While global warming itself MAY be beyond question, the REASONS for it are yet unproven. It has happened "every so often in geological history" -- long before there were power plants, automobiles, that nasty "carbon based fuel", etc. There isn't historical precedent for the rate of warming that has happened over the last 50 years, and that warming agrees in timing, rate, and magnitude with the increase of anthropogenic emissions. The fact that we are responsible for a substantial amount of the warming is no longer in question; what is unproven now is what the climate will do in the future, and what the consequences will be.
Let's say for sake of argument that they are correct: Man's use of fossil fuels is destroying the environment, and we have passed the "tipping point." What, then, are they proposing as the solution? There have been many proposed solutions, from reducing emissions and altering land use patterns to injecting aerosols into the atmosphere. Whether any of those solutions is any good is still the subject of much debate.
h2o vapor is the predominate ghg. Clouds are very serious in their immediate effects on temperatures and hence on energy absorption available to heat sinks. Cloud formation is where the solar sunspot cycle tends to have its most serious impact.
Variations in cloud cover due to solar variations still do not compete with anthropogenic CO2 as far as climate is concerned.
The religious global warming crowd I referred to would have stopped those danish scientists from publishing were they to have had the power
Yes, well, it's nice of you to support your argument with imaginary outcomes about what certain people would or wouldn't do, but it's hardly convincing.
and the whole point of the thread is that weather girl's public pronouncements to punish people for doing such research.
If you had bothered to read what she wrote, you would have learned that what she actually said was that certified broadcast meterologists ought to be well-informed about climate change if they are to speak about it on the TV news. She said nothing whatsoever about climate researchers.
I find it impossible to believe your statement on measuring other factors and acccounting for them very well.
I am sure your disbelief is an informed one.
It's been only a few months that bovine flatulence made the news.
Bovine flatulence has been known about for a long time (and in fact most of the bovine methane comes from belching, not flatulence). There are revised estimates of it, but they don't significantly change anything; livestock overall accounts for less than 20% of the global warming, compared to >50% of warming from anthropogenic CO2.
Also, while the sources I mentioned are known, there is the possibility of sources not known and hence unaccounted for which by definition cannot be discussed in any specifics.
We don't need to account for all the sources in order to know how much greenhouse gas is in the atmosphere; that can be measured. We can also account for our contribution. The remainder is natural, whether we have identified the source or not. And, in fact, the known sources add up pretty closely to the measured total.
Co2 is only a moderate ghg of a very small fraction of the whole. It's far less effective than methane as I recall. That's why the bovines are so effective.
It's something like 20 times less effective than methane, but there is also more anthropogenic CO2 than there is bovine methane, and it's the total amount that ends up winning out when you crunch the numbers.
While these might be manmade or caused by man, these are not due to man's technology which is the main excuse for man not being a part of nature.
I'm not arguing about "man being part of nature" (whatever that means), I'm talking about how much global warming humans are responsible for. It's not like we have no choice, either; we could turn to food sources that emit less methane.
there has to be a great deal of technological pollution created per person in order to have enough for similar effects
There is a great deal of technological pollution and over the last 50+ years it has outweighed all the natural sources put together.
Of course, fossil fuels contain carbon that was once part of the atmosphere in the form of co2 so even burning oil and coal is merely returning to the atmosphere that which was already present at one time.
Again you're setting up some irrelevant comparison between "man" and "nature". It doesn't matter whether the CO2 was once in the atmosphere or not. It doesn't matter whether the Earth was once hotter or colder or not. What matters is that our activities are contributing to climate change in ways that may not be overall desirable to us.
As for the data I mentioned, our direct observations are limited to long ago
For example, real time surface temperature sensing is biased to the northern hemisphere, and excludes the polar regions. This includes man's written record. Historical analogues, on the other hand, especially ones going back farther than tree rings, is incredibly biased towards polar regions (ice cores being a large constituent of the data). Since the global mean temperature is an aggregate global data value, and ice core samples contain a lot of localized data and not as much global data (which are primarily, from what I understand, gas isotopes from biogenic activity),
saying you know what the temperature was, with any certainty, 10,000 or 100,000 years ago is scientific fraud. That is, of course, nonsense. A bunch of handwaving about "whoa, we don't know everything perfectly, therefore we don't know anything" is not a scientific argument. The temperatures near the poles tell us something about the temperature everywhere else. We have ice cores from both poles as well as from some non-polar regions. We also have independent sources from all over the Earth, such as tree rings, boreholes, isotope ratios in preserved sediments and in the oceans, we have fossils to indicate the amount and nature of vegetation present at different locales, and so on.
