.27 mm/year to the global sea level rise budget (Arendt et al., 2002). ...
... This finding is relevant given that the glaciological response to warming is far more widespread than our melt layer record from Mt. Hunter. Studies throughout Alaska have found that summer temperature is the most important control on glacial mass balance and that glaciers will become increasingly sensitive to temperatures as summers warm further (Arendt et al., 2009;Criscitiello et al., 2010;Josberger et al., 2007;Molnia, 2007;Wiles et al., 2002Wiles et al., , 2004. Glaciers in this region have already undergone significant mass loss in response to rapid warming (Arendt et al., 2009;Berthier et al., 2010). ...
Warming in high-elevation regions has societally important impacts on glacier mass balance, water resources, and sensitive alpine ecosystems, yet very few high-elevation temperature records exist from the middle or high latitudes. While a variety of paleoproxy records provide critical temperature records from low elevations over recent centuries, melt layers preserved in alpine glaciers present an opportunity to develop calibrated, annually resolved temperature records from high elevations. Here we present a 400-year temperature proxy record based on the melt layer stratigraphy of two ice cores collected from Mt. Hunter in Denali National Park in the central Alaska Range. The ice core record shows a sixtyfold increase in water equivalent total annual melt between the preindustrial period (before 1850 Common Era) and present day. We calibrate the melt record to summer temperatures based on weather station data from the ice core drill site and find that the increase in melt production represents a summer warming rate of at least 1.92 ± 0.31°C per century during the last 100 years, exceeding rates of temperature increase at most low-elevation sites in Alaska. The Mt. Hunter melt layer record is significantly (p < 0.05) correlated with surface temperatures in the central tropical Pacific through a Rossby wave-like pattern that enhances high temperatures over Alaska. Our results show that rapid alpine warming has taken place in the Alaska Range for at least a century and that conditions in the tropical oceans contribute to this warming.
... The chronology of land-terminating glaciers in southeast coastal Alaska, Eagle, Mendenhall, and Herbert glaciers, as well as outlets of the Juneau Icefield, show advances between CE ~200 and ~320 according to radiocarbon ages (R€ othlisberger, 1986). An advance occurred in the Wrangell Mountains about CE 300 (Wiles et al., 2002 ). Other evidence of ice expansion at this time is rare. ...
... Along the southern coast, most glaciers reached their Holocene maxima in the past few centuries. However, some glaciers in the Alaska Range (Bijkerk, 1984) and one in the Wrangell Mountains (Wiles et al., 2002) show a more extensive first millennium advance. In general summer temperature is the primary limiting factor for land-terminating glaciers along the southern coast of Alaska in the Kenai, Chugach, St. Elias and the Coast Mountains (Barclay et al., 1999Barclay et al., , 2013 Wiles et al., 2004) (Fig. 2). ...
A global compilation of glacier advances and retreats for the past two millennia grouped by 17 regions (excluding Antarctica) highlights the nature of glacier fluctuations during the late Holocene. The dataset includes 275 time series of glacier fluctuations based on historical, tree ring, lake sediment, radiocarbon and terrestrial cosmogenic nuclide data. The most detailed and reliable series for individual glaciers and regional compilations are compared with summer temperature and, when available, winter precipitation reconstructions, the most important parameters for glacier mass balance. In many cases major glacier advances correlate with multi-decadal periods of decreased summer temperature. In a few cases, such as in Arctic Alaska and western Canada, some glacier advances occurred during relatively warm wet times. The timing and scale of glacier fluctuations over the past two millennia varies greatly from region to region. However, the number of glacier advances shows a clear pattern for the high, mid and low latitudes and, hence, points to common forcing factors acting at the global scale. Globally, during the first millennium CE glaciers were smaller than between the advances in 13th to early 20th centuries CE. The precise extent of glacier retreat in the first millennium is not well defined; however, the most conservative estimates indicate that during the 1st and 2nd centuries in some regions glaciers were smaller than at the end of 20th/early 21st centuries. Other periods of glacier retreat are identified regionally during the 5th and 8th centuries in the European Alps, in the 3rde6th and 9th centuries in Norway, during the 10the13th centuries in southern Alaska, and in the 18th century in Spitsbergen. However, no single period of common global glacier retreat of centennial duration, except for the past century, has yet been identified. In contrast, the view that the Little Ice Age was a period of global glacier expansion beginning in the 13th century (or earlier) and reaching a maximum in 17the19th centuries is supported by our data. The pattern of glacier variations in the past two millennia corresponds with cooling in reconstructed temperature records at the continental and hemispheric scales. The number of glacier advances also broadly matches periods showing high volcanic activity and low solar irradiance over the past two millennia, although the resolution of most glacier chronologies is not enough for robust Quaternary Science Reviews 149 (2016) 61e90 statistical correlations. Glacier retreat in the past 100e150 years corresponds to the anthropogenic global temperature increase. Many questions concerning the relative strength of forcing factors that drove glacier variations in the past 2 ka still remain.
