NASA: World of Change - Part 1
Posted by Ricardo Marcenaro | Posted in NASA: World of Change - Part 1 | Posted on 6:08
Water Level in Lake Powell
Water Level in Lake Powell - March 25, 1999
World of Change
Earth is constantly changing. Some changes are a natural part of the climate system, such as the seasonal expansion and contraction of the Arctic sea ice pack. The responsibility for other changes, such as the Antarctic ozone hole, falls squarely on humanity’s shoulders. Our World of Change series documents how our planet’s land, oceans, atmosphere, and Sun are changing over time.
Combined with human demands, a multi-year drought in the Upper Colorado River Basin caused a dramatic drop in the Colorado River’s Lake Powell in the early part of the 2000 decade. The lake began to recover in the latter part of the decade, but as of May 2010, it was still less than 60 percent of capacity.
Earth is constantly changing. Some changes are a natural part of the climate system, such as the seasonal expansion and contraction of the Arctic sea ice pack. The responsibility for other changes, such as the Antarctic ozone hole, falls squarely on humanity’s shoulders. Our World of Change series documents how our planet’s land, oceans, atmosphere, and Sun are changing over time.
Combined with human demands, a multi-year drought in the Upper Colorado River Basin caused a dramatic drop in the Colorado River’s Lake Powell in the early part of the 2000 decade. The lake began to recover in the latter part of the decade, but as of May 2010, it was still less than 60 percent of capacity.
Water Level in Lake Powell - April 7, 2010
The Colorado River flows from the Rocky Mountains in Colorado through the southwestern United States. Along its route, the river passes through an elaborate water-management system designed to tame the yearly floods from spring snowmelt and to provide a reliable supply of water for residents as far away as California. The system is appreciated for the water it supplies, but criticized for the environmental problems and cultural losses that have resulted from its creation.
Among the dams on the Colorado is Arizona’s Glen Canyon Dam, which creates Lake Powell. The deep, narrow, meandering reservoir extends upstream into southern Utah. In the early twenty-first century, this modern marvel of engineering faced an ancient enemy: severe, prolonged drought in the American Southwest. Combined with water withdrawals that many believe are not sustainable, the drought has caused a dramatic drop in Lake Powell’s water level over the past decade. The changes are documented in this series of natural-color images from the Landsat 5 satellite between 1999 and 2010.
The images show the northeastern reaches of Lake Powell. The Colorado River flows in from the east around Mille Crag Bend and is swallowed by the lake. At the west end of Narrow Canyon, the Dirty Devil River joins the lake from the north. (At normal water levels, the both rivers are essentially part of the reservoir). Sunlight brightens plateaus and southeast-facing slopes, casting shadows on the northern and western faces of the rugged landscape.
At the beginning of the series, in 1999, water levels in Lake Powell were relatively high, and the water was a clear, dark blue. The sediment-filled Colorado River appeared green-brown. Throughout the first years of the next decade, water levels began to drop. The declines were first apparent in the side canyons feeding the reservoir, which thinned and then shortened. By 2002, the lake level had dropped far enough that the exposed canyon walls created a pale outline around the lake.
Dry conditions and falling water levels were unmistakable in the image from April 13, 2003. Lake Powell’s side branches had all retreated compared to the previous year’s extents. Water levels in Narrow Canyon had dropped enough to show canyon floor features not visible in earlier images. In the image acquired on May 1, 2004, the reservoir’s northwestern branch is isolated from the main reservoir; the shallow water upstream could not crest raised areas in the lake bed.
Lake Powell’s water levels plummeted in early 2005, according to the U.S. Department of the Interior Bureau of Reclamation, and the lowest water levels seen in this time series appear in the image from April 2, 2005. The northwestern side branch of Lake Powell remained cut off from the rest of the reservoir. In the main body of Lake Powell, water pooled along its eastern edge, while large expanses of dry canyon floor were visible in the west.
