Bookmark Topic Watch Topic
  • New Topic

The story of the Sahara from the last podcast, I don't think it's true.  RSS feed

 
Emerson White
Posts: 1206
Location: Alaska
  • Mark post as helpful
  • send pies
  • Report post to moderator
In the last podcast Paul told a story like this.

*The Sahara was once a lush jungle
*People had to walk a long way to get their food
*People discovered that they could plant food
*People discovered that they got more food if they cut down the trees and planted there
*The degraded their forest one patch at a time until there was no forest left and the Sahara was desert

I don't buy this story, it's very attractive from the angle where I consider how much I love love love the forest. However, I realize that my deep love of being in and around trees has no bearing on the facts.

Some things that suggest that this story isn't true.

*The Lush Sahara was probably a savanna/ mixed grassland, the nubians who settled there 9,500 years ago kept cattle (we know this from the cave art) cows are not well suited to the jungles, but rather to semiarid places. That is why their milk has so much water when compared to a non desert animal like a water buffalo.
*If you chop down a forest on fertile land your crops grow well, but as paul pointed out these warm places don't really build soil all that well. Since these were stone age farmers it's a safe bet that they weren't practicing slash and burn agriculture, and the forests of the Saharah would have been the least convenient and least fertile places in the area to plant the cereal grains that the agricultural revolution was built on.
*The Sahara was watered by a monsoon, for a monsoon to happen the ground needs to heat up and lift the air straight up and replace it with air off the oceans (a conveyor belt for moist ocean air to go up and ring the water out with low pressure). If it's getting this hot and your cattle haven't got shade you haven't got cattle, these people probably prized trees and would not have cut them all down.
*They had tree crops, Olives and dates and figs were probably prized as food stuffs long before cereal grains and probably were valued more than the infertile ground they grew in. The semi-modern pastoral/agrarian societies didn't cut down their fruit trees to make way for grain, why would the ancient ones do it?

Now if we look at the flip side we know that the Sahara was most lush as the planet was tilted further than it is now, We know that before this axial tilt was reached the Sahara was a desert. We know that at the earth's axis has straightened out more the desert has crept further (because the monsoon stopped happening). We know that lots of people became established within 500 years of the greening up (when we came out of the last ice age) and we know that they lived there for 2500 years until the earths axis shifted back. Now I don't know about you guys, but I don't think forests can spread over a 1000X3000 mile area in a scant 500 years. The only way a forest could have spread that fast is if humans had planted it. If the jungle was anthropogenic then that means for certain that it didn't cause the pleasant climate.

So we know that climate forces could have done it. We know that the only way a jungle could have gotten there is if people had put it there. We know that people had a strong reason to plant and maintain trees.

I just don't see any wiggle room for the story from the podcast to be true.
 
Terri Matthews
Posts: 469
Location: Eastern Kansas
4
  • Mark post as helpful
  • send pies
  • Report post to moderator
I do not know enough about the sahara to debate: I DO know about the midwest, a little.

My part of the Midwest was covered by the ocean, as seen by the limestones full of fossils. Climate change happens!

And, in spite of our fame as grasslands, this land would rather grow trees. It took the efforts of the Indians to make Eastern Kansas into praries: if the lightning did not set fires the Indians did!

Having big sweeps of grassland meant that there were big herds of buffalo, and they got more nourishments from meat than fron the native fruit trees. (Plum and chokecherry were good in the Midwest).

So, it is possible that mankind did play a part in keeping the sahara as grass lands. They did here in Kansas. though it is true that grass will grow like wildfire as well as trees. The thing about slash and burn agriculture, though, is that trees will grow back just as soon as man smoves on: it would take more than that to change a climate.

The again, what do the archaeologists say? Archaeologists do things like digging holes so that they can look at pollen: that means they KNOW what plants were common at any given time period!
 
Emerson White
Posts: 1206
Location: Alaska
  • Mark post as helpful
  • send pies
  • Report post to moderator
My key explanation of why that wouldn't have happened is two part. Firstly the cattle were property of some sort, secondly the middle east is under a bit more of an intense sun region than the midwest. The top of the Sahara would be in Florida. The savanna with both trees and grass would have given them more meat nourishment than just the grass.
 
