Earth's climate has warmed, its sea levels have risen, ice masses have diminished, precipitation patterns have shifted, and acidity and salinity of bodies of water have increased, atmospheric circulation patterns are more variable, and global chemical cycles have changed.
Easton Glacier on Mt. Baker, Washington in 2003. The red line marks the extent of the glacier in 1985.
Limestone is a sedimentary rock whose chief mineral component is calcite (calcium carbonate: CaCO3). Limestone can be formed by precipitation of calcite...
Video: AAAS Global Climate-Change Video - CLEANLast Updated on 2011-02-17 00:00:00
This video has been selected for inclusion in the CLEAN Collection.
Residents of Shishmaref, Alaska, and experts like John Holdren, exploring the human impacts of global climate change.
Glacial landformsLast Updated on 2011-02-06 00:00:00
Glaciers are very effective agents in sculpting a landscape. Glaciers have mainly played a role in the modifying landscapes in the middle and high latitudes and in alpine environments. Their ability to erode soil and rock, transport sediment, and deposit sediment is extraordinary. During the last glacial period (20,000 year ago) more than 50 million square kilometers (19 million square miles) of land surface were influenced by the presence of glaciers.
Glacial Landforms Caused by Erosion
Two major erosional processes occur at the base of a glacier. First, at the base of a glacier, large amounts of loose rock and sediment are incorporated into the moving glacial ice by partial melting and refreezing. The second process of erosion involves the abrasive action of the held rock and sediment held by the ice on the surface underneath the glacier. This... More »
Global Forecast for the 21st CenturyLast Updated on 2010-11-29 00:00:00
Average global temperatures are anticipated to warm by somewhere between 1.5°C and 6.8°C from 2000 to 2100, depending on human activities . These changes will not be uniform, although no regions are expected to cool. Landmasses will warm more than the oceans, and Arctic regions will warm more than other parts of the world, perhaps by as much as 8°C or 9°C above 1975 temperatures. This will melt more of the northern ice and snow pack, thereby decrease albedo of these regions, and accelerate warming.
Sea ice in the polar oceans is melting and may disappear entirely during summer months. This will shorten sea routes, say, from Europe and the east coast of the United States to China. It will also make more accessible some natural resources such as oil deposits in the Arctic seabed. Sea level is predicted to rise as higher temperatures expand the volume of ocean... More »
Lecture: Stephen Schneider Climate Change Mitigation and Adaptation Video Last Updated on 2010-10-07 00:00:00
This video is of a lecture that Stephen Schneider presented a number of times. It covers climate change from a risk perspective, discussing the underlying science, uncertainties, and implications of different possible decisions. Here is it captured with many (although not all) of his graphics. It is a well organized, evenly presented lecture that carefully differentiates questions of "what we know" from "what we should do." It presents data and modelling at a level appropriate for undergraduates.
LimestoneLast Updated on 2010-08-08 00:00:00
Limestone is a sedimentary rock whose chief mineral component is calcite (calcium carbonate: CaCO3). Limestone can be formed by precipitation of calcite dissolved in water or by depostion of marine organisms and entrainment of secondary minerals. Approximately 80 to 90% of limestone composition are skeletal fragments of marine organisms such as coral or foraminifera.
Some other carbonate grains comprising limestones are soil types such as ooids, peloids, intraclasts, and extraclasts; moreover, certain limestones do not consist of grains at all, but rather and are formed completely by the chemical precipitation of calcite or aragonite, the latter also known as travertine.
Due to the ease of dissolution and precipitation processes of calcium carbonate, limestone occurrences are linked to fascinating topographic phenomena of cave, karst and limestone... More »
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