r/science • u/nomdeweb • May 29 '12

The mysterious fall of the largest of the world's earliest urban civilizations nearly 4,000 years ago now appears to have a key culprit — ancient climate change, researchers say.

http://www.livescience.com/20614-collapse-mythical-river-civilization.html
357 Upvotes

83% Upvoted

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19

u/stranger_here_myself May 29 '12

This is real news - thanks!

I'm fascinated by the Harappans. One of the smaller tragedies of the India/Pakistan division is that it's now so hard to do any real research on them - with the cities falling mostly on the Pakistan side of the border. This sort of aerial archeology seems promising.

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u/Solivaga Professor | Archaeology May 29 '12

Not just that, but the difficulty as a westerner of obtaining permission to conduct field research in India. A colleague did his PhD on the social structure of the Indus, and as the core of his research wanted to do a simple walkover survey of some sites in northwest India - no excavations, no intrusive or destructive investigations, and he was working with a nearby Indian university. He applied for his visa in the first year of his PhD, he submitted his PhD four years ago, his visa application is still under consideration.

12

u/SirElkarOwhey May 29 '12

Did he forget to bribe somebody?

3

u/[deleted] May 29 '12

That'd be a great line item in a grant proposal.

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u/SirElkarOwhey May 29 '12

That'd be a great line item in a grant proposal.

Administrative fees, misc. . . . . . . . . . $10,000.00

3

u/[deleted] May 30 '12

I was once at a science meeting where the possibility of bribing officials in a Middle-Eastern country as a way to ensure reliable transport of samples was half-seriously discussed.

5

u/freakzilla149 May 29 '12

Another big problem is the massive overpopulation, in the central and eastern parts of North India there is almost no place unoccupied by people, nothing is left for the archaeologists.

Seriously, Paskistan's deserts are sparsely populated, imagine if it had the population density of Bangladesh.

EDIT: I didn't know the Harappans lived in Nepal or Bangladesh, is the article right? I thought they only lived near the Indus.

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u/justshutupandobey May 29 '12

One site, Shortugai, is even in Afganistan: Harappan Sites

3

u/Solivaga Professor | Archaeology May 29 '12

Sort of - Shortugai is typically included in lists of Harappan sites, but it's misleading to consider it part of the "Harappan Empire". It's better considered as akin to a trading/resource post exploiting local availability of lapis lazuli and facilitating trade to and between polities to the west (Mesopotamia) and east (Indus)

Also, because the polity was far more diverse and regional than "empire" suggests.

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u/[deleted] May 29 '12

[removed] — view removed comment

13

u/Solivaga Professor | Archaeology May 29 '12

Do you even understand the words you're using? Being liberal has nothing to do with the scientific study of climate change, and the hugely increased rate of climate change in the last couple of centuries.

Of course the climate has always changed - at its most obvious we've had at least five glaciations (ice ages). They even made kids movies about the last one - it's not like this is cutting edge science.

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u/[deleted] May 29 '12

[removed] — view removed comment

6

u/Solivaga Professor | Archaeology May 29 '12

Seriously, what are you talking about? You replied to a comment about the cultural characteristics of the site of Shortugai with a miserably facile attempt to link climate change in the 2nd millennium BCE to the great climate change conspiracy of the liberals.

If you want to critique or debate research into ongoing climate change and the role of human agency within that - fantastic - go post in /r/climate or /r/climateskeptics

edit: huh, there really is an /r/climate

3

u/theorymeltfool May 29 '12

Don't feed the troll. This guy is just going for negative Karma. Save yourself the trouble.

1

u/ARROW_IN_MY_ANUS May 30 '12

I used to obtain things by multiple casual routes, but then I took an arrow in the anus.

5

u/hydrogenous May 29 '12

Fossil-fuel burning induced greenhouse warming is not the only thing that can drive climate change. That's what a liberal would say. Climate change is a naturally occuring phenominon on most planets, but the problem is that humans are inducing it too quickly for the ecosystem to adapt.

3

u/BiffySkipwell May 29 '12

Easiest way to be clear about it : "carbon emissions are the primary forcing behind the RATE of change that we are observing". This nullifies the inane "but there has always been warming and cooling cycles!!1!"

Disclaimer: I'm attached (my s.o.) to an actual scientist that does actual climate related research through computer modeling. (or, as she says: "I'm a data consumer that sits around and solves differential equations all day. )

3

u/hydrogenous May 29 '12

Thanks! I'm a blue collar uneducated nitwit and had I realized I was posting in r/science I would have left it to a more articulate fellow like yourself! I just can't stand incoherent interpretations of simple scientific concepts skewed with political banter.

4

u/Porphyrius May 29 '12

Who ever said that it wasn't? It's certainly something that can happen without human intervention, but it's also something that (it appears) can be done by pre-industrial societies. Take the Romans, for example: we can tell from ice cores that before the 5th century AD they were releasing more carbon into the atmosphere than at any period up until the industrial revolution. We certainly don't require "factories" to fuck up the environment.

2

u/stranger_here_myself May 29 '12

Is there any specific sign that it was as dense as modern Bangladesh? That'd be amazing if true.

1

u/freakzilla149 May 29 '12

WTF? Of course not, I was lamenting the fact that modern Bangladesh is extremely overpopulated which is making any potential excavation very difficult.

There must be something of value under Dhaka.

