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Glacial Retreat
The retreat of glaciers since 1850 affects the availability of fresh water for irrigation and domestic use, mountain recreation, animals and plants that depend on glacier-melt, and, in the longer term, the level of the oceans. Deglaciation occurs naturally at the end of ice ages, but glaciologists find the current glacier retreat is accelerated by the measured increase of atmospheric greenhouse gases—an effect of climate change. Mid-latitude mountain ranges such as the Himalayas, Rockies, Alps, Cascades, Southern Alps, and the southern Andes, as well as isolated tropical summits such as Mount Kilimanjaro in Africa, are showing some of the largest proportionate glacial losses. Excluding peripheral glaciers of ice sheets, the total cumulated global glacial losses over the 26 year period from 1993–2018 were likely 5500 gigatons, or 210 gigatons per yr.Fox-Kemper, B., H.T. Hewitt, C. Xiao, G. Aðalgeirsdóttir, S.S. Drijfhout, T.L. Edwards, N.R. Golledge, M. Hemer, R.E. Kopp, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glacier Peak Wilderness
Glacier Peak Wilderness is a , , wilderness area located within portions of Chelan, Snohomish, and Skagit counties in the North Cascades of Washington. The area lies within parts of Wenatchee National Forest and Mount Baker National Forest and is characterized by heavily forested stream courses, steep-sided valleys, and dramatic glacier-crowned peaks. The dominant geologic feature of the area is Glacier Peak. It is the most remote major volcanic peak in the Cascade Range and has more active glaciers than any other place in the lower forty-eight states. Glacier Peak is a volcanic cone of basalt, pumice, and ash which erupted during periods of heavy glaciation. History Glacier Peak Wilderness was created by the U.S. Forest Service in 1960 through the efforts of the North Cascades Conservation Council, four years before the 1964 wilderness legislation of the Congress. Ecology Forest vegetation comprises several species of fir, Douglas fir, hemlock, red cedar as wel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indonesia
Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guinea. Indonesia is the world's largest archipelagic state and the 14th-largest country by area, at . With over 275 million people, Indonesia is the world's fourth-most populous country and the most populous Muslim-majority country. Java, the world's most populous island, is home to more than half of the country's population. Indonesia is a presidential republic with an elected legislature. It has 38 provinces, of which nine have special status. The country's capital, Jakarta, is the world's second-most populous urban area. Indonesia shares land borders with Papua New Guinea, East Timor, and the eastern part of Malaysia, as well as maritime borders with Singapore, Vietnam, Thailand, the Philippines, Australia, Palau, and India ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ablation Zone
Ablation zone or ''ablation area'' refers to the low-altitude area of a glacier or ice sheet below firn with a net loss in ice mass due to melting, sublimation, evaporation, ice calving, aeolian processes like blowing snow, avalanche, and any other ablation. The equilibrium line altitude (ELA) or snow line separates the ablation zone from the higher-altitude accumulation zone. The ablation zone often contains meltwater features such as supraglacial lakes, englacial streams, and subglacial lakes. Sediments dropped in the ablation zone forming small mounds or hillocks are called kames. Kame and kettle hole topography is useful in identifying an ablation zone of a glacier. The seasonally melting glacier deposits much sediment at its fringes in the ablation area. Ablation constitutes a key part of the glacier mass balance. The amount of snow and ice gained in the accumulation zone and the amount of snow and ice lost in the ablation zone determine glacier mass balance. Ofte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glacier Ice Accumulation
Glacier ice accumulation occurs through accumulation of snow and other frozen precipitation, as well as through other means including rime ice (freezing of water vapor on the glacier surface), avalanching from hanging glaciers on cliffs and mountainsides above, and re-freezing of glacier meltwater as superimposed ice. Accumulation is one element in the glacier mass balance formula, with ablation counteracting. With successive years in which accumulation exceeds ablation, then a glacier will experience positive mass balance, and its terminus will advance. Accumulation zones Glaciologists subdivide glaciers into glacier accumulation zones, based on the melting and refreezing occurring. These zones include the dry snow zone, in which the ice entirely retains subfreezing temperatures and no melting occurs. Dry snow zones only occur within the interior regions of the Greenland and Antarctica ice sheets. Below the dry snow zone is the percolation Percolation (from Latin ''perc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Climate Change
In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to Earth's climate. The current rise in global average temperature is more rapid than previous changes, and is primarily caused by humans burning fossil fuels. Fossil fuel use, deforestation, and some agricultural and industrial practices increase greenhouse gases, notably carbon dioxide and methane. Greenhouse gases absorb some of the heat that the Earth radiates after it warms from sunlight. Larger amounts of these gases trap more heat in Earth's lower atmosphere, causing global warming. Due to climate change, deserts are expanding, while heat waves and wildfires are becoming more common. Increased warming in the Arctic has contributed to melting permafrost, glacial retreat and sea ice loss. Higher temperatures are also causing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Little Ice Age