Terri Matthews
Posts: 469
Location: Eastern Kansas
4
  • Mark post as helpful
  • send pies
  • Report post to moderator
Have you seen the size of the herds that Africans people prefer? Trampling feet will also kill many tree seedlings.

About the intensity of the sunlight I have no answer: I have never lived down South and I do not know enough of the ecosystem!
 
Emerson White
Posts: 1206
Location: Alaska
  • Mark post as helpful
  • send pies
  • Report post to moderator
Well yes but if they had cattle they had mastered either the fence or the vigilant watch.
 
Tyler Ludens
pollinator
Posts: 9742
Location: Central Texas USA Latitude 30 Zone 8
184
  • Mark post as helpful
  • send pies
  • Report post to moderator
I believe Emerson is correct.


"Sahara's Abrupt Desertification Started By Changes In Earth's Orbit, Accelerated By Atmospheric And Vegetation Feedbacks

ScienceDaily (July 12, 1999) — WASHINGTON -- One of the most striking climate changes of the past 11,000 years caused the abrupt desertification of the Saharan and Arabia regions midway through that period. The resulting loss of the Sahara to agricultural pursuits may be an important reason that civilizations were founded along the valleys of the Nile, the Tigris, and the Euphrates. German scientists, employing a new climate system model, have concluded that this desertification was initiated by subtle changes in the Earth's orbit and strongly amplified by resulting atmospheric and vegetation feedbacks in the subtropics. The timing of this transition was, they report, mainly governed by a global interplay among atmosphere, ocean, sea ice, and vegetation. Their research is published in the July 15 issue of Geophysical Research Letters.

The researchers, headed by Martin Claussen of the Potsdam-Institut fuer Klimafolgenforschung (Potsdam Institute for Climate Impact Research) employed a model of intermediate complexity to analyze climate feedbacks during the past several thousand years of the current, or Holocene, era. Called CLIMBER-2 (for CLIMate and BiosphERe, version 2.1), the model led to the conclusion that the desertification of North Africa began abruptly 5,440 years ago (+/- 30 years). Before that time, the Sahara was covered by annual grasses and low shrubs, as evidenced by fossilized pollen."

http://www.sciencedaily.com/releases/1999/07/990712080500.htm

Present climate change seems to be changing the Sahara again:

"Sahara Desert Greening Due to Climate Change?
James Owen
for National Geographic News
July 31, 2009

Desertification, drought, and despair—that's what global warming has in store for much of Africa. Or so we hear.

Emerging evidence is painting a very different scenario, one in which rising temperatures could benefit millions of Africans in the driest parts of the continent.

Scientists are now seeing signals that the Sahara desert and surrounding regions are greening due to increasing rainfall.

If sustained, these rains could revitalize drought-ravaged regions, reclaiming them for farming communities.

This desert-shrinking trend is supported by climate models, which predict a return to conditions that turned the Sahara into a lush savanna some 12,000 years ago."

http://news.nationalgeographic.com/news/2009/07/090731-green-sahara.html
 
Terri Matthews
Posts: 469
Location: Eastern Kansas
4
  • Mark post as helpful
  • send pies
  • Report post to moderator
There is a really cool map of projected global warming on that site.

They accurately predicted a slightly greener Sahara.

They are also predicting more rain in the midwest- which is good because the ogalalla aquifer might be in trouble, so irrigation might end up decreased or worse.

Rising sea levels and greater storms would seem to threaten Louisiana. For that matter, San Jose is partly below sea level so that city might also be at risk.

Less snow pack in Colorado, which means less water in the summer. Though I suppose they could build more reservoirs.
 
Tyler Ludens
pollinator
Posts: 9742
Location: Central Texas USA Latitude 30 Zone 8
184
  • Mark post as helpful
  • send pies
  • Report post to moderator
Terri wrote:
Though I suppose they could build more reservoirs.


Reservoirs actually lose water, not store it.  Water is best stored in the soil or small earthworks.

Reference:  "Rainwater Harvesting for Drylands and Beyond" by Brad Lancaster
                  "Water for Every Farm" by PA Yeomans
 
Terri Matthews
Posts: 469
Location: Eastern Kansas
4
  • Mark post as helpful
  • send pies
  • Report post to moderator
Water in the soil is hard to drink.
 
