[another_someone]

quote:Originally posted by VAlibrarian
 To me, the data represents a danger that my great-grandkids (if any) will inherit a world of higher temperatures and a higher likelihood of both floods and droughts.

Although there is constantly a shifting pattern of weather, and some areas will become drought ridden where they were not before, but global warming as such is unlikely to cause that.  Historic data, as well as common sense, associates widespread drought with global cooling.  Drought is not caused by heat but by lack of water, which infers lack of rainfall, which when taken on a global scale will relate to reduced evaporation caused by lower temperatures.

George

[JimBob (OP)]

Not quite accurate. 10,000 years ago earth was cooloer than it is now and there was much less desert than now. All the area of central asia was much more lush: areas that are now the worst deserts of the world (such as the Taklamakan) were irrigated, had no erosion and no sand. Today you die in them. This is true for all of Africa as well. There was no Sahara Desert, no Namibian Desert, etc.

All of these deserts were well watered, had a diverse fauna and flora as well as human habitation.

The warming of the earth during this interglacial is real. The question is whether or not man has accelerated this process so: Again I ask ---

Is Global Warming real? Is the data coming in now only reflective of normal changes? WHY do you view the data as you do?


 


The mind is like a parachute. It works best when open.  -- A. Einstein

[another_someone]

quote:Originally posted by JimBob

Not quite accurate. 10,000 years ago earth was cooloer than it is now and there was much less desert than now. All the area of central asia was much more lush: areas that are now the worst deserts of the world (such as the Taklamakan) were irrigated, had no erosion and no sand. Today you die in them. This is true for all of Africa as well. There was no Sahara Desert, no Namibian Desert, etc.

All of these deserts were well watered, had a diverse fauna and flora as well as human habitation.

The warming of the earth during this interglacial is real. The question is whether or not man has accelerated this process so: Again I ask ---

http://www.scienceblog.com/community/older/1996/A/199600627.html

quote:
MADISON -- Water would seem like a mirage today in the sweltering Sahara Desert, but climate researchers at the University of Wisconsin-Madison are finding the ancient Sahara was a wetter, greener place than ever imagined.
Writing in today's (Dec. 19) edition of the British journal Nature, UW-Madison climatologist John Kutzbach and colleagues report that the Sahara and Sahel regions of northern Africa were much wetter 12,000 to 5,000 years ago than earlier climate models predicted.

A slight shift in the earth's orbit forced those changes, causing stronger summer monsoons to sweep through the region. This naturally produced more vegetation and increased water content in the soil.

http://www.innovations-report.com/html/reports/earth_sciences/report-54055.html

quote:
The earliest humans in the area were Palaeolithic hunter-gatherers, who lived in the Fazzan between about 400,000 and 70,000 years ago. They survived by hunting large and small game in a landscape that was considerably wetter and greener than it is now. A prolonged arid phase from about 70,000 to 12,000 years ago apparently drove humans out of the region, but then the rains returned – along with the people.

Around 5,000 years ago the climate began to dry out again, but this time people adapted by developing an agricultural civilization with towns and villages based around oases. This process culminated with the emergence of the Garamantian society in the first millennium BC.

http://upload.wikimedia.org/wikipedia/en/c/ca/Holocene_Temperature_Variations.png


You will see that around 10,000 the weather was not much different from what it is today, and was still getting warmer.  If you go back to beyond 12,000 years ago, the weather was indeed cooler than it is today, but that was the period in which the sahara was just coming out of its long arid phase.

The weather started to become slightly cooler around 5,000 years ago, as the sahara started to dry out again.

George

[JimBob (OP)]

quote:Originally posted by another_someone

...  Historic data, as well as common sense, associates widespread drought with global cooling.  Drought is not caused by heat but by lack of water, which infers lack of rainfall, which when taken on a global scale will relate to reduced evaporation caused by lower temperatures.

George

This just isn't the way we earth scientists believe that desert climates are brought about and sustained. Although arid, the Sahara was not a desert until recently (I am not going to carp about dates). Common sense, my 40 years as an earth scientist and personal observations have convinced me cold is NOT the cause of the majority of desert climates.

The majority of land area covered by desert is HOT. I have long been aware that a hot desert is caused not by cold or lack of rain but primarily by excessive heat evaporaiting rainfall before it can reach the ground. This mechanism is what forms all deserts except those at high latitudes, the cold deserts. By deifnition, I live in one of the hot deserts, the Sonoran Desert - average rainfall less than 15 cm of rain a year and high heat. It is to be 100 degrees F and above this weekend. I live amid grass, deer, cougars, trees including pine trees, rabbits, and cattle in profusion, etc, etc. Arid does not mean void of life. I live at about the same latitude as the deep Sahara, about 32 deg N. To the west of where I live is dessicated desert but this is also the real-life location of the huge cattle ranches of the classic western movies. Billions of pounds of beef have been produced off this land and driven north to the 1860-70 rail lines. It was originally grass land, had a higher rainfall, but is now dessicated desert due to over-grazing.