We can in fact construct temperature reconstructions back tens of millions of years and more. They're not hugely accurate, but they're not frauds either — they can tell us that, say, the Cretaceous period was very tropical compared to today, and they can pick out ice ages. Reconstructions of more recent temperatures can do much better.
Regarding skeptics of global warming, not all of us are "holocaust deniers". No, but you apparently are a science denier. Uncertain projections into the future are one thing, but it's simple ignorance to claim that we don't know anything reliable about the past climate.
It is that the debate has stopped and anyone not towing the line is in for problems. I have made this statment in the past and it is even more evident today were some are trying to decertify anyone who doesn't tow the line. Wow, you really haven't read the comments to this story at all. Please, name one person who is trying to "decertify anyone who doesn't toe the line". (Hint: Heidi Cullen isn't.)
If we weren't here how many forests would have burnt releasing particulate matter? How many less? There are just too many variables involved. We can estimate that. Unless you are postulating a ridiculously different rate of forest fires, it just doesn't make much difference.
Current meteorological science can't even tell me with much certainty that it is going to rain next month how am I expected to believe that they are 100% certain of anything. Uh, meteorological science can tell you whether it's going to rain next month: except in the desert, the answer is generally "yes". If you mean tell you if it's going to rain on some particular day a month in the future, they can't tell you that at all; the useful predictive horizon for weather doesn't extend past a week or so. But the useful predictive horizon for global climate does; it's easier to predict global averages than individual weather events.
And no, climatologists aren't 100% certain of everything, but they are certain that the Earth is getting warmer, and they can say with great confidence that human emissions are responsible for a large amount of the recent warming. Where things get much more uncertain is in predicting what will happen in the future. They can say that there will be continued warming, but not exactly how much (especially since it depends on what, if anything, we choose to do about it).
BTW, I live in southern Texas where it seems that the climate does cycle some with the 11 year sunspot cycle. Solar variations do have impact on climate, but they are not responsible for the majority of the climate change being discussed in the context of global warming.
There was an interesting tv show presentation by some Danish scientists who discovered the link between sunspot cycles and cloud formation (cosmic ray flux) and their attempts to get the information out past the global warming religious crowd You will note that, snide remarks about the "global warming religious crowd" aside, these scientists got their work published and it is cited by mainstream climatologists.
I suspect man's contributions to global warming might forestall the coming ice age - by only a few days rather than by a few years. I am sure that your suspicions are well informed.
By the way, when is this ice age coming again, and what does that have to do with the impact of global warming over the next century?
That is assuming that co2 actually does have a measureable effect and that its increase is in fact due to man rather than to more important factors - things like insects, plant dormancy, termites, bacteria, plankton activity, volcanic activity, forest fires and possibly other factors. Each of those individually can exceed man's technilogical contributions. The contributions from each of those factors are measured, particularly well for the major contributors, and they do not outweigh man's emissions.
Heck, we just learned cows have a greater effect producing methane than man's transportation system. That may be, but the warming effects of man's CO2 emissions are greater still. (And as another poster noted, man is also the reason why there are so many cows around.) You make it sound like we don't know anything about the true sources of GHGs, which is not the case. And even if we didn't know where any of the non-anthropogenic GHGs came from, we do know how much of the CO2 is ours (CO2 from burning fossil fuels has a unique isotopic signature), and that alone (in combination of our knowledge of how many other GHGs are in the atmosophere, regardless of source) is enough to tell us that humans are a major contributor to greenhouse warming.
This controversy isn't the first time that some have fudged data when it couldn't be made to agree with their conclusions What data are you referring to?
