I wonder if any of the more scientifically minded people on here could help me, please.

[mrzz]

Thanks a lot for the answers, @Chris Koziarz . I need some time to digest it and probably will come back with more questions. The "counter-argument" point was just that people raise the limited time-scale of modern temperature measures issues as it would somehow invalidate or limit the possible conclusions. Given that you state that indirect measures are reliable, that "counter-argument" is void.

@Horsa , have you considered the idea of asking easy questions?

Coincidentally, when @mrzz posed the question about climate change yesterday, I'd just read that "in 2013, Mongolia had been hit by climate change that badly that 90% of the country was likely to be subjected to desertification.".

That quote is the classical case of the press writing about something they have no idea about. Never doubt how small a journalist's knowledge about a given subject can be.

I had a very little idea about climate change (better now after readind Chris' posts), but it is obvious that "climate change" is a global effect, on a non-immediate time-scale. Mongolia was not "hit by climate change in 2013" like it was a storm or something like that. Mongolia, and all places for that matter, are being constantly hit by climate change. That is the whole point. And the following phrase with the percentage in it makes it all more alarming. It gives the false impression that one day people will wake up in the middle of the desert (it can happen, but not from one day to the other). It is that kind of thing that helps the climate change "deniers" win more followers. (with that I am not saying that we don't need to act about it now).

 

[Horsa]

Thanks a lot for the answers, @Chris Koziarz . I need some time to digest it and probably will come back with more questions. The "counter-argument" point was just that people raise the limited time-scale of modern temperature measures issues as it would somehow invalidate or limit the possible conclusions. Given that you state that indirect measures are reliable, that "counter-argument" is void.

@Horsa , have you considered the idea of asking easy questions?



That quote is the classical case of the press writing about something they have no idea about. Never doubt how small a journalist's knowledge about a given subject can be.

I had a very little idea about climate change (better now after readind Chris' posts), but it is obvious that "climate change" is a global effect, on a non-immediate time-scale. Mongolia was not "hit by climate change in 2013" like it was a storm or something like that. Mongolia, and all places for that matter, are being constantly hit by climate change. That is the whole point. And the following phrase with the percentage in it makes it all more alarming. It gives the false impression that one day people will wake up in the middle of the desert (it can happen, but not from one day to the other). It is that kind of thing that helps the climate change "deniers" win more followers. (with that I am not saying that we don't need to act about it now).

@mrzz If I asked easy questions I wouldn't need to ask the questions in the 1st place. What is hard for 1 person is easy for others & vice versa. You & Chris are extremely intelligent gentlemen. I'm Little Miss Average. Some of the things I wonder about & expect to be hard you'll find easy so I don't always realise I'm asking you difficult questions. I'm very sorry for annoying you both by asking too many questions. I'll try not to ask as many in future. I'd like to thank you both for answering my questions. :0)

That quote is actually from the book "The age of the horse" by Susannah Forrest. There is some information about Mongolia in there as she went to Mongolia to study the horses that still lived wild. I guess she did her research but as she is a historian with interest in equines most of her expertise lies there.

I know that climate change is having a world-wide effect on a longer time-scale.

 

[Horsa]

What is the Higgs Boson?

 

[Chris Koziarz]

I've got a question which may be classed as an archaeology question too, I guess.

Radio-carbon dating is often used in archaeology. Does anyone know how it works, please?

Answer includes "radio-active decay" phenomenon we've discussed previously. I already mentioned therein, that Carbon exists on earth in couple stable (infinite lifetime) isotopes and one "semi-stable" isotope 14C.
This is the first and most obvious method of dating carbon containing dead matter (e.g. animal/plant fossils) in the range from some 50 to 50000 years. We estimate the "age" of the fossil (time elapsed since the organism died) by measuring the 14C isotope depletion in the fossil. Said range is determined by the speed of 14C decay. Half life of 14C isotope is about 5000 years. Which means the short time lapse (<50y) is not enough to produce measurable 14C depletion (compared to background), while too long time lapse (>50000y) results in 14C depletion down to zero, so we cannot distinguish between 50000y and infinity using this method. There exists other methods using isotopes of different elements (if present, sometimes difficult to find) with slower decay.
14C remains constant in the air, because cosmic rays produce new amounts of it by means of a nuke reaction (I think involving neutrons or beta radiation & nitrogen but I'm not sure), to counter-balance 14C decaying process. Living organisms assimilate 14C as well as other stable isotopes (12C & 13C), although in slightly lesser amounts because "heavy carbon" is more difficult to assimilate. So, the 14C is already slightly depleted in living organisms but stays at constant level throughout their lives. But, after the death, there is no exchange with atmospheric carbon anymore, so exponential decay of 14C starts. Find out how much 14C has depleted in a given sample to calculate the age of the given sample since death. In old days, we used to just listen to the on-going 14C depletion process with Geiger-like instrument counting instrument's "beeps" Nowadays, we can literally measure number of 14C atoms in a sample using wonderful instruments called mass spectrometers. Very powerful tools they are!