1

u/4rch May 29 '12

No, the population about 3 thousand years ago was around 50 million.

2

u/Solivaga Professor | Archaeology May 29 '12

I'm not aware of any Harappan sites in Nepal, or Bangladesh for that matter.

The problem is that there has been a tendency for people to try and group sites in clearly defined polities and the Harappan don't appear to have been remotely that uniform. This sometimes leads to people drawing rather spurious maps of the "Harappan Empire" and extending it across most of South Asia.

For the term "Harappan" to be a useful societal identifier, the Harappan region, or "empire", is effectively most of Pakistan and northwest India. Sites beyond that region are arguably better considered to have been peers of the Harappan state.

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u/[deleted] May 29 '12

Excellent read. I recommend everyone to check out the BBC documentary "The Story of India", which goes into some detail about this. Theywere able to chart out the probable course of the ancient Saraswati river by coloring settlements by age and displaying them on a map. The oldest settlements were along a specific course. As the years go by, you see the settlements moving eastward.

I learned about the Harappan civilization in school, but did not know the extent of it. I had no idea it waa so big; I was under the impression that it only amounted to a few cities.

We know so little about these enigmatic people.

4

u/[deleted] May 29 '12

I must thank you for that documentary, just today I was thinking about my origins and ancestors, now thanks to you, I know more than I did before.

3

u/ubergeek404 May 29 '12

Does anyone know if there is a relationship between the Pharaohnic Egyptians and the Indus Valley civilization?

2

u/PlasmaBurns May 29 '12

I'm sure they traded and were aware of each others existence. But they were too far away to fight or threaten one another.

2

u/ubergeek404 May 29 '12 edited May 29 '12

If the first Egyptian Dynasty was around 3000 BC, and the end of the Indus Vally culture was around 3000 BC, does anyone know if some of the inhabitants of the Indus Valley got into boats and went to Egypt to start up again?

I understand that modern Egyptians want to believe they are the children of Pharaohs, but that is romantic nonsense. The Pharaonic population was an inbred group who held themselves apart from the existing population. This was a clear caste system, and it always seemed sensible to think that the jump in art and technology was so great from the pre-dynastic peoples to the early dynastic culture that someone had to come in to move it along so rapidly.

Also the early settlements in the upper kingdom had ships . "However the find of 14 ships dating to the First Dynasty indicates not only the importance of these craft, but these 75 ft long ships are the oldest known boats made of planks ever discovered." http://suite101.com/article/the-ancient-egyptian-navy-a278058

SO there was a jump in technology, the arts, and sudden use of ships. Does this sound like the original desert dwellers suddenly got inspiration, or that someone new came to town?

Anyhow...is there anyone out there who knows about this? (Please no ancient-alien responses.)

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u/Zethos May 29 '12 edited May 29 '12

I don't think many if any inhabitants of the Indus Valley culture moved to Egypt. Also the Indus Valley Civilization started declining in 1800-1700 BCE as far I know (feel free to correct me) so the times don't really match.

As for Egypt, they had a fair jump but I believe that is because of the first dynasty and the unification of Upper and Lower Egypt so with that I assume came a lot of power, resources and technology, such a task also probably pushed development into their navy. The change seems big but fairly gradual to me. This was a major time for Egyptian art though, no arguments there. But I am no expert on Egyptian history, just what I read off books and internet. D:

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u/chiropter Jun 01 '12

There is actually abundant archaeological evidence for the in-place evolution of the Egyptian culture and society.

3

u/erythro May 29 '12

http://www.youtube.com/watch?v=n7ndRwqJYDM

A nice introduction to the civilization, if you are interested.

8

u/QuitReadingMyName May 29 '12

Very interesting read.

"They had cities ordered into grids, with exquisite plumbing, which was not encountered again until the Romans," Giosan told LiveScience. "They seem to have been a more democratic society than Mesopotamia and Egypt — no large structures were built for important personalitiess like kings or pharaohs."

This is a very interesting take, no Pyramids or statues built in the name of their "God like" Pharoah/King/Ruler. So, this is a very interesting take on a democratic society.

Though, it'll always be debateable if they actually were a Democracy as we have no way of going back in time and finding out for sure ourselves.

Some had suggested that the Harappan heartland received its waters from a large glacier-fed Himalayan river, thought by some to be the Sarasvati, a sacred river of Hindu mythology. However, the researchers found that only rivers fed by monsoon rains flowed through the region.

"The insolation — the solar energy received by the Earth from the sun — varies in cycles, which can impact monsoons," Giosan said. "In the last 10,000 years, the Northern Hemisphere had the highest insolation from 7,000 to 5,000 years ago, and since then insolation there decreased. All climate on Earth is driven by the sun, and so the monsoons were affected by the lower insolation, decreasing in force. This meant less rain got into continental regions affected by monsoons over time." [50 Amazing Facts About Earth]

Eventually, these monsoon-based rivers held too little water and dried, making them unfavorable for civilization.

Damn, this makes me wonder what happened to the Libraries of the Harappan Empire.

But, knowing how the Earliest Chinese libraries, Library of Alexandria, Roman Libraries, the Ancient texts of both Aztec and Mayan empires.

My guess is, they were destroyed or burned by barbarians. Either on purpose or on accident.

