Romans, Han Dynasty, kick-started climate change Anthropogenic climate change may not be a recent phenomenon, with researchers reporting ice cores from the first two centuries AD show big spikes in methane prevalence. Those two centuries, the researchers note, co-incide with the most prosperous periods for the Roman Empire and Han Dynasty. A Nature paper, Natural and …
I don't suppose these retards have bothered to notice that forest fires (much larger forested areas in Roman times) would reduce human cooking fires to insignificance?? Or perhaps even consider that if these things happenned before any significant human impact it might NOT (gasp!) be caused by the poor little villagers burning wood (most of which would have gone up anyway in those natural fires, so even less impact...)
Of course not, lets just blame it all on the humans (again) and get the old begging bowl out for more grant money.
"I don't suppose these retards have bothered to notice that forest fires (much larger forested areas in Roman times) would reduce human cooking fires to insignificance??"
And if the Romans caused MORE forest fires in order to clear land? didn't think of that did you?
God your post is as anti-scientific as it comes. It's quite clear from the tone of your comment that you want this kind of research and knowledge shut down because you don't like the answers that might emerge.
"Mega-forcings of a few cooking fires.
I don't suppose these retards have bothered to notice... "
I don't suppose you picked up a history book in order to learn what you were talking about before labelling others as retards, did you?
We're not talking about cooking fires: We are talking about massive deforestation, for timber, wood for fuel (it was the fuel of industry at the time. Rome had some pretty serious industry, and wood is a lot less efficient than coal), and land clearance. But don't take my word on it: Go and read a book or two. Before waffling on a bunch of nonsense about cooking fires.
Massive? By modern standards?
You greenies just hate the idea that it ISN'T our fault, don't you?
Go and look up the amount of forestation in Roman times relative to now (careful, this might need the use of numbers. Real ones, not the ones used by the warmista industry)
The only 'massive' deforestation wasnt caused by cooking fires, it was caused by goats.
"You greenies just hate the idea that it ISN'T our fault, don't you?"
I'm not a 'greenie': I'm disagreeing with you on your mis-informed ideas about history and fat-draw attitude of labelling people as 'retards' when they disagree with you.
I'm not sure how you get from that to trying to label me as a 'greenie' and using the word like some kind of insult, but thanks for displaying to us how your mind works and the way you jump to totally misinformed conclusions.
"I heard of the Romans cutting down entire forests (as in no tree left in sight) just to siege one city. That city was Jerusalem amongst others IIRC."
You got down-voted by someone who disagrees with history and doesn't believe an Empire could cut down *an entire forest*, I'm guessing.
Kudos.
>You greenies just hate the idea that it ISN'T our fault, don't you?
Scientific findings, and the political ramifications of said findings, are separate issues. Views like yours are expressed in a journal called The Spectator (a vehicle for advertising £20,000 wristwatches and art auctions) by a man called James Delingpole.
This is him being gently interviewed by the current president of the Royal Society, Sr Paul Nurse PhD:
http://www.youtube.com/watch?v=36Xu3SQcIE0
Delingpole: "I haven't the time to read peer-reviewed papers", "I haven't the scientific expertise", "I am an interpreter of interpretations"... and afterwards, he said the interview amounted to 'intellectual rape'.
Mount Mazama, Oregon - 4650 BC
Kikai, Japan - 4300 BC
Mount Thera, Greece - 1610 BC
Santorini, Greece - 1470 BC
Ambrym Island, Republic of Vanuatu – 50 AD
Mount Vesuvius, Campania - 79 AD
Hatepe, New Zealand - 180 AD
Taupo, New Zealand - 186 AD
Ilopango, El Salvador - 260 AD
Ilopango Volcano, El Salvador – 450 AD
Rabaul, New Guinea - 536 AD
Hekla, Iceland - 850 AD
Changbaishan Volcano, China/Korea – 1000 AD
Baitoushan, China/Korea - 1010 AD
Huaynaputina, Peru – 1600 AD
Mount Etna, Italy - 1669 AD
Laki, Iceland - 1783 AD
Tambora, Indonesia - 1815 AD
Krakatoa, Indonesia - 1883 AD
Mount Pelée, Martinique - 1902 AD
Katmai, Alaska - 1912
All had a measurable effect on the climate of the northern hemisphere. All released methane into the atmosphere. This is by no means an exhaustive list.
