3
   

Wildclickers #73: Brown - The progression of life

 
 
sumac
 
  1  
Reply Sat 29 Jul, 2006 03:55 am
https://www.livescience.com/images/060720_sahara_map_02.jpg

http://www.livescience.com/history/060720_sahara_rains.html

Sahara Desert Was Once Lush and Populated

By Bjorn Carey
LiveScience Staff Writer
posted: 20 July 2006
02:07 pm ET



At the end of the last Ice Age, the Sahara Desert was just as dry and uninviting as it is today. But sandwiched between two periods of extreme dryness were a few millennia of plentiful rainfall and lush vegetation.

During these few thousand years, prehistoric humans left the congested Nile Valley and established settlements around rain pools, green valleys, and rivers.

The ancient climate shift and its effects are detailed in the July 21 issue of the journal Science.

When the rains came

Some 12,000 years ago, the only place to live along the eastern Sahara Desert was the Nile Valley. Being so crowded, prime real estate in the Nile Valley was difficult to come by. Disputes over land were often settled with the fist, as evidenced by the cemetery of Jebel Sahaba where many of the buried individuals had died a violent death.

But around 10,500 years ago, a sudden burst of monsoon rains over the vast desert transformed the region into habitable land.

This opened the door for humans to move into the area, as evidenced by the researcher's 500 new radiocarbon dates of human and animal remains from more than 150 excavation sites.

"The climate change at [10,500 years ago] which turned most of the [3.8 million square mile] large Sahara into a savannah-type environment happened within a few hundred years only, certainly within less than 500 years," said study team member Stefan Kroepelin of the University of Cologne in Germany.

Frolicking in pools

In the Egyptian Sahara, semi-arid conditions allowed for grasses and shrubs to grow, with some trees sprouting in valleys and near groundwater sources. The vegetation and small, episodic rain pools enticed animals well adapted to dry conditions, such as giraffes, to enter the area as well.

Humans also frolicked in the rain pools, as depicted in rock art from Southwest Egypt.

In the more southern Sudanese Sahara, lush vegetation, hearty trees, and permanent freshwater lakes persisted over millennia. There were even large rivers, such as the Wadi Howar, once the largest tributary to the Nile from the Sahara.

"Wildlife included very demanding species such as elephants, rhinos, hippos, crocodiles, and more than 30 species of fish up to 2 meters (6 feet) big," Kroepelin told LiveScience.

A timeline of Sahara occupation [See Map]:

22,000 to 10,500 years ago: The Sahara was devoid of any human occupation outside the Nile Valley and extended 250 miles further south than it does today.
10,500 to 9,000 years ago: Monsoon rains begin sweeping into the Sahara, transforming the region into a habitable area swiftly settled by Nile Valley dwellers.
9,000 to 7,300 years ago: Continued rains, vegetation growth, and animal migrations lead to well established human settlements, including the introduction of domesticated livestock such as sheep and goats.
7,300 to 5,500 years ago: Retreating monsoonal rains initiate desiccation in the Egyptian Sahara, prompting humans to move to remaining habitable niches in Sudanese Sahara. The end of the rains and return of desert conditions throughout the Sahara after 5,500 coincides with population return to the Nile Valley and the beginning of pharaonic society.
Related Stories

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Singing Sand Dunes: The Mystery of Desert Music
Ancient People Followed 'Kelp Highway' to America
Scientists To Study Monsoon Formation
0 Replies
 
sumac
 
  1  
Reply Sat 29 Jul, 2006 03:57 am
There is nothing the matter with that image URL. I just posted it on Science News and it came out.

http://i76.photobucket.com/albums/j30/PeggyMartin/Mother%20Nature/324b4cef.jpg
0 Replies
 
sumac
 
  1  
Reply Sat 29 Jul, 2006 03:59 am
http://www.livescience.com/forcesofnature/060720_wind_greatplains.html

History Suggests Major Wind Shift Could Again Bring Drought to Great Plains

By Sara Goudarzi
LiveScience Staff Writer
posted: 20 July 2006
04:17 pm ET

http://images.livescience.com/images/060720_nebraska_sand_01.jpg

Nebraska's Sand Hills might look like a place fit only for cattle grazing, but to geologists the expanse of grasslands hide sand dunes that contain a valuable record of ancient climate.

A crisscross pattern in the dunes serves as a record of changes in wind direction and shows that 800 to 1,000 years ago, during the Medieval Warm Period, the winds brought drought to that region, according to a new study.