"It is a common misconception that droughts cause desertification."
http://en.wikipedia.org/wiki/Desertification

I can assure you that man has also lived here for much more than 10,000 years. The area where I live was the home of Karankawa, Tonkawa, and Comanche Indians. The classic Clovis point of the Native Americans is found 600 miles north-west of where I am, in the deep desert. Clovis, New Mexico is in the heart of cattle country.

The Sahara as we know is new. It was inhabited and much more productive than present, although an arid place, until primarily the pig was domesticated. The pig is what is thought to be the main caused the denudation and desertification of the Sahara. Up until about the time of the pig domestication it is believed the Sahara ws only arid, not a sand waste. Even as it is now the Sahara is inhabited and productive or people could not live there. Yes, I know what your references say. The man from Reading is in a small minority.

"Neolithic rock engravings, or 'petroglyphs' and the megaliths in the Sahara desert of Libya attest to early hunter-gatherer culture in the dry grasslands of North Africa during the glacial age. The region of the present Sahara was an early site for the practice of agriculture (Wavy-line ceramics). However, after the desertification of the Sahara, settlement in North Africa became concentrated in the valley of the Nile, where the pre-literate Nomes of Egypt laid a base for the culture of ancient Egypt. Archeological findings show that primitive tribes lived along the Nile long before the dynastic history of the pharaohs began. By 6000 B.C., organized agriculture had appeared."

http://en.wikipedia.org/wiki/History_of_Africa

Present day -  

"2.5 million people live in the Sahara, most of these in Egypt, Mauritania, Morocco and Algeria. Dominant ethnicities in the Sahara are various Berber groups, ..."

http://en.wikipedia.org/wiki/Sahara.

And from http://www.worldwildlife.org/wildworld/profiles/terrestrial/pa/pa1327_full.html

"The Sahara is the largest desert in the world and occupies approximately 10 percent of the African Continent. The ecoregion includes the hyper-arid central portion of the Sahara where rainfall is minimal and sporadic. Although species richness and endemism are low, some highly adapted species do survive with notable adaptations. Only a few thousand years ago the Sahara was significantly wetter, and a large mammal fauna resided in this area. Climatic desiccation over the past 5000 years, and intense human hunting over the past 100 years, has obliterated these faunas. Now only rock, sand and sparse vegetation exist over huge areas. The remnant large mammal fauna is highly threatened by over-hunting." BOLD IS MINE.

I am also aware you will argue that the Sahara was wetter ONLY during the period from ~12,000 to ~5000 years ago. That just isn't supported by the amount of data gathered.  

Again I ask, do you believe man has accelerated global warming?



The mind is like a parachute. It works best when open.  -- A. Einstein

[another_someone]

There are a number of issues you have mentioned, and it is not easy to disentangle them.

quote:
Although arid, the Sahara was not a desert until recently

quote:
By deifnition, I live in one of the hot deserts, the Sonoran Desert - average rainfall less than 15 cm of rain a year and high heat. It is to be 100 degrees F and above this weekend. I live amid grass, deer, cougars, trees including pine trees, rabbits, and cattle in profusion, etc, etc. Arid does not mean void of life.

So, arid does not mean devoid of life (no problem with that), but is a desert defined by its aridity or its life?

You say you live in a desert because it is hot and arid, yet is teaming with life.

You say the sahara was not a desert until recently, although it was hot and arid (I assume you are saying it was not a desert because it was, like the sonoran, teaming with life).

You seem to be saying that until recently the sahara was like the sonoran is today, yet the sahara was not a desert but the sonoran is?

Semantics aside, the issue I was raising was not so much about whether man has effected the flora and fauna over the millennia, but only what the relationship between temperature and rainfall is (not between the flora and fauna and temperature), and what the relationship between human activity and global temperature is.

Clearly, man has had a major impact upon the flora and fauna, in all sorts of ways, and continues to do so.  That overuse of the soil, and that denuding the soil of its vegetable cover, has had a major impact, and that man has been a major component in the impact, is (at least by me) accepted without question.  None of this is to do with global warming, nor with global rainfall (whether it impacts on local rainfall – possibly so, although even your own comments do not seem to suggest that man's activity made the deserts arid, only that man denuded the soil; but I would contend that man's impact on global rainfall is marginal, if exists at all).

George

[JimBob (OP)]

I appreciate the answer, it is all I have been trying to get to.

"Desert" has been applied to areas over the world that have many different characteristics. Usually the word means less than 250 mm of rainfall, but it is often applied to regions that are technically 'steppe' or 'savanna'i.e., up to 500 mm of rainfall. I live in a near-savanna region that is considered part of the Sonoran Desert. From ~3,000 to ~70,000 years ago, the Sahara was actually savanna. Please read the references, last post, in toto to begin to understand the intricacies. Desert and simi-arid regions are very complex ecosystems. Also note the modern examples of man changing the land from steppe to desert (ref. for desertification, last post) in the Aral Sea region and in the U.S. 'Dust Bowl' of the 30's.