... Finally, during the late Holocene the glaciers of Alaska experienced the last major glacial expansion during the LIA. LIA glacial chronologies are well represented and studied in several ice fields and individual glaciers of south-central Alaska (Barclay et al. 2003(Barclay et al. , 2006(Barclay et al. , 2009Calkin et al. 2001;Crossen 2007;Wiles 1994;Wiles et al. 1995Wiles et al. , 1999Wiles et al. , 2002Wiles et al. , 2008. Dates for LIA advances of College Fjord tidewater glaciers are still unknown due to the lack of datable material and the fact that some glaciers such as Harvard and Smith have not yet retreated from their LIA maximum positions. ...
... Elias, and Kenai Mountain Ranges , as well in the Wrangell Mountains ca. 2.0 ka [Wiles et al. 2002], which would be expected under an increase in winter storms and snow accumulation in the region. ...
... 20% Alnus increase paralleling a 2 C increase in temperature over the last 60 years, calculated from sedimentation rate inFig. 2. Neoglacial advances in southern Alaskan as early as 4 ka have been noted (Tuthill et al., 1968; Denton and Karlen, 1977; Mann and Hamilton, 1995; Wiles et al., 2002), and Barclay et al. (2009) summarize the data for advances beginning at 4 ka and major advances at 3 ka with perhaps 2 distinct expansions occurring from 3.3 to 2.9 ka and from 2.2 to 2.0 ka. Focusing on the last two millennia, tree ring studies from four adjacent valley glacier-killed stumps and logs demonstrate the Sheridan Glacier advances at 530 to 640 CE, then 1240se1280s CE, and in the Little Ice Age from 1510 to 1700's and 1810se1860s CE (Barclay et al., 2013). ...
Pollen, spore, macrofossil and carbon data from a peatland near Cordova, Alaska, reveal insights into the climate-vegetation-carbon interactions from the initiation of the Holocene, c. the last 11.5 ka, to the present (1 ka = 1000 calibrated years before present where 0 = 1950 CE). The Holocene period is characterized by early deposition of gyttja in a pond environment with aquatics such as Nuphar polysepalum and Potamogeton, and a significant regional presence of Alnus crispa subsp. sinuata. Carbon accumulation (50 g/m2/a) was high for a short interval in the early Holocene when Sphagnum peat accumulated, but was followed by a major decline to 13 g/m2/a from 7 to 3.7 ka when Cyperaceae and ericads such as Rhododendron (formerly Ledum) groenlandicum expanded. This shift to sedge growth is representative of many peatlands throughout the south-central region of Alaska, and indicates a drier, more evaporative environment with a large decline in carbon storage. The subsequent return to Sphagnum peat after 4 ka in the Neoglacial represents a widespread shift to moister, cooler conditions, which favored a resurgence of ericads, such as Andromeda polifolia, and increased carbon accumulation rate. The sustained Alnus expansion visible in the top 10 cm of the peat profile is correlative with glacial retreat and warming of the region in the last century, and suggests this colonization will continue as temperature increases and ice melts.
... Elias and Kenai Mountains (Barclay et al., 2009a,b). Ice advance is recognized in the Wrangell Mountains at about 2.0 ka (Wiles et al., 2002) and in the Coast Mountains about 2.2e2.0 ka (R€ othlisberger, 1986). ...