Tyler Ludens
pollinator
Posts: 9742
Location: Central Texas USA Latitude 30 Zone 8
184
  • Mark post as helpful
  • send pies
  • Report post to moderator
Terri wrote:
Water in the soil is hard to drink.


Relatively little of the water in reservoirs is used as drinking water.  It would make more sense to spend the money and resources on restoring watersheds.


 
                    
Posts: 0
  • Mark post as helpful
  • send pies
  • Report post to moderator
Groundwater is unavailable unless one digs a well, or finds a spring on the side of a hill. 

There has been a nice debate about the whole concept of 'desertification' over the past decades. For the most part, I don't think it is strictly accurate to say that humans cause deserts - that is from changes in precipitation. But areas like the Sahel, Lebanon, Israel, Greece, and coastal North Africa clearly have been ravaged by humans - trees are cut for their wood and to prepare fields, the fields are tilled and the topsoil washes away, areas become barren and unproductive. Maybe climate change over the past 4,000 years has made the degradation process more rapid and harder to reverse. Maybe land use / land cover changes only affect climate when they cover huge areas and are quite dramatic.

None of that really changes the permaculture ethic, as I see it. Even if the story about the man who planted trees and grew happiness contains points we can quibble over, it is still essentially true. Terrascaping to utilize water, rebuild soil, and restore useful ecosystems is a good thing. These actions may not increase the amount of rain that falls, but they can lead to effective use of what water does fall.

http://www.bing.com/videos/watch/video/the-man-who-planted-trees/866e295b45828a7e3b0b866e295b45828a7e3b0b-494231486637?q=the+man+who+planted+trees&FORM=VIRE2

 
Tyler Ludens
pollinator
Posts: 9742
Location: Central Texas USA Latitude 30 Zone 8
184
  • Likes 1
  • Mark post as helpful
  • send pies
  • Report post to moderator
Jonathan Byron wrote:
Groundwater is unavailable unless one digs a well, or finds a spring on the side of a hill. 



Yes, but if watersheds are damaged, the water table is lowered until springs dry up and wells can't be dug by hand anymore.  Spending vast amounts of resources on reservoirs does nothing to solve the underlying problem of watershed destruction.

Human activity has definitely "desertified" my region more than climate change has.  It used to be Tallgrass and Midgrass prairie savannah here until settlers stopped the fires and overgrazed with cattle, sheep, and goats.  There used to be many year-round streams and the area was known for its healthful springs.  Most of the creeks are dry except in wet seasons and most of the springs are gone. 
 
                    
Posts: 0
  • Mark post as helpful
  • send pies
  • Report post to moderator
It all goes to words and definitions. Yes, humans can degrade the landscape - if a barren landscape is a desert, then yes. But if a desert is defined by the amount of rainfall, then no, humans have not desertified anything.  I agree that healing the land is possible and desirable, for many reasons. Capturing the water with swales, etc can reinvigorate springs, make the water more available, improve the utilization of the water ... all good.
 
Tyler Ludens
pollinator
Posts: 9742
Location: Central Texas USA Latitude 30 Zone 8
184
  • Mark post as helpful
  • send pies
  • Report post to moderator
Jonathan Byron wrote:
It all goes to words and definitions. Yes, humans can degrade the landscape - if a barren landscape is a desert, then yes. But if a desert is defined by the amount of rainfall, then no, humans have not desertified anything.  


We also need to keep in mind that many of the desert landscapes we are familiar with now are much more barren because of certain kinds of human activity than they would have been otherwise, with the same amount of rainfall.  This is the case with most of the western US.

See Mollison's discussion of the Saguaro cactus and its desert habitat: 
 
Mekka Pakanohida
Posts: 383
Location: Zone 9 - Coastal Oregon
  • Mark post as helpful
  • send pies
  • Report post to moderator
Ludi wrote:
Yes, but if watersheds are damaged, the water table is lowered until springs dry up and wells can't be dug by hand anymore.   Spending vast amounts of resources on reservoirs does nothing to solve the underlying problem of watershed destruction.

Human activity has definitely "desertified" my region more than climate change has.  It used to be Tallgrass and Midgrass prairie savannah here until settlers stopped the fires and overgrazed with cattle, sheep, and goats.  There used to be many year-round streams and the area was known for its healthful springs.  Most of the creeks are dry except in wet seasons and most of the springs are gone. 