Every time I see a social science study posted here on Slashdot, everyone comes out of the woodwork with "correlation doesn't equal causation", or "this study is obviously [true|false] because of so-and-so obvious effect", etc. Please give the authors some credit. They did consider various biasing effects, such as Nobel nominee age, the fact that nominees may die before being awarded the prize, they examined alternative causal factors such as the possibility that the winners' longevity was due to their increased income, and so on. Sure, correlation isn't causation and this study doesn't prove anything, but it's not as shoddy as the Slashdot armchair experts seem to think. Read the paper, or a brief summary by a statistician unrelated to the study.
The authors performed a survival analysis (see here) to correct for nominees who might have won but died first, as well as other methods to reduce possible biases.
I'm saying that the first link decides what is science, I'm not seeing an analysis of all relevant published papers and the ratio between a global cooling trend and a warming one. Look at the second link. William Connolley has gone through which has gone through as many references from the 1970s as he could find, restricting himself to references that appeared in the scientific literature, as opposed to the media. The first link is merely a high-level overview.
Incidentally, the issue is not "how many people predicted cooling vs. warming", but "how many predicted that cooling would take place over the next century, vs. how many predicted it would take place over the next century if then-unquantifiable anthropogenic contributions turned out not to contribute".
That implies that you are prescient or have access to models or data that are vastly more accurate than what we have today. I don't have to be "prescient" to know what the scientific mainstream was saying 40 years ago. Sheesh.
Did you also manage to miss my first sentence somehow? Yes, I read your first sentence, you're apparently trying to construct an ill-conceived analogy. But please explain how today's dissenters are similar to yesterday's mainstream.
The fact that string theory makes no predictions which are testable today which are different from the standard model is often raised as an objection to string theory That's not really a fact. There are plenty of string theory models which make testable predictions; some of them have already been tested (and falsified, much like the majority of field theory models ever proposed). String theory just doesn't make any unambiguous testable predictions; i.e., there are not features testable today which all string models possess which all field theories lack.
That being said, your main point remains accurate; even without testable predictions the two remain on the same experimental footing and have to be judged on other grounds (simplicity, consistency with other theories such as gravity, etc.)
And what do crashed WWII planes have to do with the reliability of ice core temperature reconstructions? (Note, by the way, that unlike those planes, ice core samples are not taken from active glaciers.)
"Suppose the average temperature of the Earth in 1850 was 70 degrees."
How do we know what the average temperature of the Earth was in 1850, considering we only recently had the ability to measure the global mean?
You missed the entire point of my argument. The average temperature of the Earth in 1850 was not 70 degrees. It was a completely made-up number used to demonstrate why anthropogenic CO2 is a significant contributor to global warming.
But now that you mention it, we have, as you say, tree rings, ice core samples, temperature measurements, and other methods.
In other words, it's a guess, built off of a computer model. Just because the estimates have error bars doesn't mean they're useless. We can quantify our uncertainty in the reconstructions.
Which is then used to provide evidence for another computer model. Not really. Global climate models are calibrated off of observational data, not reconstructions. But even if they were, that just means there's more uncertainty in the model output, and that uncertainty can still be quantified. If the errors are too large, the models are not useful. The errors are not so large that the model predictions are useless.
Saying you know the global mean temperature 10,000 years ago because the trace argon isotope percentage was x is just so much b.s. That's incorrect. Isotope ratios obey known physical processes. Their accuracy can be calibrated and they can be checked against the results of independent methods. You can't reconstruct the temperature perfectly, but you can reconstruct it within a known amount of error, and that error turns out to be small enough that climate trends can be reliably reconstructed.
This is the problem with the global warming crowd. They present their hypotheses, theories, and their models as FACT. This is the problem with the denialist crowd. They refuse to admit that evidence is evidence.
There is no "science" showing that we cause the change because we have no controls to prove it. Simple as that. We don't need a "control planet" in order to evaluate climate theories. You have an absurd 8th-grade view of what science is. (I also note that you went from claiming that Mars is our "control" to claiming there are no controls.)
Sorry, that is the way it works and you are just buying into it, much like a Earth Flatter or a Intellegent Design believer. What's next, locking up on house arrest because I don't buy your brand of soap? I wish I could say it was edifying to witness your departure from scientific discourse in this thread.
