Quaternary Science Reviews 31, Save my name, email, and website in this browser for the next time I comment. This site uses Akismet to reduce spam.
Learn how your comment data is processed. Survey Manual. Yes and no. It depends on which glaciers you are considering. Parts of the Antarctic Continent have had continuous glacier cover for perhaps as long as 20 million years.
Other areas, such as valley glaciers of the Antarctic Peninsula and glaciers of the Transantarctic Mountains may date from the early Pleistocene. For Greenland, ice cores and related data suggest that all of southern Greenland and most of northern Greenland were ice-free during the last interglacial period, approximately , years ago. Then, climate was as much as o Fahrenheit warmer than the interglacial period we currently live in.
Although the higher mountains of Alaska have hosted glaciers for as much as the past 4 million years, temperate glaciers in Alaska are generally much, much younger. Many formed as recently as the start of the Little Ice Age, approximately years ago. Others may date from other post-Pleistocene colder climate events. Some, such as the glaciers in the summit craters of Mount Redoubt and Katmai Volcanoes, have reformed following eruptions during the 20 th century.
Satellite measurements indicate that during the past few decades the Yakutat microplate has moved northwest at a rate of nearly Since its inception in , USGS has collected, preserved In the other 10 chapters, each of which concerns a specific glacierized region of Earth, the authors used remotely The Alaskan landscape is changing, both in terms of effects of human activities as a consequence of increased population, social and economic development and their effects on the local and broad landscape; and those effects that accompany naturally occurring hazards such as volcanic eruptions, earthquakes, and tsunamis.
Some of the most prevalent Geological Survey USGS researchers are at the forefront of paleoclimate research, the study of past climates. With their unique skills and perspective, only geologists have the tools necessary to delve into the distant past long before instrumental records were collected in order to better understand global environmental conditions that Glaciers cover about 75, km2 of Alaska, about 5 percent of the State. The glaciers are situated on 11 mountain ranges, 1 large island, an island chain, and 1 archipelago and range in elevation from more than 6, m to below sea level.
Alaska's glaciers extend geographically from the far southeast at lat 55 deg 19'N. Between and , optimum satellite images were distributed to a team of 70 scientists, representing 25 nations and 45 institutions, who agreed to author sections of the Professional Paper concerning either The warming climate has dramatically reduced the size of 39 glaciers in Montana since , some by as much as 85 percent, according to data released by the U.
Geological Survey and Portland State University. Frozen bodies of ice cover nearly 10 percent of the state of Alaska, but the influence of glaciers on the environment, tourism, fisheries, hydropower, and other important Alaska resources is rarely discussed. The simulation below reflects the predicted exponential rise in atmospheric CO2 concentrations, a 2xCO2 "global warming" scenario, with a concurrent warming of degrees centigrade degrees Fahrenheit by the year In addition it assumes that precipitation, primarily in the form of rain, will increase over the same time period about 10 percent based on the.
Most glaciers in Washington and Alaska are dramatically shrinking in response to a warming climate. USGS scientist Edward Josberger discusses research from the past 50 years to measure changes in the mass length and thickness of three glaciers in Alaska and Washington.
None - all the calving glaciers in Alaska fill their fjords completely to the bed. In Alaska, parts of some retreating calving glaciers are close to floating such as Columbia and Portage Glaciers. What makes a glacier different from an ice cube or ice in a hockey rink?
A glacier must: be formed from natural atmospheric precipitation snow move by internal deformation due to its own weight NOTE: these criteria exclude "aufeis" which is the technical term for the "glaciering" or "icing" that form during winter where emerging ground water freezes, often encroaching onto highways and trails. A good guess is that the ice thickness is about one-half of the surface width of the glacier.
Although few glaciers have been measured, the measured thicknesses range from a few tens of meters for small glaciers to about 1, meters for the largest glaciers in Alaska. They are real - they are annelid worms class Oligochaeta ; several species are recognized. Also, there are several insects and algae that live on the surfaces of glaciers.
Alaska was covered by glaciers during the Great Ice Age Pleistocene. No - interior Alaska was a grassland refuge habitat for a number of plant and animal species during the maximum glaciation.
Today's glaciers are leftovers from the ice age … and … Glacier ice is "really old. Sort-of and no - we must distinguish between glaciers and the ice in glaciers. Like the difference between rivers and the water in rivers: it takes a few weeks for water to travel the full length of the Mississippi river; however there has been a Mississippi River for thousands of years.
Likewise, glaciers have existed in the mountains ever since the ice age, but glacier flow moves the snow and ice through the entire length of the glacier in years or less. So, most of the glacier ice in Alaska is less than years old!
Therefore, most of the glacier ice is not ice-age leftovers. What about the mammoths and giant bison found in ice? The buried glacier is allegedly the oldest on earth with an age of more than 8 million years; that would be almost ten times older than ice currently being cored from the Antarctic ice sheets. If the ice is indeed that old, gases trapped within the buried glacier ice represent a potential archive of climate data stretching back to the time of the earliest hominids.
The ice cores were shipped to Boston and Princeton universities where analysis of the trapped gases will provide a more robust chronology for the glacier and provide insight about past atmospheric temperatures and precipitation.
To establish further evidence that buried glaciers can persist for over 8 million years in the dry, albeit cold environment of Antarctica, Doug conducted in-situ experiments and modeling studies to calculate the existing rate of glacier ice sublimation the change of state from solid directly to gas, a process that slowly reduces the size of glacier and over time may eliminate the glacier completely.
For model input, Doug and his colleagues monitored atmospheric temperatures, wind speed, amount of solar radiation received, and relative humidity.
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