 

[Horsa]

Answer includes "radio-active decay" phenomenon we've discussed previously. I already mentioned therein, that Carbon exists on earth in couple stable (infinite lifetime) isotopes and one "semi-stable" isotope 14C.
This is the first and most obvious method of dating carbon containing dead matter (e.g. animal/plant fossils) in the range from some 50 to 50000 years. We estimate the "age" of the fossil (time elapsed since the organism died) by measuring the 14C isotope depletion in the fossil. Said range is determined by the speed of 14C decay. Half life of 14C isotope is about 5000 years. Which means the short time lapse (<50y) is not enough to produce measurable 14C depletion (compared to background), while too long time lapse (>50000y) results in 14C depletion down to zero, so we cannot distinguish between 50000y and infinity using this method. There exists other methods using isotopes of different elements (if present, sometimes difficult to find) with slower decay.
14C remains constant in the air, because cosmic rays produce new amounts of it by means of a nuke reaction (I think involving neutrons or beta radiation & nitrogen but I'm not sure), to counter-balance 14C decaying process. Living organisms assimilate 14C as well as other stable isotopes (12C & 13C), although in slightly lesser amounts because "heavy carbon" is more difficult to assimilate. So, the 14C is already slightly depleted in living organisms but stays at constant level throughout their lives. But, after the death, there is no exchange with atmospheric carbon anymore, so exponential decay of 14C starts. Find out how much 14C has depleted in a given sample to calculate the age of the given sample since death. In old days, we used to just listen to the on-going 14C depletion process with Geiger-like instrument counting instrument's "beeps" Nowadays, we can literally measure number of 14C atoms in a sample using wonderful instruments called mass spectrometers. Very powerful tools they are!

Thank you very much for the information. I get you now. Archaeological radio-carbon dating would happen in a somewhat similar way to the paleontological radio-carbon dating you mentioned then except that they would be dating bones etc. Sometimes they still date wood the old way though which is they count tree rings.

 

[Chris Koziarz]

What is the Higgs Boson?

All of your previous questions were "answerable" (even if classified "hard" by mrzz) but this one is not answerable by me, I'm afraid. At least not to the level you might expect, given the history of my answers. Because my knowledge of particle physics stops at common neutrons, protons electrons. I also remember that nuclear particles are composed of quarks, and that there exists anti-mater equivalents of all of them. But beyond that is the black void of my ignorance. So, I would need at least a primer on different class of particles such as bosons, before even attempting to pretend I know Higgs boson. I remember (as you likely do) the historical perspective: Higgs the existence predicted of said boson in 1964. It took along time, until powerful accelerator (CERN) has been built, where in 2012 they confirmed Higgs finding, gave him Nobel Prize and named the particle after him. The particle mass: 125 GeV/c2, looks very heavy (some 130times heavier than Neutron which is some 930MeV/c2), so no wonder they needed a powerful accelerator to create so much energy in banging traditional particles, to create this new one. I read on Wiki, that Higgs boson half life is some e-22secs, which amuses me: that's pretty much equal to non-existence for all classical processes we deal with. How far can it travel at the speed of c (3e8m/s) before it disappears? Simple answer: less than e-13 of meter.

 

[Horsa]

All of your previous questions were "answerable" (even if classified "hard" by mrzz) but this one is not answerable by me, I'm afraid. At least not to the level you might expect, given the history of my answers. Because my knowledge of particle physics stops at common neutrons, protons electrons. I also remember that nuclear particles are composed of quarks, and that there exists anti-mater equivalents of all of them. But beyond that is the black void of my ignorance. So, I would need at least a primer on different class of particles such as bosons, before even attempting to pretend I know Higgs boson. I remember (as you likely do) the historical perspective: Higgs the existence predicted of said boson in 1964. It took along time, until powerful accelerator (CERN) has been built, where in 2012 they confirmed Higgs finding, gave him Nobel Prize and named the particle after him. The particle mass: 125 GeV/c2, looks very heavy (some 130times heavier than Neutron which is some 930MeV/c2), so no wonder they needed a powerful accelerator to create so much energy in banging traditional particles, to create this new one. I read on Wiki, that Higgs boson half life is some e-22secs, which amuses me: that's pretty much equal to non-existence for all classical processes we deal with. How far can it travel at the speed of c (3e8m/s) before it disappears? Simple answer: less than e-13 of meter.

