Cold Environments A study into how and why global distribution of cold environments has changed and continues to change.
The distribution of cold environments has changed throughout time. What’s certain is that there have been repeated glacial periods separated by warmer interglacial times. Alpine: high altitude areas within mountain ranges where glaciers and small ice caps can be found. Periglacial: Bordering a glacial area but not actually covered by ice all year round, having similar climatic and environmental characteristics. Polar: Regions around the poles of the earth that are permanently covered with ice. During the last glaciation, the ice was at its maximum extent about 18,000 years ago. At this time there was a continental ice sheet across most of North America with many glaciers in the mountains of the west. The North of Europe had areas glaciated as well as areas of high altitude e.g. the Himalayas. Most of Greenland was covered in ice, one of he largest areas. The World has been covered by glaciers, and evidence shows that 17 glacial cycles have advanced to different areas. But since the end of the last ice age, there has been a net retreat of glaciers and ice sheets.
Across the globe there have been many cold environments that have experienced change. <ul><li>Glaciers can exist at high altitudes because the air is thinner, so less heat is absorbed. </li></ul><ul><li>Huascaran, in the Andes mountains over 6,500m above sea level, yet only 9° south of </li></ul><ul><li>the equator. </li></ul>The Grinnell Glacier is located in Montana, USA, in the Lewis Mountain range, and has been subject to change in its size and depth. Polar ice caps are areas of high latitude that receive little sun light, making it extremely cold. These high latitude areas include The Arctic, Greenland, Siberia and Norway. Alaska is an area that contains many glaciers that are subject to change Periglacial means ‘on the edge of ice’. They are cold, treeless locations but they are not ice covered. Typically below 3°C. Periglacial areas have frozen ground or permafrost Canada contains permafrost areas that are changing
<ul><li>Repeated photography over the decades since 1850 clearly show that glaciers throughout the Glacier National Park, Montana such as Grinnell Glacier are all retreating. The larger glaciers are now approximately a third of their former size when first studied in 1850, and numerous smaller glaciers have disappeared completely. Only 27% of the 99 km ² area of Glacier National Park covered by glaciers in 1850 remained covered by 1993. </li></ul><ul><li>The Grinnell glacier has lost an estimated 90% of its mass: </li></ul><ul><ul><li>In 1850 the glacier measured 2.88km ² . </li></ul></ul><ul><ul><li>By 1993 this had reduced to 0.88km ² . </li></ul></ul><ul><li>Future predictions expect that by 2030 the Glacier would have melted away. </li></ul><ul><li>These images show the changes to glacier over time… </li></ul>The Grinnell Glacier
<ul><li>Historical temperature trends show a warming of nearly 2°C during the last century in the western Canadian Arctic. In addition, extreme conditions such as the El Niño year of 1998 resulted in mean annual temperatures 5°C warmer than the average conditions. </li></ul><ul><li>Climate change since the end of the Little Ice Age, especially during the 20th century, has induced degradation of permafrost in most of Canada: From the 1850s to the 1990s, the area underlain by permafrost was reduced by 5.4% </li></ul><ul><ul><li>For those areas where permafrost existed in all the years throughout the period 1850–2002, the mean depth to the base of permafrost became shallower by 3 m </li></ul></ul><ul><ul><li>The mean active layer thickness decreased by 0.21 m, or 34%. </li></ul></ul><ul><ul><li>The mean depth to permafrost table decreased by 0.39 m. </li></ul></ul>Changes to Canadian permafrost It is anticipated that ground temperatures will continue to increase with future warming, permafrost levels will therefore decrease even more. Reduced permafrost means reduced albedo, meaning more heat being absorbed resulting with more thawing.
Alaskan Glaciers Glaciers in the Northwest United States have been shrinking, under pressure from rising temperatures, longer summer seasons, and a rising snowline. Studies by the Climate Impacts Group at University of Washington show regional temperature has been 1.5° F warmer in the 20th century, with decreasing mountain snow pack, and earlier spring runoff. Alaska's glaciers, 34,000 square miles of ice, are receding at twice the rate previously thought and beginning to contribute significantly to sea level rise, according to studies in Science journal. There are thousands of glaciers in Alaska, though only a relative few of them have been named. Of the nineteen glaciers of the Juneau Ice field, eighteen are retreating, and one, the Taku Glacier, is advancing. Eleven of the glaciers have retreated more than 1 km from 1940. The advances range from 5.4 km to 1.1 km. The glaciers are not only retreating but they are also thinning. Taku Glacier has been advancing since at least 1890, Inlet. The advance of Taku Glacier averaged 17 m per year between 1988 and 2005. In Denali National Park, all glaciers monitored are retreating, with an average retreat of 20 m per year. The Toklat Glacier has been retreating 26 m per year and the Muldrow Glacier has thinned 20 m since 1979.
Changes in the Earth's orbit: Changes in the shape of the Earth's orbit as well as the Earth's tilt and precession affects the amount of sunlight received on the Earth's surface. These orbital processes, which function in cycles of around 75,000 years ,are thought to be the most significant drivers of ice ages according to the theory of Mulitin Milankovitch. Changes in the sun's intensity: Changes occurring within the sun can affect the intensity of the sunlight that reaches the Earth's surface. The intensity of the sunlight can cause either warming (stronger solar intensity) or cooling (weaker solar intensity). According to NASA research, reduced solar activity from the 1400s to the 1700s was likely to be a key factor in the “Little Ice Age” which resulted in a slight cooling of North America, Europe and probably other areas around the globe. Why have cold environments changed?
Volcanic eruptions: Volcanoes can affect the climate because they can emit aerosols and carbon dioxide into the atmosphere… Aerosol emissions: Volcanic aerosols tend to block sunlight and contribute to short term cooling. Aerosols do not produce long-term change because they leave the atmosphere not long after they are emitted. According to the USGS, the eruption of the Tambora Volcano in Indonesia in 1815 lowered global temperatures by as much as 5ºF and historical accounts in New England describe 1816 as “the year without a summer.” Carbon dioxide emissions: Volcanoes also emit carbon dioxide, which has a warming effect. For about two-thirds of the last 400 million years, geologic evidence suggests CO2 levels and temperatures were considerably higher than present…However, the evidence for this theory is not conclusive and there are alternative explanations for historic CO2 levels. Current Greenhouse affect : While volcanoes may have raised pre-historic CO2 levels and temperatures, according to the USGS, human activities now emit 150 times as much CO2 as volcanoes. This has been a major factor for recent glacial retreats.