... A strong advance during the first millennium AD (~600e900 CE) is dated with radiocarbon (Wiles et al., 2002(Wiles et al., , 2004 and tree-rings (Barclay et al., 2013) along the coast and with lichen in the Brooks and Alaska Ranges (Barclay et al., 2009a,b) and in the Alaska Range using 10 Be and lichen (Young et al., 2009). This expansion is especially strong along the coastal ranges of Canada and the Gulf of Alaska (Reyes et al., 2006;Barclay et al., 2009aBarclay et al., , 2009b. ...
A global overview of glacier advances and retreats (grouped by regions and by millennia) for the Holocene is compiled from previous studies. The reconstructions of glacier fluctuations are based on 1) mapping and dating moraines defined by 14C, TCN, OSL, lichenometry and tree rings (discontinuous records/time series), and 2) sediments from proglacial lakes and speleothems (continuous records/time series). Using 189 continuous and discontinuous time series, the long-term trends and centennial fluctuations of glaciers were compared to trends in the recession of Northern and mountain tree lines, and with orbital, solar and volcanic studies to examine the likely forcing factors that drove the changes recorded. A general trend of increasing glacier size from the early–mid Holocene, to the late Holocene in the extra-tropical areas of the Northern Hemisphere (NH) is related to overall summer temperature, forced by orbitally-controlled insolation. The glaciers in New Zealand and in the tropical Andes also appear to follow the orbital trend, i.e., they were decreasing from the early Holocene to the present. In contrast, glacier fluctuations in some monsoonal areas of Asia and southern South America generally did not follow the orbital trends, but fluctuated at a higher frequency possibly triggered by distinct teleconnections patterns. During the Neoglacial, advances clustered at 4.4–4.2 ka, 3.8–3.4 ka, 3.3–2.8 ka, 2.6 ka, 2.3–2.1 ka, 1.5–1.4 ka, 1.2–1.0 ka, 0.7–0.5 ka, corresponding to general cooling periods in the North Atlantic. Some of these episodes coincide with multidecadal periods of low solar activity, but it is unclear what mechanism might link small changes in irradiance to widespread glacier fluctuations. Explosive volcanism may have played a role in some periods of glacier advances, such as around 1.7–1.6 ka (coinciding with the Taupo volcanic eruption at 232 ± 5 CE) but the record of explosive volcanism is poorly known through the Holocene. The compilation of ages suggests that there is no single mechanism driving glacier fluctuations on a global scale. Multidecadal variations of solar and volcanic activity supported by positive feedbacks in the climate system may have played a critical role in Holocene glaciation, but further research on such linkages is needed. The rate and the global character of glacier retreat in the 20th through early 21st centuries appears unusual in the context of Holocene glaciation, though the retreating glaciers in most parts of the Northern Hemisphere are still larger today than they were in the early and/or mid-Holocene. The current retreat, however, is occurring during an interval of orbital forcing that is favorable for glacier growth and is therefore caused by a combination of factors other than orbital forcing, primarily strong anthropogenic effects. Glacier retreat will continue into future decades due to the delayed response of glaciers to climate change.
... The Cabin Lake sedimentary sequence implies a glacial advance during the early 12th century (1110 CE), whereas other records typically place the earliest Little Ice Age advance at 1180 CE (Wiles et al., 2008). Our record adds to evidence from the forefields of Kennicott Glacier in the Wrangell Mountains and Princeton Glacier west of Prince William Sound (Wiles et al., 1999Wiles et al., , 2002) indicating that glaciers in southern Alaska were advancing during the early 12th century. Tree-ring-based temperature reconstructions indicate that the early 12th century was relatively warm in the Gulf of Alaska region (D'Arrigo et al., 2006). ...