But yeh, the methane increases in the ice cores must have been caused by 2 specific pre-industrial cultures . Why do the researchers ignore all the other civilisations on the planet at the time? Is it because their rise and decline doesn't neatly correlate with their data?
These charletans will not be satisfied until every last human being is either dead or reduced to scratching in the dirt for tubers and roots.
Maybe the spike they've found was the Romans burning their ecofascist gaia worshiping nutjobs at the stake?
< I vote we create a methane spike of our own.
Does the all-knowing Goat Jam already know how pre-industrial land use changes affected climate? Maybe he should write a paper to explain it to everyone else.
Until then I guess anyone who studies the subject and finds a result Goat Jam doesn't like must be "charlatans". Or perhaps merely studying the subject makes a person a charlatan?
I would be more impressed if they had hypothesised that Roman deforestation and use of charcoal would cause a spike in methane and then gone to look for it in the ice cores. It didn't happen that way.
The original title of the paper in May was:
"Isotope Variations in Atmospheric Methane Over the Last Two Millennia"
but evidently that wasn't getting enough publicity so they changed it to:
"Natural and anthropogenic variations in methane sources during the past two millennia"
The original paper also made no mention of either the Roman Empire or the Han Dynasty in its abstract.
I've no doubt that had the spike occurred two centuries earlier or later then they would have found some other human events to blame for it.
It is also curious that there is no similar spike between 1100 and 1500AD when the Northern hemisphere as a whole underwent a massive deforestation as populations and demand for wood significantly increased.
By the time we got to Lord Nel and Lady Ham we'd not got much in the way of trees left suitable for laying down a keel for a decent sized ship. We were already importing trees from mainland Europe.
I wonder at what point we (that's Blighty) had reached the stage where there weren't big enough trees for a decent sized longhouse.
England was also a *massive* importer of bow staves, dating back well before Henry VIII. We've been importing wood of one kind or another for a long while.
Following the plague years and resultant reduction in industry, population and farmed land, a lot of forests in Europe/UK had the chance to regrow a bit, but it was new growth, and never got back to Dark Age levels.
Perhaps by some extraordinary trick of scale that defies the modern mind's concept of logic, the Romans managed to change the climate at the peak of their prosperity. Or, perhaps because the weather became a bit warmer, the prosperity of the Romans increased. Hmmm. I was not there, I don't know.
"Perhaps by some extraordinary trick of scale that defies the modern mind's concept of logic, the Romans managed to change the climate at the peak of their prosperity."
I don't really understand how that defies logic. To me it simply reflects this massive underestimation of our forefathers that we are constantly subjected to. We have this idea that our predecessors can't pile rocks up without aliens helping, can't change the very landscape, can't figure out the world is round et cetera. Rome was a massive Empire, and did massive things. Let's not underestimate our own abilities here. And let's not jump to conclusions about the resilience of the environment, or lack thereof.
Additionally, we still don't know how much or little effort it really takes to change the climate. So it's not logical to assume that they didn't, based on our limited understanding.
"Or, perhaps because the weather became a bit warmer, the prosperity of the Romans increased. Hmmm. I was not there, I don't know."
Maybe. I don't know either. But I think it's a bit limited for us to say "No, the couldn't have changed the climate with a few cooking fires".
> So it's not logical to assume that they didn't, based on our limited understanding.
And it is not logical to assume they did.
> But I think it's a bit limited for us to say "No, the couldn't have changed the climate with a few cooking fires".
And it is a bit extravagant to say they did change the climate with a few cooking fires.
"And it is not logical to assume they did."
No; but it's logical to keep an open mind about it, instead of labelling the authors of a Paper on the matter 'retards' while knowing FA about the subject.
"And it is a bit extravagant to say they did change the climate with a few cooking fires."
Not that it was a few cooking fires (see above). Maybe they did, maybe they didn't. But I'll certainly take the time to read the Paper in question before jumping to conclusions about the author's mental acuity.
@psyx get a grip. *massive* 2000 years ago does not compare to *massive* today or even 100 years ago.
While "we still don't know how much or little effort it really takes to change the climate" we can make some educated guesses based on an estimate of the scale of the carbon cycle and the output of relevant materiel by dramatic but mundane sources like volcanism and compare that to effect of the relatively small human population of the time burning wood and the few other combustables that were easily extracted.
As others pointed out the mass deforestation of northern Europe 1000 years later does not appear to have had similar effect.