Schauberger showed in his research notes, of his families multi-generational years as foresters in Europe, prior to clear cutting, that if one replants properly, the capillary reaction of plants helps bring the water table back up. 

However, only 1 type of plant won't cut it, as we know now, there is a vast network of different types of roots helping in the soil which is why the Midwest of the US had the Great Dust bowl event.  Prior to US Westward expansion there was a multi-root type system holding the soil in place.  The settlers called them weeds and removed them in order to plant monocultures of agricultural products because after all, this is the Great Plains which caused a lack of plants to sufficiently hold the soil.

Fires just helped those plants re-establish themselves & Bison, were moving tillers back then. 

 
Emerson White
Posts: 1206
Location: Alaska
  • Mark post as helpful
  • send pies
  • Report post to moderator
Bison don't till like pigs do. Also The Dust bowl only happened in the low rainfall area at the southern end of the great plains. The northern end was supplied with water from the great lakes and the jet stream and managed to stay lush even under monoculture.
 
John Polk
steward
Posts: 8019
Location: Currently in Lake Stevens, WA. Home in Spokane
289
  • Mark post as helpful
  • send pies
  • Report post to moderator
The original post questioned: Why would they cut/remove valuable trees?
Possibly for the same reasons that Native Americans burned entire valleys of apples and other fruits.
At that time (world wide), most tribes were nomadic, and only a few were 'agrarian'.  There was competition for territories.  One tribe migrated to the valley each autumn to harvest the fruit for winter food.  A competing tribe felt the valley was part of their territory, and hence burned all of the fruits so their enemies would no longer have reason to migrate through "their" territory.  Even though the arsonist tribe valued the fruit, they were willing to sacrifice it in order to deprive it to their enemies.
Selfish?  Absolutely, but that is the human/tribal nature in a competitive world.

 
Emerson White
Posts: 1206
Location: Alaska
  • Mark post as helpful
  • send pies
  • Report post to moderator
We know that the Nubian people were not nomadic though.  Also Nomadic tribes would not fit with Paul's story. It all sounds like special pleading.
 
Tyler Ludens
pollinator
Posts: 9742
Location: Central Texas USA Latitude 30 Zone 8
184
  • Mark post as helpful
  • send pies
  • Report post to moderator
RustysDog wrote:
The original post questioned: Why would they cut/remove valuable trees?
Possibly for the same reasons that Native Americans burned entire valleys of apples and other fruits.


What valleys of apples in the Americas are you referring to?

Native Americans burned forest trees to provide better edge or grassland habitat for game, not to deny resources to their enemies (which would have guaranteed their own extinction as well, of course).
 
Emerson White
Posts: 1206
Location: Alaska
  • Mark post as helpful
  • send pies
  • Report post to moderator
Destroying a common resource is totally something that humans do (though I doubt that there were apples of significant food value in America before the Europeans planted them); ever hear the story of the american bison?
 
John Polk
steward
Posts: 8019
Location: Currently in Lake Stevens, WA. Home in Spokane
289
  • Mark post as helpful
  • send pies
  • Report post to moderator
I don't recall the valley, nor tribes involved, but it was part of a PBS series that dealt with the French and Indian wars.  Certain tribes aligned with the French, and others with the English, all in the name of furthering their goals in eradicating competing tribes in "their" territories.  Human nature at its best (or worst).
 
Tyler Ludens
pollinator
Posts: 9742
Location: Central Texas USA Latitude 30 Zone 8
184
  • Mark post as helpful
  • send pies
  • Report post to moderator
RustysDog wrote:
I don't recall the valley, nor tribes involved, but it was part of a PBS series that dealt with the French and Indian wars.  Certain tribes aligned with the French, and others with the English, all in the name of furthering their goals in eradicating competing tribes in "their" territories.  Human nature at its best (or worst).



The apple part doesn't sound accurate. 
 
Tyler Ludens
pollinator
Posts: 9742
Location: Central Texas USA Latitude 30 Zone 8
184
  • Mark post as helpful
  • send pies
  • Report post to moderator
Emerson White wrote:
Destroying a common resource is totally something that humans do (though I doubt that there were apples of significant food value in America before the Europeans planted them); ever hear the story of the american bison?