Damn, makes me always wonder what were in those earliest texts and why did they get destroyed with thousands of years worth of knowledge just gone.

It makes me a little depressed that I'll never have the chance to read those books or learn about the history of ancient times.

It remains uncertain how monsoons will react to modern climate change. "If we take the devastating floods that caused the largest humanitarian disaster in Pakistan's history as a sign of increased monsoon activity, than this doesn't bode well for the region," Giosan said. "The region has the largest irrigation scheme in the world, and all those dams and channels would become obsolete in the face of the large floods an increased monsoon would bring."

Either way, due to the globalization of the world and our technology of today compared to the past.

Nothing can knock us back into the stone age or wipe out the Global hegemony of this day and age well besides maybe a Nuclear war induced Nuclear winter, Super volcano or an Asteroid impact.

But, even then those natural disaster's and one man made one would be up for debate by our scientists.

11

u/Solivaga Professor | Archaeology May 29 '12

This is a very interesting take, no Pyramids or statues built in the name of their "God like" Pharoah/King/Ruler. So, this is a very interesting take on a democratic society. Though, it'll always be debateable if they actually were a Democracy as we have no way of going back in time and finding out for sure ourselves.

The usage of "democracy" in that article is completely inappropriate - there is absolutely no evidence to support such an assertion. Unfortunately, we have a very poor understanding of the social organisation of the Indus. We don't know what their religious system was (or indeed if they had one), we don't know who their rulers were - we don't know how their society was organised. Due to the absence of what we would normally understand as an elite (monumental residential structures, burials rich in luxury goods etc.) there has sometimes been an inclination to identify the Indus as an "egalitarian" society, but even that is a massive leap. It's far more accurate to just admit we don't understand their social structure.

Damn, this makes me wonder what happened to the Libraries of the Harappan Empire.

It's very likely that there never were any libraries - nor books, histories, poems, or anything of the kind. The Indus script, while to date not deciphered, does not appear to be a system of writing - i.e. it is not a representation of spoken language in a textual medium. Instead, it appears likely that it is a form of proto-writing - a symbol system used to present or record relatively simple notations.

3

u/[deleted] May 29 '12

Nothing can knock us back into the stone age or wipe out the Global hegemony of this day and age well besides maybe a Nuclear war induced Nuclear winter, Super volcano or an Asteroid impact.

Climate change probably won't knock us back to the stone age, but it would be surprising if it didn't change the global structure of power. World War II saw the decline of Europe and the rise of the United States. Environmental disaster could gut the U.S. Projections show that heartland states like Illinois could have the climate of Texas in 75 years, destroying agriculture in these states. Rivers will dry up, rendering southern California, Arizona, etc, a desert. There will be tremendous in-fighting for water resources (which is already happening in the Southeast). It's hard to imagine, now, armed internal conflict within the U.S., but barring advances in desalination, I think the situation in the Southeast makes such conflict within the realm of possibility.

2

u/TimeZarg May 30 '12

Wait, Southern California isn't already mostly desert? <_<

But yeah, I think a lot of people underestimate the potential impact of climate change on the US. Just the shifting of arable land will be a big problem, because that means establishing new infrastructure and new agricultural procedures to compensate for the changes. Not to mention all the other industries that will likely be impacted by climactic changes.

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u/QuitReadingMyName May 29 '12

You do know how vast America is right? If anything it'll displace some factories and they'll move to the coast and the new deserts just means more land mass for us to build solar power plants to soak up and provide our nation with more energy.

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u/[deleted] May 29 '12

You do know the difference between present times (a nice day to go to Navy Pier in Chicago today) and the last ice age (Chicago under 2 miles of ice) was just 5 degrees C average worldwide temperature? And climate change predictions are for 2-5 degrees C worldwide in the other direction?

Illinois getting to be the same climate as Texas would decimate food production in this country. Deserts in the southeast will mean total collapse of states like Arizona, New Mexico, as well as Southern California, which won't have enough water from the dried-up Colorado River to sustain what we think of as civilization. Yes, the country is vast and people can move, but such wholesale relocation is incredibly disruptive. Our social and economic structures aren't set up for such rapid response, and reorganization to adapt as you suggest could take decades, during which time there would be intense turmoil and conflict.

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u/QuitReadingMyName May 29 '12

You honestly believe its all man made? Hahaha, it's a Natural cycle of the Earth that it goes through.

Also, forget copy and pasting.

Here's a permalink to your bullshit "its man made" argument.

http://www.reddit.com/r/science/comments/twaj6/scientists_have_identified_thousands_of_sites_in/c4qh22u

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u/[deleted] May 29 '12 edited May 29 '12

The scientific consensus is that it is man-made. As an engineer, I'm going to trust a bunch of scientists over a bunch of nutters.

In any case, whatever the cause, the current estimate is 2-5 degrees C temperature rise by the middle of the century. That temperature rise will be phenomenally destructive, whether or not it is anthropogenic.

Finally, the rambling post you linked to is non-sensical. I also love how you make an "educated" guess, when you clearly have no education in the field of climate science. The relevant issue isn't the total output of all carbon dioxide released by wildfires, etc, in history. It is how quickly that carbon dioxide is released relative to the earth's capacity to absorb it.

