Most sea level rise due to melting polar ice, study confirms
Image Credit: Sean O'Flaherty on Wikimedia Commons
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Scientists published results in a February 2012 issue of Nature
that reveal a detailed picture of how Earth’s glacier regions have
changed over the last eight years. In previous publications, GRACE
satellite data confirmed that Earth’s polar regions are the major
contributors to rising sea levels. The recent publication focuses on
the high mountain areas, such as the Himalayas and Andes, and shows that
these ecosystems are remarkably robust: they are not losing nearly as
much water to the ocean as the polar regions.
Earth’s ocean levels are rising at a rate of 1.48 millimeters – about .06 inches – annually. This might sound like a small number, but actually equates to approximately 500 billion tons of water added to our oceans every year! GRACE scientists wanted to know for certain where this water is coming from. One of the central mandates of the GRACE satellite project – which has been making detailed measurements of Earth’s gravity since its launch in March 2002 – is to ascertain the source of the water being added to Earth’s oceans.
From simple visual evidence, if nothing else, it is clear that our polar glacier regions are depleting due to melting ice.
Arctic report card for 2011
Meanwhile, exactly how much water is being lost by glaciers in high-mountain regions, including the Alps, Andes, the Himalayas among others? In the February 2012 Nature article, GRACE researchers report that the polar regions are losing 502 billion tons of water annually out of the total amount 536 billion tons lost annually worldwide.
How does GRACE track ice loss to the oceans? The
GRACE project measures minute discrepancies in the Earth’s gravitational
field in order to track changes in mass (the amount of matter) through
different regions of our planet. Earth possesses an approximately spherically symmetric shape. If it were exactly so, it would produce a spherically symmetric
gravitational field. That would mean that, regardless of one’s
latitude or longitude, Earth’s gravitational field would pull on us with
the same force.
Of course, this isn’t exactly the case. Earth is not exactly spherically symmetric. Instead, Earth is bulged along its equator as a result of its rotation. Mountainous regions also cause the planet to be slightly loop-sided. These deviations from perfect spherical symmetry cause slight alterations in the orbits of satellites around our planet. It is by experiencing these discrepancies in the orbits of satellites that GRACE is able to track minute variations in mass from place to place within our planet.
The GRACE project actually consists of two satellites, one following
the other in orbit around Earth. The distance between them is measured
by a radio frequency laser bouncing between the two satellites. This
method of distance measurement, known as interferometry, utilizes the
wavelength of the laser as its measuring stick and is capable of
resolving a distance of a few micrometers over hundreds of kilometers.
If the Earth were perfectly spherically symmetric, the distance between
the satellites would remain constant. This is not the case however, and
to complicate the picture even more, the mass distribution of our
planet changes with time. It is exactly these time dependent processes
that GRACE wishes to track.
The GRACE satellites are still transmitting data more than 10 years after the start of their mission. What’s more the mission has been multifaceted. For example, GRACE’s precise measurement of Earth’s gravitational field anomalies provide images of places where our planet’s tectonic plates – the great blocks of Earth’s crust that slide around slowly over very long timescales to create ocean basins and mountain ranges – are overlapping. In addition to providing data on mass loss to the oceans, the project – through its ability to track heat – has provided us with never before seen details of our ocean’s currents.
GRACE stands for Gravity Recovery and Climate Experiment. The project is headed by Dr. Bryon Tapley at the University of Texas.
Bottom line: A publication in Nature in February 2012 presents the results of an analysis of GRACE satellite data, showing that high mountain areas, such as the Himalayas and Andes, are not losing nearly as much water to the ocean as Earth’s polar regions.
Earth’s ocean levels are rising at a rate of 1.48 millimeters – about .06 inches – annually. This might sound like a small number, but actually equates to approximately 500 billion tons of water added to our oceans every year! GRACE scientists wanted to know for certain where this water is coming from. One of the central mandates of the GRACE satellite project – which has been making detailed measurements of Earth’s gravity since its launch in March 2002 – is to ascertain the source of the water being added to Earth’s oceans.
Map
showing the September ice extent in the Arctic in 1980, 2007, 2008,
2009, 2010, and 2011. The magenta line indicates the median September
ice extent for the period 1979-2000. Image Credit: National Snow and
Ice Data Center Sea Ice Index:
Arctic report card for 2011
Meanwhile, exactly how much water is being lost by glaciers in high-mountain regions, including the Alps, Andes, the Himalayas among others? In the February 2012 Nature article, GRACE researchers report that the polar regions are losing 502 billion tons of water annually out of the total amount 536 billion tons lost annually worldwide.
Glaciers
in the Alps and other high mountain areas are not the greatest
contributors to sea level rise, according to data from the two GRACE
satellites. Courtesy of J. Balog, Extreme ICE Survey
Of course, this isn’t exactly the case. Earth is not exactly spherically symmetric. Instead, Earth is bulged along its equator as a result of its rotation. Mountainous regions also cause the planet to be slightly loop-sided. These deviations from perfect spherical symmetry cause slight alterations in the orbits of satellites around our planet. It is by experiencing these discrepancies in the orbits of satellites that GRACE is able to track minute variations in mass from place to place within our planet.
The GRACE project actually consists of two satellites, one following the other in orbit around Earth.
The GRACE satellites are still transmitting data more than 10 years after the start of their mission. What’s more the mission has been multifaceted. For example, GRACE’s precise measurement of Earth’s gravitational field anomalies provide images of places where our planet’s tectonic plates – the great blocks of Earth’s crust that slide around slowly over very long timescales to create ocean basins and mountain ranges – are overlapping. In addition to providing data on mass loss to the oceans, the project – through its ability to track heat – has provided us with never before seen details of our ocean’s currents.
GRACE stands for Gravity Recovery and Climate Experiment. The project is headed by Dr. Bryon Tapley at the University of Texas.
Bottom line: A publication in Nature in February 2012 presents the results of an analysis of GRACE satellite data, showing that high mountain areas, such as the Himalayas and Andes, are not losing nearly as much water to the ocean as Earth’s polar regions.
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France’s Bubble Hotel Phenomenon is a Hit (Bangstyle.com)end quote from:http://earthsky.org/water/most-sea-level-rise-due-to-melting-polar-ice-study-confirmsrepeat Quote from Above article: Researchers report that Earth’s polar regions are losing 502 billion tons of water annually out of the total amount 536 billion tons lost annually worldwide. end quote.If the earth is losing 502 billion tons of ice just from the two arctic regions melting out of a total loss of 536 billion tons of ice lost this seems pretty serious in its long term ramifications. Also, it appears that so far the most ice melted out of the arctic in 2007 in looking at the maps above. However, the continued low ice during summers and fall has possibly permanently changed arctic weather patterns to what happened this winter and to what is happening now. Since the two hottest spots in the last 30 years of relative weather on earth at least this March are the eastern half of the U.S. and just east of Greenland this also likely will create more arctic melting than last year this year very likely during the summer and fall. What that will create next winter and where the arctic air mass will go this next winter is anybody's guess at this point.
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