The Little Ice Age (LIA) was a period of regional cooling, particularly pronounced in the North Atlantic region. It was not a true ice age of global extent. The term was introduced into scientific literature by François E. Matthes in 1939. Matthes described glaciers in the Sierra Nevada of California that he believed could not have survived the hypsithermal; his usage of "Little Ice Age" has been superseded by " Neoglaciation". The period has been conventionally defined as extending from the 16th to the 19th centuries, (noted in Grove 2004:4). but some experts prefer an alternative timespan from about 1300 to about 1850. The NASA Earth Observatory notes three particularly cold intervals. One began about 1650, another about 1770, and the last in 1850, all of which were separated by intervals of slight warming. The Intergovernmental Panel on Climate Change Third Assessment Report considered that the timing and the areas affected by the Little Ice Age suggested largely independ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ablation Zone
Ablation zone or ''ablation area'' refers to the low-altitude area of a glacier or ice sheet below firn with a net loss in ice mass due to melting, sublimation, evaporation, ice calving, aeolian processes like blowing snow, avalanche, and any other ablation. The equilibrium line altitude (ELA) or snow line separates the ablation zone from the higher-altitude accumulation zone. The ablation zone often contains meltwater features such as supraglacial lakes, englacial streams, and subglacial lakes. Sediments dropped in the ablation zone forming small mounds or hillocks are called kames. Kame and kettle hole topography is useful in identifying an ablation zone of a glacier. The seasonally melting glacier deposits much sediment at its fringes in the ablation area. Ablation constitutes a key part of the glacier mass balance. The amount of snow and ice gained in the accumulation zone and the amount of snow and ice lost in the ablation zone determine glacier mass balance. Ofte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Accumulation Zone
On a glacier, the accumulation zone is the area above the firn line, where snowfall accumulates and exceeds the losses from ablation, (melting, evaporation, and sublimation). The annual equilibrium line separates the accumulation and ablation zone Ablation zone or ''ablation area'' refers to the low-altitude area of a glacier or ice sheet below firn with a net loss in ice mass due to melting, sublimation, evaporation, ice calving, aeolian processes like blowing snow, avalanche, and any ... annually. The accumulation zone is also defined as the part of a glacier's surface, usually at higher elevations, on which there is net accumulation of snow, which subsequently turns into firn and then glacier ice. Part of the glacier where snow builds up and turns to ice moves outward from there. External links * * Glaciology {{Glaciology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glacier Mass Balance
Crucial to the survival of a glacier is its mass balance or surface mass balance (SMB), the difference between accumulation and ablation (sublimation and melting). Climate change may cause variations in both temperature and snowfall, causing changes in the surface mass balance. Changes in mass balance control a glacier's long-term behavior and are the most sensitive climate indicators on a glacier. From 1980 to 2012 the mean cumulative mass loss of glaciers reporting mass balance to the World Glacier Monitoring Service is −16 m. This includes 23 consecutive years of negative mass balances. A glacier with a sustained negative balance is out of equilibrium and will retreat, while one with a sustained positive balance is out of equilibrium and will advance. Glacier retreat results in the loss of the low elevation region of the glacier. Since higher elevations are cooler than lower ones, the disappearance of the lowest portion of the glacier reduces overall ablation, thereby incr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sea Level Rise
Globally, sea levels are rising due to human-caused climate change. Between 1901 and 2018, the globally averaged sea level rose by , or 1–2 mm per year on average.IPCC, 2019Summary for Policymakers InIPCC Special Report on the Ocean and Cryosphere in a Changing Climate .-O. Pörtner, D.C. Roberts, V. Masson-Delmotte, P. Zhai, M. Tignor, E. Poloczanska, K. Mintenbeck, A. Alegría, M. Nicolai, A. Okem, J. Petzold, B. Rama, N.M. Weyer (eds.) Cambridge University Press, Cambridge, UK and New York, NY, USA. https://doi.org/10.1017/9781009157964.001. This rate is accelerating, with sea levels now rising by 3.7 mm per year. Climate scientists expect further acceleration during the 21st century. Climate change heats (and therefore expands) the ocean and melts land-based ice sheets and glaciers. Between 1993 and 2018, the thermal expansion of water contributed 42% to sea level rise; melting of temperate glaciers, 21%; Greenland, 15%; and Antarctica, 8%. Over the next 2 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice Sheet
In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacial ice that covers surrounding terrain and is greater than . The only current ice sheets are in Antarctica and Greenland; during the Last Glacial Period at Last Glacial Maximum, the Laurentide Ice Sheet covered much of North America, the Weichselian ice sheet covered Northern Europe and the Patagonian Ice Sheet covered southern South America. Ice sheets are bigger than ice shelves or alpine glaciers. Masses of ice covering less than 50,000 km2 are termed an ice cap. An ice cap will typically feed a series of glaciers around its periphery. Although the surface is cold, the base of an ice sheet is generally warmer due to geothermal heat. In places, melting occurs and the melt-water lubricates the ice sheet so that it flows more rapidly. This process produces fast-flowing channels in the ice sheet — these are ice streams. The present-day polar ice sheets are relatively young in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