Yep, the "white man" has done a pretty impressive job of destroying all our common resources here in North America. 

Some Plains tribes figured out non-lethal ways to determine territorial boundaries.  It might have been interesting to see how they continued to co-exist and share resources between tribes.  Just as it would have been interesting to see how the German settlers of my region shared resources with the Comanche.  But non-German settlers and the government had other ideas. 
 
Emerson White
Posts: 1206
Location: Alaska
  • Mark post as helpful
  • send pies
  • Report post to moderator
The "red man" is made of the same stuff as the "white man". If they were the ones with guns and swords all of Europe would be speaking Cherokee.
 
Tyler Ludens
pollinator
Posts: 9742
Location: Central Texas USA Latitude 30 Zone 8
184
  • Mark post as helpful
  • send pies
  • Report post to moderator
Emerson White wrote:
The "red man" is made of the same stuff as the "white man". If they were the ones with guns and swords all of Europe would be speaking Cherokee.


Most people I meet seem to be part Cherokee. 

 
Mekka Pakanohida
Posts: 383
Location: Zone 9 - Coastal Oregon
  • Mark post as helpful
  • send pies
  • Report post to moderator
Emerson White wrote:
Bison don't till like pigs do. Also The Dust bowl only happened in the low rainfall area at the southern end of the great plains. The northern end was supplied with water from the great lakes and the jet stream and managed to stay lush even under monoculture.


Bison don't till?  Estimates of the pre-European herd size vary from 30,000,000 to 70,000,000 & you are claiming that the herds of buffalo didn't till the soil as they ran from one area to another? 

Oh, and American Bison aka the buffalo was found in all 49 US continental states...  ..that's a lot of mass slaughtering in the 1800's.
 
Tyler Ludens
pollinator
Posts: 9742
Location: Central Texas USA Latitude 30 Zone 8
184
  • Mark post as helpful
  • send pies
  • Report post to moderator
Mekka Pakanohida wrote:
the herds of buffalo didn't till the soil as they ran from one area to another? 


Probably not.  Prairie grass roots and crowns are very tough and adapted to being periodically trampled.  The primary difference between the action of bison and the action of cattle is the bison tended to move seasonally over large areas rather than staying in one place like cattle.  This is why the prairie grasses have been grazed out by cattle but were fine with bison.

The extremely large herds of bison may have only existed after many of the native americans had been killed by european disease.

http://www.theatlantic.com/past/docs/issues/2002/03/mann.htm
 
maikeru sumi-e
Posts: 313
  • Mark post as helpful
  • send pies
  • Report post to moderator
Mekka Pakanohida wrote:
Bison don't till?  Estimates of the pre-European herd size vary from 30,000,000 to 70,000,000 & you are claiming that the herds of buffalo didn't till the soil as they ran from one area to another? 

Oh, and American Bison aka the buffalo was found in all 49 US continental states...  ..that's a lot of mass slaughtering in the 1800's.


It's my understanding they "prick" the soil with their hooves rather than flatten and compact or root, dig, and turnover as pigs do, and the effect is very light on the upper surface of the topsoil. Deer, elk, etc. have a similar effect. Probably helps out a lot with aeration and water infiltration.
 
Walter Jeffries
Posts: 1095
Location: Mountains of Vermont, USDA Zone 3
45
  • Mark post as helpful
  • send pies
  • Report post to moderator
I've seen several scientific articles that point to a totally non-human cause of the desertification. They time it with the up thrust of mountain ranges which changed wind patterns which in turn changed rainfall patters as well as the change in tilt of the earth which also changed weather patterns and rainfall patterns. The earth does wobble and the timing of the changes in the Sahara fit this perfectly. The mountains do up thrust and they do change wind patterns. Man has nothing to do with either of these things. There is a politically correct tendency to blame humanity for everything. This misses the real point of fixing what we can fix and do effect. Earth Day is a scam that makes people feel good by turning their lights out for an hour when they should be making a difference all year. Don't get sucked in by this sort of thing.
 