In the spring and summer, during the growing season, southerly winds from the Gulf of Mexico bring moisture and rainfall up to the open expanse of prairie east of the Rocky Mountains, an area known as the Great Plains.

Today, the net force of southerly summer winds combined with northerly winds of winter would push the sand dunes to migrate in a southeastern direction. But the dunes don't move because they are stabilized by vegetation.

Back during the Medieval Warm Period, the dunes were not vegetated and were free to move.

The direction that the dunes moved back then, recorded in their crisscross pattern, is a result of the net force of the winds during that time. Assuming that winter winds came from the north like today, scientists were able to figure out which direction the spring and summer winds came from.

Their analysis found that spring and summer winds back then did not come from the Gulf of Mexico but instead blew from the Southwest. These warm and dry winds likely caused the drought conditions that had previously been documented for the region back then, explained study co-author David Loope of the University of Nebraska.

And what if a similar shift occurred today?

"This argues for a conservative position of water resources, because there's a possibility of a super drought," Loope told LiveScience. "Being more conservative would be the lesson here."

The study is detailed in the July 21 issue of the journal Science.

Drought Conditions Worsen in Parts of U.S.
Singing Sand Dunes: The Mystery of Desert Music
Expedition Explains Strange Antarctic Megadunes
Sand Dunes on Mars Reach Dizzying Heights
Weather 101: All About Wind and Rain

http://images.livescience.com/images/060720_nebraska_sand_00.jpg

Northward aerial view of sand dunes in the eastern Nebraska Sand Hills. The dunes, now stabilized by prairie grass, were formed only 800-1,000 years ago during droughts of the Medieval Warm Period. Credit: David Loope and Jon Mason
0 Replies
 
sumac
 
  1  
Reply Sat 29 Jul, 2006 04:01 am
0 Replies
 
sumac
 
  1  
Reply Sat 29 Jul, 2006 04:13 am
http://www.washingtonpost.com/wp-dyn/content/article/2006/07/28/AR2006072801994_pf.html



On the Roof of Peru, Omens in the Ice
Retreat of Once-Mighty Glacier Signals Water Crisis, Mirroring Worldwide Trend

By Doug Struck
Washington Post Foreign Service
Saturday, July 29, 2006; A01



QUELCCAYA GLACIER, Peru -- In the thin, cold air here atop the Andes mountains, the blue ice that has claimed these peaks for thousands of years and loyally fed the streams below is now disappearing rapidly.

Mountain glaciers such as this are in retreat around the Earth, taking with them vast stores of water that grow crops, generate electricity and sustain cities and rural areas.

Farmers here say that over the past two decades they have noticed a dramatic decrease in the amount of ice and snow on their mountaintops. The steady supply of water they need to grow crops has become erratic.

"There is less water now. If there is no water, this land becomes a desert," said Benedicto Loayza, a 52-year-old farmer, standing under pear trees fed by channels dug on the mountain centuries ago to collect runoff.

Cuzco, a city of 400,000, has already resorted to periodic water rationing and started pumping from a river 15 miles away for its drinking supply. In Peru's capital, Lima, engineers have urged successive governments to drill a tunnel through the Andes and build big lagoons to ensure that the city's 8 million residents have water. Citing the expense, authorities have dawdled. Cities in China, India, Nepal and Bolivia also face drastic water shortages as the glaciers shrink.

"You can think of these glaciers as a bank account built over thousands of years," said Lonnie Thompson, one of the first scientists to sound the alarm, as he stood by the largest ice cap in the Andes. "If you subtract more than you gain, eventually you go bankrupt. That's what's in process here."

Thompson arrived at the blue-white face of the Quelccaya glacier this month after a two-day hike from the nearest road, climbing into the oxygen-thin air of 17,000 feet above sea level. Since he started his annual visits here in 1974, he said, the huge ice cap has shrunk by 30 percent. In the last year, the tongue of the ice has pulled back 100 yards, breakneck speed for a glacier.

He examined it as if it were a sick patient. The mountain of ice was pocked with holes where the surface had melted. A large chunk had broken off in March, crashing into the meltwater lake below and sending a flood wave into alpacas' lower grazing grounds. The face of the glacier, once frozen so perfectly that Thompson could identify the yearly snowfalls back 1,500 years, now sagged and dripped.

"It's not just a retreat," he said. "It's an accelerating retreat."

Since Thompson's first reports, he and others have confirmed a rapid recession of glaciers worldwide. Snows on Africa's Mount Kilimanjaro, extolled by Ernest Hemingway as "wide as all the world, great, high, and unbelievably white," will be gone within 14 years, Thompson estimates. Glaciers in the Alps, the Himalayas and throughout the Andes are also shrinking, he and other researchers have found.