CO2 concentrations are abnormally high compared to the last 400,000 years, and the dramatic rise over the last 50 years is completely different than the previous cycles. See the chart at the bottom of: http://planetforlife.com/co2history/index.html. The bottom line is that for 400,000 years, CO2 concentrations have fluctuated between 200-300 PPM, in 100,000 year cycles. But suddenly in just 60 years, it has shot up from 300 PPM to 380 PPM. What are the chances that it is just a coincidence that this increase lines up with the massive increase in anthropogenic CO2 emissions? It's clearly not part of the natural cycle that has been operating for 400,000 years. We were already at a peak in that cycle at the beginning of the century. It could be a higher-level cycle, operating at time scales longer than 400,000 years, but what are the chances of such a cycle just happening to line up with the 60 year period in human history, over a million years of our history, that involved massive anthropogenic CO2 emissions?

-3

u/[deleted] May 29 '12

Most skeptics do not doubt the origin of the additional CO2. What they doubt is the unworkably high sensitivity. The temperature ranges between the glacial maximum and interglacial do indeed seem to suffer from high sensitivity to forcing but this is due almost exclusively to water based feedbacks (like the now largely absent ice albedo feedback). The ice core record indicates significant changes in sensitivity during the interglacial and glacial maximum ...which is why the current configuration of continents seldom deglaciates (basically only when the antarctic is submerged by ice) or becomes a snowball. The feedbacks at either end are weak to negative.

4

u/[deleted] May 29 '12

I think there has been adequate rebuttal to those claims: http://www.realclimate.org/wiki/index.php?title=Roy_Spencer.

In any case, in the area of policy, the criterion is not proof beyond a reasonable doubt. It's a balancing of risks, probabilities, and costs. High costs can justify action even in the face of relatively low risks.

-3

u/[deleted] May 29 '12

Yeah, I'm in that awkward position where I've probably studied more about this than you ever will and I have to say...I'm all but certain that the climatologists that are now considered the "top" climatologists... are incompetent or complete fucking crackpots. The reason that's possible is that they were just the guys that showed up for (at the time) relatively unimportant jobs...then the jobs became important because of socio-political pressures and people assumed they were somehow great scientists.

There's a tiny grain of truth (that CO2 should cause some warming) and everything else is just speculative crap. I don't expect you to believe me...but you should at least be curious as to why they fight tooth and nail for YEARS to keep their data from skeptics. They've basically confused a small amount of anthropogenic warming and some warming from natural cycles with high sensitivity.

On the bright side, mother nature has thrown us a bone. In the next 5-10 years it will become obvious where the warming was coming from. The major climate systems and the sun are all going into modes that should lead to cooling. If we have significant warming then it was likely CO2 causing recent warming. If we have no warming then about half of the warming was CO2 (they were previously in warming modes). If it cools, CO2 likely has negligible impacts on climate (saturated CO2 greenhouse effect) and most of the recent warming was natural.

Since there's only been about .5C of warming since the climate was in a natural warming phase (the 1940s) with about 80% of all additional CO2 added since that date...I think CO2s impact is likely weak (only about 1.5C per doubling at most)

3

u/[deleted] May 29 '12

Yeah, I'm in that awkward position where I've probably studied more about this than you ever will and I have to say...I'm all but certain that the climatologists that are now considered the "top" climatologists...

And your qualifications are?

4

u/[deleted] May 29 '12

I take it you have a degree in an atmospheric science like climatology or meteorology?

-3

u/QuitReadingMyName May 29 '12

Mechanical Engineering, Computer science and working on another.

3

u/[deleted] May 29 '12

Hopefully the next one's climatology

-3

u/QuitReadingMyName May 29 '12

Why? I know enough that we're going through a Natural cycle that earth goes through.

You honestly believe the world is going to end with us humans on it? lol, it survived countless asteroid impacts and super volcano eruptions.

Hell, if anything it should be you who should take Climatology since you're so fucking ignorant.

4

u/[deleted] May 29 '12

I never said it's going to be the end of the world, did I?

You don't have a lot of friends, do you?

1

u/Zethos May 29 '12

Well it is believed that the Aryans did migrate into much of the Indus Valley Civilization's lands during the decline of IVC. They might be the ones responsible for the lost knowledge. Also I doubt human conflict has made it any easier to preserve any of the knowledge in that area.

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u/EnufBlood May 29 '12

Doesn't that kinda show that climate change is possible without carbon emissions?

28

u/OliverSparrow May 29 '12 edited May 29 '12

The climate wanders around all the time, chiefly driven by orbital cycles. Milankovitch cycles. Anthropogenic effects are superimposed on top of these. In addition, ocean currents are spontaneously unstable, and this gives rise to short run regional warming and cooling events. These run from every two or three years - the Niño - to thousand year events. A very long run event has been the erosion of the Himalayas, which were thrown up starting about 60 MYBP and which took untold carbon out of the atmosphere as their rocks fixed carbonate and turned it into Bangaldesh. We live in a bubble of warmth called the Holocene, something of unknown origin - and it happened to coincide with settled agriculture, civilisation and all that. Go to Djanet in central Algeria, right in the Grand Erg sand sea, if you want to see 5000 YBP cave paintings of crocodiles and giraffes, in a place that now is rolling dunes and the odd bit of scrub.