One of the most important aspects of a scientfic theory is that it is repeatable. No. This "definition" excludes pretty much every observational science, including astronomy, geology, paleontology, etc. What matters is that results are reproducible, not that you can performed repeatable experiments. Repeatable experiments are nice, but they're not necessary to formulate theories. Repeatable observations also work (and even then, plenty of theories are formulated on unique observations; witness all the work in supernova theory that went on as a result of the 12 or so neutrinos observed from SN1987A).
Actually most honest scientists don't talk about theories, they talk about models. Models are specific realizations of theories. There are plenty of climate theories, and when you plug in specific assumptions about which factors you're going to include and what the parameters are, you get a model which can be used to calculate.
If you don't see that Mars and Earth climates are far more similar than different, I just don't know what to tell you. You're insane. They have nothing in common other than the Sun. Note by "climate" we're talking primarily about their global temperatures.
So there are clearly processes that happen regardless of our input that have wrought bigger changes than what we have going on. That's irrelevant to the issue of whether we are causing a big change and what the consequences are.
Once upon the time, the Earth was molten. We get it. The Earth was different in the past. The debate is over what's happening to us now, the extent to which we're responsible for it, and what we can do about it.
If you just eliminated human effects, mostly likely you will see little effect on the warming trend. It might change a little, but not much. Your opinion is in disagreement with the actual science.
Nobody is talking about stripping scientists of their credentials. They're at best talking about stripping TV weatherpeople untrained in climatology of their meteorological credentials, if they spout off about something they're not certified in (namely, climate science). And if you read the original blog, it was really worded as more of a suggestion that anybody with professional meteorology credentials ought to inform themselves of the scientific debate.
True enough. But all the informed, meteroligist we have heard from Is contributing it to natural forces. I don't know if they are saying anthropogenic disturbances are influencing those natural forces or not. But the one,
As an aside, might I ask that you try to be more literate? I can barely tell what you're saying here. Are you saying that meteorologists are attributing something in the weather (or climate?) to "natural forces"? If so, what is that "something" that is being attributed to natural forces?
We don't even know what causes to a repeatable degree (El Nino). We cannot even predict it's behavior outside expecting a large interaction or a smaller one. The atlantic currents are pretty much predicable and we do know much more about it. But something we don't know is how the El Nino effects are powerful enough to effect the north atlantic oscillation wich effect the atlantic currents as well as weather pattern across north america as well as northern Europe.
That's correct. What is your point?
We do know that El Nino can effect it but the NAO is another one of many El Nino like effects that we don't understand in ways to make complete blanket statments like humans are destroying the world thru the weather.
We're not talking about "humans are destroying the world through weather", we are talking about the extent to which humans are responsible for climate change, the extent to which the climate will change in the future, and what are the consequences.
And you asumptions are wrong. The site I linked to shows that the amounts of human greenhouse gasses are a fraction of what is the true effect. I think your statment about without the other greenhouse gasses the earth would be cooler by 10 degees. But the fact show that man made green house gasses acount for less then 1 percent of total gasses contributing to the effect.
That's true and STILL IRRELEVANT. You're missing the point.
Yet the less then one percent is supposed to move the climate to more then half the effect of all the other greenhouse gasses combined.
No. More than half of the change in temperature over the last century is due to anthropogenic GHGs. That is completely different from the change in temperature produced by the Earth's total greenhouse effect.
Look, I'm going to make up some fake numbers here to produce an example to more clearly illustrate the point.
Suppose the average temperature of the Earth in 1850 was 70 degrees. Without the 99% of the natural greenhouse gases, including natural water vapor and CO2, the temperature of Earth in 1850 would be more like 0 degrees, and the planet would be a frozen iceball. The 99% of greenhouse gases that are natural are responsible for raising the Earth's temperature from 0 degrees to its "normal" 1850 temperature of 70 degrees. Got that?
Now, say the extra 1% of GHGs that are man-made in the year 2000 raise the Earth's temperature from 70 to 71 degrees. That is the effect called "global warming".