In the latter half of the decade, the drought eased somewhat. Precipitation was near, but still slightly below average in the Upper Colorado River Basin. The lake level began to rebound; only the 2008 image appeared to deviate from the trend toward rising water levels. While the lake was significantly higher in May 2010 than in 2005, a careful comparison of the side canyons reveals that the level was still not back to 1999 levels, when the lake was near full capacity.
The peak inflow to Lake Powell occurs in mid- to late spring as the winter snow in the Rockies melts. According to the Bureau of Reclamation, the April 2010 inflow to Lake Powell was 94.5 percent of average, much greater than the 66 percent of average forecasted at the start of the month. According to the Bureau’s May 2010 summary, the larger-than-expected April inflow was likely due to an earlier-than-expected spring thaw, and so it probably was not a sign that total spring runoff volume would be larger than forecast. The forecast for maximum elevation at summer pool, which usually occurs in late July or early August, was 3,634 feet above sea level, about 66 feet below full pool.
A century of river flow records combined with an additional four to five centuries of tree-ring data show that the drought of the late 1990s and early 2000s was not unusual; longer and more severe droughts are a regular part of the climate variability in that part of the continent. Global warming is expected to make droughts more severe in the future. Even in “low emission” climate scenarios (forecasts that are based on the assumption that future carbon dioxide emissions will increase relatively slowly), models predict precipitation may decline by 20-25 percent over most of California, southern Nevada, and Arizona by the end of this century. Precipitation declines combined with booming urban populations will present a significant challenge to Western water managers in the near future.
1.
References
2. Committee on the Scientific Bases of Colorado River Basin Water Management, National Research Council. (2007). Colorado River Basin Water Management: Evaluating and Adjusting to Hydroclimatic Variability. National Academies Press. Accessed May 11, 2010.
3. Stokstad, E. (2007, February 21). Western drought: The worst is yet to come. ScienceNOW. Accessed May 6, 2009.
4. U.S. Department of the Interior Bureau of Reclamation. Upper Colorado Region Water Operations: Current Status: Lake Powell. Accessed May 11, 2010.
5. U.S. Global Change Research Program. (2009). Regional Climate Change Impacts: Southwest. In Global Climate Change Impacts in the United States. [Karl, T. R., Melillo, J. M., & Peterson, T. C., eds.]. Cambridge University Press.
6. Wikipedia. (2009, May 3). Colorado River. Accessed May 6, 2009.
Among the dams on the Colorado is Arizona’s Glen Canyon Dam, which creates Lake Powell. The deep, narrow, meandering reservoir extends upstream into southern Utah. In the early twenty-first century, this modern marvel of engineering faced an ancient enemy: severe, prolonged drought in the American Southwest. Combined with water withdrawals that many believe are not sustainable, the drought has caused a dramatic drop in Lake Powell’s water level over the past decade. The changes are documented in this series of natural-color images from the Landsat 5 satellite between 1999 and 2010.
The images show the northeastern reaches of Lake Powell. The Colorado River flows in from the east around Mille Crag Bend and is swallowed by the lake. At the west end of Narrow Canyon, the Dirty Devil River joins the lake from the north. (At normal water levels, the both rivers are essentially part of the reservoir). Sunlight brightens plateaus and southeast-facing slopes, casting shadows on the northern and western faces of the rugged landscape.
At the beginning of the series, in 1999, water levels in Lake Powell were relatively high, and the water was a clear, dark blue. The sediment-filled Colorado River appeared green-brown. Throughout the first years of the next decade, water levels began to drop. The declines were first apparent in the side canyons feeding the reservoir, which thinned and then shortened. By 2002, the lake level had dropped far enough that the exposed canyon walls created a pale outline around the lake.
Dry conditions and falling water levels were unmistakable in the image from April 13, 2003. Lake Powell’s side branches had all retreated compared to the previous year’s extents. Water levels in Narrow Canyon had dropped enough to show canyon floor features not visible in earlier images. In the image acquired on May 1, 2004, the reservoir’s northwestern branch is isolated from the main reservoir; the shallow water upstream could not crest raised areas in the lake bed.