This article is beginning to scrape the bottom of the barrel. And the disappointing thing about such articles is that if there really is an anthropogenic component the climate change they invite skepticism. And the insistence on the concerned side of the argument of supporting such article come hell or high water invites yet more skepticism.
Always dangerous to assume Event A was caused by Event B simply because they happened at the same time, there are always other factors involved.
But it's equally stupid to assume that man's activities have absolutely no influence on our environment. While I'm not in the belief that we're all doomed, Mr Mainwaring, I do believe that we should take *reasonable* steps to reduce our impact on the environment. The continued deforestation and destruction of wildlife habitat seems to have taken a back seat in the drive to reduce co2 emissions at all costs.
We should concentrate on what we can achieve, not on what will cripple our economies and (quite possibly) achieve nothing, while continuing to try and understand our incredibly complicated climate/eco-system and the effect our activities have on it.
I have to say that I have similar feelings here.
It seems that "traditional" environmental concerns of lowering pollution, reducing waste, protecting habitats etc have become second to CO2. However surely if you deal with these issues then CO2 kind of falls into place anyway as a consequence.
Just my 2p anyway.
Indeed all the ice cores tell us is that in Greenland there was an abundance of methane in the air when the ice was forming, it doesn't mean it was global.
Also where is the proven link to humans?
Did the Han Dynasty and Roman Empire suddenly have an outbreak of flatulance to account for the abundance of methane? Wouldn't those cooking fires probably produce more carbon than anything else?
Can methane also be released by geological sources?
Looks like someone just saw the time period matched up with the Romans and Han Dynasty and said "oh well it must be them".
"Did the Han Dynasty and Roman Empire suddenly have an outbreak of flatulance to account for the abundance of methane? Wouldn't those cooking fires probably produce more carbon than anything else?"
Seriously: Get past the idea that all vast historical Empires did to use wood was cook unleavened bread around camp fires. You don't make an Empire without industry. That industry uses and burns wood at a ridiculous rate: Fuel for industry, as a building material, in support of building projects, furniture, shipping, et al. This resulted in massive deforestation. Plus coal was being burned, too. And there were a lot of mouths to feed, and that required clearing more land...
And you know all those shiny bits of armour and pointy things those famous Roman blokes wandered around with. Just sit down with a calculator and figure out how much energy was required for all that smelting and smithing, and ponder where it had to come from. That's a *lot* of burning going on.
It's actually a known fact that human population in both western europe and in china reached peak levels compared to then available (agricultural) technology during those times. The Y. Pestis *pandemic* also did it's fair share with regards to thinning out human population "a bit".
I think the biggest problem is that most people have a completely warped idea of what the ancient and medieval world looked like, especially in the vicinity of the cultural centers of Empire. The use of the term "Dark Ages" by some people says enough and shows their knowledge is stuck at primary school level.
> Seriously: Get past the idea that all vast historical Empires did to use wood was cook unleavened bread around camp fires.
The commenter was talking about conclusions based on correlation and assumptions rather than proven causality.
It really is not enough to say there was major stuff going on at the same time, so that must have been it no matter how momentous those events were. That's primary school thinking. Proper science has bigger ideals and more rigorous principles.
From the article: Lead author Celia Sapart of Utrecht University...
...breathed a sigh of relief as she successfully submitted another paper for publication. She doesn't have to worry about her job for another 6 months. The content of the paper is irrelevant, just get something out there with your name on it.
Next up, a taxpayer funded investigation into fossilized Anatolian rat droppings for their rich source of methane data. Did the ancient Hittites contribute to climate change? Were the Byzantines as gassy as legend has it? Find out in the next installment of Pointless Climate Research. You're paying for it, you might as well hear about it.
Yes the content of the paper is so irrelevant it managed to get published in Nature, which after-all is just some crumby little journal that everyone finds it remarkably easy to get published in.
Presumably you also find the large hadron collider and space telescopes pointless too.
Maybe we could scrap all "Pointless Research" and spend the money on something useful instead like another Olympics with extra BBC coverage or a second Iraq War or Bank Bailout. In 1000 years we won't know anything more about the universe than we know now, but at least we'll have spent taxpayer money on genuinely useful things.
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Presumably you also find the large hadron collider and space telescopes pointless too.
