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This thread is relevant to my interests.
On the subject of the "diamond" planet, I'm actually surprised to see the lead author of the paper in question referring to it as a "diamond planet". I thought that was just a media label. I read the paper when it came out, and all that was indicated was that an extremely large (Jupiter-mass) extremely dense (much smaller than Jupiter) body was detected orbiting a pulsar. The density was consistent with something reasonably close to diamond, but I would have thought that there always has to be some other elements in there... and in any case I wasn't convinced that the vast majority of the interior would be cool enough to be crystalline rather than liquid carbon. So while I'm very confident that there's some extremely massive, extremely dense planet orbiting that star, I'm yet to be one hundred percent convinced that "diamond" is the correct label for it.
Which brings me neatly to the actual point of the article, on climate change. I'm somewhat out of my field here, but no more than the author is. The reason I'm skeptical about the hypothesis "burning fossil fuels is likely to cause significant and disastrous climate change in the future" is that it's all based on simulations which can't be tested against experiment. And I do simulations for a living, so I know enough about them to be very skeptical whenever confronted with simulations in the absence of experiment. Maybe it's true, and I wouldn't be surprised if it were, but I'm certainly not willing to talk about it as if it's as strongly supported as... well, the vast majority of other stuff that we mean when we talk about 'science'.
The strength of a scientific theory is (and I'm still working on figuring out exactly how to phrase this) determined by the question of "If this turned out to be false, how much experimental data would suddenly be very difficult to explain?" If evolution were false, then pretty much all of biology is suddenly very difficult to explain. If the hypothesis "big dense planet thing orbiting PSR J1719−1438" turns out to be false, then there's a bunch of measurements which are very hard to explain. On the other hand if the hypothesis "diamond planet orbiting PSR J1719−1438" is false then it's not at all difficult to explain. And if the hypothesis of significant anthropogenic climate change turns out to be false, then this makes very little difference to our ability to explain existing experimental data.
For one thing, the article is not suggesting that the climate change hypothesis is based on some random simulations that someone came up with (it's based on an incredibly rich amount of observational data, see final point below). He's talking about a hypothetical discovery, and he uses very careful words to describe it:
"Let’s say we studied computer models of the influence of excessive greenhouse gases, verified them through observations, then had them peer-reviewed and published in Science." (my emphasis)
Secondly, I don't find your counter-argument to climate change very convincing:
- There is overwhelming evidence that the world is heating up dramatically and at an accelerating pace, whether or not you agree that the cause is man-made (cf. Gruber, http://daringfireball.net/linked/2011/09/07/krugman-shape-of...). If it's due to some other cause, what is said cause? Why has no one suggested any credible alternative?
- If you are of the "it's not us, it's something else" camp, this website does a great job laying out the reasons why so many scientists (~95%) believe that climate change is human-caused: http://www.skepticalscience.com/its-not-us-basic.htm (already linked somewhere in this thread).
In science, a majority means very little. There have been many cases throughout history where one person was right and everyone else was wrong. The majority of people in China believe that eating shark fins prevents cancer - it does not mean they are right.
I implore everybody to at least take a look at the arguments from the other side. Mind you, these are all very smart people, not just yahoos:
http://en.wikipedia.org/wiki/List_of_scientists_opposing_the...
Please, please, take at least a little bit of time to read some of their quotes. I'm not asking you to agree with me, I am asking you to form your own opinion on the matter.
So you admit that you're out of your field but then go on to opine about how the scientists that actually are in the field are doing something wrong, and denigrate the predictions they're making as "just simulations" without any experiments. According to you all those smart scientists working on climate change have never thought about the problem with computer models, have never run an experiment, have never thought about statistical confidence intervals for their predictions.
I think you keep bringing up the nitpicky point about diamond to make this guy look dumb. But just like you can call out this guy on the diamond thing climate scientists call each other out in peer reviewed articles when they make weak assertions, that's the scientific method. Among the scientists that actually know what they're talking about a consensus has formed and they are trying to ring the alarm bell. It is dumb and arrogant to ignore them.
