Mauri Pelto

Nichols College · Academic Affairs

Globally, glaciers and icefields contribute significantly to sea level rise. Here we show that ice loss from Juneau Icefield, a plateau icefield in Alaska, accelerated after 2005 AD. Rates of area shrinkage were 5 times faster from 2015–2019 than from 1979–1990. Glacier volume loss remained fairly consistent (0.65–1.01 km³ a⁻¹) from 1770–1979 AD, r...

The highest reaches of our planet experience some of the most extreme weather on Earth and hold very significant supplies of freshwater for communities downstream. However, we know very little of the meteorological detail about this high‐altitude frontier. We address this here with new winter weather observations from the upper reaches of Mount Eve...

The thirty-eight-year record (1984–2021) of glacier mass balance measurement indicates a significant glacier response to climate change in the North Cascades, Washington that has led to declining glacier runoff in the Nooksack Basin. Glacier runoff in the Nooksack Basin is a major source of streamflow during the summer low-flow season and mitigates...

Globally, mountain glaciers and ice caps are losing dramatic volumes of ice. The resultant sea‐level rise is dominated by contributions from Alaska. Plateau icefields may be especially sensitive to climate change due to the non‐linear controls their topography imparts on their response to climate change. However, Alaskan plateau icefields have been...

Worldwide the resilience of mountain ecosystems to transient changes in climate and anthropogenic footprint has been reduced (Schirpke et al., 2017; Chettri et al., 2020). The reduced resilience has a direct impact on the sustenance of the biotic and abiotic resources that include snow, glaciers, permafrost, soils, forests, alpine meadows, alpine l...

We find that the historic first wintertime ascent of K2 in January 2021 by a Nepalese team was aided by weather that was anomalously favourable. An upper‐level ridge brought low wind speeds, and relatively high temperatures and air pressures that were quite uncharacteristic of winter. Extraordinary ability in the climbing team aligning with opportu...

Recent observations of rising snow lines and reduced snow-covered areas on glaciers during the October 2020–January 2021 period in the Nepal–China region of Mount Everest in Landsat and Sentinel imagery highlight observations that significant ablation has occurred in recent years on many Himalayan glaciers in the post-monsoon and early winter perio...

From 1981 to 2019 I have spent every summer working on alpine glaciers examining the mass balance response to climate change. It is evident that the changes are significant, not happening at a “glacial” pace and are profoundly affecting alpine regions. The World Glacier Monitoring Service (2020) provides a detailed examination of alpine glacier mas...

This study reports the changes in glacier extent and streamflow similar to many Himalayan studies, but takes the unusual step of also linking these to downstream land use changes in Kashmir Valley. This study assessed changes in the area, snout, and equilibrium line altitude (ELA) of four parts of the Kolahoi Glacier using earth observation data fr...

We reanalyzed mass balance records at Taku and Lemon Creek Glaciers to better understand the relative roles of hypsometry, local climate and dynamics as mass balance drivers. Over the 1946–2018 period, the cumulative mass balances diverged. Tidewater Taku Glacier advanced and gained mass at an average rate of +0.25 ± 0.28 m w.e. a –1 , contrasting...

We present PATICE, a GIS database of Patagonian glacial geomorphology and recalibrated chronological data. PATICE includes 58,823 landforms and 1,669 geochronological ages, and extends from 38°S to 55°S in southern South America. We use these data to generate new empirical reconstructions of the Patagonian Ice Sheet (PIS) and subsequent ice masses...

Glacier-mass changes are a reliable indicator of climate change. On behalf of the worldwide network of glacier observers, we urge parties to the United Nations Framework Convention on Climate Change to boost international cooperation in monitoring these changes, and to include the results in the Paris agreement’s global stocktake.

The Juneau Icefield Research Program (JIRP) has been examining the glaciers of the Juneau Icefield since 1946. The height of the transient snowline (TSL) at the end of the summer represents the annual equilibrium line altitude (ELA) for the glacier, where ablation equals accumulation. On Taku Glacier the ELA has been observed annually from 1946 to...

In 1983, the North Cascade Glacier Climate Project (NCGCP) began the annual monitoring of the mass balance on 10 glaciers throughout the range, in order to identify their response to climate change. Annual mass balance (Ba) measurements have continued on seven original glaciers, with an additional two glaciers being added in 1990. The measurements...

