Posts tagged Climate Change

The figure above is a [very] simple model displaying isostatic rebound of Greenland if its ice sheet were not present. The Greenland ice sheet (GISh) is 2,500 km north-south, 1,000 km east-west, 3 km thick, and covers almost 2 million square kilometers (or 80% of the island). Because of the weight of GISh, the continental lithosphere is depressed in an elastic motion. If the GISh were to be removed, the lithosphere would rise in reaction. This rebounding process is known as isostasy and in case of ice sheets, glacial rebound. Underneath any vast ice sheet is a land surface not unlike any other ice-free surface on earth. It has valleys, hills, plains, etc. Therefore, we see that in Greenland the underlying topography, the Bedrock (or simply the Bed), is shaped as a concave, and with the removal of the ice sheet it rises and assumes a less curved form. PS: Please note that this is purely for visualization purposes and not to be used in scientific analysis.

The figure above is a [very] simple model displaying isostatic rebound of Greenland if its ice sheet were not present. The Greenland ice sheet (GISh) is 2,500 km north-south, 1,000 km east-west, 3 km thick, and covers almost 2 million square kilometers (or 80% of the island). Because of the weight of GISh, the continental lithosphere is depressed in an elastic motion. If the GISh were to be removed, the lithosphere would rise in reaction. This rebounding process is known as isostasy and in case of ice sheets, glacial rebound.

Underneath any vast ice sheet is a land surface not unlike any other ice-free surface on earth. It has valleys, hills, plains, etc. Therefore, we see that in Greenland the underlying topography, the Bedrock (or simply the Bed), is shaped as a concave, and with the removal of the ice sheet it rises and assumes a less curved form.

PS: Please note that this is purely for visualization purposes and not to be used in scientific analysis.

NASA Operation IceBridge Returns to Antarctica

Operation IceBridge Returns to Antarctica

satellite image acquired October 5, 2011 
download large image (5 MB, JPEG) 
download GeoTIFF file (42 MB, TIFF)


For the third consecutive October, NASA research aircraft are flying over Antarctica in search of clues about the health and dynamics of the frozen continent’s massive ice sheets and shelves. Part of the NASA-funded IceBridge mission, planes carry instruments to measure the thickness of snow and ice, as well as the shape of the land andseafloor beneath the ice.

On October 5, 2011, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured this clear view of the Antarctic Peninsula, the Larsen Ice Shelf, and the sea ice covered waters around the region. The Peninsula stands out as the raised terrain amidst the ice from the lower left to upper middle of the image.

On October 12, 2011, NASA’s DC-8 aircraft flew from Punta Arenas, Chile, across the Antarctic Peninsula and Weddell Sea, and back to Chile—making two 1,700-kilometer transects from east to west across the region. Several early flights in the 2011 campaign will take the team over sea ice near the Antarctic Peninsula before too much of it melts in the southern spring. Scientists are trying to understand why sea ice in the Southern Hemisphere is not following the steady decline of sea ice thickness and extent observed in the Arctic.

Operation IceBridge is designed to continue critical ice sheet measurements for the next few years between the end of the ICESat I mission and the launch of ICESat II in 2016. Researchers make instrumented flights to Greenland and the Arctic each March through May, and over Antarctica each October and November. Many flight lines retrace previous ICESat-1 tracks or future ICESat-2 tracks. Some also align with current observations made by the European Space Agency’s CryoSat-2 satellite.

The overlapping flight lines and satellite tracks help scientists improve the accuracy of their data. Scientists are concerned about how quickly key glaciers and ice shelves are thinning. Better understanding this type of change is crucial to projecting impacts like sea-level rise.

NASA image provided courtesy of Jeff Schmaltz, MODIS Rapid Response team. Caption by Michael Carlowicz and Patrick Lynch.

Instrument: Aqua - MODIS

earthobservatory.nasa.gov

One of the projects we’re working on here at the Lamont-Doherty Earth Observatory is assessing spatial extent of subglacial features under the Greenland ice sheet using airborne geophysics. This is to better understand the dynamics of the ice sheet and to monitor the affects of climate change on its flow.

One of the projects we’re working on here at the Lamont-Doherty Earth Observatory is assessing spatial extent of subglacial features under the Greenland ice sheet using airborne geophysics. This is to better understand the dynamics of the ice sheet and to monitor the affects of climate change on its flow.

This is the world’s most authoritative atlas. It’s published every four years. This edition, published on Thursday, September 15th 2011, is full of changes that the editors were forced to make because of climate change — shrinking lakes, changing coastlines, and whole new islands exposed by melting glaciers. Maps in the 13th edition of the Atlas show large areas of the eastern and southern coasts of Greenland coloured brown and pink, and the permanent ice cap now covering a significantly smaller area than it did in the 1999 12th edition of the atlas. The atlas suggests that 300,000 sq km, or 15%, of Greenland’s ice cover had been lost in the period. Find out more. UPDATE: Leading scientists have accused the world’s top cartographers of making a blunder in their representation of the effects of climate change in Greenland, prompting a robust defence by the map-makers’ publisher. A spokeswoman for Times Atlas robustly defended the 15% figure and the new map on Monday, September 19th 2011: “We are the best there is. We are confident of the data we have used and of the cartography. We use data supplied by the US Snow and Ice Data Centre (NSIDC) in Boulder, Colorado. They use radar techniques to measure the permanent ice. We have compared the extent of the ice surface in 1999 with that of 2011. Our data shows that it has reduced by 15%. That’s categorical.”  The publishers of the Times Atlas were forced to admit on Tuesday, September 20th 2011, that they were wrong to claim the Greenland ice pack had shrunk by 15%, as Arctic scientists rounded on the company for misinterpreting data and failing to consult them.