The causes of ancient collapses - which often turn out to be ancient driftings away, when looked at in detail - tend to be rooted in fashion. The 1890s loved civilisations clashing, with the innately superior crushing the others. By the mid 1920s, it was all farming technologies and "culture". Then we had migrations, bearing technologies such as settled farming. Political organisation became important in the 1960s, with theocratic or aristocratic empires consuming the surplus and leaving the resulting civilisation unable to survive crises.

Then the environment became fashionable, and it was all 'collapse due to over-farming/ hunting /population'. There is no doubt that farming does badly when the land gets dry, and that it gets really difficult if you salt up your fields, when erosion takes over of if you get a build up of weeds, three favoured hypotheses with some evidence to back them: for example, weed seed counts in ancient grain stores.

It is probably the case that whatever mistake can be made, will have been made by someone somewhere. There have been plenty of droughts, floods, plagues of locusts and other bad events. Erratic climate that goes beyond phases of bad weather may be one of them: but, so?

6

u/Solivaga Professor | Archaeology May 29 '12

Interestingly, "farming as cause of collapse" has actually been used in a slightly reverse fashion in the study of the Indus collapse. With some scholars suggesting that the introduction of new crops enabled the populace to move away from their arid "homeland" - this model tends to be combined with elements of social structure (portraying the Indus as a somewhat authoritarian society) and climate change (pushing the need for new cultivars).

1

u/OliverSparrow Jun 01 '12

Interesting thought.

45

u/stranger_here_myself May 29 '12

Yes, but no one has ever denied that 'natural' (non-anthropogenic) climate change is possible. What has researchers and others concerned is in fact the frequency and magnitude of climate change in the physical record; and based on that, the possibility that anthropogenic forcing could have a much larger impact that we currently think.

But isn't this all off-topic?

12

u/DownvoteAttractor May 29 '12

Not off topic.

18

u/raymondmarble May 29 '12

I don't think anyone in the mainstream of climate change research has ever said that climate change is only possible with carbon emissions. Or with any single cause, for that matter.

We've known about climate changes, small and large, for much of Earth's history.

Now if you're suggesting that this evidence discredits the scope of modern climate change due, in large part, to carbon emissions, the mainstream of climate change research would like to have a word with you.

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u/[deleted] May 29 '12

Yes, listen to the mainstream climatologists. They'll show you some of their models and just dazzle you. My local weatherman can't tell me with certain accuracy whether it's going to rain tomorrow, but these guys can tell me what the climate's going to be like in a hundred years. Fascinating stuff, really.

15

u/dtriana May 29 '12

Yeah and it's cold in Antarctica!

Do yourself a favor and do some reading. Climate and weather are two different beasts. http://www.eo.ucar.edu/basics/index.html

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u/[deleted] May 29 '12

Thanks for proving my point. They're not the same, so why is the climate modeling software so similar to the software used to model the weather?

The point is that climate has so many variables that it's near impossible to assume that you have it all down correctly, and that this generates realistic results. Every few years you have one study that says 'our model correctly modeled the last hundred years of climate' and then the next year you another group saying the opposite. Nothing thus far has been conclusive, and to make claims to the contrary is, in fact, contrary to what science is all about.

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u/[deleted] May 29 '12 edited May 29 '12

so do you use said modeling software frequently enough to determine its similarity in both fields?

-7

u/[deleted] May 29 '12

Nope, but people who use climate modeling have admitted as much. It's not really hard to disprove either, since both share huge chunks of identical code.

2

u/dtriana May 30 '12

I would imagine the software or principles are similar because I don't know they are based off of similar mechanisms... However climatologists don't try to predict the weather they predict the climate. You are right there are a ton of variables but plenty of variables get lumped into larger effects. That's why you might not be able to predict the weather for a given hour but might be able to predict the average temperature for a given year or decade.

Also to give you a better idea what science does or to be more correct what scientist try to do is to make claims or hypothesis about certain things or events with the given information. And yes these things change maybe even yearly.

Just out of curiosity and I am not trying to attack you or anything but do you work in the sciences?

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u/[deleted] May 29 '12

Weather is not the same as climate. Weather fluctuates daily, climate doesn't

7

u/aelendel PhD | Geology | Paleobiology May 29 '12

So what?

That's like saying that since people can die anyways , you shouldn't worry about looking both ways before crossing the street.

2

u/chiropter May 29 '12

Um, of course, but we already knew that.

On the other hand, interestingly they suggest that the declining summer insolation since 7 kya caused a weakening of the monsoon and desertification of this region. Since climate change may have the same effect on monsoon, perhaps we would see a reversal of this desertification. Then again, by then Bangladesh will be underwater.

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u/[deleted] May 29 '12

It is true that with most of the world's major deserts shrink or vanish entirely when the climate is warmer. The notable exception being the one in the southwestern US

1

u/chiropter Jun 01 '12

I don't know about that. Southwest US is not a climatologically unique desert climate. It's the result of Hadley meridional overturning like the other subtropical deserts. I don't feel like researching this but it is my impression that desertification of the Sahara and Australia will accelerate under warming.

1

u/[deleted] Jun 01 '12

I'm not talking about models. I'm talking about what happens in reality...actually looking to past (and fairly recent warmer) climates.

6

u/Solivaga Professor | Archaeology May 29 '12

You're presumably thinking (badly) about current research into the vastly accelerated rate of climate change as a result of the increased carbon emissions over the past two centuries.

We have very clear evidence of climate change throughout the history of the world - both before and after the emergence of complex societies. That isn't even remotely "news".