Assessing and modeling precipitation in mountainous areas remains a major challenge in glacier mass balance modeling. Observations are typically scarce and reanalysis data and similar climate products are too coarse to accurately capture orographic effects. Here we use the linear theory of orographic precipitation model (LT model) to downscale wint...

In 1983 the North Cascade Glacier Climate Project (NCGCP) began annual monitoring 10 glaciers throughout the range, to identify their response to climate change. The annual observations include mass balance, terminus behaviour, and accumulation area ratio (AAR). Annual mass balance (Ba) measurements have been continued on 7 original glaciers that s...

Recent inventories indicate that glacier area and volume losses are currently large and accelerating in Western Canada. This chapter examines a series of Landsat images from 1986 to 2015 to identify the retreat and to forecast whether the glacier can survive even current climate conditions. Yoho Glacier is the largest southern outflow draining the...

The glaciers of northern Novaya Zemlya, Russia, are truly generally out of sight out of mind, their remoteness and lack of importance as a water resource being the key reasons. It seems important to pay attention to these glaciers due to the recent changes in sea ice cover that have left a much longer duration of open water around the island partic...

The North Cascades, Washington, are host to more glaciers than any other region of the United States outside of Alaska. The glaciers are small and occupy a temperate maritime climate setting, making them particularly sensitive to climate. Glacier retreat and changes in summer runoff have been pronounced in the Skykomish River Basin, North Cascades,...

Glacier fluctuations in terminus position, mass balance, and area are recognized as one of the most reliable indicators of climate change. The recognition of glacier sensitivity to climate led to the development of a global reporting system for glacier terminus change and glacier mass balance during the International Geophysical Year (IGY). Observa...

Most of the large glaciers in Svalbard are tidewater calving glaciers. This chapter focuses on the glaciers of Hornsund Fjord that in 2014 almost cuts through the southern island of Svalbard. There are five glaciers along the south coast of Hornsund Fjord. From east to west, they are Svalisbreen, Mendeljevbreen, Chomjakovbreen, Samarinbreen, and Ko...

The Southern Alps of New Zealand are host to over 3000 glaciers that owe their existence to high amounts of precipitation ranging from 3 to 10m. Lake Tekapo and Lake Pukaki are both utilized for hydropower. The reduction of glacier area in the region will reduce summer runoff into Lake Pukaki and this hydropower system. Mueller Glacier drains the e...

The European Alps have been the most thoroughly observed glaciated mountain range in the world. Recent inventories from Austria, France, Italy, and Switzerland reveal the same trend of accelerating mass loss and retreat since 1990. This chapter examines a pair of satellite images from 1990 and 2015 that span the Alps from Mont Blanc, France, to the...

Loss of area and volume of alpine glaciers is persistent across alpine ranges of the world. The homogenous response of glaciers from region to region indicates the global nature of the climate change when forcing a glacier response. Geographically glacier retreat is leading to the development and expansion of numerous alpine lakes. Regionally glaci...

The Andes Mountains in the Patagonia region of Chile and Argentina are host to three significant icefields and numerous regions of mountain glaciers. The rate of change was observed to be fastest for the more northerly glaciers, with the Northern Patagonia Icefield (NPI) glaciers shrinking particularly rapidly. Reichert Glacier is at the northwest...

Climate change may cause variations in both temperature and snowfall, causing changes in the surface mass balance. In the ablation zone, ablation measurements are made using stakes inserted vertically into the glacier either at the end of the previous melt season or the beginning of the current one. Geodetic mass balance methods are employed for th...

Southern Alaska is one of the most glaciated alpine regions on Earth. Volume losses in the region have been a key contributor to global sea level in the last century. This chapter examines the Juneau Icefield as an example of what has been occurring in the region. The icefield has a temperate maritime climate dominated by the passage of frequent cy...

This chapter examines glaciers from region that straddles the Nepal-Sikkim-China border. This region provides a transect from the drier/colder climate in China to the wetter/warmer climate of Nepal and Sikkim. All the glaciers are summer accumulation-type glaciers. Middle Lhonak Glacier is an unnamed glacier between North Lhonak Glacier and South L...