Total warming via 99% natural GHGs: 70 degrees Total warming via 99% natural GHGs + 1% manmade GHGs: 71 degrees Global warming: 1 degree
Suppose the actual temperature in 2000 is 72 degrees, for 2 degrees of global warming. Then we say that the 1% manmade GHGs were responsible for half of the global warming, and the other half is due to non-greenhouse climate effects.
If you ignore water vapor, then it makes more sence.
Nobody is ignoring water vapor.
I don't know if you looked at that page I linked to in the other post or not, but the conclusion is that human GHG contribution is as negligable too.
It makes the same mistake you do. The human GHG contribution is small compared to the natural GHG contribution (in my made-up example, 1 degree vs. 70 degrees), but nevertheless, the human GHG contribution is still at least half of the global warming (meaning t
The whole point, of course, is that we DON'T know that X amount of greenhouse gas emissions produces Y amount of warming. Yes, we do; it's simple adsorption physics. The uncertainty is about the other factors that also contribute to the climate.
The fact, however, is that surface temps follow solar output with a very stable time constant. The annual global surface temperatures are actually not that well correlated with fluctuations in solar output. For a study of the climatic effects of solar variations and an analysis of the extent to which ignoring solar variations influences climate predictions, see Stott et al., J. Clim. 16, 4079 (2003). The upshot: solar variations can account for about 15-30% of the observed warming.
They just don't get reported because it runs counter to global warming religious doctrine. Piffle. They don't get reported because the media can't turn it into a scare story. Climatologists themselves know that you have to look beyond record highs or lows to tell what the climate is doing.
Evidence that the earth was much warmer during periods long before human industrialization is routinely ignored here with each new report that this is the "warmest year _EVER_". The fact that the Earth was once much warmer is no secret. (Who hasn't seen depictions of the steamy jungles with the dinosaurs?) It's also not terribly relevant to what the climate is doing now.
People love to say that _EVERYONE_ knows that global warming is true, but here we have a proposal to silence heretics. There isn't a proposal to "silence heretics", merely a suggestion that TV weatherpeople who receive professional certification ought not be voicing uneducated opinions on the daily news. The media reporting scientific statements (pro or con) from climatologists is one thing; meteorologists masquerading as climatologists is another. The lay public thinks of TV weatherpeople as climate experts even though they're not, and in light of that, said TV weatherpeople should stick to what they know.
The point of the article was about removing the certification of meteorologists who continue to hold that global warming is not man made (or at least predominately man made). How would that not be considered silencing the minority? Well, because (1) nobody was advocating removing the certification of meteorologists, what Cullen actually said was that broadcast meteorologists shouldn't be certified if they're not educated about the science of climate change, and (2) even if TV meteorologists weren't allowed to talk about global warming, that has nothing to do with what scientists can or can't say about global warming in the scientific literature, or otherwise stifling the debate among scientists.
Yeah, I've seen the Minnis contrail paper, but followup work hasn't really substantiated those predictions. At this point, I think we have to say "we don't know" about the future climatic effects of contrails.
How do you know, or determine that? References? For the Earth, see for instance Stott et. al, J. Climate 16, 4079 (2003). Solar variations contribute to some warming, but not nearly as much as greenhouse gases. For Mars, see here, which notes that Mars's south pole is warming (no evidence for the north pole), at the same time that the Sun's output decreased.
mars goes back to drawings made with telescopes because they can see and chart the whole icecap at once First, what is your citation to evidence that Mars has been warming continuously for the same period of time that Earth has? And second, 17th century telescopic observations of polar cap areas are far more unreliable than the proxy data we use for terrestrial reconstructions.
Earth and mars are very similiar on planetary scale. Both are rocky worlds inside the gas giant belt, with thin atmospheres and tri-state water conditions. Your "differences" are on the biological scale and while they matter to some life forms such as humans, it is pretty clear life could exist on Mars in its current conditions. Who cares? The point is that the climates of Earth and Mars are vastly different. We're not in an argument about Martian life here.
Mercury is different, no atomosphere. Venus is different, no tri state water and a thick atmosphere. Titan is different as it does not have an atmosphere and is in the gas giant band where Solar input to the planetary energy cycle is almost nil. Again, so what? What does that have to do with global warming on Earth?