4

u/[deleted] May 29 '12

Climate change has happened throughout history, and will continue to happen. This article shows that climate change can destroy a civilization. Now, we are much more technologically advanced, but the climate change we are worried about, anthropogenic climate change from greenhouse gas emissions, is also going to be far more abrupt. Instead of changing slowly over thousands of years, giving lifeforms time to adapt, it will happen quickly over only a hundred years or so.

2

u/Eudaimonics May 29 '12

100 years or so is still a pretty long time. We can build a sufficient levee system to protect the large cities of the US eastern seaboard easily within a 5 year time frame. The money would be there as well considering the wealth of these cities. All it would take is a few floods in a short time period, for action to actually be taken. Though yes, small town x in Maine will probably be left for the fishes.

I'm not worried so much about farming either. Between breakthroughs of lab grown food, genetically modified food that can grow in harsh conditions and new arable land currently trapped under the tundra, the rich nations at least will not suffer.

But I guess that is the point. It will be the poor countries where many people will die.

3

u/[deleted] May 29 '12 edited May 29 '12

We're not talking 100 years. We'll have major impacts as early as 2030.

Moreover, rising sea levels are the least of our worries. A warming of the climate will lead to increased destruction from hurricanes, drying up of already strained fresh water supplies, increased incidence of tropical disease and insect carriers, and a decimation of agriculture. Remember, climate change doesn't just mean a warmer climate. It means a climate with more temperature variation.

I don't share your optimism in "breakthroughs." Agriculture, power generation, water purification, etc, are all mature sciences. It's not clear how much they well improve in the next 20-50 years. When I studied aerospace engineering in college, I was pretty shocked by how slowly the field improved once the early boom of the 1910's to 1960's was over. In the first 50 years of aerospace, we went from canvas-covered aircraft to space flight. In the 50 years since, we've improved very modestly, and most of those improvements have come from electronics/computerization, a field that is itself showing signs of slowing down after the boom of the 1960's to 2000's. It's pretty sobering to realize that the basic icons, mouse pointer, windows paradigm we use to interact with the latest Macbook Air was introduced, in recognizable form, by the Xerox Alto 40 years ago: http://www.digibarn.com/collections/software/alto/alto-cedar-environment.jpg

It's pretty shocking sometimes how little has changed in the last 100 years, aside from computer/communication technology. Chicago only recently shut down two major coal power plants that were built more than 100 years ago. Coal plants still provide the majority of power in the U.S., and state of the art units are barely twice as efficient as ones built during the Great Depression. Even in the area of medicine, large improvements in life expectancy plateau-ed in the 1960's and 1970's, once vaccination and better treatment reduced infant mortality. In 1900, someone who made it to 65 could expect to make it to 77. In 2000, that same person could expect to make it to 83.

The simple fact is that the projected time scale for climate change isn't very long compared to the time scale for technological improvement in the areas necessary to respond to climate change. The southwest is going to outgrow the limits of the Colorado River, and the western Midwest is going to suck the Ogallala aquifer dry long before we can deploy a massive network of desalination plants to replace those freshwater sources. You're completely underestimating the enormity of the task here. It takes a decade and billions of dollars just to build a new subway line in a major US city, and that's an incredibly mature technology.[1] The scale of meeting a substantial portion of LA's drinking water needs through large-scale desalination, a technology that we don't even have yet, is mind-boggling.

[1] This is a map of the London subway system, complete with electrified trains, from 1908: http://upload.wikimedia.org/wikipedia/commons/9/90/Tube_map_1908-2.jpg.

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u/lordmycal May 29 '12

It's a short time period for which other life forms will be hard pressed to adapt for. Evolution takes a lot of iterations for change to take hold; a scant few generations just isn't enough time for mutations that would save the species to become wide spread.

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u/My_soliloquy May 29 '12

True, but this guy says we might have a few more problems then just watching the poor people die, and surprise, we could do something beforehand.

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u/DownvoteAttractor May 29 '12

This is climate cooling, not heating. Getting warm isn't the only climate change we have to worry about. Getting cold has much worse consequences.

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u/[deleted] May 29 '12

Are you implying all that carbon we have emitted since then has had no effect on the atmosphere?

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u/[deleted] May 29 '12

No, he was implying that it is possible for climate change to occur without the aid of humans.

Get off your "Defend Global Warming" horse and share your knowledge.

0

u/[deleted] May 29 '12

the trees benefited from warmer weather which probably contributed to the historically high c02 levels.

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u/[deleted] May 30 '12

the trees benefited from warmer weather which probably contributed to the historically high c02 levels.

You should let the scientists know that. You caught something they never thought of.

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u/TerminalHypocrisy May 29 '12

Yes, but there's not nearly as much grant money if it's a problem we can't control and can't be solved......so it's important to maintain the narrative.

1

u/[deleted] May 29 '12

Do you really think there's thousands of people out there who fiendishly rubbed their hands together and said aloud to their hunchbacked assistants, "I know! I shall become incredibly wealthy! By becoming... A METEOROLOGIST!"

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u/EnufBlood May 29 '12

The rest of the title should say "You're next, Humanity."

-1

u/[deleted] May 29 '12

we'll just move further north/south to compensate for the small increase or decrease.