Lake Powell’s water levels plummeted in early 2005, according to the U.S. Department of the Interior Bureau of Reclamation, and the lowest water levels seen in this time series appear in the image from April 2, 2005. The northwestern side branch of Lake Powell remained cut off from the rest of the reservoir. In the main body of Lake Powell, water pooled along its eastern edge, while large expanses of dry canyon floor were visible in the west.
In the latter half of the decade, the drought eased somewhat. Precipitation was near, but still slightly below average in the Upper Colorado River Basin. The lake level began to rebound; only the 2008 image appeared to deviate from the trend toward rising water levels. While the lake was significantly higher in May 2010 than in 2005, a careful comparison of the side canyons reveals that the level was still not back to 1999 levels, when the lake was near full capacity.
The peak inflow to Lake Powell occurs in mid- to late spring as the winter snow in the Rockies melts. According to the Bureau of Reclamation, the April 2010 inflow to Lake Powell was 94.5 percent of average, much greater than the 66 percent of average forecasted at the start of the month. According to the Bureau’s May 2010 summary, the larger-than-expected April inflow was likely due to an earlier-than-expected spring thaw, and so it probably was not a sign that total spring runoff volume would be larger than forecast. The forecast for maximum elevation at summer pool, which usually occurs in late July or early August, was 3,634 feet above sea level, about 66 feet below full pool.
A century of river flow records combined with an additional four to five centuries of tree-ring data show that the drought of the late 1990s and early 2000s was not unusual; longer and more severe droughts are a regular part of the climate variability in that part of the continent. Global warming is expected to make droughts more severe in the future. Even in “low emission” climate scenarios (forecasts that are based on the assumption that future carbon dioxide emissions will increase relatively slowly), models predict precipitation may decline by 20-25 percent over most of California, southern Nevada, and Arizona by the end of this century. Precipitation declines combined with booming urban populations will present a significant challenge to Western water managers in the near future.
1.
References
2. Committee on the Scientific Bases of Colorado River Basin Water Management, National Research Council. (2007). Colorado River Basin Water Management: Evaluating and Adjusting to Hydroclimatic Variability. National Academies Press. Accessed May 11, 2010.
3. Stokstad, E. (2007, February 21). Western drought: The worst is yet to come. ScienceNOW. Accessed May 6, 2009.
4. U.S. Department of the Interior Bureau of Reclamation. Upper Colorado Region Water Operations: Current Status: Lake Powell. Accessed May 11, 2010.
5. U.S. Global Change Research Program. (2009). Regional Climate Change Impacts: Southwest. In Global Climate Change Impacts in the United States. [Karl, T. R., Melillo, J. M., & Peterson, T. C., eds.]. Cambridge University Press.
6. Wikipedia. (2009, May 3). Colorado River. Accessed May 6, 2009.
Antarctic Sea Ice
Unlike the Arctic—an ocean basin surrounded by land, where sea ice extends all the way to the pole—the Antarctic is a large continent surrounded by ocean. Because of this geography, sea ice has more room to expand in the winter, but it is also closer to the equator. The result is that Antarctica’s sea ice extent is larger than the Arctic’s in winter, but smaller in the summer. Total Antarctic sea ice peaks in September (the end of Southern Hemisphere winter) and retreats to a minimum in February.
These image pairs show Antarctic sea ice during the September maximum (left) and the following February minimum (right) for a time series beginning in September 1999 and ending in February 2010. Land is dark gray, and ice shelves—thick slabs of glacial ice grounded along the coast—are light gray. The yellow outline shows the median sea ice extent in September and February from 1979 (when routine satellite observations began) to 2000. Extent is the total area in which ice concentration is at least 15 percent. The median is the middle value. Half of the extents over the time period were larger than the line, and half were smaller.