If you cannot understand the difference between technological prowess, and proper use of the scientific method, and climate science gibberish then there is probably not much hope for you. Here is a hint, at the LHC they made a prediction, they tested it. Their theory lived or died by that test. Space telescopes are great achievements of technology. Most climate science is: hypothesis -> find evidence to back up hypothesis -> declare hypothesis as fact. Or perhaps you can finally tell us the test we can use to falsify AGW theory? Thought not. Because it's a circular reasoning where contradictory facts cannot penetrate.
Maybe we could scrap all "Pointless Research" and spend the money on something useful instead like another Olympics with extra BBC coverage or a second Iraq War or Bank Bailout. In 1000 years we won't know anything more about the universe than we know now, but at least we'll have spent taxpayer money on genuinely useful things.
No. Scrap climate change "research". Put the money into the following: quantum computers, cancer research, science education (that's physics, maths, chemistry and biology before you get your hopes up), robotics (including advanced prosthetics) etc.
Surely you can see the distinction ?
Why? Isn't understanding (or attempting to understand) the climate a valid line of scientific enquiry? You might for example suggest that we pay less attention to the results for some reason (perhaps if you judge it unreliable), but that's hardly a reason to just give up. It's a reason for maintaining some funding so that the science can be improved. Who knows? - maybe your judgement about the current status of climate science could be proved right. Or not. It's hard to say. But why just give up?
Why? Isn't understanding (or attempting to understand) the climate a valid line of scientific enquiry? You might for example suggest that we pay less attention to the results for some reason (perhaps if you judge it unreliable), but that's hardly a reason to just give up. It's a reason for maintaining some funding so that the science can be improved. Who knows? - maybe your judgement about the current status of climate science could be proved right. Or not. It's hard to say. But why just give up?
You didn't see the distinction I was getting at. Physics, by and large, gets by on a single test. It agrees with experimentation or it doesn't. The theory can be used for its predictive powers or it can't. If you predict anew particle of a given mass, charge, spin then you can predict its behavior in particle accelerators. If it doesn't show up, your particle doesn't exist.
What (a) is the predictive power of AGW "theory"? (b) can we use as a falsifiability test? Any well formed idea should be falsifiable, yet AGW is true in any case. It is a prioi assumed true and climate scientists traverse the world looking for "evidence" to back this up.
There is no evidence that can be conceivably presented that could disprove it. I could disprove the Theory of Gravity by finding a floating rock, or finding an orbiting object that didn't follow the inverse square law.
This isn't the only problem with climate science. It has a total and utter disregard for rigor. Or logical sequencing. If you want to perform an experiment or retrieve data to prove AGW then you first have to explain clearly what the world would be like without AGW theory. Otherwise you can't possibly show anything with any experiment.
This kind of reminds me of Feynman's famous story about rats running in a maze. Google it, because he really shows how pointless a lot of this "research" is.
"What (a) is the predictive power of AGW "theory"?"
You have it backwards. agw IS the prediction.
AGW is a prediction based on theory concerning the greenhouse effect - absorption properties of greenhouse gases in the atmosphere and the energy balance of planets. The observation of greenhouse gas trends in the atmosphere and theory as to the cause of those trends leads to a prediction of AGW.
"Any well formed idea should be falsifiable, yet AGW is true in any case."
Well it's hard to falsify a fact sure. For example it's hard to falsify the fact dinosaurs once roamed the Earth. Does that mean it's not science?
But you could always falsify the underlying theory. Eg falsify the theories that link fossils to past life, or eg falsify the greenhouse effect doesn't exist by showing that CO2 is transparent to IR or that CO2 isn't rising or the CO2 rise is not caused by man. Plenty of ways to falsify the theory that underlies AGW.
In fact ironically the half the climate skeptics out there claim agw HAS been falsified. Go figure.
AGW is a prediction based on theory concerning the greenhouse effect - absorption properties of greenhouse gases in the atmosphere and the energy balance of planets. The observation of greenhouse gas trends in the atmosphere and theory as to the cause of those trends leads to a prediction of AGW.
AGW is NOT a prediction. What is the prediction? That the world will get hotter? You are taking great leaps and bounds from the absorption properties of gas particles, to global climate effects.
What is your hypothesis here? And what test can we do to prove/disprove it? There isn't one. Global temps have been essentially flat for over a decade. Oh, but wait, somebody has come up with a model that says temps will suddenly start rising fast. Can't say when, but soon. There is no theory here.
Well it's hard to falsify a fact sure. For example it's hard to falsify the fact dinosaurs once roamed the Earth. Does that mean it's not science?