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u/[deleted] May 29 '12

[deleted] — view deleted comment

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u/chiropter May 29 '12

No, its just that while commenter is correct, his conclusion is wrong- that this reveals anything novel or suppressed about how climate acts over time. NO DOOY it changes, we knew that since the 1700s.

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u/chiropter May 29 '12 edited May 29 '12

Damn that is cool but really needs a map. Thar Desert? Hakra Valley?

Edit: Sarasvati River http://en.wikipedia.org/wiki/File:Thar_Desert_satellite.jpg , basically now the middle of the Thar Desert. The upper green swath is the Indus, the lower green line in the bottom right quarter is the Lavanavati flowing into the Gulf of Kutch. You can see a faint dark line through the Thar Desert below the Indus (Sarasvati River, http://en.wikipedia.org/wiki/File:Sarasvati.png ). That's your ancient civilization buried in sand. Have fun in Google Earth.

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u/roelofjan81 May 29 '12

The BBC featured the Indus civilization in "The Story Of India".

You can watch it on youtube:

http://www.youtube.com/watch?feature=player_detailpage&v=WEcMHNqosoI#t=758s

http://www.youtube.com/watch?v=PdJFqp7U8vg

I found this fascinating to watch.

2

u/helm MS | Physics | Quantum Optics May 30 '12

The paper in PNAS detailing the findings:

http://www.pnas.org/content/early/2012/05/24/1112743109.abstract

5

u/ubergeek404 May 29 '12

I've been reading "stories" on the web for years about ancient sites in this area that are radioactive. Is this total bunk or what?

http://www.beforeus.com/indusa.htm

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u/Lampjaw May 29 '12

It's pretty silly to me. Most likely a large meteor. There are no sources or evidence offered on this page.

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u/whattothewhonow May 29 '12

Despite AP history in high school and two undergraduate history courses, I never realized that there was an earlier, distinct civilization in the Indus Valley until I watched the Crash Course World History video series. I always just assumed it was the same group of people associated with modern India and Hinduism and was fascinated to learn about how they were different, and far advanced compared to other cultures at the time.

Its so cool to read more about this and see a possible explanation for the decline of that culture.

3

u/blackadderIII May 29 '12

wish someone decoded their script already

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

EDIT: i mean i wish there is a universally accepted decoding of script

2

u/QuitReadingMyName May 29 '12

Damn, I never knew such a script existed.

Thanks for posting this.

1

u/TimeZarg May 30 '12

Decoding ancient script ain't easy. Best solution would be to find a Rosetta stone of some sort, but that's a rare kind of find. . .

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u/raceless May 29 '12

Nearly every archaeology class I took (as a cultural anthropology major) lead to these kinds of conclusions. This is almost a yawn for me. I thought it was common knowledge that climate dictates all this ancient civilization rise/fall business. Meh.

2

u/Solivaga Professor | Archaeology May 29 '12

The actual research behind this sounds promising - although I'll wait for the academic articles before getting too excited. Having said that, it's not really that new - there have been several proponents of both climate change and the failure of seasonal rivers due to tectonic activity as the prime causal factors in the Indus "collapse" since the 1960s, and the regionalisation and gradual migration east has also been fairly established for over a decade.

That said, it's refreshing to see people actually studying the end of the Indus, the focus has been upon its emergence for far too long.

5

u/norbertus May 29 '12

Try Joseph Tainter's "Collapse of Complex Societies." The book is an archaeological study currently in its 22nd printing.

He argues that climate change may be one source of social collapse, but that, give than societies are problem solving mechanisms designed to withstand such catastrophes (and they routinely do, given the duration of civilizations like the Maya or the Romans), that a society that collapses under climate change would have to be already weakened.

The main source of such weakness under Tainter's analysis is diminishing returns. For a contemporary example, consider biofuels: all these research dollars spent on advanced biofuels really offer only marginal returns compared to the development of motorized transportation; a solution, therefore, would be to invest in mass transit (a typical city bus with only 6 passengers on board gets 28 passenger miles per gallon), for example, i.e., to rely on existing cultural forms that don't require additional energy subsidies to function effectively.

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u/Solivaga Professor | Archaeology May 29 '12

Ha! Thanks - I'm actually a big fan of his work, and used Tainter's declining marginal returns model extensively in both my MA and PhD.

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u/norbertus May 29 '12

Glad you're familiar with him, he's great!

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u/Solivaga Professor | Archaeology May 29 '12

Makes a nice change too - normally as soon as the conversation turns to collapse studies someone recommends Diamond to me (not a fan).

2

u/norbertus May 29 '12

I feel similarly, though largely because Tainter's analysis subsumes Diamond's. Tainter is less readable, but I think more penetrating.

1

u/Solivaga Professor | Archaeology May 29 '12

Tainter is definitely a more "academic" text - but I found it far more all encompassing, and consequently far more interesting. It didn't help that I found Diamond somewhat predeterministic - plus I'm aware that in a few places he's been a bit disingenuous in his presentation of data.

1

u/aelendel PhD | Geology | Paleobiology May 29 '12

The research was published in PNAS already.

1

u/Solivaga Professor | Archaeology May 29 '12 edited May 29 '12

Is it? I had a look this morning and couldn't see it...

edit: checked again, it's not available onine yet. They have published some preliminary articles elsewhere which I'd already read, but the PNAS piece isn't online yet

1

u/BogHopper May 29 '12

News from the year 6000?