Are humans impacting global tempatures. Sure. Are they responsable for all of it? No. Of course we're not responsible for all of it. But we are responsible for most of the recent warming.
Earth has been at higher and lower tempatures, jurassic global jungles and possiblely a total ice cap WITHOUT the existance of humans. Like I said, duh. This is irrelevant to evidence supporting anthropogenic global warming.
So where is the balance? 90/10? 70/30? 50/50? That is the science we don't have yet and should be discussed. Balance of what? If you're talking anthropogenic global warming / natural global warming, then it's somewhere between 50/50 and 80/20, and we have enough science to know it's not something like 30/70 or 10/90.
Slashdot Mirror
h2o vapor is the predominate ghg. Clouds are very serious in their immediate effects on temperatures and hence on energy absorption available to heat sinks. Cloud formation is where the solar sunspot cycle tends to have its most serious impact.
Variations in cloud cover due to solar variations still do not compete with anthropogenic CO2 as far as climate is concerned.
The religious global warming crowd I referred to would have stopped those danish scientists from publishing were they to have had the power
Yes, well, it's nice of you to support your argument with imaginary outcomes about what certain people would or wouldn't do, but it's hardly convincing.
and the whole point of the thread is that weather girl's public pronouncements to punish people for doing such research.
If you had bothered to read what she wrote, you would have learned that what she actually said was that certified broadcast meterologists ought to be well-informed about climate change if they are to speak about it on the TV news. She said nothing whatsoever about climate researchers.
I find it impossible to believe your statement on measuring other factors and acccounting for them very well.
I am sure your disbelief is an informed one.
It's been only a few months that bovine flatulence made the news.
Bovine flatulence has been known about for a long time (and in fact most of the bovine methane comes from belching, not flatulence). There are revised estimates of it, but they don't significantly change anything; livestock overall accounts for less than 20% of the global warming, compared to >50% of warming from anthropogenic CO2.
Also, while the sources I mentioned are known, there is the possibility of sources not known and hence unaccounted for which by definition cannot be discussed in any specifics.
We don't need to account for all the sources in order to know how much greenhouse gas is in the atmosphere; that can be measured. We can also account for our contribution. The remainder is natural, whether we have identified the source or not. And, in fact, the known sources add up pretty closely to the measured total.
Co2 is only a moderate ghg of a very small fraction of the whole. It's far less effective than methane as I recall. That's why the bovines are so effective.
It's something like 20 times less effective than methane, but there is also more anthropogenic CO2 than there is bovine methane, and it's the total amount that ends up winning out when you crunch the numbers.
While these might be manmade or caused by man, these are not due to man's technology which is the main excuse for man not being a part of nature.
I'm not arguing about "man being part of nature" (whatever that means), I'm talking about how much global warming humans are responsible for. It's not like we have no choice, either; we could turn to food sources that emit less methane.
there has to be a great deal of technological pollution created per person in order to have enough for similar effects
There is a great deal of technological pollution and over the last 50+ years it has outweighed all the natural sources put together.
Of course, fossil fuels contain carbon that was once part of the atmosphere in the form of co2 so even burning oil and coal is merely returning to the atmosphere that which was already present at one time.
Again you're setting up some irrelevant comparison between "man" and "nature". It doesn't matter whether the CO2 was once in the atmosphere or not. It doesn't matter whether the Earth was once hotter or colder or not. What matters is that our activities are contributing to climate change in ways that may not be overall desirable to us.
As for the data I mentioned, our direct observations are limited to long ago
When you would like to
We can in fact construct temperature reconstructions back tens of millions of years and more. They're not hugely accurate, but they're not frauds either — they can tell us that, say, the Cretaceous period was very tropical compared to today, and they can pick out ice ages. Reconstructions of more recent temperatures can do much better. Regarding skeptics of global warming, not all of us are "holocaust deniers". No, but you apparently are a science denier. Uncertain projections into the future are one thing, but it's simple ignorance to claim that we don't know anything reliable about the past climate.
