Greenhouse gases are several chemical species present in the atmosphere which have the property of trapping much of the solar radiation reflected from the Earth . When irradiated by incoming solar radiation,the atmosphere permits entry of most of the impinging energy of the solar electromagnetic spectrum; however, the spectrum of reflected sunlight is altered and has a higher fraction of long wave radiation, which is preferentially absorbed by greenhouse gases. Thus the net effect of higher concentrations of greenhouse gases is to encourage net heat buildup of the Earth’s atmosphere. Through normal heat exchange processes between the atmosphere and Earth’s surface, the temperature at the Earth’s surface is correspondingly elevated.
The steady increase in atmospheric concentrations of the three main greenhouse gases to which humans make notable contributions – carbon dioxide, methane, and nitrous oxide– is clear from the data sets for these gases over the last 420,000 years. Since the Industrial Revolution, concentrations of carbon dioxide, methane, and nitrous oxide have all risen sharply. Intensification of agriculture, fossil fuel combustion, land cover alteration to peatlands and wetlands have been the primary causes for these changes; however, all of these drivers are underlain by a root cause of the expanding global human population.
The analysis of greenhouse gas impacts on climate is the object of intense study, but is extremely complex due to the interactions of ocean currents and the diversity of carbon dioxide and methane sinks, which include forests, surface waters, peatlands and tundra. The situation is also complex since methane levels are rising faster percentagewise than carbon dioxide, and methane has approximately 30 times the greenhouse potency of carbon dioxide. The issue would be relatively simple, if all greenhouse gas emissions were merely the result of combustion processes, but production of methane is preponderantly from livestock grazing, rice farming and other non-point sources that are often linked to livelihoods of people in developing countries.
The seas in which corals and other calcifying species dwell are turning acidic, their pH slowly dropping as Earth's oceans acidify in response to increased carbon dioxide...
U.S. Endangered Species Act and the Polar BearLast Updated on 2014-06-12 17:17:05
The Obama administration has followed the essential strategies of the administration of George W. Bush in disallowing the use of greenhouse gas control as an element of interpreting the protection of the polar bear under the U.S.Endangered Species Act.
On October 17, 2011 Federal Judge Emmet Sullivan struck down a provision of the Obama Interior Department, stating that a proper environmental review of the Interior Department's rule has not been done. The Obama administration agreed with the Bush administration, asserting that activities outside of the polar bear's habitat such as emissions from a power plant could not be controlled using the Endangered Species Act. Interior Secretary Ken Salazar was ordered by the federal court to respond to the environmental inadequacy of the Interior Department rule that denied the polar bear protection that could be afforded by... More »
Biochar: Concept to Sequester CarbonLast Updated on 2014-06-11 15:45:52
Biochar is a charcoal produced under high temperatures using crop residues, animal manure, or any type of organic waste material. Depending on the feedstock, biochar may look similar to potting soil or to a charred substance. The combined production and use of biochar is considered a carbon-negative process, meaning that it removes carbon from the atmosphere.
Biochar has multiple potential environmental benefits, foremost the potential to sequester carbon in the soil for hundreds to thousands of years at an estimate. Studies suggest that crop yields can increase as a result of applying biochar as a soil amendment. Some contend that biochar has value as an immediate climate change mitigation strategy. Scientific experiments suggest that greenhouse gas emissions are reduced significantly with biochar application to crop fields.
Obstacles that may stall rapid adoption of biochar... More »
AnthropoceneLast Updated on 2013-09-03 12:23:40
The Anthropocene defines Earth's most recent geologic time period as being human-influenced, or anthropogenic, based on overwhelming global evidence that atmospheric, geologic, hydrologic, biospheric and other earth system processes are now altered by humans. The word combines the root "anthropo", meaning "human" with the root "-cene", the standard suffix for "epoch" in geologic time. The Anthropocene is distinguished as a new period either after or within the Holocene, the current epoch, which began approximately 10,000 years ago (about 8000 BC) with the end of the last glacial period.
Anthropocene is a new term, proposed in 2000 by Nobel Prize winning scientist Paul Crutzen. A similar term, Anthrocene, was coined by Andrew Revkin in his 1992 book Global Warming: Understanding the Forecast, but was not adopted by scientists.... More »
Tracking the Global Carbon CycleLast Updated on 2013-07-11 09:56:26
Carbon dioxide (CO2) is the primary anthropogenic (man-made) greenhouse gas in terms of concentration and effect. It is responsible for about one-third of the global warming that derives from human activities.  Concentrations of CO2 in the atmosphere depend on the global carbon cycle that accounts for the fluxes of carbon among various storage pools. The vast majority of carbon on Earth is part of limestone and other sedimentary rocks. The decomposition of rocks, called weathering, as well as the high temperatures used during cement production, release CO2 from limestone and enters the atmosphere or dissolves in bodies of water.
Photosynthetic organisms absorb CO2 from the atmosphere or bodies of water and then use solar radiation to convert this low-energy carbon into the high-energy carbon in organic compounds. This process reverses when organisms breathe in and out (respire) or... More »
Ocean acidification troublesLast Updated on 2012-08-09 00:00:00
The seas in which corals and other calcifying species dwell are turning acidic, their pH slowly dropping as Earth's oceans acidify in response to increased carbon dioxide in the atmosphere.
Trouble in Paradise:
Ocean Acidification This Way Comes
Sustainability of tropical corals in question, but some species developing survival mechanisms
The following Discovery article is part two in a series on the National Science Foundation's Science, Engineering and Education for Sustainability (SEES) investment. Visit parts one, three, four, five, six and seven in this series.
The following is part five in a series on the National Science Foundation's Long-Term Ecological Research (LTER) Network. Visit parts one, two, three, four, six, seven, eight and nine in this series.
Double, double toil and trouble;
Fire burn, and caldron bubble.
—Shakespeare,... More »
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