Friday, December 10, 2010

Global Warming


Global warming is the increase in the average temperature of Earth's near-surface air and oceans since the mid-20th century and its projected continuation. According to the 2007 Fourth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC), global surface temperature increased 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the 20th century.[2][A] Most of the observed temperature increase since the middle of the 20th century has been caused by increasing concentrations of greenhouse gases, which result from human activity such as the burning of fossil fuel and deforestation.[3] Global dimming, a result of increasing concentrations of atmospheric aerosols that block sunlight from reaching the surface, has partially countered the effects of warming induced by greenhouse gases.
Climate model projections summarized in the latest IPCC report indicate that the global surface temperature is likely to rise a further 1.1 to 6.4 °C (2.0 to 11.5 °F) during the 21st century.[2] The uncertainty in this estimate arises from the use of models with differing sensitivity to greenhouse gas concentrations and the use of differing estimates of future greenhouse gas emissions. An increase in global temperature will cause sea levels to rise and will change the amount and pattern of precipitation, probably including expansion of subtropical deserts.[4] Warming is expected to be strongest in the Arctic and would be associated with continuing retreat of glaciers,permafrost and sea ice. Other likely effects include changes in the frequency and intensity ofextreme weather events, species extinctions, and changes in agricultural yields. Warming and related changes will vary from region to region around the globe, though the nature of these regional variations is uncertain.[5] As a result of contemporary increases in atmospheric carbon dioxide, the oceans have become more acidic, a result that is predicted to continue.[6][7]
The scientific consensus is that anthropogenic global warming is occurring.[8][9][10][B]Nevertheless, political and public debate continues. The Kyoto Protocol is aimed at stabilizing greenhouse gas concentration to prevent a "dangerous anthropogenic interference".[11] As of November 2009, 187 states had signed and ratified the protocol.[12]

Wednesday, December 8, 2010

Properties of Ocean Water

Properties of Ocean Water,(:


Earth receives its warmth from the sun. Because the world rotates on an angle to its path around the sun, radiation is spread more evenly and seasons are experienced worldwide.
Read what underwater photographers need to know about light in the sea and other physical properties.
Sea water consists of salt and other minerals. They are important for life. 
Visit the page with sea water properties, including dissolved gases.(4p)
The ocean's physical properties like temperature, salinity and density are crucial to the ways in which the ocean water moves.
The ocean's reservoir in resources seems inexhaustible, but is it? This chapter looks at the ocean's capacity to feed humans and to recycle their wastes.
Also visit our large section about soil, its properties, geology and fertility and how we are losing it, perhaps the world's foremost problem! Read how the sea suffers and degrades, and read about our revolutionary discoveries about sick seas.

go back to the oceanography contents index.