And no, climatologists aren't 100% certain of everything, but they are certain that the Earth is getting warmer, and they can say with great confidence that human emissions are responsible for a large amount of the recent warming. Where things get much more uncertain is in predicting what will happen in the future. They can say that there will be continued warming, but not exactly how much (especially since it depends on what, if anything, we choose to do about it).
By the way, when is this ice age coming again, and what does that have to do with the impact of global warming over the next century? That is assuming that co2 actually does have a measureable effect and that its increase is in fact due to man rather than to more important factors - things like insects, plant dormancy, termites, bacteria, plankton activity, volcanic activity, forest fires and possibly other factors. Each of those individually can exceed man's technilogical contributions. The contributions from each of those factors are measured, particularly well for the major contributors, and they do not outweigh man's emissions. Heck, we just learned cows have a greater effect producing methane than man's transportation system. That may be, but the warming effects of man's CO2 emissions are greater still. (And as another poster noted, man is also the reason why there are so many cows around.) You make it sound like we don't know anything about the true sources of GHGs, which is not the case. And even if we didn't know where any of the non-anthropogenic GHGs came from, we do know how much of the CO2 is ours (CO2 from burning fossil fuels has a unique isotopic signature), and that alone (in combination of our knowledge of how many other GHGs are in the atmosophere, regardless of source) is enough to tell us that humans are a major contributor to greenhouse warming. This controversy isn't the first time that some have fudged data when it couldn't be made to agree with their conclusions What data are you referring to?
Every time I see a social science study posted here on Slashdot, everyone comes out of the woodwork with "correlation doesn't equal causation", or "this study is obviously [true|false] because of so-and-so obvious effect", etc. Please give the authors some credit. They did consider various biasing effects, such as Nobel nominee age, the fact that nominees may die before being awarded the prize, they examined alternative causal factors such as the possibility that the winners' longevity was due to their increased income, and so on. Sure, correlation isn't causation and this study doesn't prove anything, but it's not as shoddy as the Slashdot armchair experts seem to think. Read the paper, or a brief summary by a statistician unrelated to the study.
The authors performed a survival analysis (see here) to correct for nominees who might have won but died first, as well as other methods to reduce possible biases.
For what it's worth, this story hasn't talked about the credentials of scientists at all, but rather TV news weather anchors.
Incidentally, the issue is not "how many people predicted cooling vs. warming", but "how many predicted that cooling would take place over the next century, vs. how many predicted it would take place over the next century if then-unquantifiable anthropogenic contributions turned out not to contribute".
I wasn't linking to yesterday's dissenters, I was linking to yesterday's mainstream.
That being said, your main point remains accurate; even without testable predictions the two remain on the same experimental footing and have to be judged on other grounds (simplicity, consistency with other theories such as gravity, etc.)
And what do crashed WWII planes have to do with the reliability of ice core temperature reconstructions? (Note, by the way, that unlike those planes, ice core samples are not taken from active glaciers.)
How do we know what the average temperature of the Earth was in 1850, considering we only recently had the ability to measure the global mean?
You missed the entire point of my argument. The average temperature of the Earth in 1850 was not 70 degrees. It was a completely made-up number used to demonstrate why anthropogenic CO2 is a significant contributor to global warming.
But now that you mention it, we have, as you say, tree rings, ice core samples, temperature measurements, and other methods. In other words, it's a guess, built off of a computer model. Just because the estimates have error bars doesn't mean they're useless. We can quantify our uncertainty in the reconstructions. Which is then used to provide evidence for another computer model. Not really. Global climate models are calibrated off of observational data, not reconstructions. But even if they were, that just means there's more uncertainty in the model output, and that uncertainty can still be quantified. If the errors are too large, the models are not useful. The errors are not so large that the model predictions are useless. Saying you know the global mean temperature 10,000 years ago because the trace argon isotope percentage was x is just so much b.s. That's incorrect. Isotope ratios obey known physical processes. Their accuracy can be calibrated and they can be checked against the results of independent methods. You can't reconstruct the temperature perfectly, but you can reconstruct it within a known amount of error, and that error turns out to be small enough that climate trends can be reliably reconstructed. This is the problem with the global warming crowd. They present their hypotheses, theories, and their models as FACT. This is the problem with the denialist crowd. They refuse to admit that evidence is evidence.