I am a climate expert either, but I can easily identify a fallacy or bad experiment when I see one. I think hugh3 has written one of the most rational posts I have ever seen on HN. I think it is everybody else who is unclear on the scientific process. Being peer-reviewed DOES NOT constitute to the scientific process. Remember when every person and their peer believed that the earth was flat and it was the center of the universe? Guess what, it turns out popular assumptions are often wrong. Being peer-reviewed does very little when your peers are so eager to approve your work.
The scientific process is as follows:
1. Ask a Question 2. Do Background Research 3. Construct a Hypothesis 4. Test Your Hypothesis by Doing an Experiment 5. Analyze Your Data and Draw a Conclusion <-- this is where people are messing up; insufficient data, jumping to conclusions, fallacies, etc. 6. Communicate Your Results
You seem a bit unclear about the scientific process as it applies to climate change.
Firstly, here are the undisputable facts - facts that can be reproduced in a laboratory without relying on simulations.
a) Sunlight bouncing off the Earth's surface is red-shifted.
b) CO2 and other greenhouse gases absorb red light more than other forms of light, which they re-emit, often back towards the ground / lower atmosphere.
c) The amount of greenhouse gases in our atmosphere are increasing, as directly measured
d) this increase correlates with calculations associated with how much CO2 we are emittting through the burning of coal, oil and natural gas.
Those are the facts. Looking at those facts, it seems pretty clear that the null hypothesis for climate change is that the temperature of the lower atmosphere should be increasing. We would expect the temperature to rise, unless there is some process that we don't know about that is affecting the numbers
When we put the hypothesis to the test - is the temperature increasing? - we see that it is indeed increasing, which confirms the model.
Now, about those simulations. Yes, they are not as reliable as the science I just when through above. We know that. But they all agree with the null hypothesis that the temperature will rise if we keep increasing the amount of CO2 in the atmosphere. If you want to throw that result into dispute, you need to show that there is some process going on that we didn't know about, and hence haven't been included in the models, or you need to show that the simulations themselves are actually wrong.
What you can't do, if you want to be scientific about, is just state that you are skeptical about the simulations, and therefore we shouldn't act/create policy based on those simulations. I mean, sure, you can hold to that, but you have to admit that you are just being irrationally skeptical, and not scientific at all if that's the position you wish to hold.
If only those four factors would affect climate, you'd have a point. Alas, weather is extremely complex system, and it is pretty difficult to say for sure what is correlation, what is causation.
And I am pretty sure, that by tweaking some variables in your models you can get any outcome you want.
Thank you for being rational rather then being distorted to one view or the other.
You seem a bit unclear about the scientific process as well. Take hugh3's example and throw out anthropogenic global warming. Do the facts still hold?
The earth had dramatic warm and cool periods long before humans, and will continue to despite us.
No one is questioning whether or not humans or CO2 have an impact - we all know that we do. The question is whether or not we have a SIGNIFICANT impact. That is, enough of an impact that we should actually give a damn, given we probably wont be using fossil fuels in 100 years anyway.
If the case for anthropogenic global warming is so strong, why are scientists falsifying data like in ClimateGate?
Much evidences suggests that we are headed into another "Little Ice Age" like in the 1700s. But few people talk about this for some reason.
I very much agree with your skepticism when it comes to believing the results of large scale simulations of complex systems. I personally think many people incorrectly transfer the certainty that we have of the underlying phenomena to the results of these complex simulations. No rational person disputes the direct effects that CO2 has on the absorption and re-emission of IR but once this is included into hugely complex simulations, I believe a very large degree of skepticism is warranted.
However for almost exactly the same reasons I maintain some skepticism over the simulation results, I am personally very strongly in favor of minimizing man's impact on the environment. Precisely because it is a hugely complex system and I don't believe we can predict the effects of any changes we make to the environment.