Since the start of the satellite record, total Antarctic sea ice has increased by about 1 percent per decade. Whether the small overall increase in sea ice extent is a sign of meaningful change in the Antarctic is uncertain because ice extents in the Southern Hemisphere vary considerably from year to year and from place to place around the continent. Considered individually, only the Ross Sea sector had a significant positive trend, while sea ice extent has actually decreased in the Bellingshausen and Amundsen Seas.
September/February(maximum/minimum) September Average Extent (millions of square kilometers) February Average Extent (millions of square kilometers)
1979–2000 mean 18.7 2.9
1999/2000 19.0 2.8
2000/2001 19.1 3.7
2001/2002 18.4 2.9
2002/2003 18.2 3.8
2003/2004 18.6 3.6
2004/2005 19.1 2.9
2005/2006 19.1 2.6
2006/2007 19.4 2.9
2007/2008 19.2 3.7
2008/2009 18.5 2.9
2009/2010 19.2 3.2
The year-to-year and place-to-place variability is evident in these images from the past decade. The winter maximum in the Weddell Sea, for example, is above the median in some years and below it others. In any given year, sea ice concentration may be below the median in one sector, but above the median in another; in September 2000, for example, ice concentrations in the Ross Sea were above the median extent, while those in the Pacific were below it.
At summer minimums, sea ice concentrations appear even more variable. In the Ross Sea, sea ice virtually disappears in some summers (2000, 2005, 2006, and 2009), but not all. The long-term decline in the sea ice in the Bellingshausen and Amundsen Seas is detectable in the past decade’s summer minimums: concentrations were below the median in all years.
This time series is made from a combination of observations from the Special Sensor Microwave/Imagers (SSM/Is) flown on a series of Defense Meteorological Satellite Program missions and the Advanced Microwave Scanning Radiometer for EOS (AMSR-E), a Japanese-built sensor that flies on NASA’s Aqua satellite. These sensors measure microwave energy radiated from the Earth’s surface (sea ice and open water emit microwaves differently). Scientists use the observations to map sea ice concentrations.
*
References
* Cavalieri, D. J., and C. L. Parkinson (2008). Antarctic sea ice variability and trends, 1979–2006, Journal of Geophysical Research Oceans. 113, C07004.
* NSIDC. (2007, September 25). Bootstrap Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I. Accessed May 15, 2009.
* NSIDC. Frequently Asked Questions about Sea Ice. Accessed May 20, 2009.
* NSIDC. Sea Ice Index. Accessed May 13, 2009.
* Raphael, M.N. (2007). The influence of atmospheric zonal wave three on Antarctic sea ice variability. Journal of Geophysical Research. 112, D12112.
* Steig, E.J., Schneider, D.P., Rutherford, S.D., Mann, M.E., Comiso, J.C., Shindell, D.T. (2009). Warming of the Antarctic ice-sheet surface since the 1957 International Geophysical Year. Nature. 457, 459-463.
These image pairs show Antarctic sea ice during the September maximum (left) and the following February minimum (right) for a time series beginning in September 1999 and ending in February 2010. Land is dark gray, and ice shelves—thick slabs of glacial ice grounded along the coast—are light gray. The yellow outline shows the median sea ice extent in September and February from 1979 (when routine satellite observations began) to 2000. Extent is the total area in which ice concentration is at least 15 percent. The median is the middle value. Half of the extents over the time period were larger than the line, and half were smaller.
Since the start of the satellite record, total Antarctic sea ice has increased by about 1 percent per decade. Whether the small overall increase in sea ice extent is a sign of meaningful change in the Antarctic is uncertain because ice extents in the Southern Hemisphere vary considerably from year to year and from place to place around the continent. Considered individually, only the Ross Sea sector had a significant positive trend, while sea ice extent has actually decreased in the Bellingshausen and Amundsen Seas.