The mind is like a parachute. It works best when open.  -- A. Einstein

[VAlibrarian]

JimBob-
I think I sort of answered your question "Is global warming real", but let me do so with more frankness.
Yes global warming is real. Yes it is caused primarily by human activities, namely the burning of enormous amounts of fossil fuel which produce a jump in the amount of atmospheric CO2, thus reducing the amount of solar heat able to escape our atmosphere. You could call this "normal", as higher temperatures are the normal result of CO2 in the atmosphere, but it is also true that the 30% increase of CO2 is entirely due to human activity, and that is not the normal functioning of nature. Yes the result of this fuel burning is going to become clearer in the future, but it is not needful to wait a thousand years to develop a meaningful baseline. The jump in fossil fuel use over the past 150 years produced a jump in global temperatures by means of CO2 pollution. End of discussion as far as I am concerned.
I understand that this makes me a crackpot in the eyes of a few, but I am reminded of the physician (his name escapes me) who noticed 200-odd years ago that women in hospitals were dying of infection at a much higher rate than women giving birth at home. When he hypothesized that doctors were passing infection from one mother to another while attending childbirth without washing their hands, he was kicked out of the hospital and publicly called a buffoon. The women continued to die for a few years until he was proved correct. As far as I am concerned, atmospheric scientists are doing their jobs, attempting to create accurate analyses of causality in order to suggest sustainable public policies. As far as I am concerned, critics of global warming are doing their jobs, protecting the profitability of Exxon and General Motors.

chris wiegard

[another_someone]

quote:Originally posted by VAlibrarian
I understand that this makes me a crackpot in the eyes of a few, but I am reminded of the physician (his name escapes me) who noticed 200-odd years ago that women in hospitals were dying of infection at a much higher rate than women giving birth at home. When he hypothesized that doctors were passing infection from one mother to another while attending childbirth without washing their hands, he was kicked out of the hospital and publicly called a buffoon. The women continued to die for a few years until he was proved correct.

No, it doesn't make you a crackpot, but it may make you wrong.

It is certainly the case that most people who come up with a revolutionary idea are initially disbelieved; but equally, most people who come up with radical ideas, and are initially disbelieved, are actually wrong.  For every one radical idea that is proven right, there are many that are wrong, so simply claiming that your idea is radical enough not to convince everyone else of it does not prove your to be right (it neither proves you to be wrong).  The fact that both sides of this debate have people who believe they are radical, and right; and the other side are radical and wrong; means that the same argument for being 'ahead of their time' can be claimed by both sides.

Ofcourse, it is much easier to perform double blind trials on pregnant women than it is on the Environment, so proving things one way or the other is far more difficult with Environmental issues.  The best argument you can try and use is to make historic comparisons, but if you are trying to argue for a situation that you claim has no historic precedent, then it is very difficult to find positive proof for your case in the historic records.

For those of us who do see similarities with past events, and can thus claim the present is just an approximate repeat of history, the matter is easier.  Certainly, there are historic events that can be shown to be similar to the present, but then your argument would have to rely on the fact that history, while it may approximately repeats itself, never exactly repeats itself, and so you would still claim that the present situation is subtly unique and not precisely comparable to the pre-human historic events.

George

[crandles]

I agree that the science is in on the subject of whether anthropogenic global warming is real. It is real and the IPCC have reported saying so. There remain questions over how much of an affect it will have and what are the appropriate policy responses.

[VAlibrarian]

In the meantime, sell that property in south Florida while the market is still high. When the flooding from global warming's increase in sea levels starts, insurance rates will go up and nobody will want to buy your house.

chris wiegard

[another_someone]

quote:Originally posted by VAlibrarian
In the meantime, sell that property in south Florida while the market is still high. When the flooding from global warming's increase in sea levels starts, insurance rates will go up and nobody will want to buy your house.

But, hey, you might get a good deal on a house in Alaska that might appreciate in price.

George

[crandles]

I agree that the science is in on the subject of whether anthropogenic global warming is real. It is real and the IPCC have reported saying so. There remain questions over how much of an affect it will have and what are the appropriate policy responses.

[VAlibrarian]

In the meantime, sell that property in south Florida while the market is still high. When the flooding from global warming's increase in sea levels starts, insurance rates will go up and nobody will want to buy your house.

chris wiegard

[another_someone]

quote:Originally posted by VAlibrarian
In the meantime, sell that property in south Florida while the market is still high. When the flooding from global warming's increase in sea levels starts, insurance rates will go up and nobody will want to buy your house.

But, hey, you might get a good deal on a house in Alaska that might appreciate in price.

George

[mocathe1st]

Hi, Just stumbled across this forum. Very interesting. A link you might find useful (at least those of you from the UK should) is:
newbielink:http://greenspaceresearch.uhi.ac.uk/greenspace [nonactive]
This is a Google map representation of all carbon emission levels in the UK down to the square km level with a detailed breakdown of the level of each type of emission. It also allows users to add suggestions for what they think can be done to reduce carbon emisssions levels in their area. This is a brand new site and has the potential to become very powerful.