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Why and when the Sahara Desert was green: new research

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Re: Why and when the Sahara Desert was green: new research

#71

Post by christkv »

kibwen wrote: post #35
hasmanean wrote: post #30

So with the co2 forcing function, is it possible that Canada be glaciated again And that the Sahara be green? That would fly in the face of conventional thinking which is that Canada will be temperate and the Sahara will be more arid.

The article is saying that the green Sahara coincides with periods of greater seasonal rainfall and humidity, caused by changes to the procession of the Earth and the effect that has on the seasons. It's possible that current anthropogenic climate change could make the Sahara greener, but it's also possible that it might not. In any case, the greening would probably take hundreds of years or more to happen.

Does anyone know where one can find the estimated size per year of the Sahara. All I kind find are reductionist crap like it’s 10% bigger now than 1920. But this does not say if it’s in a growing or shrinking trend just that it’s bigger now than then. Was it even bigger in 2000? And now shrinking from a top or has it been a gradual increase?

Re: Why and when the Sahara Desert was green: new research

#72

Post by strogonoff »

ImHereToVote wrote: post #68
goatlover wrote: post #66

Earlier quoted context omitted.

It's like how the model for a snow slab doesn't prove there was a snow slab that slipped over the Dyatlov Pass tent that night, despite what the media claimed about the case being solved. It only shows that it could have, assuming the data and assumptions are correct for that specific location. Or models showing some solution to the Fermi Paradox, and proponents claiming that the mystery is finally solved. How do the…

Because the only thing you can ever have is a theory. The strongest theory is the one that gets chosen. Theories vary in strength over time. Nothing is ever solved or proven. Theories get stronger and stronger evidence. Believing in a theory doesn't in any way help you make sense of the world. We just do it for expediency of communication.

Theories being ultimately all we have, there is (or should be) no “chosen” one. People are free to believe whatever—this is a pre-requisite for theories to evolve.

There may be a theory that enjoys better predictive success for a while, but if everyone always believed in a singular “chosen” theory then we’d get nowhere: to evolve a better theory, you have to come up with and believe in something other than the preexisting one. Thus, it is normal for multiple theories to coexist at any given time.

Crucially, a theory is all map no territory, always and necessarily. It describes something we do not understand in terms of something that we do understand. At its core, it is a metaphor—and more than one metaphor can be useful, each in a slightly different context.

Re: Why and when the Sahara Desert was green: new research

#73

Post by meheleventyone »

strogonoff wrote: post #72
ImHereToVote wrote: post #68

Earlier quoted context omitted.

Because the only thing you can ever have is a theory. The strongest theory is the one that gets chosen. Theories vary in strength over time. Nothing is ever solved or proven. Theories get stronger and stronger evidence. Believing in a theory doesn't in any way help you make sense of the world. We just do it for expediency of communication.

Theories being ultimately all we have, there is (or should be) no “chosen” one. People are free to believe whatever—this is a pre-requisite for theories to evolve. There may be a theory that enjoys better predictive success for a while, but if everyone always believed in a singular “chosen” theory then we’d get nowhere: to evolve a better theory, you have to come up with and believe in something other than the preexi…

The chosen explanation should be held to be contingent and corrigible but that doesn’t mean all explanations should be held to the same regard particularly when some can be harmful as well as contradictory.

Re: Why and when the Sahara Desert was green: new research

#74

Post by ImHereToVote »

strogonoff wrote: post #72
ImHereToVote wrote: post #68

Earlier quoted context omitted.

Because the only thing you can ever have is a theory. The strongest theory is the one that gets chosen. Theories vary in strength over time. Nothing is ever solved or proven. Theories get stronger and stronger evidence. Believing in a theory doesn't in any way help you make sense of the world. We just do it for expediency of communication.

Theories being ultimately all we have, there is (or should be) no “chosen” one. People are free to believe whatever—this is a pre-requisite for theories to evolve. There may be a theory that enjoys better predictive success for a while, but if everyone always believed in a singular “chosen” theory then we’d get nowhere: to evolve a better theory, you have to come up with and believe in something other than the preexi…

There is no need to believe a theory, but when it comes time to make an irreversible choice; you better pick the strongest theory. No belief necessary. Sometimes you do have to choose, and you have to accept that your choice will have a degree of uncertainty.

Re: Why and when the Sahara Desert was green: new research

#75

Post by agent327 »

raylad wrote: post #49
bgroat wrote: post #31

I'm not a historian, archeologist, or any sort of relevant expert. But I've long had the pet theory that the Green Sahara is the origin of the Eden Myth. Homo Sapiens origin, lush vegetation, turns to dessert for some reason beyond our comprehension...