Thank you very much. I'm very sorry. I don't remember 1964 because I wasn't born then but I vaguely remember reading about C.E.R.N. Ha! Now I've got it. Thank you very much for your information.

 

[Chris Koziarz]

I had a very little idea about climate change (better now after reading Chris' posts), but it is obvious that "climate change" is a global effect, on a non-immediate time-scale. Mongolia was not "hit by climate change in 2013" like it was a storm or something like that. Mongolia, and all places for that matter, are being constantly hit by climate change. That is the whole point. And the following phrase with the percentage in it makes it all more alarming. It gives the false impression that one day people will wake up in the middle of the desert (it can happen, but not from one day to the other). It is that kind of thing that helps the climate change "deniers" win more followers. (with that I am not saying that we don't need to act about it now).

Very good comment for someone who asserts that he has "very little idea about climate change". Thank you, mrzz for your input into this topic.

 

[Chris Koziarz]

@mrzz If I asked easy questions I wouldn't need to ask the questions in the 1st place. What is hard for 1 person is easy for others & vice versa. You & Chris are extremely intelligent gentlemen. I'm Little Miss Average. Some of the things I wonder about & expect to be hard you'll find easy so I don't always realise I'm asking you difficult questions. I'm very sorry for annoying you both by asking too many questions. I'll try not to ask as many in future. I'd like to thank you both for answering my questions. :0)

I like the challenge of your questions. Don't hesitate to ask even if non-answerable by me/mrzz, someone else may chip in and teach all of us.

 

[mrzz]

@mrzz If I asked easy questions I wouldn't need to ask the questions in the 1st place

You people take me way too seriously! But the (serious) point is that your questions, besides being hard (which, as you noted, is good), they touch subtle subjects, that require a thoughtful response.

For example, Chris' detailed answer above about carbon dating is built over the concept of stable and unstable isotopes. This is not an easy concept to grasp. First you need to know what an isotope is. Two nuclei are said to be isotopes of each other if they have the same number of protons, but a different number of neutrons. If they have the same number of protons, the whole atom will have the same number of electrons, and both isotopes will be part of atoms with the same chemical properties. That's (also) why you have all the different isotopes mixed together in a sample of matter. In the carbon case, it means that ordinary carbon will have the 12C, 13C and 14C (had to check above post to be sure about the specific isotopes) in a sample.

But since the nuclei of the atoms are different, the nuclear properties of them are different. Think of this like the nuclei are the basement structure, and the electrons (therefore chemical properties) are the exterior parts of a house. The analogy here would be basement structures of the same shape but made of different materials. Above them you build exactly the same houses, so they all "look" the same. But given that the materials of the structure are different, some of those houses may collapse all of a sudden.

And that is exactly what happens with the 14C isotope. It can collapse all of a sudden. That is why it is called an "unstable" isotope.

You never know when a particular one of those collapses, but if you put a lot of them together you know the rate by which they collapse over time (which is the important information needed for carbon dating).

And why some are stable while are others aren't? (I know you would ask that). The forces that keep a nucleous together are quite complicated. They depend on the balance between protons and neutrons to begin with. The 14C has too many neutrons and is unstable as a result (gross simplification, but pointing in the right direction).

 

[Horsa]

I like the challenge of your questions. Don't hesitate to ask even if non-answerable by me/mrzz, someone else may chip in and teach all of us.

Thank you very much. I can wonder & ask as much as I like then. The fact that @mrzz thinks some of my questions are hard actually makes me feel slightly better because it tells me I'm not just asking stupid questions that annoy people & make people think why is she asking this when she could work it out for herself. :0) The information produced as a result of our questions is definitely fascinating & I feel I've learnt a lot. I think that a lot of interested people may be reading this & learning from everything we've got to say too. Someone else may actually join in with asking questions too.

 

[Horsa]

You people take me way too seriously! But the (serious) point is that your questions, besides being hard (which, as you noted, is good), they touch subtle subjects, that require a thoughtful response.