South Georgia, Kerguelen, and Heard Islands are all in or just south of the Antarctic Convergence Zone, which is the polar front separating Antarctic and temperate air masses. The British Antarctic Survey (BAS) has been the principal research group examining glacier change on South Georgia Island. Twitcher Glacier is the next glacier south of Herz...

The World Glacier Monitoring Service (WGMS) record of mass balance and terminus behavior provides a global index for alpine glacier behavior. The WGMS dataset for terminus change contains 42 000 observations from 2000 glaciers extending from the mid-19th century. There are 5200 geodetic and glaciological mass balance observations in this dataset. A...

Supraglacial debris cover is an important component of glacier mass balance, especially in areas characterised by widespread glacier recession. Mapping of the spatial and temporal changes in debris cover on the surface of the receding outlet glaciers of the temperate North Patagonian Icefield (NPI) in southern South America between 1987 and 2015 sh...

This book presents the impact of climate change on Mount Baker glaciers, USA, and the rivers surrounding them. Glaciers are natural reservoirs that yield their resource primarily on warm dry summer days when other sources are at their lowest yield. This natural tempering of drought conditions will be reduced as they retreat. Mount Baker, a volcano...

Observations show that glaciers around the world are in retreat and losing mass. Internationally coordinated for over a century, glacier monitoring activities provide an unprecedented dataset of glacier observations from ground, air and space. Glacier studies generally select specific parts of these datasets to obtain optimal assessments of the mas...

Glacier runoff is a major source of streamflow during the summer low-flow season and mitigates both low flow and high water temperatures. Measurement of ablation and discharge immediately below Sholes Glacier quantifies the volume of glacier runoff to the North Fork Nooksack River, which provided more than 40 % of total river runoff on 21 days in A...

Changes in mass balance control a glacier’s long term behavior. Glacier termini respond to the changes in mass with a period of negative balance driving retreat. The glacier will lose the highest ablating lower sections of the glacier, which may bring it back into equilibrium with climate. A period of positive mass balance will cause a glacier to a...

A 31 year record (1984–2014) of glacier mass balance and areal extent indicate a significant glacier response to climate change in the North Cascades of Washington state. Glacier runoff is a major source of streamflow during the summer low-flow season and mitigates both low flow and high water temperatures. Measurement of ablation and discharge imm...

Field Observations supplemented with Google Earth imagery illustrates the significant retreat of all ten major Mount Baker Glaciers between 1984 and 2014. All but the Sholes Glacier advanced from 1950 to 1979, Sholes Glacier was stable during this period. The average retreat has been 380 m during the last 35 years.

Annual mass balance is recognized as the most sensitive climate variable observed on alpine glaciers. This has led the WGMS to establish both a long term data archive, but also protocol for mass balance observations and reporting. NCGCP has measured annual mass balance for the last 31 years on North Cascades glaciers. The glaciers have all lost sig...

The headwaters of the North Fork and Middle Fork Nooksack River are the glaciers of Mount Baker, the South Fork Nooksack River lacks glacier cover. The glaciers are a critical source of runoff for the North Fork contributing 30–40 % of the total runoff during late summer. In the last 30 years glacier retreat and climate change is altering the timin...

This book presents the impact of climate change on Mount Baker glaciers, USA, and the rivers surrounding them. Glaciers are natural reservoirs that yield their resource primarily on warm dry summer days when other sources are at their lowest yield. This natural tempering of drought conditions will be reduced as they retreat. Mount Baker, a volcano...

The annual surface mass balance records of the Lemon Creek Glacier and Taku Glacier observed by the Juneau Icefield Research Program are the longest continuous glacier annual mass balance data sets in North America. Annual surface mass balance (Ba) measured on Taku Glacier averaged +0.40 m a−1 from 1946–1985, and −0.08 m a−1 from 1986–2011. The rec...

Brady Glacier is a large Alaskan tidewater glacier that is beginning a period of substantial retreat. Examination of 27 Landsat and MODIS images from the period 2003 to 2011 indicates that Brady Glacier has a mean equilibrium line altitude (ELA) of 745 m and accumulation area ratio (AAR) of 0.40. The zero balance ELA is 600 m and equilibrium AAR 0....

