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Megafauna Extinction Due to Climate
jvchamary writes "Most biologists believe that Earth is currently undergoing its sixth mass extinction. The cause? Human activity, either directly (e.g. the Dodo) or indirectly (e.g. the Amazon rainforests). The disappearance 30,000-45,000 years ago of the Australian megafauna, large animals such as the marsupial lion, is often attributed to hunting by Aboriginal settlers. However, recent research in Proceedings of the National Academy of Sciences suggests that it was more likely a shift in climate, rather than hunting, that caused the over-sized organisms to die-out (via Nature and the BBC)."
Yet the Americans continue to deny global warming. Gives you a nice feeling about the future, doesn't it, when the nation that release the most greenhouse gasses denies it is even causing a problem :-/
What percentage of animals that once lived are now extinct? (this is sort of a trick question for the christian "scientists" who go looking for dinosaurs in Africa, but lets ignore those morons for a moment.)
Over 99%? Oh.
Yes, species die off. Sucks for the those animals, and makes us feel guilty if were are causing it, but the fact is that natural processes have killed off more animals than humans have.
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Hmm. I know a relatively famous (in his field, at least) paleoanthropologist,and was just talking to him about this very thing. I asked him his thoughts about the two competing theories of large animal extinction.
He said that while it was currently fashionable to blame the climate and exonerate aboriginal hunters, he said it makes perfect sense that it was probably a combination of the two.
We modern humans have a definite tendency to underestimate the intelligence, resourcefulness and persistence of our forebears. A good example of this is all the mysticism and voodoo crackpot theories of how Stonehenge, the pyramids, etc. were built. The fact is that ancient people were quite -- sometimes ingeniously -- resourceful at accomplishing what they wanted to do.
Along that same vein, I have no doubt that they became quite expert at killing such things as mammoths, which would feed a whole clan for months (esp. if you dry some of the meat, etc) and provide ivory, bone and fur besides. Mammoth hunting would also have been a great opportunity for clan members to show their skills, bravery and dedication to the tribe -- something of great importance in many aboriginal societies.
Paleoanthropologists are a pretty interesting bunch to talk to.
- Alaska Jack
Don't give it up so quickly. There are some huge problems with the "climate-only" theory. Namely
A) In most of the world (even if not for some animals in Australia) extinctions were timed, as well as we can measure, with the arrival of humans into each region, even though the global climate was changing as a whole
B) Species survived far more dramatic climate changes in the past, with nowhere even approaching the degree of megafauna losses. The scale of megafauna losses last ice age was staggering - for the largest animals, often over 90% of species.
C) We've seen this occurring in more modern times. For example, the Moa of New Zealand; there is essentially no doubt that they were butchered by the Maori, because their fossilized cooking pits are filled with Moa remains in nice neat layers - huge numbers of them that the species clearly couldn't have sustained. When the Maori were discovered, they talked about hunting and killing them. There's a sudden cutoff point in Maori sites in which suddenly Moas disappear from the diet.
Also, climate change isn't the only alternative theory. There's also the concept of humans being a carrier for diseases/pests, human-induced environmental changes, human killing of "keystone" species, and my favorite, "many of the above combined".
Aeris Died For Your Sins.
Have any /.ers read it?
That's not quite accurate. The "little ice age" lasted from 1450 to 1820, a time during which there were sunspot highs and lows. The lows of 1645-1715 (the Maunder minimum) and 1795-1820 (the Dalton minimum) just happened to be the coldest points of it. Some of their other minimum numbers seem a bit odd, too.
The whole "sunspots affecting temperature to the degree we're seeing recently" thing has always been rather suspect. It's not going to affect directly - radiant energy varies by only 0.1-0.2%. But perhaps indirect effects might be occurring, and some have been suggested (such as through altering ozone levels). Nonetheless, the best-predicting climate models currently show that the most important role is played by humans.
Aeris Died For Your Sins.
I think it's a coincidence. We keep hearing about global warming tied to our activity. I could just see everyone on the planet agreeing to some preposterous rules to remove any of our interference and the warming would continue.
Much like watering your flowers in the rain. Turning off the human interference (the hose) doesn't stop what nature is already doing.
The human reaction|solution to control this is stupid - we do it in every situation: credits. Companies can then buy|sell|trade those credits. The big boys obtain the credits from the factories who aren't going to use all of theirs and the large(r|st) factories make few, if any changes and are still in compliance with the letter of the law (but obviously not the intent). On top of that, the little companies get a little extra income.
What would happen if they distributed penalty points for licensed drivers in the same way? You'd have plenty of people paying people to assume a couple of their points to avoid losing their license. Drunk drivers would never lose their licenses as long as they had people who would be bought off.
