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Carbon Emissions 'Will Defer Ice Age'
Sven-Erik writes "Due to subtle variations in the Earth's orbit, researchers have calculated that the next Ice Age is due within 1,500 years. However, a new study suggests greenhouse gas emissions mean it will not happen that soon (abstract). 'Dr Skinner's group ... calculates that the atmospheric concentration of CO2 would have to fall below about 240 parts per million (ppm) before the glaciation could begin. The current level is around 390ppm. Other research groups have shown that even if emissions were shut off instantly, concentrations would remain elevated for at least 1,000 years, with enough heat stored in the oceans potentially to cause significant melting of polar ice and sea level rise.'"
Larry Niven, Jerry Pournelle and Michael Flynn.
Fallen Angels
General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.
Neither melting ice caps nor a new ice age sound particularly appealing.
Wonder how many hypocrites who previously excoriate all climatologists who caution about global warming as corrupt and biased instantly trumpeting that these brilliant, honest, decent climatologists have to be right because the end result is one that they want.
And people said global warming deniers didn't care about future generations. They were trying to help them all along!
The only thing necessary for evil to triumph is for it to be pitted against a slightly greater evil
What about the ones that live in areas that are going to be covered in water?
Maybe because of this:
http://www.bbc.co.uk/news/science-environment-15342682
Check your premises.
It's hard to get funding for an experiment that takes two identical planets and changes the global CO2 concentration on one.
Climatology is an observational science like geology or astronomy. Models can be checked. It's not just curve fitting to the temperature record: climatologists figure they're on the right track when their models predict phenomena like El Nino.
Except... that isn't quite how it works.
Global warming means that we're changing a massively complex system. And like all massively complex system, when you tweak the parameters beyond a certain point, the system as a whole can itself wind up altering other parameters drastically as it seeks a new stable state.
Or, to put it simply, global warming could potentially lead to a sudden and drastic cooling:
http://science.nasa.gov/science-news/science-at-nasa/2004/05mar_arctic/
Check your premises.
Describing the impact of global warming as "a bit more war and some starvation" is rather like describing the situation of living living in Pompeii in AD 79 as being "minorly inconvenienced by relatively minor geological events".
Check your premises.
Good book, IMHO.
For those interested, "Fallen Angels" is available at Jim Baen's Free Library to read online, or download. (linked below)
"Fallen Angels"
*Discaimer*
I'm just an enthusiastic fanboy, not affiliated with Baen Books in any way other than being a happy customer.*
Down With Slashdot BETA!!! I've been around the corner and seen the oliphant; you can only abuse me from your perspecti
I buy that CO2 could prevent or delay the onset of an ice age. What I don't by is the suggestion that an ice age is due to start 1500 years from now. Looking more carefully, I see that the value of CO2 level required to prevent an ice age 1500 years from now is below the pre-industrial level. In other words they've predicted an ice age that would, under no conceivable circumstance, occur and then said, look, it won't occur because of CO2. Yes, but then again our lakes aren't frozen in the summer now because of CO2. Maybe we should send out a press release.
Support SETI@home
How do you know that? Some models predict increased desertification in the mid latitudes but then many show increasing crop productivity at more northern latitudes. What we do know is that during previous ice ages the human species went through some bottleneck events that reduced our numbers to what we would now considered near extinction for a large animal species.
There are 4 boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order. Starting now.
How do you know that? Some models predict increased desertification in the mid latitudes but then many show increasing crop productivity at more northern latitudes. What we do know is that during previous ice ages the human species went through some bottleneck events that reduced our numbers to what we would now considered near extinction for a large animal species.
Go visit the tundra, tell me what you think that place will smell like when it thaws.
Sure, in about 1000 years when the toxic rot has run its course, there will be productive land there able to grow crops, but it won't get there without a lot of pain during the transition.
Intrinsically, people are inconvenienced by change, change of this magnitude is inconvenient enough that people will go to war over it.
Hating ice ages doesn't mean liking global warming. If you want to prevent the planet from cooling into an ice age, you don't need to warm it up above present temperatures. You just have to keep it from cooling below present temperatures.
Human civilization has adapted itself to a relatively stable range of climate over the last 10,000 years. Large warming or large cooling pushes us outside of that range. It may be costly to adapt our civilization to a completely different climate, particularly if it happens "fast" (century time scale). Thus, it's possible to hate both global warming and "ice ages".
If you want to use the greenhouse effect to prevent the planet from falling into a glacial period, then you should want to save fossil fuels for when we need them, rather than using them up now, when we don't. That is, dole them out slowly over thousands of years to keep the interglacial climate stable, as the next glacial period gradually deepens, instead of our current course of using them up rapidly and elevating temperatures well above the Holocene climate range.