                
Posts: 3
  • Mark post as helpful
  • send pies
  • Report post to moderator
Walter Jeffries wrote:I've seen several scientific articles that point to a totally non-human cause of the desertification. They time it with the up thrust of mountain ranges which changed wind patterns which in turn changed rainfall patters as well as the change in tilt of the earth which also changed weather patterns and rainfall patterns. The earth does wobble and the timing of the changes in the Sahara fit this perfectly. The mountains do up thrust and they do change wind patterns. Man has nothing to do with either of these things. There is a politically correct tendency to blame humanity for everything. This misses the real point of fixing what we can fix and do effect. Earth Day is a scam that makes people feel good by turning their lights out for an hour when they should be making a difference all year. Don't get sucked in by this sort of thing.


The factors you discuss happened in pre settlement times, we have not had an upthrust in most of the world in a very long time, and even then they are not large areas. There is plenty of radiation data that shows that there have not been significant increases over time in the suns radiation to the earth. What man does is create cumulative effects that act in concert with naturally caused effects. Add vegetation manipulation to changes in earth /mountain range formation and you have a loss of vegetation and desertification. Species evolved with changes in climate due to a variety of factors, but they did not evolve with man made disturbances outside of the range of natural variability (pre agriculture and industrialism). I can show you plenty of places that are on their way to becoming deserts, not due to any mountain upthrust or earth tilt, but due to over grazing. Now combine grazing effects with climate change and we can create alot of desert real fast.
 
Jordan Lowery
pollinator
Posts: 1528
Location: zone 7
12
  • Mark post as helpful
  • send pies
  • Report post to moderator
im with emerson, the sahara was once lush and now is a desert, given enough time the amazon will become a desert and the Sahara will become jungle again. such are the cycles of the earth. thankfully permaculture systems are adaptable to these situations vs a conventional farm. and we will still have food to eat.
 
Tyler Ludens
pollinator
Posts: 9742
Location: Central Texas USA Latitude 30 Zone 8
184
  • Likes 3
  • Mark post as helpful
  • send pies
  • Report post to moderator
It's been well-established that cutting down trees can cause desertification, whether the trees are cut to clear for agriculture or killed by browsing animals makes no difference. Under certain climate conditions removing trees causes desertification. Under other circumstances it can result in a lush grassland as it did in the North American prairies where humans burned the forest to create better hunting edges. The same activity over a longer period of time may have caused the desertification of parts of Australia. Humans have lived in North Africa for a long time so human-caused effects might be more dramatic, even as dramatic as the Sahara and the deserts of the Middle East. Obviously human activity is not happening in a vacuum, it's happening in conjunction with climate changes over a long period of time.
 
Willy Kerlang
Posts: 106
1
  • Likes 1
  • Mark post as helpful
  • send pies
  • Report post to moderator
Regarding the size of bison herds in the Americas pre-Columbus, I just read an amazing book called 1491 by Charles Mann, in which he explains the theory that the vast numbers of buffalo that the second and subsequent wave of explorers saw were actually not "normal". The disease-bearing effect of the first wave of Europeans in the 16th century was far greater than we had previously believed. Some anthropologists now think that up to 95% of the human population of the Americas was killed by European-borne disease, and that the total population may have been 25 million or higher--not the 1 million in what is now the US that many have thought for some time. Mann further explains that native peoples engaged in far more terrain modification than we realized, through slash-and-burn, deliberate fires, terracing, etc. The herds of bison would have been much smaller for most of their existence. The deaths of all those people meant that there were less hunters to cull them, and as a result the numbers grew exponentially. The size of those herds was therefore not something that most native peoples would have been accustomed to since the last Ice Age, and in fact were not sustainable. They were therefore actually a result of European influence, as bizarre as that may seem.

All this is just a theory, and I encourage you to check out the book for yourself, especially if you are interested in the pre-Columbian history of the Americas. It's a fascinating read.
 
Nicola Marchi
Posts: 79
4
  • Mark post as helpful
  • send pies
  • Report post to moderator
On the native americans there are very strong indications that they did do a lot of terrain maintenance and agriculture.

Near many old californian oak trees there are crushed shells that have been brought 500+ miles from the ocean that certain experts believe the native americans brought for the specific purpose of augmenting the soil with what the oak trees needed.
I have heard from the same sources that the native american tribes in california also practiced controlled burning to manage the grasses in such a way that the natural fires didn't get out of control and to help nourish those same oak trees.
 