You are comparing apples and oranges. Paleontology is a descriptive science. Along with archeology etc. It finds evidence to construct a picture. It makes no predictions. These sciences only loosely follow "scientific" methods of physical sciences. Do you see the distinction?
...falsify the greenhouse effect doesn't exist by showing that CO2 is transparent to IR or that CO2 isn't rising or the CO2 rise is not caused by man. Plenty of ways to falsify the theory that underlies AGW.
There is no test to show the "greenhouse effect" is an actually occuring phenomena. You are wildly grasping at straws since you jump from properties of particles to an effect on the whole globe. If you suggest these particles are causing climate change. Then what is the test? How will you discount the myriad of other factors? How will you make sure you perform a fair test? No, you can't. Don't worry nobody can. Because AGW has the predictive power of phrenology.
If you believe the properties of particles is causing global climate upheaval, then kindly explain what the global climate would be doing if these particles' effects were not being felt, or were damped by another force. Don't worry, I don't expect you will.
"There is no test to show the "greenhouse effect" is an actually occuring phenomena."
Yet there is overwhelming scientific evidence the greenhouse effect exists. Not only on Earth but also on other planets, eg Venus to pick an especially impressive example of the phenomenon.
So either there IS a test for it, or you've just disproven your own premise that ideas must have a test to constitute science. Decide which.
"AGW is NOT a prediction. What is the prediction? That the world will get hotter?"
AGW follows from the fact humans are elevating CO2 levels in the atmosphere, the radiative properties of CO2 and the greenhouse effect. In the idea of AGW was tentatively suggested over 100 years ago by one of the discoverers of the greenhouse effect upon realizing that man's emission of greenhouse gases could be significant.
"If you suggest these particles are causing climate change. Then what is the test? How will you discount the myriad of other factors? How will you make sure you perform a fair test? No, you can't. Don't worry nobody can. Because AGW has the predictive power of phrenology."
Now you are talking about how much warming from AGW rather than the existence of AGW itself. If the hypothesis is 3C warming for a doubling of CO2 then the test is obvious. We double CO2 levels and see how much temperature changes, keeping an eye on natural variation in order to control for that. Just because we can't do that test immediately doesn't mean there isn't a test.
There are also other less direct ways to test the idea. Test results might only be suggestive rather than conclusive, but you are barking up the wrong tree if you think this isn't science. Science doesn't mean things are either 0% or 100% certain.
"If you believe the properties of particles is causing global climate upheaval, then kindly explain what the global climate would be doing if these particles' effects were not being felt, or were damped by another force. Don't worry, I don't expect you will."
The weight evidence suggests about 1C to 5C global warming per doubling of CO2. So given the lag times and CO2 emitted to date, I expect the Earth would be cooler today without the CO2 increases, about half the warming of the last 100 years.
> Now you are talking about how much warming from AGW rather than the existence of AGW itself. If the hypothesis is 3C warming for a doubling of CO2 then the test is obvious. We double CO2 levels and see how much temperature changes, ....
And just how exactly do you propose to perform this test? And in a proper scientific framework with appropriate controls and sufficiently isolated to rule out other influences such as solar activity variations, volcanic emissions, etc, etc of which there are many.
You can't. It is impossible. That's is exactly why it is not science. To properly perform this great experiment, you must make a specific prediction and raise the CO2 levels of the earth and observe the effect. No only that, it has to be repeatable in a way that can be verified by others. And all other factors have to be systematically eliminated.
And it's not use saying, "Well that's not practical, we can't really do that, it's not fair!". Well that's how it is. That's why real science is so damned expensive, hard and meticulous.
In practice, climate science works like this:
1) Look at historical climate data
2) Build a simplified model to generate that pattern.
3) Extrapolate the model to predict future trends.
4) Observe temparature data and tweak model to fit it.
5) Rinse and repeat
This is *not* science.
It's economics, and we all know how reliable economic models are.
Pretending that AGW is a done deal and accurate science is a monstrous over-simplification and an insult to real science not to mention patently untrue.
"And just how exactly do you propose to perform this test? And in a proper scientific framework with appropriate controls and sufficiently isolated to rule out other influences such as solar activity variations, volcanic emissions, etc, etc of which there are many."
The test isn't supposed to prove the hypothesis, that's often impossible. How for example do we set up a test that proves man evolved from ape-like species? We can't. I suppose in your eyes that means it's not science?