Identification of the transient snowline (TSL) from high spatial resolution Landsat imagery on Lemon Creek Glacier (LCG), southeast Alaska, USA, and Mittivakkat Gletscher (MG), southeast Greenland, is used to determine snow ablation rates, the equilibrium-line altitude (ELA) and the accumulation-area ratio (AAR). The rate of rise of the TSL during...

For the first time in serveral years, the El Nino-Southern Oscillation did not dominate regional climate conditions around the globe. A weak La Ni a dissipated to ENSOneutral conditions by spring, and while El Nino appeared to be emerging during summer, this phase never fully developed as sea surface temperatures in the eastern conditions. Neverthe...

The annual surface mass balance records of the Lemon Creek Glacier and Taku Glacier observed by the Juneau Icefield Research Program are the longest continuous glacier annual mass balance data sets in North America. Annual surface mass balance ( B a) measured on Taku Glacier averaged +0.40 m a-1 from 1946-1985, and -0.08 m a-1 from 1986-2011. The r...

Mount Baker, North Cascades, WA, has a current glacierized area of 38.6 km ² . From 1984 to 2010, the North Cascade Glacier Climate Project has monitored the annual mass balance (Ba), accumulation area ratio (AAR), terminus behaviour and longitudinal profiles of Mount Baker glaciers. The Ba on Rainbow, Easton and Sholes Glaciers from 1990 to 2010 a...

The World Glacier Monitoring Service (WGMS) record of mass balance and terminus behavior (WGMS 2011) provides a global index for alpine glacier behavior. Mass balance was -766 mm in 2010, negative for the 20th consecutive year. Preliminary data for 2011 from Austria, Norway, New Zealand, and United States indicate it is highly likely that 2011 will...

On Taku Glacier, Alaska a combination of field observations of snow water equivalent (SWE) from snowpits and probing in the vicinity of the transient snowline (TSL) are used to quantify the mass balance gradient. The balance gradient is determined from the difference in elevation and SWE from the TSL to snowpits at 1000 m from 1998-2010 and ranges...

On Taku Glacier, Alaska a combination of field observations of snow water equivalent (SWE) from snowpits and probing in the vicinity of the transient snowline (TSL) are used to quantify the mass balance gradient. The balance gradient derived from the TSL and SWE measured in snowpits at 1000 m from 1998–2010 ranges from 2.6–3.8 mm m⁻¹. Pr...

On Taku Glacier, Alaska a combination of field observations of snow water equivalent (SWE) from snowpits and probing in the vicinity of the transient snowline (TSL) are used to quantify the mass balance gradient. The balance gradient derived from the TSL and SWE measured in snowpits at 1000 m from 1998–2010 ranges from 2.6–3.8 mm m−1. Probing trans...

Glacier retreat and changes in summer runoff have been pronounced in the Skykomish River Basin, North Cascades, Washington from 1950 to 2009. An analysis comparing USGS streamflow records for the 1950–1985 to the 1985–2009 period indicates that during the recent period the Skykomish River summer streamflow (July–September) has declined 26% in the w...

Several large-scale climate patterns influenced climate conditions and weather patterns across the globe during 2010. The transition from a warm El Nino phase at the beginning of the year to a cool La Nina phase by July contributed to many notable events, ranging from record wetness across much of Australia to historically low Eastern Pacific basin...

North Cascade glacier annual balance measured on 10 glaciers from 1984 to 2009 yielded mean annual balance (ba) of −0.51 m/y, and −13.26 m cumulatively. This is a significant loss for glaciers that average 30–60 m in thickness, 20–40% of their entire volume. This rapid volume loss has led to the complete loss of two glaciers, Spider and Lewis Glaci...

Temperate alpine glacier survival is dependent on the consistent presence of an accumulation zone. Frequent low accumulation area ratio values, below 30%, indicate the lack of a consistent accumulation zone, which leads to substantial thinning of the glacier in the accumulation zone. This thinning is often evident from substantial marginal recessio...

Analysis of key components of the alpine North Cascade hydrologic system indicate significant changes in glacier mass balance, terminus behavior, alpine snowpack, and alpine streamflow from 1950 to 2005. North Cascade glacier retreat is rapid and ubiquitous. All 47 monitored glaciers are currently undergoing a significant retreat and four of them h...