Depressingly, it seems that the chances of persuading America to really embrace a serious reduction in its CO2 emissions (especially if the Republicans get any more power) is extremely small. And even if America were on-board getting world-wide consensus would still be difficult in the extreme.
It may very well be that the only option we have is deal with consequences of climate change as they arise. This will likely be more expensive than if we were investing in reducing our impact now but the way politics works the world over means that people are very reluctant to take short-term pain for long-term gain. And it should be remembered that even if the climate changes even faster than has been predicted, it will still be a gradual process, and countries will adapt to it the best way they can as and when it is required. By this I merely mean to dispel the idea that some people seem to have of utter catastrophe if action is not taken.
At its core, the CO2 argument is an energy balance argument and many of the details are unnecessary. To determine long-term, global temperature rise, you just need to know the energy in and energy out, which can be done in principle without knowing anything about climate.
The problem is that some things that affect the radiation balance, chiefly changes in water vapor and clouds, are products of the local conditions, and it is to estimate the effects of those that you need simulations.
The problem is that people seem to transfer their skepticism of the global climate simulations to the basic energy balance argument. Humans ARE affecting the climate, it's just that we may be affecting it in such a way that the net warming is hard to estimate because there are fairly large forcing terms that cancel.
The reason I'm skeptical about the hypothesis "burning fossil fuels is likely to cause significant and disastrous climate change in the future" is that it's all based on simulations which can't be tested against experiment.
There are also empirical observations - such as the facts that burning fossil fuels release measurable amounts of CO2, that CO2 behaves as a greenhouse gas, that CO2 content of the atmosphere observed over many years has been rising steadily, and that this correlates with the historical record of fuel consumption.
Frankly I'm sick to the back teeth of 'let me explain what skepticism means' arguments. I've been interested in climate change for something like 15 years now, although I am not an activist of any kind. And all I ever hear from the 'skeptic' lobby is that they 'need more data,' but never any willingness to state what sort of confidence intervals they would find acceptable or why their models are any more reliable, or even any predictions of their own. About the climate that is. For some reason, almost all skeptics feel qualified to declare that climate mitigation efforts of any kind will be a huge economic disaster without presenting even the most rudimentary economic argument for why this should be so.
This is how we end up with would-be presidential candidates who intone platitudes very similar to yours about falsifiability and standards of proof in between holding prayer meetings asking god to send more rain and revive the national spirit.
And if the hypothesis of significant anthropogenic climate change turns out to be false, then this makes very little difference to our ability to explain existing experimental data.
Fine, with so many alternatives it should be no trouble to make some clear and testable predictions that will blow the anthropogenic theory out of the water and settle the debate. We have plenty of satellites and observation platforms measuring solar output, cosmic rays and so on.
>The reason I'm skeptical about the hypothesis "burning fossil fuels is likely to cause significant and disastrous climate change in the future" is that it's all based on simulations which can't be tested against experiment
I'm skeptical that this is your true reason. Many, if not most, fields of science are built in areas where it's hard to run a true physical simulation of the model. For example, take machine learning, where nearly every method is developed without novel collection of new data, but is run entirely on data that has previously been collected and been analyzed over and over again.
If you run simulations, you should already know ways to test them without collecting new raw data, particularly if you have a large corpus of data from the real system.
What's your true reason? Is it that you just think that humans can't impact the climate?
> What's your true reason?
It's always good to throw out a nasty insinuation.
> Is it that you just think that humans can't impact the climate?
How about fact that none of the proposed "solutions" actually address the supposed problem, but instead just give control over to a bunch of folks who were demanding that kind of control long before anyone thought of AGW?
Then there's the rent-seeking.
Then there's the fact that almost none of these people act like it's a serious problem. They want me to pay, but their only change is to line up to collect a check.
I've done research in speech recognition, a branch of machine learning, and analyzing the same data over and over again is the classic blunder. It is called "testing on the training data" and it over-estimates accuracy to an uncontrollable degree.