I've always interpreted the Eden myth as a memory of the development of agriculture. Before agriculture, people lived as hunters and (mainly) gatherers. The life of a Hunter-gatherer is, surprisingly, mostly leisure, because of the abundance of food and the low population density. Even Kalahari Bushmen, who had been forced to live in the dessert, were found to average only about 1 1/2 to 2 1/2 hours of productive lab…

I've always thought that being cast out of Eden was not so much a punishment, as merely an unavoidable consequence: having eaten from the tree of knowledge, we now also have the ability to appreciate suffering, and thus no longer experience paradise. That would make paradise a state of mind, rather than a place.

After eating the fruit God lists a number of consequences, which sounds somewhat like a punishment, but that could just as easily be interpreted as "well, I didn't want this to happen to you, but now that you got to this point, you'll have to deal with the following". That includes increased pain in giving birth (a consequence of having larger brains), and the rise of agriculture. Eve is also only named after eating the fruit, not before.

The snake gets cursed for what it did, and so does the ground, but not Man. God even goes so far to provide them with clothes, and acknowledges their growth.

Re: Why and when the Sahara Desert was green: new research

#76

Post by strogonoff »

meheleventyone wrote: post #73
strogonoff wrote: post #72

Earlier quoted context omitted.

Theories being ultimately all we have, there is (or should be) no “chosen” one. People are free to believe whatever—this is a pre-requisite for theories to evolve. There may be a theory that enjoys better predictive success for a while, but if everyone always believed in a singular “chosen” theory then we’d get nowhere: to evolve a better theory, you have to come up with and believe in something other than the preexi…

The chosen explanation should be held to be contingent and corrigible but that doesn’t mean all explanations should be held to the same regard particularly when some can be harmful as well as contradictory.

It is not abnormal for multiple theories or hypotheses to contradict each other. In strictly natural sciences it is usually possible to experimentally rule out some of them, but not always so (for example, sometimes the technology is not there). In philosophy it is often not the case (no experimental means available where concepts like “objective reality” are involved).

Re: Why and when the Sahara Desert was green: new research

#77

Post by fklewjflkew »

bradley13 wrote: post #64

Models help test test our understanding of past events. If you can create a model that reproduces past events, there is a chance that you have understood something about those events. Equally, however, there is a chance that you have created a model that only coincidentally works, because you forced it to do so. When "scientific" articles write that a model "confirms" some conclusion, they are just wrong. Given enoug…

[flagged]

Re: Why and when the Sahara Desert was green: new research

#78

Post by Hammershaft »

jazzyjackson wrote: post #28

I think it was in Michael Palin's show Sahara, he's talking to some locals living in a village in the middle of the desert, and while I'm wondering why anyone would ever settle out there, the person being interviewed relayed that many more people used to live there before it became a desert. It wasn't that they moved out there, they were all that was left. Kind of post-apocalyptic. Edit: found the mention, he's talki…

Pretty amazing clip, sent me down a rabbit hole. I can't help but think what extreme climate niches our descendants 500 years from now might be surviving in, that were once fertile & lush.

Re: Why and when the Sahara Desert was green: new research

#79

Post by yakubin »

agent327 wrote: post #75
raylad wrote: post #49

Earlier quoted context omitted.

I've always interpreted the Eden myth as a memory of the development of agriculture. Before agriculture, people lived as hunters and (mainly) gatherers. The life of a Hunter-gatherer is, surprisingly, mostly leisure, because of the abundance of food and the low population density. Even Kalahari Bushmen, who had been forced to live in the dessert, were found to average only about 1 1/2 to 2 1/2 hours of productive lab…

I've always thought that being cast out of Eden was not so much a punishment, as merely an unavoidable consequence: having eaten from the tree of knowledge, we now also have the ability to appreciate suffering, and thus no longer experience paradise. That would make paradise a state of mind, rather than a place. After eating the fruit God lists a number of consequences, which sounds somewhat like a punishment, but th…

The snake always seemed to me to be a Promethean figure in this story. It brought us knowledge, like Prometheus brought us fire, and got punished for it by a god.

Re: Why and when the Sahara Desert was green: new research

#80

Post by strogonoff »

ImHereToVote wrote: post #74
strogonoff wrote: post #72

Earlier quoted context omitted.

Theories being ultimately all we have, there is (or should be) no “chosen” one. People are free to believe whatever—this is a pre-requisite for theories to evolve. There may be a theory that enjoys better predictive success for a while, but if everyone always believed in a singular “chosen” theory then we’d get nowhere: to evolve a better theory, you have to come up with and believe in something other than the preexi…

There is no need to believe a theory, but when it comes time to make an irreversible choice; you better pick the strongest theory. No belief necessary. Sometimes you do have to choose, and you have to accept that your choice will have a degree of uncertainty.

The point is that there is no “strongest” theory. Different theories are different maps. There is no perfect map, at that point it is no longer a map but territory.

Better not use a bad map, but there can be more than one good map depending on what you need it for.

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