The dramatic rise in carbon dioxide that has accompanied the industrial age has brought a spike in global temperatures. Scientists have found that the jump in temperatures is even greater in the upper atmosphere, where the glaciers reign on silent mountain peaks.

Glaciers store an estimated 70 percent of the world's fresh water. Water that falls as snow moves through the slowly churning ice and may emerge from the glacier's edge thousands of years later as meltwater. Humans have long depended on the gradual and faithful runoff.

The melting of glaciers in the Himalayas, which feed seven great Asian rivers, will bring "massive eco and environmental problems for people in western China, Nepal and northern India," a World Wildlife Fund report concluded last year.

"The repercussions of this are very scary," agreed Tim Barnett, a climate scientist with the Scripps Institution of Oceanography in San Diego. "When the glaciers are gone, they are gone. What does a place like Lima do? Or, in northwest China, there are 300 million people relying on snowmelt for water supply. There's no way to replace it until the next ice age."

At least three times a day, Eva Rondon, 38, walks the 18 worn steps carved out of the hillside of a shantytown on the far outskirts of Lima. She carries a plastic bucket to an old Shell Oil barrel with a rusty top and lid fashioned out of a few boards nailed together. She has paid a private water trucker to fill the barrel with water -- the only source for her family and neighbors -- and even that water is often dirty.

An estimated 2 million of Lima's 8 million people have no water service. Some live decades without it, buying water at as much as 30 times the price per gallon paid by customers whose homes are connected to the government-owned water utility. They are organizing to demand service from a government they say is corrupt and uncaring. But they have no doubt who will be deprived if the melting glaciers make Lima's water even scarcer.

"The poor will suffer. Our children will suffer," said Adolfo Peña, the local representative of the grass-roots political movement Peruvians Without Water. "Lima is built on a desert, and in 20 years, there's not going to be water."

If every home were connected to the utility system, there would not be enough water to pump through the pipes, said Romolo Carhuaz. He is the engineer for Sedapal, the capital's public water company, and is in charge of monitoring the reservoirs that feed Lima its water.

Each week, Carhuaz puts on a baseball cap, grabs an oxygen bottle and drives out of Lima up a jolting dirt road into the Andes mountains. He negotiates past bulls, llamas and fierce sheepdogs on his 13-hour circuit, finally grinding to a halt at a mountain plateau where cactuses bake in the cold sun. There, at 15,000 feet, lies a series of brilliant blue lagoons filled by rainwater and glacial runoff from the peaks above. Both sources, the historic lifelines for arid Lima, are now fickle, he said.

"Look at those mountains," Carhuaz said, gesturing to the rocky heights that tower over his reservoirs. White patches of snow and ice cling to some of the higher crevices. "They used to be covered with glaciers to halfway down the mountains 20 years ago."

"We call that Cat's Eye," he said, pointing out one small circle of ice left on a mountain. "It used to be huge."

Carhuaz blames the changing weather. He said average temperatures here have risen significantly in little over a decade. What used to fall as snow, adding to the glaciers, now comes as rain. And that rainfall is erratic, he said.

The changing rainfall and shrinking glaciers have also alarmed the companies that operate Peru's hydroelectric plants, which supply most of the country's electricity. "What we have seen in the past three years is a pattern that is quite different from the 40-year average," said Mark Hoffmann, the head of ElectroAndes, a private power company. "The historical data is not particularly useful in projecting anymore. We are hoping it's a blip."

Uncertain of the water supply, electric companies are building plants to generate power by using natural gas, relying on a new gas field discovered in southern Peru and government controls on prices.

"The 'wise men' believe natural gas is going to be the solution. They are clearly wrong," said Guillermo Romero, an official of Electroperu, which operates the two largest hydroelectric plants in the country. Natural gas eventually will run out, he said -- sooner rather than later if the government builds a liquefied natural gas port to export the gas. He expressed hope that the recently elected government would return its attention to building reservoirs and hydro plants.

"The problem isn't with us. It's with the government," he said.

The government has put off projects to relieve Lima's looming water deficit. Such large initiatives are expensive for a poor country, and some plans -- including the one to drill a tunnel through the Andes -- carry risks in this earthquake-prone region. In 1970, an earthquake shook loose a wall of ice and rock from the Huascaran mountain in the Andes north of Lima, burying the town of Yungay and killing tens of thousands of people.