Of course there are plenty of tests that could potentially falsify the idea that man evolved from apelike species and also plenty of positive evidence that man did, similarly if temperatures don't rise in response to a doubling of CO2 then the hypothesis of 3C for 2xCO2 is falsified. There you go, a test that could potentially falsify that hypothesis.
You seem to be under the misconception that science is about 100% proofs. It isn't. If it were we couldn't call the evolution of man a fact. but we can. We can weigh up the evidence to find it's overwhelming and we can conclude that yes, man evolved from apelike species as close to fact as we can get about this kind of thing. We'll call it scientific fact. Science isn't maths. Even knowing something with 80% confidence is still an achievement in knowledge compared to knowing nothing at all and that is where we are with the warming from a doubling of CO2.
Weighing up the evidence (past climate changes, models, atmospheric physics) it is very unlikely that the warming from a doubling of CO2 is below 1C or above 5C. The range of confidence doesn't support disbelief of AGW.
"Pretending that AGW is a done deal and accurate science is a monstrous over-simplification and an insult to real science not to mention patently untrue."
AGW is a done deal, just as the Theory of Evolution is a done deal. Man evolved from ape-like ancestors and man has a net warming effect on the climate through greenhouse gas emissions. That warming effect is significant. If you don't factor in the warming impact man will have you don't have a chance of predicting future global temperature. Nature isn't the only factor in the game anymore.
Yet there is overwhelming scientific evidence the greenhouse effect exists. Not only on Earth but also on other planets, eg Venus to pick an especially impressive example of the phenomenon.
So either there IS a test for it, or you've just disproven your own premise that ideas must have a test to constitute science. Decide which.
Observing the gas dynamics on Venus and extrapolating them for Earth is NOT a scientific test. There are completely different gases in Venus' atmosphere. It's proximity to the Sun is different. etc etc.
Venus' atmosphere is 95% CO2, it is incomparable to the trace gas amount on Earth.
AGW follows from the fact humans are elevating CO2 levels in the atmosphere, the radiative properties of CO2 and the greenhouse effect. In the idea of AGW was tentatively suggested over 100 years ago by one of the discoverers of the greenhouse effect upon realizing that man's emission of greenhouse gases could be significant.
No it doesn't follow. If you say it follows then you show me how that conclusion came about and how you verified it. We aren't talking about logical consequence here, we're talking about a hypothesis that you are proposing and you are supposed to present evidence.
Now you are talking about how much warming from AGW rather than the existence of AGW itself. If the hypothesis is 3C warming for a doubling of CO2 then the test is obvious. We double CO2 levels and see how much temperature changes, keeping an eye on natural variation in order to control for that. Just because we can't do that test immediately doesn't mean there isn't a test.
OK, you double CO2 levels and then get back to me with your results. I could build a time machine if I could rotate infinitely fast around infinitely long rotating cylinders in space. There's a test for time travel, therefore time travel is real!!!
There are also other less direct ways to test the idea. Test results might only be suggestive rather than conclusive
You know where I've heard this kind of phrase before? Homeopathy.
but you are barking up the wrong tree if you think this isn't science. Science doesn't mean things are either 0% or 100% certain.
But hypotheses should be 100% testable.
The weight evidence suggests about 1C to 5C global warming per doubling of CO2. So given the lag times and CO2 emitted to date, I expect the Earth would be cooler today without the CO2 increases, about half the warming of the last 100 years.
No it doesn't. The weight of extrapolated modelling may suggest this. There is not much evidence to suggest this.And yet global temps are basically flat. The 1930s were the second hottest decade by some measure of the last century. What happened to CO2 in the 1940s~1980s?
"Observing the gas dynamics on Venus and extrapolating them for Earth is NOT a scientific test."
I didn't extrapolate anything on Venus to Earth, let alone claim it was a test.
My point is that the greenhouse effect exists and we can see it exists on both Venus and Earth. Venus just happens to be a super-obvious example of it. Do you dispute the greenhouse effect exists on Venus or just that it exists on Earth?
"There are completely different gases in Venus' atmosphere. It's proximity to the Sun is different. etc etc.
Venus' atmosphere is 95% CO2, it is incomparable to the trace gas amount on Earth."
Venus actually absorbs less sunlight than Earth. Yet it's far warmer than Earth. It's even warmer than Mercury which is closer to the Sun and absorbs even more sunlight than Venus. Why do you think that is? It is because of the 95% CO2 (and other greenhouse gases) that make up Venus's greenhouse effect.