This is the world’s most authoritative atlas. It’s published every four years. This edition, published on Thursday, September 15th 2011, is full of changes that the editors were forced to make because of climate change — shrinking lakes, changing coastlines, and whole new islands exposed by melting glaciers. Maps in the 13th edition of the Atlas show large areas of the eastern and southern coasts of Greenland coloured brown and pink, and the permanent ice cap now covering a significantly smaller area than it did in the 1999 12th edition of the atlas. The atlas suggests that 300,000 sq km, or 15%, of Greenland’s ice cover had been lost in the period. Find out more.

UPDATE:

Leading scientists have accused the world’s top cartographers of making a blunder in their representation of the effects of climate change in Greenland, prompting a robust defence by the map-makers’ publisher.

A spokeswoman for Times Atlas robustly defended the 15% figure and the new map on Monday, September 19th 2011:

“We are the best there is. We are confident of the data we have used and of the cartography. We use data supplied by the US Snow and Ice Data Centre (NSIDC) in Boulder, Colorado. They use radar techniques to measure the permanent ice. We have compared the extent of the ice surface in 1999 with that of 2011. Our data shows that it has reduced by 15%. That’s categorical.” 

The publishers of the Times Atlas were forced to admit on Tuesday, September 20th 2011, that they were wrong to claim the Greenland ice pack had shrunk by 15%, as Arctic scientists rounded on the company for misinterpreting data and failing to consult them.

onearth

After having been to northern Greenland (Thule Air Base) for the first time back in May (see Part I & Part II), there might be a chance that I’ll travel down to the southern tip of South America in November. The Antarctic part of NASA Operation IceBridge (OIB) is based at Punta Arenas, Chile, and involves science flights on the NASA DC-8 over Antarctica to take airborne remote sensing measurements similar to those taken in the Arctic. The image above displays a segment of the flight plan over Antarctica that covers Recovery (including Recovery Ice Stream), Slessor Glaciers and the Bailey Ice Stream. There will also be flights that go further inland to the Recovery Subglacial Lakes, part of which was covered by the AGAP project during the International Polar Year 2007/2008.

After having been to northern Greenland (Thule Air Base) for the first time back in May (see Part I & Part II), there might be a chance that I’ll travel down to the southern tip of South America in November. The Antarctic part of NASA Operation IceBridge (OIB) is based at Punta Arenas, Chile, and involves science flights on the NASA DC-8 over Antarctica to take airborne remote sensing measurements similar to those taken in the Arctic.

The image above displays a segment of the flight plan over Antarctica that covers Recovery (including Recovery Ice Stream), Slessor Glaciers and the Bailey Ice Stream. There will also be flights that go further inland to the Recovery Subglacial Lakes, part of which was covered by the AGAP project during the International Polar Year 2007/2008.

A simple exercise: compare these two New York City maps. One is a map of areas that will be impacts by a rise in sea level resulting from climate change and the other is a map of Hurricane Irene evacuation zones. They show that both a hurricane and climate change can have similar impacts on humans living in low-lying areas. The only difference is that one is a devastating weather event with rapid impacts, while the other is a gradual process that’s not immediately noticeable (and thus easily deniable). So, if you live in low-lying areas, then you better get used to evacuating. Seven billion human beings and everything associated with them does impact the natural environment, to say otherwise is a rejection of common sense.

A simple exercise: compare these two New York City maps. One is a map of areas that will be impacts by a rise in sea level resulting from climate change and the other is a map of Hurricane Irene evacuation zones. They show that both a hurricane and climate change can have similar impacts on humans living in low-lying areas. The only difference is that one is a devastating weather event with rapid impacts, while the other is a gradual process that’s not immediately noticeable (and thus easily deniable).

So, if you live in low-lying areas, then you better get used to evacuating. Seven billion human beings and everything associated with them does impact the natural environment, to say otherwise is a rejection of common sense.

Australia Puts Greenhouse Gas Data Online

Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO) has made data about greenhouse gas levels available online in a newinteractive website. The readings are taken at Cape Grim on the northwest tip of Tasmania since 1976 and show a steady increase in the level of CO2.

vector1media.com

IceBridge, a six-year NASA mission, is the largest airborne survey of Earth’s polar ice ever flown. It will yield an unprecedented three-dimensional view of Arctic and Antarctic ice sheets, ice shelves and sea ice. These flights will provide a yearly, multi-instrument look at the behavior of the rapidly changing features of the Greenland and Antarctic ice.

Data collected during IceBridge will help scientists bridge the gap in polar observations between NASA’s Ice, Cloud and Land Elevation Satellite (ICESat) — in orbit since 2003 — and ICESat-2, planned for late 2015. ICESat stopped collecting science data in 2009, making IceBridge critical for ensuring a continuous series of observations.

IceBridge will use airborne instruments to map Arctic and Antarctic areas once a year. IceBridge flights were conducted in March/May 2009 and 2010 over Greenland and in October/November 2009 and 2010 over Antarctica. Other smaller airborne surveys around the world are also part of the IceBridge campaign.