Politicians find the scientists' broader warnings easy to ignore amid the more immediate water problems posed by burgeoning populations, increased agricultural development and contamination of water sources by mines. Some authorities acknowledge the looming crisis; others deny it.

At the local power company in Cuzco, "we are conscious that it will affect us a lot," said Mario Ortiz, a top director. But Ortiz acknowledged the company does not really know how much of its main source, the Vilcanota River, originates from glaciers. What would it mean in the dry season if the glacier is not there? Ortiz simply looks down at his desk and shakes his head.

"We're like firefighters. We only move when there is a fire," he said sadly.

The warming climate is causing other effects. In the Andes mountains north of Lima, Hugo Osoria, 32, used to work as an "ice fetcher," walking two hours from his village of Paria to cut off a chunk of glacier ice, haul it down and take a short minibus ride to the city of Huaraz to sell it. But the glaciers have retreated so much, the longer walk each way is no longer worth it. Osoria noticed changes in the local crops -- potatoes were not growing well, and worms not seen in the area before were attacking corn. So he experimented by growing flowers that were also new to village. His wife puts them in a wheelbarrow to sell them at hotels and markets in Huaraz.

"Only a few of us are trying to take advantage of the changes and make it positive," he said. For most, the climate change portends hardship.

"We are in a real critical situation," said Vincente Velasquez, 42, who grows potatoes in an area near Cuzco that the Incas called the "sacred valley" because it was so fertile. "We are talking about the melting glaciers, but we don't know what to believe. If the glaciers go away, people will think it's God's punishment."

Loayza, the 52-year-old farmer who grows fruit trees and rosemary on his land north of Cuzco, said he and his neighbors often discuss the bleak future.

"Everyone in the valley is worried about the melting ice," he said, standing in his fields, now thriving with winter sun and irrigation. "Without water, how can you work? How can you live?"

Correspondent Monte Reel in Buenos Aires, special correspondent Lucien O. Chauvin in Lima and researcher Natalia Alexandrova in Toronto contributed to this report.
0 Replies
 
teenyboone
 
  1  
Reply Sat 29 Jul, 2006 08:38 am
sumac wrote:
There is nothing the matter with that image URL. I just posted it on Science News and it came out.

http://i76.photobucket.com/albums/j30/PeggyMartin/Mother%20Nature/324b4cef.jpg

Just checking in to see where everyone is. I hope to particpate and glad to be back,
Teeny Cool
0 Replies
 
sumac
 
  1  
Reply Sat 29 Jul, 2006 10:00 am
Good to see you, teeney.

Some folks are on holiday (Ul, ehBeth), some are AWOL or MIA.

But we're here!!!!!
0 Replies
 
Merry Andrew
 
  1  
Reply Sat 29 Jul, 2006 03:09 pm
Hey, teeney! Welcome home!
0 Replies
 
danon5
 
  1  
Reply Sat 29 Jul, 2006 05:25 pm
Hi Teeny, Glad to see ya again......

Hi Merry Andrew, How are things with you?

Finally clicked for today.................

(the provervial =)

"Aw, clicked"
0 Replies
 
Merry Andrew
 
  1  
Reply Sat 29 Jul, 2006 09:21 pm
Hi, Danon. With me things are regular as the Mexicans say. And your own self?
0 Replies
 
Amigo
 
  1  
Reply Sun 30 Jul, 2006 01:57 am
Click Very Happy
0 Replies
 
sumac
 
  1  
Reply Sun 30 Jul, 2006 03:03 am
Tring to get a handle on the heat where Ul is. Back to the atlas.
0 Replies
 
sumac
 
  1  
Reply Sun 30 Jul, 2006 12:52 pm
http://www.able2know.com/forums/viewtopic.php?p=2178750#2178750

http://www.able2know.com/forums/viewtopic.php?p=2178754#2178754
0 Replies
 
danon5
 
  1  
Reply Sun 30 Jul, 2006 05:01 pm
Nice links sumac... bookmarked and will check in to see what's new.

The article about Earth wobbling was good - there is no exact point at the N or S poles the Earth rotates around. The rotation travels around an approximately fifteen foot circle.

Merry,
Things are ok here. We have beaten a path between our home and the hospital - but, other than that.....? Glad to see you.

clicked
0 Replies
 
ehBeth
 
  1  
Reply Sun 30 Jul, 2006 06:46 pm
Checking in from Kingston.

Setanta and I just finished watching The Motorcycle Diaries on a DVD I took out from the local library on mrs. hamburger's card. I can't recommend the film enough. I've been meaning to see it ever since I saw the previews when I saw Maria Full of Grace. I'm simply wowed by the scenery, the story, the diaries, the music, the acting. Wowed.