Similar story for the Earth. The Earth's surface is far warmer than the sunlight Earth absorbs alone could maintain. Earth absorbs about 240wm-2 sunlight. A 240wm-2 blackbody would have an average temperature of no more than -18C. Yet Earth's average temperature is about +15C. The difference is because of the greenhouse effect.
"No it doesn't follow. If you say it follows then you show me how that conclusion came about and how you verified it."
See http://www.aip.org/history/climate/co2.htm
"OK, you double CO2 levels and then get back to me with your results. I could build a time machine if I could rotate infinitely fast around infinitely long rotating cylinders in space. There's a test for time travel, therefore time travel is real!!!"
It matters a big deal what your hypothesis is based on. If you pulled it out of thin air then it's pretty much worthless without testing. But if it follows from something we have confidence in, such as general relativity, then some of that confidence transfers to the hypothesis. Especially if it follows from general relativity such that general relativity would be falsified if it wasn't true.
AGW is a result calculated from empirical observations and laws of physics we have confidence in. if AGW is wrong then a lot of empirical observations and laws of physics would be thrown into doubt. That's why people have confidence that AGW is right.
Similar way we have confidence that man evolved from ape-like ancestors. It's based on multiple lines of empirical evidence. We can't reproduce that evolution in a controlled lab to test it, but we can still be confident in the theory because the evidence points that way.
"But hypotheses should be 100% testable."
Yes, but that doesn't mean that until they are tested we can have no confidence in them. Positive empirical evidence does count for something.
"No it doesn't. The weight of extrapolated modelling may suggest this."
Climate models are not based on extrapolating past trends. Temperature data does not get fed into climate models as an input.
Our understanding of how the physics of climate work is coded into the model and then it is run to show what emerges. The output of climate models is the emergent behavior of subscale climate systems as we understand them.
All models, simple and complex exhibit AGW. Even napkin models of the climate do. It's so blatantly obvious that CO2 being a greenhouse gas and increasing CO2 will cause warming that it's simply fact. You can't avoid that answer if you plug the figures into physics equations.
"There is not much evidence to suggest this.And yet global temps are basically flat."
Not so. See the red line, it's tracked a similar upward path for the last 40 years:
http://data.giss.nasa.gov/gistemp/graphs_v3/Fig.A2.gif
"The 1930s were the second hottest decade by some measure of the last century."
Not so, they were much cooler than recent decades:
http://data.giss.nasa.gov/gistemp/graphs_v3/Fig.A2.gif
"What happened to CO2 in the 1940s~1980s?"
Given CO2 isn't the only factor influencing temperature, it's quite a good fit. You might have more concern for the idea the Sun can explain it.
http://ourchangingclimate.files.wordpress.com/2010/04/720px-temp-sunspot-co22.png
Dunno why you are getting the down votes. The problem with climate "science" is, as you say, its lack of a record of prediction (or retrodiction).The system it proports to understand is hideously complex, so the models are massively under-contrained and it always will be. You are spoiled for choice in proposing mechanisms for whatever effects you see in the data. This is quite explicit in the practicioners' Detect and Atribute methodology, which is clearly distinct from bottom-up inderstandings where all of the sub-mechanisms are well understood quantatively with fewer free parameters than data. and the system behaviour can be uniquely preditced from these understandings.
"Natural" is, within the context of science, usually applied to processes that do not involve humans. The reason being that we are (at least supposedly) able to behave rationally and not be completely driven by instinctive behaviours.
So in the case of AGW we can *choose* to carry on as usual, then have some significant issues with water and food scarcity, or we can *choose* to modify our behaviour to prevent or alleviate negative future events.
We know that this freight train is bearing down on us (even the "deniers" / "sceptics" have given up disputing the data; they're just arguing that it is "natural" so will be fine -- a faith-based approach, apparently) so the only question is what we will choose to do. So far, we're assuming that it will just stop by itself, or that being hit by it will be less of an inconvenience than attempting to prevent that occurrence.
""Natural" is, within the context of science, usually applied to processes that do not involve humans. The reason being that we are (at least supposedly) able to behave rationally and not be completely driven by instinctive behaviours."
Yes and it is commonly accepted and people are used to think in terms of "us" v "nature". But my point was that I question this approach. In fact I find it a bit ridiculous how everything including fish, finches and bonobos is considered to be part of the mother nature but, somehow suddenly, we are not. Why the hell?