The Taku Glacier, Alaska has advanced 7.5 km since the late nineteenth century, while all other primary outlet glaciers of the Juneau Icefield are in retreat. The Juneau Icefield Research Program has completed field work on the Taku Glacier annually since 1946. The collected observations of surface mass balance, glacier velocity and glacier thickne...

Ice shelves are floating platforms of ice fed by mountain glaciers and ice sheets flowing from the land onto the ocean. The ice flows from the grounding line where it becomes floating to the seaward front, where icebergs calve. For a typical glacier when the climate warms the glacier merely retreats, reducing its low elevation, high melting area by...

The net loss in volume and hence sea level contribution of the Greenland Ice Sheet (GIS) has doubled in recent years from 90 to 220 cubic kilometers/year has been noted recently (Rignot and Kanagaratnam, 2007). The main cause of this increase is the acceleration of several large outlet glaciers. There has also been an alarming increase in the numbe...

North Cascade glacier annual balance measured on 10 glaciers from 1984?2006 yielded mean annual balance (b_a) of ?0.54 m/a, and ?12.38 m cumulatively. This is a significant loss for glaciers that average 30?60 m in thickness, 20?40% of their entire volume. Two observed glaciers, Lewis Glacier and Spider Glacier, no longer exist. The b<...

North Cascade glacier annual balance measured on 10 glaciers from 1984?2006 yielded mean annual balance (ba) of ?0.54 m/a, and ?12.38 m cumulatively. This is a significant loss for glaciers that average 30?60 m in thickness, representing 20?40% of their entire volume. Two observed glaciers, Lewis Glacier and Spider Glacier, no longer exist. The b...

Three lines of evidence indicate that North Cascade (Washington, USA) glaciers are currently in a state of disequilibrium. First, annual balance measured on nine glaciers yields a mean cumulative balance for the 1984–2004 period of −8·58 m water equivalent (w.e.), a net loss of ice thickness exceeding 9·5 m. This is a significant loss for glaciers...

Centreline surface elevation longitudinal profiles have been completed for three different points in time from historic photographs (∼1900), US Geological Survey maps (1964 and 1985), and field measurements (annually between 1984 and the present) for three North Cascade glaciers. Comparison of thinning and terminus behaviour over this time period i...

In the North Cascade Range, Washington snowpack accumulation and the resultant ablation provide critical summer water resources. Utilizing SWE data from 10 USDA Snotel sites and nine glaciers in the North Cascades, the variation in ablation rates with location and temperature are analyzed. How variable is ablation of alpine snowpack during the prin...

Annual balance measurements on the Lemon Creek Glacier, Alaska conducted by the Juneau Icefield Research Program (JIRP) from 1953 through 1998 provide a continuous 46 year record. This is one of the nine American glaciers selected in a global monitoring network during the International Geophysical year, 1957/58. These data have been acquired primar...

Since 1984, annual glacier mass balance measurements have been conducted on eight glaciers by the North Cascades Glacier Climate Project (NCGCP). Since 1993 the National Park Service (NPS) has monitored the mass balance of four glaciers, and the NCGCP an additional two glaciers. This 14 glacier monitoring network, covering an area of 14 000 km ² ,...

Observation of the terminus behavior of 38 North Cascade glaciers, Washington, U.S.A., since 1890 shows three different types of glacier response: (1) Continuous retreat from the Little Ice Age (LIA) advanced positions from 1890 to approximately 1950, followed by a period of advance from 1950 to 1976, and then retreat since 1976. (2) Rapid retreat...

To assess the impact of sampling density on the determination of a glacier's annual mass balance, we used varying densities of measurements to determine annual mass balance on Columbia Glacier, Washington and Lemon Creek Glacier, Alaska. Mass balance was determined solely from field measurements. The density of the mass balance networks ranged from...

As part of the ongoing annual mass balance measurements on Lyman Glacier and Columbia Glacier, North Cascades, Washington, measurements were completed from 1986-1998 on adjacent clean and debris-covered sections of each glacier. On Columbia Glacier annual ice ablation is 3.3 m water equivalent for clean glacier ice and 2.3 m water equivalent for de...