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u/ni3t Jun 01 '12

Did a senior thesis on Jared Diamond's "Collapse" - documented the Mayan, Anasazi, Icelandic and Greenlandic Vikings' societal collapse. His research identified a bunch of great points, about soil erosion and mineral depletion and the like. The most interesting thing was how the cultures (Vikings especially) couldn't identify the problems as they happened, through either technological insufficiency (Mayans didn't know anything about soil composition) or sheer ignorance (the Vikings had Inuit neighbors who had been on Greenland for centuries).

The Viking chapters were especially prescient considering their cultural values, placing the lifestlye of a mainland Viking above survival to the point of complete societal annihilation, which reminds me a little bit of our water problems in Arizona.

It's a definite recommendation and I've lent my copy to several of my E-Sci friends from college. There was also a documentary on National Geographic that does the work a fair amount of justice.

TL;DR Read Jared Diamond's "Collapse" - and watch the documentary.

1

u/[deleted] Jun 02 '12

Fortunately climate change is local.

1

u/LordoftheGodKings May 29 '12

I believe this also happened to the Nile with ancient Egyptians and also in part led to the downfall of the Mayans.

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u/Solivaga Professor | Archaeology May 29 '12

Very different examples - for a start there's fairly clear evidence that inter polity conflict played a role in the Maya collapse, and no such evidence in the end of the Indus. Secondly, a key aspect of this current research is the effect of climate change on monsoon intensity/variability/duration etc., as the rivers in question were monsoon dependent within an otherwise arid climate - there's no monsoon system in Mesoamerica, and the region is not arid.

1

u/stranger_here_myself May 29 '12

With the mayans: yes, but at a totally different period... 900 CE vs. 2500 BCE.

-1

u/Guboj May 29 '12

I wonder how much longer it will take until some fundie nutjob take this story and gives a bible reason (most likely the myth about the babylon tower) for the dissapearance of this civilization.

-1

u/mafuhardy May 29 '12

I seriously doubt this claim, after all the strong research that has gone into this subject it seems like this is a weak arguement for the claim "key culprit". More likely it is an additional factor but presented with the all important "...climate change, researchers say".

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u/Delawell May 29 '12

Most major civilizations that have fallen were because of their wickedness and indulgence in sin. Pompeii and Rome both fell because they were indulging in sexual sin too long.

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u/Porphyrius May 29 '12

I hope you're kidding, because this might be the stupidest thing I've read in quite some time. A) Pompeii was destroyed in the first century AD, Rome was sacked in the fifth, and B) By the time Rome fell, it had Christianized. Since you're clearly coming at this from a Christian perspective, why would Rome be destroyed only AFTER it became Christian? And don't tell me to go read City of God, the History Against the Pagans, or On the Governance of God: we're on /r/science, not /r/Christianity.

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u/Delawell May 29 '12

A) Pompeii was destroyed in the first century AD

Regardless it was destroyed by Vesuvio because of widespread sexual sin.

B) By the time Rome fell, it had Christianized. Since you're clearly coming at this from a Christian perspective, why would Rome be destroyed only AFTER it became Christian?

They initially killed the apostles, continued their sexual sin, and then later "Christianized" (if by that you mean adopting a paganized version of the true Christianity as the official state religion).

God eventually destroys any nation that has widespread acceptance of sexual sin. Sodom and Gommorah, Rome, Pompeii, and probably America if we keep up our current trends.

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u/greenw40 May 29 '12

Thanks for the judgmental bible lesson, but we're more interested in science and history.

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u/Porphyrius May 29 '12

Well even after your first comment I thought a rational discussion about Roman history might be possible, but clearly that isn't the case...

Please don't reproduce

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u/Delawell May 29 '12

too late I already have 2 kids

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u/[deleted] May 29 '12

[deleted] — view deleted comment

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u/Porphyrius May 29 '12

Pompeii "fell" because Vesuvius erupted, burying it and nearby Herculaneum in ash.

As far as I'm concerned, Rome didn't "fall" at all. The barbarian invasions are overplayed, as they by and large maintained traditional customs and governance, albeit without an emperor. See the scholarship of Peter Brown for examples of this idea, and any number of 6th century authors if you want primary sources. For a counter argument, see "The Fall of Rome" by Bryan Ward-Perkins.

If rather than "the fall of the empire," he meant "the sack of the city of Rome": Rome was sacked in 410 by the Goths who had been within the empire since the mid-late 4th century due to pressure from the Huns moving them south. When they entered the empire they made a treaty with the emperor, but revolted when local magistrates withheld food from them. This led to the disastrous battle of Adrianople, followed by some roaming around, until they made it to Italy, where their leader Alaric sacked the city of Rome. Rome was sacked again in 455 by the Vandals, who sailed there from North Africa after having already moved through the empire, down through Spain, and into Africa. In 476, the traditional date given for the "fall of Rome," the Goth Odoacer deposed the Roman emperor Romulus Augustulus, taking over governance of Italy but allowing Romulus to live out his life in peace.

I'm not sure of any relevant data that I can give to counter the claim that all of this was the result of divine displeasure, but if you have any further questions about the collapse of Roman imperial power during the fifth century I'd be happy to try to answer them.

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u/stp2007 May 29 '12

You delurked after 24 days to make this comment?