Isn't that how it always seems to be? It is in a plutocracy
1) The Golden Rule: He who has the gold, makes the rules.
2) Life is like a sh%t sandwich: the more bread you have, the less sh%t you have to eat.
The first linked article's author, at least, could use a cold shower. Every time an interesting and insightful fact was revealed, it seemed that the author took a moment to wallow in polite hatred for all things human, who are, in fact, wreched abominations engaged in widespread destruction of this fragile little blue and green ball of dirt. Apparently I'm supposed to feel guilty.
Fuck that.
Earth activists love to envision a world where we all can live in peace and harmony with mother earth; never stepping out of bounds; preserving the earth as it is ( or was ) for all time. It is a beautiful ideal, and I can at least applaud them for having ideals. It also happens to be completely impossible.
The universe is self-destructive by it's very nature, always building and destroying and reworking atoms on a scale impossible for us to comprehend. The systems of this planet, too, are constantly in flux. This is normal folks. We are supposed to have self-corrections in the ecosystem, as evidence of these corrections date back much farther than our existence.
"But Corbin, the difference is that we're the ones causing it! We're destroying our home, not some giant asteroid!." Heh. How arrogant and presumptuous of a human to suggest that they operate outside of the ecosystem, outside of the natural ways of the universe. We as a species are not capable of knowing the correct course for this planet any more than a dog. As smart as we think we are, humans are still pretty stupid when it comes to the workings of the ecosystem, the way it ties in with the planet's activities, and the infulence of celestial bodies. Even if preservation was the right course of action, we do not know the correct balance of actions that would be required to reverse current trends and restore "balance". And even if we did know, what if it means cooling the oceans, or changing solar activity? Do we really have that kind of power? ( That was retorical, by the way. )
Let it ride. We're already hip-deep in this mass-extinction, we can't stop it even if we wanted to. People inclined to recycle and ride bikes to work should do so, by all means. It will make a small difference, but a difference none the less. Could this cycle kill humans? Very possibly. However, as most people would agree, the earth is over-populated with humans anyway. This can only be a good thing. Could the human race die? Yeah, that's possible too. If we did, then at least there's historical evidence that a better species would evolve in our place. Plus, as an added bonus, we wouldn't be around to screw up the planet anymore. That should make the environmentalists happy. Right?
Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote.
"the best-predicting climate models" ... um suck.
We cant even predict the weather without real-time pictures, to say nothing of climate prediction. However I do agree with your main point. I've never quite understood the sunspot-climate relationship. As everyone knows the Sun works on an 11 year cycle (or 22 year for you purists). The number of sunspots goes up and down like clockwork, yet I have not seen any study that shows an 11 or 22 year cycle in temperature. Perhaps they are out there and I haven't seen them? Perhaps it takes more than the few years of low sunspot numbers during solar minimum to cause an effect of the climate? If anyone has credible references on this I would like to see them.
"Truth is much too complicated to allow anything but approximations"
You will fit right in with this group...
http://www.vhemt.org/
It's actually a pretty good cause if you ask me.
Meh.
Yes and no, sunspot activity does have a direct effect on our weather, just not an intuitive one that has anything to do with fluxuations in solar radiation output. I took a graduate course in the near-earth space environment (really space weather) and the organization was quite insightful. We began discussing the interior of the sun, then moved outward to the sun's atmosphere (chromosphere and corona), and solar wind. You see, the solar wind interacts with the Earth's magnetosphere in very complex ways and in turn shapes the Earth's ionosphere - the effective "outer limit" of our atmosphere. As my professor lead off the course,... "You can't teach about the Earth's weather without starting with solar weather."
"It takes considerable knowledge just to realize the extent of your own ignorance." - Thomas Sowell
In 10 million years, perhaps all primary terrestrial life will be descendents of Homo Sapiens. Perhaps we are just in the process of a morphological gene renormalization.
We will have human-derivitive predators, human-derivative herbavores, human-derivitive sea mammals, etc..
Sound strange? It shouldn't. Every once in a while, a specific set of genes shows so much ability to dominate that it completely overwhelm all others and then slowly specializes in the ecosystem, taking on the familiar roles we see. The first Dinosaurs were all morphologically identical with differentiation only occuring as the other species in the ecosystem were driven to extinction and leaving room for the different ecological niches to be filled through evolved Dinosaur morphology. Same with Mammals.
I suppose this vision could require a collapse of civilization such that humans actually had to fill all the various niches in the ecosystem, but given 10 million years, I'd say that is pretty likely. It would be pretty gruesome in the beginning, with canabilism and whatnot being fairly common, but after a few hundred millenia it should shake out to a variety of different predators and prey subspecies quite readily.