What's next, locking up on house arrest because I don't buy your brand of soap? I wish I could say it was edifying to witness your departure from scientific discourse in this thread.
Once upon the time, the Earth was molten. We get it. The Earth was different in the past. The debate is over what's happening to us now, the extent to which we're responsible for it, and what we can do about it. If you just eliminated human effects, mostly likely you will see little effect on the warming trend. It might change a little, but not much. Your opinion is in disagreement with the actual science.
Nobody is talking about stripping scientists of their credentials. They're at best talking about stripping TV weatherpeople untrained in climatology of their meteorological credentials, if they spout off about something they're not certified in (namely, climate science). And if you read the original blog, it was really worded as more of a suggestion that anybody with professional meteorology credentials ought to inform themselves of the scientific debate.
True enough. But all the informed, meteroligist we have heard from Is contributing it to natural forces. I don't know if they are saying anthropogenic disturbances are influencing those natural forces or not. But the one,
As an aside, might I ask that you try to be more literate? I can barely tell what you're saying here. Are you saying that meteorologists are attributing something in the weather (or climate?) to "natural forces"? If so, what is that "something" that is being attributed to natural forces?
We don't even know what causes to a repeatable degree (El Nino). We cannot even predict it's behavior outside expecting a large interaction or a smaller one. The atlantic currents are pretty much predicable and we do know much more about it. But something we don't know is how the El Nino effects are powerful enough to effect the north atlantic oscillation wich effect the atlantic currents as well as weather pattern across north america as well as northern Europe.
That's correct. What is your point?
We do know that El Nino can effect it but the NAO is another one of many El Nino like effects that we don't understand in ways to make complete blanket statments like humans are destroying the world thru the weather.
We're not talking about "humans are destroying the world through weather", we are talking about the extent to which humans are responsible for climate change, the extent to which the climate will change in the future, and what are the consequences.
And you asumptions are wrong. The site I linked to shows that the amounts of human greenhouse gasses are a fraction of what is the true effect. I think your statment about without the other greenhouse gasses the earth would be cooler by 10 degees. But the fact show that man made green house gasses acount for less then 1 percent of total gasses contributing to the effect.
That's true and STILL IRRELEVANT. You're missing the point.
Yet the less then one percent is supposed to move the climate to more then half the effect of all the other greenhouse gasses combined.
No. More than half of the change in temperature over the last century is due to anthropogenic GHGs. That is completely different from the change in temperature produced by the Earth's total greenhouse effect.
Look, I'm going to make up some fake numbers here to produce an example to more clearly illustrate the point.
Suppose the average temperature of the Earth in 1850 was 70 degrees. Without the 99% of the natural greenhouse gases, including natural water vapor and CO2, the temperature of Earth in 1850 would be more like 0 degrees, and the planet would be a frozen iceball. The 99% of greenhouse gases that are natural are responsible for raising the Earth's temperature from 0 degrees to its "normal" 1850 temperature of 70 degrees. Got that?
Now, say the extra 1% of GHGs that are man-made in the year 2000 raise the Earth's temperature from 70 to 71 degrees. That is the effect called "global warming".
Total warming via 99% natural GHGs: 70 degrees
Total warming via 99% natural GHGs + 1% manmade GHGs: 71 degrees
Global warming: 1 degree
Suppose the actual temperature in 2000 is 72 degrees, for 2 degrees of global warming. Then we say that the 1% manmade GHGs were responsible for half of the global warming, and the other half is due to non-greenhouse climate effects.
If you ignore water vapor, then it makes more sence.
Nobody is ignoring water vapor.
I don't know if you looked at that page I linked to in the other post or not, but the conclusion is that human GHG contribution is as negligable too.
It makes the same mistake you do. The human GHG contribution is small compared to the natural GHG contribution (in my made-up example, 1 degree vs. 70 degrees), but nevertheless, the human GHG contribution is still at least half of the global warming (meaning t
Yeah, I've seen the Minnis contrail paper, but followup work hasn't really substantiated those predictions. At this point, I think we have to say "we don't know" about the future climatic effects of contrails.