Setanta and I were watching some of the extra features on the DVD when mrs. hamburger appeared on the scene. Now she and hamburger are watching it again, and I'm listening to the soundtrack from the website.

http://www.motorcyclediariesmovie.com/home.html

(click on travelling music on the lower right hand side)

~~~~~~~~~~~

and well, you know I clicked Very Happy

aktbird57 - You and your 299 friends have supported 2,494,020.2 square feet!

Marine Wetlands habitat supported: 123,075.0 square feet.
You have supported: (0.0)
Your 299 friends have supported: (123,075.0)

American Prairie habitat supported: 54,449.1 square feet.
You have supported: (13,461.0)
Your 299 friends have supported: (40,988.1)

Rainforest habitat supported: 2,316,496.1 square feet.
You have supported: (172,336.3)
Your 299 friends have supported: (2,144,159.8)

~~~~~~~~~~~~

1 Aktbird57 .. 1535 57.252 acres
0 Replies
 
sumac
 
  1  
Reply Mon 31 Jul, 2006 10:20 am
http://www.cbsnews.com/stories/2006/07/31/tech/main1847758.shtml

"Calif., U.K. Teaming Up On Environment

WASHINGTON, July 31, 2006
--------------------------------------------------------------------------------
(AP) Britain and California are preparing to sidestep the Bush administration and fight global warming together by creating a joint market for greenhouse gases.

British Prime Minister Tony Blair and California Governor Arnold Schwarzenegger plan to lay the groundwork for a new trans-Atlantic market in carbon dioxide emissions, The Associated Press has learned. Such a move could help California cut carbon dioxide and other heat-trapping gases scientists blame for warming the planet. President Bush has rejected the idea of ordering such cuts.

Blair and Schwarzenegger are expected to announce their collaboration Monday afternoon in Los Angeles, according to documents provided by British government officials on condition of anonymity because the announcement is forthcoming.

The aim is to fix a price on carbon pollution, an unwanted byproduct of burning fossil fuels like coal, oil and gasoline. The idea is to set overall caps for carbon and reward businesses that find a profitable way to minimize their carbon emissions, thereby encouraging new, greener technologies. ..."

More at linked article.
0 Replies
 
danon5
 
  1  
Reply Mon 31 Jul, 2006 06:01 pm
More appropriately, sumac, I would think the PhD's would be pursuing a more viable method of capturing the carbon and using it to create usable stuff - like - airplanes and helicopter rotor blades and stuff like that. Additionally, the things that can be made using carbon are only limited to the imagination. Why not use it???

clicked
0 Replies
 
ehBeth
 
  1  
Reply Mon 31 Jul, 2006 06:54 pm
You and your 299 friends have supported 2,495,565.5 square feet!

Marine Wetlands habitat supported: 123,238.9 square feet.
You have supported: (0.0)
Your 299 friends have supported: (123,238.9)

American Prairie habitat supported: 54,449.1 square feet.
You have supported: (13,461.0)
Your 299 friends have supported: (40,988.1)

Rainforest habitat supported: 2,317,877.5 square feet.
You have supported: (172,359.7)
Your 299 friends have supported: (2,145,517.7)

~~~~~~~

1 Aktbird57 .. 1536 57.287 acres
0 Replies
 
ehBeth
 
  1  
Reply Tue 1 Aug, 2006 12:03 pm
A pinch and a punch for the first of the month.

~~~~~~~~

aktbird57 - You and your 299 friends have supported 2,497,040.5 square feet!

Marine Wetlands habitat supported: 123,379.3 square feet.
You have supported: (0.0)
Your 299 friends have supported: (123,379.3)

American Prairie habitat supported: 54,449.1 square feet.
You have supported: (13,461.0)
Your 299 friends have supported: (40,988.1)

Rainforest habitat supported: 2,319,212.0 square feet.
You have supported: (172,406.6)
Your 299 friends have supported: (2,146,805.5)

~~~~~~~

1 Aktbird57 .. 1537 57.320 acres

http://static.flickr.com/58/158416633_466dff79bc_m.jpg

man in the environment?

Cool
0 Replies
 
danon5
 
  1  
Reply Tue 1 Aug, 2006 04:10 pm
Cool pic, ehBeth.....

aw kwicked diesem tak
0 Replies
 
 

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