Reply to the comments of Meier and others on “Annual net balance of North Cascade glaciers, 1984–94” by Mauri S. Pelto - Volume 43 Issue 143 - Mauri S. Pelto

Reply to the comments of Meier and others on “Annual net balance of North Cascade glaciers, 1984–94” by Mauri S. Pelto - Volume 43 Issue 143 - Mauri S. Pelto

From 1985 to 1993, the mean summer temperature was 1.1°C above the long-term mean and the mean winter precipitation was 11% below the long-term mean at the eight Washington State Cascade Mountain weather stations. The effect of this climate fluctuation on glacier and alpine runoff has been examined in five North Cascade basins. From 1985 to 1993 th...

Annual net balance eight North Cascade glaciers during the 1984-94 period has been determined by measurement of total mass loss firn and ice melt and ice melt and, residual snow depth at the end of the Summer season. Overall spatial density of measurment points is 200 points km ⁻² . Mean annual balance of North Clascade glaciers from 1984 to 1994 h...

Annual net balance eight North Cascade glaciers during the 1984-94 period has been determined by measurement of total mass loss firn and ice melt and ice melt and, residual snow depth at the end of the Summer season. Overall spatial density of measurment points is 200 points km−2. Mean annual balance of North Clascade glaciers from 1984 to 1994 has...

Present-day and late Wisconsin glacier equilibrium line altitudes (ELA) were compared on a transect from Patagonia along the coastal Cordillera to Alaska, and a transect from Mexico along the Sierra Madre-Rocky Mountains to Alaska. Late Wisconsin ELA's were determined from cirques occupied during the late Wisconsin, and present day ELA from observa...

In the late 1970s global temperature rose abruptly, and between 1977 and 1990 has averaged 0.4 °C above the 1940–76 mean. In 1980, 50% of the the alpine glaciers observed in the Swiss Alps, Peruvian Andes, Norwegian Coast Range, Northern Caucasus and Washington’s North Cascades were advancing. By 1990 in response to the warming only 15% were still...

An analysis of the relationship between iceberg calving rates and water depth has been completed for 22 tidewater glaciers. A linear relationship provides reasonable accuracy, with a correlation coefficient of 0.85, for all tidewater glaciers examined, whether they be polar or temperate. The polar glaciers have a slightly lower calving rate for a g...

An analysis of the relationship between iceberg calving rates and water depth has been completed for 22 tidewater glaciers. A linear relationship provides reasonable accuracy, with a correlation coefficient of 0.85, for all tidewater glaciers examined, whether they be polar or temperate. The polar glaciers have a slightly lower calving rate for a g...

Since 1977 ablation-season temperature has been 1.1°C above the 1930–80 mean and winter precipitation has been 14% below the 1930–80 mean. In order to identify the effect of this climatic fluctuation on North Cascade glaciers, the North Cascade Glacier-Climate Project has monitored the terminus behavior of 107 glaciers between 1983 and 1988. The 10...

Identification of present-day climate setting and alpine glacier-balance gradients indicates that the balance gradient of alpine glaciers is primarily determined by climatic conditions. Determination of balance gradients for specific climatic settings on present-day ice sheets provides an analog for determining the mass balance on paleo and future...

The Taku Glacier, is a temperate, maritime glacier of the Juneau Icefield, southeast Alaska. This glacier is the largest of the icefield, and has advanced 6.8 km since 1890, 1.6 km since 1948. The mass balance record of the Taku Glacier (1946-1986) indicates that the glacier's continued advance has been due to positive mass balance. Due to the larg...

Since 1977 ablation-season temperature has been 1.1°C above the 1930–80 mean and winter precipitation has been 14% below the 1930–80 mean. In order to identify the effect of this climatic fluctuation on North Cascade glaciers, the North Cascade Glacier-Climate Project has monitored the terminus behavior of 107 glaciers between 1983 and 1988. The 10...

Identification of present-day climate setting and alpine glacier-balance gradients indicates that the balance gradient of alpine glaciers is primarily determined by climatic conditions. Determination of balance gradients for specific climatic settings on present-day ice sheets provides an analog for determining the mass balance on paleo and future...

Examination of mass balance records from four glaciers in the Coast Ranges of Washington, British Columbia and Alaska indicate that accumulation season precipitation is the dominant control of mass balance for each of these gla­ ciers. There is an inverse relationship between accumulation season (October-April) precipitation in northwestern Washing...