For example, Chris' detailed answer above about carbon dating is built over the concept of stable and unstable isotopes. This is not an easy concept to grasp. First you need to know what an isotope is. Two nuclei are said to be isotopes of each other if they have the same number of protons, but a different number of neutrons. If they have the same number of protons, the whole atom will have the same number of electrons, and both isotopes will be part of atoms with the same chemical properties. That's (also) why you have all the different isotopes mixed together in a sample of matter. In the carbon case, it means that ordinary carbon will have the 12C, 13C and 14C (had to check above post to be sure about the specific isotopes) in a sample.

But since the nuclei of the atoms are different, the nuclear properties of them are different. Think of this like the nuclei are the basement structure, and the electrons (therefore chemical properties) are the exterior parts of a house. The analogy here would be basement structures of the same shape but made of different materials. Above them you build exactly the same houses, so they all "look" the same. But given that the materials of the structure are different, some of those houses may collapse all of a sudden.

And that is exactly what happens with the 14C isotope. It can collapse all of a sudden. That is why it is called an "unstable" isotope.

You never know when a particular one of those collapses, but if you put a lot of them together you know the rate by which they collapse over time (which is the important information needed for carbon dating).

And why some are stable while are others aren't? (I know you would ask that). The forces that keep a nucleous together are quite complicated. They depend on the balance between protons and neutrons to begin with. The 14C has too many neutrons and is unstable as a result (gross simplification, but pointing in the right direction).

Haha! Sometimes your jokes are very subtle. You've really got a way of making people think. I get your point though. Some of the information I'm asking for is hard but you're also trying to think of a way of explaining which isn't patronising or too hard, i.e. you're trying to gauge my level so that you can speak to me on my level instead of patronising me or going over my head too much.

I already knew what isotopes were but thank you very much for the extra information.

I wasn't going to ask that question actually.

 

[Chris Koziarz]

Thank you very much. I can wonder & ask as much as I like then. The fact that @mrzz thinks some of my questions are hard actually makes me feel slightly better because it tells me I'm not just asking stupid questions that annoy people & make people think why is she asking this when she could work it out for herself. :0) The information produced as a result of our questions is definitely fascinating & I feel I've learnt a lot. I think that a lot of interested people may be reading this & learning from everything we've got to say too.

You're welcome. I understand that the answer by a "live person" has different emotional and assimilative value than an answer at the wiki, because said "live answer" can be personalised to suit the recipient's expectations if we know the recipient's interests. I noticed mrzz does skillfully shape his responses often explaining complex topics by way of examples you like and you're familiar with. E.g. nice expansion on my carbon dating response, mrzz!

 

[Horsa]

You're welcome. I understand that the answer by a "live person" has different emotional and assimilative value than an answer at the wiki, because said "live answer" can be personalised to suit the recipient's expectations if we know the recipient's interests. I noticed mrzz does skillfully shape his responses often explaining complex topics by way of examples you like and you're familiar with. E.g. nice expansion on my carbon dating response, mrzz!

Definitely. He's got a way to make hard things sound easy & keep people interested.

 

[mrzz]

Very good comment for someone who asserts that he has "very little idea about climate change". Thank you, mrzz for your input into this topic.

Ha! Thanks! But it really helps when you are able to identify, and somehow locate it in the "bigger picture" of your knowledge, the things you really don't know. My comment is based on a simple scale analysis, and the knowledge of the meaning of the word "climate". This is all that is needed to know that a comment such as "Mongolia was hit by climate change in 2013" does not make sense. And, @Horsa , if you said that you took it from a book on horses, and that the author knows the subject, I believe you. She probably -- as you noted -- on this lateral subject, reproduced some unreliable source. Then you see the importance of good science dissemination (in Portuguese we have an expression for that, "divulgação científica", I can't seem to find a good one in English). You have a good book on one subject that disseminates a miss conception on a related subject. So "bad science" is mixed up with good science and the reader cannot tell the difference....

Actually being able to identify what I do not know helps me to somehow answer about the Higgs boson too. In short, I do not know what is, as I am not an expert (not even a particular fan) of particle physics. But what can I say about this that might help is:

Very few people around the globe actually know what it is (and they might disagree heavily between themselves!). Good nuclear physicists will know, particle physicists (at least this they should know), and physicists from the theoretical fields of quantum field theory and string theory. The rest of us will struggle heavily to understand even a bit.

This is so hard because the theories that (should) explain the physics of what happens on the energy and time scales where you can observe it (as pointed out by Chris' post above) are not completely settled. And those particles are highly unstable, just like the unstable nuclei described in an earlier post (actually, in a much much worse way). So you put it all together and you get something very hard to grasp.