Marked changes in sediment types deposited in Cabin Lake, near Cordova, Alaska, represent environmental shifts during the early and late Holocene, including fluctuations in the terminal position of Sheridan Glacier. Cabin Lake is situated to receive meltwater during periods when the outwash plain of the advancing Sheridan Glacier had aggraded. A brief early Holocene advance from 11.2 to 11.0 cal ka is represented by glacial rock flour near the base of the sediment core. Non-glacial lake conditions were restored for about 1000 years before the water level in Cabin Lake lowered and the core site became a fen. The fen indicates drier-than-present conditions leading up to the Holocene thermal maximum. An unconformity spanning 5400 years during the mid-Holocene is overlain by peat until 1110 CE when meltwater from Sheridan Glacier returned to the basin. Three intervals of an advanced Sheridan Glacier are recorded in the Cabin Lake sediments during the late Holocene: 1110–1180, 1260–1540 and 1610–1780 CE. The sedimentary sequence also contains the first five reported tephra deposits from the Copper River delta region, and their geochemical signatures suggest that the sources are the Cook Inlet volcanoes Redoubt, Augustine and Crater Peak, and possibly Mt Churchill in the Wrangell Volcanic field.
... Further, moraine 3 is older than the next terminus position further inboard (position D in Fig. 1), whose date (ad 1972) and position is known from aerial photography. The age of the furthest outboard moraine (1) sits well within the age range of the LIA maximum, as known from coastal and interior sites in the vicinity of Chisma Glacier (Wiles et al. 2002). It is also consistent with independent evidence for abandonment of the LIA maximum shoreline of ice-dammed Iceberg Lakepresumably due to thinning of the impounding Tana Glacier -in ad 1825 (Loso et al. 2004). ...
Contemporary variants of the lichenometric dating technique depend upon statistical correlations between surface age and maximum lichen sizes, rather than an understanding of lichen biology. To date three terminal moraines of an Alaskan glacier, we used a new lichenometric technique in which surfaces are dated by comparing lichen population distributions with the predictions of ecological demography models with explicit rules for the biological processes that govern lichen populations: colonization, growth, and survival. These rules were inferred from size–frequency distributions of lichens on calibration surfaces, but could be taken directly from biological studies. Working with two lichen taxa, we used multinomial-based likelihood functions to compare model predictions with measured lichen populations, using only the thalli in the largest 25% of the size distribution. Joint likelihoods that combine the results of both species estimated moraine ages of ad 1938, 1917, and 1816. Ages predicted by Rhizocarpon alone were older than those of P. pubescens. Predicted ages are geologically plausible, and reveal glacier terminus retreat after a Little Ice Age maximum advance around ad 1816, with accelerated retreat starting in the early to mid twentieth century. Importantly, our technique permits calculation of prediction and model uncertainty. We attribute large confidence intervals for some dates to the use of the biologically variable Rhizocarpon subgenus, small sample sizes, and high inferred lichen mortality. We also suggest the need for improvement in demographic models. A primary advantage of our technique is that a process-based approach to lichenometry will allow direct incorporation of ongoing advances in lichen biology.
... The surface age is frequently established following examination of sequential historical images or aerial photographs (Garbarino et al., 2010; Masiokas et al., 2009; Wiles and Calkin, 1994; Winchester and Harrison, 2000). While it is recognized that ecesis is species-specific and dependent upon local geological, topographical, and microclimate controls (McCarthy and Luckman, 1993), ecesis estimates established elsewhere or for different species are often applied to local study environments (Luckman, 1995; Smith et al., 1995; Wiles et al., 1999 Wiles et al., , 2002 Wiles et al., , 2003). Under-or over-age estimation of a surface can occur as a result of false or locally absent tree rings. ...
Dendroglaciology uses tree-ring dating principles to assign ages to glacier-related sediments, landforms, and landscape processes. This article reviews some common dendroglaciological methodologies and illustrates how tree rings are used to describe episodes of glacier expansion, retreat, and/or downwasting. Applied dendroglaciology provides a means for developing proxy reconstructions of summer, winter, and net annual mass balance that highlight the influence of multiscale climate forcing mechanisms on both trees and glaciers. Combined with tree-ring dating of glacier deposits, these records provide a more complete temporal and spatial picture of paleoglacier–climate relationships, useful for understanding how glaciers may respond to future climates.