"we can *choose* to modify our behaviour to prevent or alleviate negative future events."
Or we can *choose* to upgrade our technology to avoid changing our behaviour while still preventing or alleviating negative future events. So far, humans tended to choose the latter in most cases. I don't see why the choice should be different with the climate change, if it does happen.
One irony of "global warming" is the theory that climate change due to burning/clearance of forests etc has staved off the return to an ice ace.
So without man's "influence" on the climate, we'd be knee deep in snow (and polar bears) all year round. Keep burning those fossil fuels or learn to build an igloo...
"One irony of "global warming" is the theory that climate change due to burning/clearance of forests etc has staved off the return to an ice ace."
That's not actually irony, but hey.
Anyway, there is certainly the possibility that the medieval "little ice age" was due to population drop and reforestation in the wake of a quarter of humanity being wiped out by plague.
Well that was a mistake to begin with.
Followed by a another mistake with the development of high gluten wheat around the turn of the 20th Century.
Yes the Romans were aware of Coeliac disease.
Just look at the incidence in gluten intolerance/coeliac disease (1 in 100 on average, higher in nordic populations.
Now if you don't mind im off back to my meat/veg and no carb lunch.
The icon is cider not beer, can't do barley.
Yes; even coming down from the trees was a bad idea. Personally, I think we should have never left the oceans.
You say that now. But wait until you look like a tasty guppy to some massive ocean predator.
Climate change doesn't matter so much when you won't be around to see it, which is the source of the apathy amongst the general population (despite all the current climate effects present today due to "climate change", allegedly). The chief problem for those wanting more climate research is the appearance that everything in the research process is geared for the sole purpose to obtain more grant money. When the science comes to the same conclusions without the huge public and private sector funds at play, the world will sit up and take notice.
People forget the firestick hunters, they decimated forests, in fact The Early visitors to Australia called them the smoky lands, the firestick hunting over 10's of thousands of years changed the flora. They never discovered pottery, so no kilns so no metalwork., no agriculture or settlements.
However in the rest of the world
Kilns, slash and burn agriculture replaced the firestick hunters, the kilns grew, firewood was not enough, the charcoal burners became a major trade, there were many coal mines as well as metals. The furnaces and kilns were inefficient and the forests were being destroyed. The Black Plague saved Europe's forests.
Insulation was non existant and even though not ibdustrialised and a lower population man changed the face of the Earth and produced a hell of a lot of CO2 and Soot
I think I'd be hard pressed to suggest that there was an economic decline in Roman North Africa, or in Gaul, or Hispania at this time. The large-scale migrations from the east hadn't begun. In Britannia the late 3rd century was the peak of the province's economic power under the Romans. I was reading an article yesterday on iron production which indicated that the amount of iron produced in Britain under the Romans wasn't equalled until the Industrial Revolution.
How are they measuring decline in the Roman Empire? The latifundia which produced so much of the agricultural surplus across the Empire don't show an declines in productivity until later than 200AD.
I don't know anything about the Han dynasty though, so can't comment on that.
"Sapart feels the results mean climate scientists need to rethink what is a "normal" state for Earth's climate."
Uh, that would be hot, humid, and full of CO2, just as it was for the great majority of Earth's history, for billions of years before the current short time since photosynthesis sidetracked a lot of that CO2 out of the atmosphere and it got buried underground, resulting in an anomalous cool, dry, and less stormy epoch.
Of course, this deviation from the "normal" state is only metastable, and the potential energy stored in that fossil carbon means that it will eventually be returned to the atmospheric CO2 pool again and the climate will return to its normal hot, humid, and stormy state, like it was before there was any life on land. Wonder how/when that will happen?
My knowledge of the Roman empire doesn't in anyway make me an expert, but with my rough layman knowledge, how does this spike correspond with the gradual decline of the Roman Empire? A spike would suggest a sudden and rapid change, but did the population suffer a similarly massive fall? The Roman Empire devolved into smaller empires and nations, Byzantine for example, but the population of europe and the world stayed roughly the same. Regardless of who was in charge Joeus Bloggus would still need to cook his food, clear woodland for his farm.
Hear is the news, A BLOODY BIG COMET/METEOR STRUCK PERU JUST OFF THE COAST IN THE LATE 400s disturbing the locked in methane on the seabed as well as rest of the stuff that comes with an event of this size. IT WAS IN ALL THE PAPERS OF THE TIME.
And only now are we getting back to the conditions we had before the event..
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