The little I know is that, in a sense, particle physics is a bit like chemistry. Remember those chemical reactions that you learnt in school? When you needed to find which element was missing in the picture, and you figured that out counting the protons and neutrons in both sides of the reaction? Well, particle physics is much complicated version of this, so by studying some reactions Higgs figured out that such a particle should exist, and it was later indeed found (and I bet there are groups who put the experiments in doubt).

And now, tchan tchan tchan!, a trivia answer!! There is a well known book about the Higgs boson called "The god particle". I think it is a very unfortunate title that leads to a lot of miss conceptions about science. I was very happy when I found out that the author wanted to call the book "The god damned particle" (as it was so hard to find), and that the editor didn't like that title, and somewhat changed it arbitrarily.

 

[mrzz]

You are spoiling me guys but be sure that I am very glad to read your compliments as I value both of your opinions. I had a helluva day yesterday, today is going in the same direction, but my mood is suddenly much better!

 

[Horsa]

Ha! Thanks! But it really helps when you are able to identify, and somehow locate it in the "bigger picture" of your knowledge, the things you really don't know. My comment is based on a simple scale analysis, and the knowledge of the meaning of the word "climate". This is all that is needed to know that a comment such as "Mongolia was hit by climate change in 2013" does not make sense. And, @Horsa , if you said that you took it from a book on horses, and that the author knows the subject, I believe you. She probably -- as you noted -- on this lateral subject, reproduced some unreliable source. Then you see the importance of good science dissemination (in Portuguese we have an expression for that, "divulgação científica", I can't seem to find a good one in English). You have a good book on one subject that disseminates a miss conception on a related subject. So "bad science" is mixed up with good science and the reader cannot tell the difference....

Actually being able to identify what I do not know helps me to somehow answer about the Higgs boson too. In short, I do not know what is, as I am not an expert (not even a particular fan) of particle physics. But what can I say about this that might help is:

Very few people around the globe actually know what it is (and they might disagree heavily between themselves!). Good nuclear physicists will know, particle physicists (at least this they should know), and physicists from the theoretical fields of quantum field theory and string theory. The rest of us will struggle heavily to understand even a bit.

This is so hard because the theories that (should) explain the physics of what happens on the energy and time scales where you can observe it (as pointed out by Chris' post above) are not completely settled. And those particles are highly unstable, just like the unstable nuclei described in an earlier post (actually, in a much much worse way). So you put it all together and you get something very hard to grasp.

The little I know is that, in a sense, particle physics is a bit like chemistry. Remember those chemical reactions that you learnt in school? When you needed to find which element was missing in the picture, and you figured that out counting the protons and neutrons in both sides of the reaction? Well, particle physics is much complicated version of this, so by studying some reactions Higgs figured out that such a particle should exist, and it was later indeed found (and I bet there are groups who put the experiments in doubt).

And now, tchan tchan tchan!, a trivia answer!! There is a well known book about the Higgs boson called "The god particle". I think it is a very unfortunate title that leads to a lot of miss conceptions about science. I was very happy when I found out that the author wanted to call the book "The god damned particle" (as it was so hard to find), and that the editor didn't like that title, and somewhat changed it arbitrarily.

The book is about the history of horses & their relationship with humans. She knows equine science so everything she says about that is liable to be true though I guess I could cross-reference this with some of the books I have on horses. From an early age I learnt that the purpose of reading is to "weigh things up & consider them". There are times when I forget this but shouldn't. Besides I said that I read that about Mongolia. I didn't say I believed it. I get you.

I remember.

Haha!

 

[Horsa]

You are spoiling me guys but be sure that I am very glad to read your compliments as I value both of your opinions. I had a helluva day yesterday, today is going in the same direction, but my mood is suddenly much better!

Thank you very much. I value your opinion too. I'm glad we cheered you up. I hope you have a better day tomorrow & you're feeling better soon.

 

[britbox]

Technically, depends how you define the "consensus". But practically, we are settled on the question of if current global warming is caused by human activities (if that's what you mean). 97% of experts who research in this field do agree on Anthropogenic Global Warming. Later comprehensive report by IPCC says that the probability of human cause of GW is "extremely likely" (95% or more) and IPCC is a very conservative and caution organisation. Attribution researchers estimate that the mean value of human contribution to the observed warming be even more than 100%, because the natural processes that we understand, tend to slowly cool the climate (famous impending "ice age"), so human warming overwhelmed said cooling. But if you integrate the probability distributions of A vs N warmings with uncertainty of measurements, you get 95% probability that N is greater than A. BTW, every geologist who also knows about climate science, will tell you that the consensus on e.g. plate tectonic movements theory is lower than the consensus on AGW (i.e. plate tectonic theory is less settled than AGW question).