The reason that it can be true that 1+1 > 2 is that very peculiar nonzero value of the + operator
We don't really have many large animal species in aus. I ride a kangaroo to work every day but just imagine if I had a wombat as big as a car or a man eating lizard. I think having giant drop bears would mean even more tourists get eaten though. :-)
If you want some more info check out:
Some aussie megafauna
Reasons For Extinction
The CO2 concentration was 7000 ppm during the Cambrian period, 500 million years ago. Was this a time of mass extinction? Not at all. During the Cambrian Explosion, your relatives started having sex, and evolved into animals at a tremendous rate.
What is the carbon concentration now? A measly 350-380 ppm.
What does this low rate mean. MASS EXTINCTIONS!
Or does it?
Let's recap:
350 ppm CO2 = MASS EXTINCTIONS!
7000 ppm CO2 = A pretty good time for evolution.
That's one of the problems with the human caused extinction theory in australia. The dating of stone arrow-heads doesn't tie up with the extinction period.
"There is not a single stone-spearpoint in Australia until, at the very earliest, about 15,000 years ago - long after anyone thinks the megafauna went extinct," said co-author Dr Stephen Wroe, from the University of Sydney.
From the bbc news story
We're so self-important. So self-important. Everybody's going to save something now. "Save the trees, save the bees, save the whales, save those snails." And the greatest arrogance of all: save the planet. What? Are these fucking people kidding me? Save the planet, we don't even know how to take care of ourselves yet. We haven't learned how to care for one another, we're gonna save the fucking planet?
I'm getting tired of that shit. Tired of that shit. I'm tired of fucking Earth Day, I'm tired of these self-righteous environmentalists, these white, bourgeois liberals who think the only thing wrong with this country is there aren't enough bicycle paths. People trying to make the world save for their Volvos. Besides, environmentalists don't give a shit about the planet. They don't care about the planet. Not in the abstract they don't. Not in the abstract they don't. You know what they're interested in? A clean place to live. Their own habitat. They're worried that some day in the future, they might be personally inconvenienced. Narrow, unenlightened self-interest doesn't impress me.
Besides, there is nothing wrong with the planet. Nothing wrong with the planet. The planet is fine. The PEOPLE are fucked. Difference. Difference. The planet is fine. Compared to the people, the planet is doing great. Been here four and a half billion years. Did you ever think about the arithmetic? The planet has been here four and a half billion years. We've been here, what, a hundred thousand? Maybe two hundred thousand? And we've only been engaged in heavy industry for a little over two hundred years. Two hundred years versus four and a half billion. And we have the CONCEIT to think that somehow we're a threat? That somehow we're gonna put in jeopardy this beautiful little blue-green ball that's just a-floatin' around the sun?
The planet has been through a lot worse than us. Been through all kinds of things worse than us. Been through earthquakes, volcanoes, plate tectonics, continental drift, solar flares, sun spots, magnetic storms, the magnetic reversal of the poles...hundreds of thousands of years of bombardment by comets and asteroids and meteors, worlwide floods, tidal waves, worldwide fires, erosion, cosmic rays, recurring ice ages...And we think some plastic bags, and some aluminum cans are going to make a difference? The planet...the planet...the planet isn't going anywhere. WE ARE!
We're going away. Pack your shit, folks. We're going away. And we won't leave much of a trace, either. Thank God for that. Maybe a little styrofoam. Maybe. A little styrofoam. The planet'll be here and we'll be long gone. Just another failed mutation. Just another closed-end biological mistake. An evolutionary cul-de-sac. The planet'll shake us off like a bad case of fleas. A surface nuisance.
You wanna know how the planet's doing? Ask those people at Pompeii, who are frozen into position from volcanic ash, how the planet's doing. You wanna know if the planet's all right, ask those people in Mexico City or Armenia or a hundred other places buried under thousands of tons of earthquake rubble, if they feel like a threat to the planet this week. Or how about those people in Kilowaia, Hawaii, who built their homes right next to an active volcano, and then wonder why they have lava in the living room.
The planet will be here for a long, long, LONG time after we're gone, and it will heal itself, it will cleanse itself, 'cause that's what it does. It's a self-correcting system. The air and the water will recover, the earth will be renewed, and if it's true that plastic is not degradable, well, the planet will simply incorporate plastic into a new pardigm: the earth plus plastic. The earth doesn't share our prejudice towards plastic. Plastic came out of the earth. The earth probably sees plastic as just another one of its children. Could be the only reason the earth allowed us to be spawned from it in the first place. It wanted plastic for itself. Didn't know how to make it. Needed u