Andrew Parker
pollinator
Posts: 514
Location: Salt Lake Valley, Utah, hardiness zone 6b/7a
4
  • Likes 1
  • Mark post as helpful
  • send pies
  • Report post to moderator
Woodlands were successfully converted to grasslands in North America through selective burning because the loss of forest canopy did not alter regional weather patterns. When there were no longer enough people to maintain the annual burning, the forests returned.

Forests create their own microclimate. There are many examples of localized desertification when forests are destroyed, whether by man or nature.

Much of the loss in tropical glaciers has been attributed to deforestation on the slopes of the mountains. This is a good example of localized consequences from deforestation.

Loss of surface and groundwater resources in the cloud forests of Costa Rica and Ecuador can be attributed directly to deforestation. A reforestation project in Ecuador showed that restoration of the cloud forest also restored stream flow, springs and wells. These are local effects related to local meteorological phenomena. Planting trees in areas with long term regional drought will not guarantee a positive outcome.

Climate aside, there seems to be sufficient evidence to show that land use can effect local weather patterns and alter water resources. I was raised with the understanding that it is our responsibility to be good stewards of the land. I think that, overall, we have fallen short.

On the subject of groundwater and reservoirs, the State Of Utah built Sand Hollow Reservoir specifically to recharge local aquifers. You can review the project in this report, "Assessment of Managed Aquifer Recharge from Sand Hollow Reservoir, Washington County, Utah".
 
Yone' Ward
Posts: 135
Location: Springdale, WA USA - Cold Mediterranean Climate
  • Mark post as helpful
  • send pies
  • Report post to moderator
The winds of the Sahara blow from the East to the West. That puts the Sahara in the rain shadow of the mountains of Ethiopia. Whether it's a wobble of the Earth or active geology at fault, if the rain doesn't get to Lybia, then the Sahara is going to be dry, and there will be a desert. It's the same dynamic that created the Australian Outback and most of the deserts of the North American West.

If you could irrigate Eastern Egypt and North Sudan to the equivalent of 30 inches of rain a year, The Sahara would go green again regardless of what plants and animals were involved.
 
Chad Sentman
Posts: 189
11
bee books chicken duck fish forest garden hugelkultur solar urban
  • Likes 1
  • Mark post as helpful
  • send pies
  • Report post to moderator


I just watched this video and I thought that while it provided some good explanations, it left open a lot of possibilities that permies would recognize sooner than most. Also, I've never heard anything about the 20,000 year cycle they mention, but I'm thinking that we won't need to wait so long to restore it.
 
Sean Montague
Posts: 5
  • Likes 2
  • Mark post as helpful
  • send pies
  • Report post to moderator
The Sahara is a desert because it is a desert. In the Sahel overgrazing can cause desertification, and parts of the middle east have been abused, I'm sure humans have made things worse in the Sahara, but it's a desert because that is how the climate of Earth works. Topography and location to water can alter this a bit, but generally speaking, deserts exist in and around 30 degrees of latitude north and south, plus or minus, for a reason. Too hard to explain here, below is a link to a great explanation. The Monsoons are pretty much the northern and southern extent of the Inter-Tropical Convergence Zone (ITCZ), which fluctuates between the deserts of the north and south with sun as direct rays migrate between the Tropic of Cancer and Capricorn. The ITCZ is what is responsible for tropical rainforests around the equator, plus or minus a few degrees. Can one green the desert? Yes, but it'll never be "wet". Rainfall could possibly be increased a bit, but the greening will still heavily rely on planned water conservation measures and not abusing the land.

http://gizmodo.com/5994656/why-does-the-earth-have-rain-forests-and-deserts
 
M.H. Hilliard
Posts: 8
  • Mark post as helpful
  • send pies
  • Report post to moderator
I just finished Donald Worster's book on the 1930s American Dust Bowl. Man, in fact, plays a major role in the making of deserts. Maybe not all  deserts but man does play a role. Check out 'Pan's Travail' by Donald (?) Hughes and see how man's pursuit of wood for classical temple building helped deforest the Mediterranean Basin.
 
I child proofed my house but they still get in. Distract them with this tiny ad:
Jacqueline Freeman - Honeybee Techniques - streaming video
https://permies.com/wiki/65175/videos/digital-market/Jacqueline-Freeman-Honeybee-Techniques-streaming
    Bookmark Topic Watch Topic
  • New Topic
Boost this thread!