Besides which, this study is controversial. Everyone agrees that we will see another glacial period someday, barring human intervention. The question is when. This study suggests 1500 years; a number of others have suggested that the next glacial period isn't due for as long as 50,000 years. Which is even less of an argument for global warming.
The Earth certainly has. But humans have a pretty narrow temperature band in which they can live. Humans sweat based temperature regulation would not have functioned over most of the Earth when the dinosaurs ruled.
But really, this isn't about the Earth's survival. It's about Humans. You're right - we haven't been around that long. And it seems that our refusal to acknowledge that we're soiling our niche will ensure that we aren't around for all that long, either.
Check your premises.
The earth is just a computer. You need two. See Slartibartfast.
When the foot seeks the place of the head, the line is crossed. Know your place. Keep your place. Be a shoe.
It appears you've never been in a real war. Neither have I but I've seen the pictures from WW I and WW II and read the statistics. You can academically say, "Well they were an inevitable event in the adaptation of 19th century nation-states societies to the 20th century Industrial Age", but that doesn't mean you want your kids to go through that sort of thing -- and I mean the devastation of WW II in Europe and Asia, not the relatively light touch the US got. I'll take a multi-hundred year climate change to which we can adapt over a ten year series of conflicts later called WW III.
Unfortunately, the model for aid to countries with starving people has been to deny them any semblance of security. The US (and other countries) ship in massive amounts of food in a generally inedible form - raw grains, etc. This is then given to various bodies within the country with starving people. Some of this ends up being sold for the enrichment of people that weren't starving to begin with. Some of it ends up being dumped along the road because it is too much trouble for them to actually distribute.
The truely awful scenario is the family found dead of starvation sitting around with a bag of raw wheat grain sitting there at their feet. Without a flour mill the raw grain is pretty much useless except as an animal feed, and all the animals were eaten last week.
We is the US sending bags of grain to warlords hoping they will distribute this to their "subjects" that they desperately want to keep in total subjugation? Why is the US sending bags of grain to the government of a country that has historically totally neglected their rural population? Why is the US sending bags of grain in the first place? Oh, because we have a surplus of it and it doesn't really cost anything to ship the surplus overseas.
The end result of this is the people still starve. Even if they get the food aid, it doesn't help solve the problems of why they are starving in the first place. Nor does it teach the people anything about getting out of their predicament. Food aid has been a curse to Africa since day one and nobody on either side seems to be learning anything from the history of failure.
No, I'm here. What did you want to know? Getting off the Earth? That's easy:
* Orbital velocity is root (R(e) * g), where R(e) is the radius of the Earth (6378000 meters), and g is the surface gravity (9.80665 m/s^2). That works out to 7908 m/s
* Kinetic Energy is 0.5 * m * v^2. Thus kinetic energy to reach orbit is 31.27 MJ/kg.
* One kiloWatt-hour (kWh) is the common unit of electric energy. 1000 W * 3600 seconds = 3.6 MJ.
* Therefore it takes 31.27 / 3.6 = 8.7 kWh/kg to get something into orbit.
* Multiply by your local electric rate. Where I an now, that works out to $1/kg, about what potatoes cost at the local market.
So getting off the Earth is cheap, if you use energy efficiently. You haven't been, though. You have been using about the least efficient method available: chemical rockets. The best rocket fuels only have a bit under half the energy needed to get to orbit (15 MJ/kg), and the engines are around 2/3 efficient, which leaves you at around 10 MJ/kg. So the fuel can't even get itself to orbit, much less anything else, like cargo. You end up using a lot of fuel to lift a smaller amount of fuel part way, then use that to push an even smaller amount a bit further, and finally that last bit pushes a very small cargo to orbit. For those who understand math, that is an exponential ratio of fuel to cargo, where the exponent is the ratio of mission velocity / rocket exhaust velocity. For chemical rockets, that works out to 2-3, depending on which fuel. So you use e (2.718...) raised to 2-3 power as much fuel as cargo that gets to orbit.
The answer is quite obvious: use something else. Something that has better efficiency, so you are not slaughtered by the exponential. There are a number of choices. Which one you use depends on a number of "mission requirements": What are you launching, how often, how much up front development money you can spend, how much risk do you want to take, etc.
OK, that takes care of getting out of *this* gravity well. What next?
(1) Don't go right down another one. The Moon and Mars can wait till you build up some infrastructure. Use near Earth asteroids first, followed by other asteroids, including the ones orbiting Mars, as a source of building materials. You can use efficient electric thrusters as long as you are not diving down a gravity well.
(2) Don't send humans first. Humans have all kinds of picky needs about temperature, pressure, food, radiation, etc. Robots, remote controlled, and automated equipment (which I will call just "robots" for brevity) are not as sensitive. Send robots first, have them build stuff up. Once you have enough stuff in place and can support the humans, then they can come.