September/February(maximum/minimum) September Average Extent (millions of square kilometers) February Average Extent (millions of square kilometers)
1979–2000 mean 18.7 2.9
1999/2000 19.0 2.8
2000/2001 19.1 3.7
2001/2002 18.4 2.9
2002/2003 18.2 3.8
2003/2004 18.6 3.6
2004/2005 19.1 2.9
2005/2006 19.1 2.6
2006/2007 19.4 2.9
2007/2008 19.2 3.7
2008/2009 18.5 2.9
2009/2010 19.2 3.2
The year-to-year and place-to-place variability is evident in these images from the past decade. The winter maximum in the Weddell Sea, for example, is above the median in some years and below it others. In any given year, sea ice concentration may be below the median in one sector, but above the median in another; in September 2000, for example, ice concentrations in the Ross Sea were above the median extent, while those in the Pacific were below it.
At summer minimums, sea ice concentrations appear even more variable. In the Ross Sea, sea ice virtually disappears in some summers (2000, 2005, 2006, and 2009), but not all. The long-term decline in the sea ice in the Bellingshausen and Amundsen Seas is detectable in the past decade’s summer minimums: concentrations were below the median in all years.
This time series is made from a combination of observations from the Special Sensor Microwave/Imagers (SSM/Is) flown on a series of Defense Meteorological Satellite Program missions and the Advanced Microwave Scanning Radiometer for EOS (AMSR-E), a Japanese-built sensor that flies on NASA’s Aqua satellite. These sensors measure microwave energy radiated from the Earth’s surface (sea ice and open water emit microwaves differently). Scientists use the observations to map sea ice concentrations.
*
References
* Cavalieri, D. J., and C. L. Parkinson (2008). Antarctic sea ice variability and trends, 1979–2006, Journal of Geophysical Research Oceans. 113, C07004.
* NSIDC. (2007, September 25). Bootstrap Sea Ice Concentrations from Nimbus-7 SMMR and DMSP SSM/I. Accessed May 15, 2009.
* NSIDC. Frequently Asked Questions about Sea Ice. Accessed May 20, 2009.
* NSIDC. Sea Ice Index. Accessed May 13, 2009.
* Raphael, M.N. (2007). The influence of atmospheric zonal wave three on Antarctic sea ice variability. Journal of Geophysical Research. 112, D12112.
* Steig, E.J., Schneider, D.P., Rutherford, S.D., Mann, M.E., Comiso, J.C., Shindell, D.T. (2009). Warming of the Antarctic ice-sheet surface since the 1957 International Geophysical Year. Nature. 457, 459-463.
Ricardo Marcenaro
Sculptures – Esculturas
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My blogs are an open house to all cultures, religions and countries. Be a follower if you like it, with this action you are building a new culture of tolerance, open mind and heart for peace, love and human respect.
Thanks :)
Mis blogs son una casa abierta a todas las culturas, religiones y países. Se un seguidor si quieres, con esta acción usted está construyendo una nueva cultura de la tolerancia, la mente y el corazón abiertos para la paz, el amor y el respeto humano.
Gracias :)
Sculptures – Esculturas
http://ricardomarcenaro.ning.com/
Ricardo M Marcenaro - Facebook
Blogs in operation of The Solitary Dog:
Solitary Dog Sculptor:
http://byricardomarcenaro.blogspot.com
Solitary Dog Sculptor I:
http://byricardomarcenaroi.blogspot.com
Para:
comunicarse conmigo,
enviar materiales para publicar,
propuestas comerciales:
marcenaroescultor@gmail.com
For:
contact me,
submit materials for publication,
commercial proposals:
marcenaroescultor@gmail.com
Diario La Nación
Argentina
Cuenta Comentarista en el Foro:
Capiscum
My blogs are an open house to all cultures, religions and countries. Be a follower if you like it, with this action you are building a new culture of tolerance, open mind and heart for peace, love and human respect.
Thanks :)
Mis blogs son una casa abierta a todas las culturas, religiones y países. Se un seguidor si quieres, con esta acción usted está construyendo una nueva cultura de la tolerancia, la mente y el corazón abiertos para la paz, el amor y el respeto humano.
Gracias :)
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