This 97% is such an abused figure in the media. There is no 97% agreement that human activities are the main cause of climate change. It's not really a binary argument.

Common arguments like:

"97% of scientists agree that humans cause climate change"

"Humans cause 97% of climate change"

"97% of climate change experts think humans are the main factor in climate change"...

... are frankly rubbish.

So where does the 97% come from?

They evaluated about 928 educational papers in 2004 with the keywords "global climate change". These were peer-reviewed. The 97% comes from a peer review and concluded that humans contribute to climate change. It doesn't say to what degree they contribute.

Anyone with half a brain would admit that humans contribute to climate change but if an author thought that impact was 5% then he would be included in the 97%. There is no consensus to what degree humans play in climate change... and neither should there be.

By the way, I believe in climate change, I like green energy... I just find the 97% narrative completely false and a perpetuated myth.

 

[Chris Koziarz]

This 97% is such an abused figure in the media. There is no 97% agreement that human activities are the main cause of climate change. It's not really a binary argument.

Common arguments like:

"97% of scientists agree that humans cause climate change"

"Humans cause 97% of climate change"

"97% of climate change experts think humans are the main factor in climate change"...

... are frankly rubbish.

So where does the 97% come from?

They evaluated about 928 educational papers in 2004 with the keywords "global climate change". These were peer-reviewed. The 97% comes from a peer review and concluded that humans contribute to climate change. It doesn't say to what degree they contribute.

Anyone with half a brain would admit that humans contribute to climate change but if an author thought that impact was 5% then he would be included in the 97%. There is no consensus to what degree humans play in climate change... and neither should there be.

By the way, I believe in climate change, I like green energy... I just find the 97% narrative completely false and a perpetuated myth.

You think that "97% consensus in climate science" comes from Oreskes 2004, that you mentioned above. But this is not true. Indeed Oreskes asked the imprecise question about A attribution to Global Warming and found out that all 928 papers endorsed AGW, so Oreskes' number would be 100% and not 97%. I agree her methodology was somewhat flawed, so I would suggest to simply disregard her rather than forming our opinion on her imprecise methodology. Because, there exists other attribution studies, their methodology more precise, and they found the expert consensus number between 91% and 97%. Some of said studies are:
Cook 2013 which found 97.1% consensus from abstract review process, but more importantly, they invited authors to rate their own papers,. the consensus turned out to be 97.2%, confirming the level of consensus found from reading the abstracts.
Doran 2009 a survey of 3146 earth scientists with the question "Do you think human activity is a significant contributing factor in changing mean global temperatures?". 82% overall responded yes. They also segregated their subjects into "non-climatologists" who didn't publish research (77% in that subgroup answered yes) and "climatologists" who actively publish research on climate change (97.5% in that subgroup answered yes).
Anderegg 2010 surveys all climate scientists who have publicly signed declarations supporting or rejecting the consensus. They found 97% to 98% of these experts support consensus. But further, they looked at number of publications and h-index in both groups. And they found that within the large group of "converted", the number of publications (as well as h-index) is twice higher than in the group 2-3% "skeptic" group.
So, firstly 97% consensus number comes from the studies I cited above and not from Oreskes 2004 as you mistakenly believed,
Secondly, last two studies confirm that the higher expertise level opinion we seek, the higher consensus level we get, with marginal "skeptics" showing less expertise than their "converted" colleagues. A data trend that'as hard to argue with. Maybe yourself, who do not believe in said consensus, think about 82% overall scientists in Doran 2009 who responded yes. But this is not an "expert consensus" because it necessarily includes earth scientists who have no knowledge about climate (e.g. petroleum geologists).
Finally, the conclusion that humans have caused "most of the global surface warming over the past half century" (i.e. A contribution is more than Natural contribution to GW), was stated in the 2013 IPCC report with 95% confidence. IPCC is very conservative organisation and will not issue such statement if there is no evidence for it. We can compare that IPCC 95% number to 97% expert consensus number from the above studies and say they are in agreement.
In summary, as much as I would like to agree with you BB (because I like you & because if there were no consensus among experts we would have a better chance of finding a "getaway" from increasing AGW crisis) I just cannot do that as available data tells otherwise.