People do try to avoid this by splitting their corpus into two, training on one half and testing on the other half, which works the first few times. Pretty soon though you have tuned your methods to get good results on the second half of the corpus and it is used up as a source of new data for an independent assessment of accuracy. There is a technique called "jack knifing" that sometimes helps a little.
If the Vapnik–Chervonenkis dimension of your model is low enough then success on the training data does guarantee success on fresh test data. This never works in practice. Getting decent results always requires lots of tunable parameters and your VC dimension ends up way too high. Machine learning only works, to the extent that it works at all, because many of your parameters only affect part of your model. You have an effective VC dimension much lower than the parameter count indicates, so you do get some generalisation, but if you want to know you have to gather fresh test data.
If you are doing research in machine learning you have to have a rolling program of data collection so that you can do genuine forecast testing. Hindcasting, that is to say "testing on the training data" is only really useful for finding bugs in your software. You should always be able to get good hindcast accuracy by dialing up the model dimension. If you cannot, you will never get good forecast accuracy. If you can get good hindcast accuracy that basically means that your software has passed one kind of bug test. You don't know your forecast accuracy until you gather fresh data.
There is a human side to this. Doing research in machine learning is a ordeal of perpetual disappointment. Your research runs ahead of data collection. So you measure your hindcast accuracy. It is great. You have broken through. Then fresh data comes and you measure your forecast accuracy. Terrible disappointment. Science is hard!
I'm skeptical that this is your true reason.
What's your true reason? Is it that you just think that humans can't impact the climate?
Feel free to correct me if I'm wrong, but please don't accuse me of lying about what I actually think.
It's probably wrong to call climate scientists "scientists", just like it's wrong to call rocket scientists "scientists". They are probably more like engineers, but "engineer" is almost a protected title (except in software).
No, they don't have a crystal ball. But just as nuclear weapons required a little forethought and co-ordination between nations, so does the ability to inflict colateral damage on the biosphere in a way that has never been done before.
Unlike the last 5000 or so years of human history, we are making new and significant discoveries every year, and are able to roll them out across the whole world. The cost is we need to be a little cautious about them.
Civilizations have collapsed before. New technology might be a factor - the ability to suddenly exploit a new resource can cause that a massive expansion, then a crash as the new resource becomes depleted. And more complex civilizations can be less able to survive a crash, as specialists are forced to become generalists in order to survive - doctors driving taxis or trapping gophers are much less productive.
Sometimes scientists get worried for no good reason (Y2K?), and sometimes they have a good cause (radium), but there's no way to be sure. Not everyone should listen to all the doom and gloom (from reputable sources), but world leaders certainly should. And sadly, they only seem to listen when wide-eyed protestors shout slogans outside their offices. It's kind of depressing.
<i>If evolution were false, then pretty much all of biology is suddenly very difficult to explain.</i>
There are plenty of areas of biology that would survive evolution being 'cancelled'. Biology encompasses a lot more than heredity. Heredity is a very important section of biology, but you're moving the goalposts here - claiming biology is 'pretty much' totally dependent on evolution when it's not.
I don't see how the man-mad warming camp can make-such-matter of fact assertions such as in http://daringfireball.net/linked/2011/09/07/krugman-shape-of... when the evidence does not seem to be conclusive. It's even more alarming that the other side is belittled.
Surely there must be something more compelling than "An Inconvenient Truth" on the matter?
http://www.skepticalscience.com/its-not-us-basic.htm is what you are after.
See also http://www.skepticalscience.com/its-not-us-intermediate.htm and http://www.skepticalscience.com/its-not-us-advanced.htm depending on the level of discussion you like.
How do human CO2 emissions compare to natural CO2 emissions? http://www.skepticalscience.com/human-co2-smaller-than-natur... is also related
The whole site is rather good. You can pull up your objection and erad the discussion: http://www.skepticalscience.com/argument.php
FTFA: Climate change may or may not be occurring. But there is no dispute that 98 percent of climate scientists believe that it is happening and is man-made.
The problem is in the phrasing of the question. Questions like "are global average temperatures increasing on a decade-to-decade timescale?" and "is climate change at least partly due to human activity?" are very different questions to "is the observed change in climate due primarily to anthropogenic factors?" and "to what extent is this likely to be a problem in the future" and "is it time to agree to [random policy proposal X that might help to cut CO_2 emissions slightly]?" -- but all these questions are treated as if they're the same question.
I'm so glad I work in an area of science where politics rarely intrudes.
Do you mind saying why you don't find thousands of scientific articles published in a wide variety of journals compelling?
> there is actually no difference between how science works in astronomy and climate change – or any other scientific discipline for that matter. We make observations, run simulations, test and propose hypotheses, and undergo peer review of our findings.
Things change a lot when your scientific theories need to be transformed into policies, though. If these same authors had also proposed, say, spending a significant proportion of world GDP to send a spaceship to the said diamond planet, their theories would be received more critically, I imagine.
That sentence isn't even correct. There is a MASSIVE difference between simulation based science and experiment based science.
I consider simulation based science interesting as theory (theoretical science), but it should NEVER be taken as accepted fact.
I consider simulation based science interesting as theory (theoretical science), but it should NEVER be taken as accepted fact.
It depends on the field and the degree of accuracy. For example, hydrodynamic simulations are pretty much accurate for standard(ish) shapes. Same with lighting simulations (ie, ray tracing).
Climate science isn't entirely based on simulation. For example, long-term geological records show a correlation between CO2 and global temperatures - see http://rsta.royalsocietypublishing.org/content/360/1793/659.... for example.
TL;DR version - our press was positive because their is no political agenda in astrophysics at the moment. It then goes to pity climate scientists who are pilloried because politicians have chosen to use their words to enact and enforce policies that their constituents don't like.
Astrophysics was a lot tougher discipline to be in if you were Galileo. Again the science was was being perverted to show support for what the government wanted to be true, rather than what was true. I suspect that if someone could have sold the church on a way to 'fix' difference between what science was telling them, and what they wanted to be true, they would have wasted millions doing that too.
Galileo knew that no matter how hard they wished it, the planets would not suddenly stop in its orbit and the universe begin to rotate around it. No more than any amount of wishing, better behaviors, and offerings of gold could stop the seasons (or the climate for that matter) from changing.
Not sure we've learned all that much about mixing science and policy since Galileo's time.
One big problem is that usually the person with the loudest voice gets the most attention, even if they are from the fringes of science. The real climate scientist don't want to use absolute certain language as that's not what the results tell them and their conclusions are harder to whittle down into a 30 second news report. Those without so much evidence to back them up are more than happy to deal in absolutes.
Anyone in climate science who does not understand why their work is controversial is living in a cave or willfully ignorant at this point.
1. Many climate scientists claim authority to make policy recommendations, something which is outside the realm of science. (Science ideally informs policy, but policy is about tradeoffs which climate scientists have no privileged insight into.)
2. The public face of climate science is akin to a political attack ad. Anyone who questions the policy recommendations of climate scientists is painted with the same brush as creationists or conspiracy theorists.
3. Climate scientists have mislead the public about their own science. When we have a cold winter, then "weather isn't climate", but when we have heat wave, then "we can't rule out the possibility that this is related to global warming".
Of course, some climate scientists are careful to outline the limits of their knowledge. It's just a few bad apples spoiling it for the honest 2%.
"When we have a cold winter, then "weather isn't climate", but when we have heat wave, then "we can't rule out the possibility that this is related to global warming"."
Are you sure that is the scientists talking, and not just the "common folks"? I never had the impression that climate science is terribly interested in singular spots of measurements. The public of course reacts immediately. If there is a warm winter, they all become believers in climate change, if there is a cold winter, they become convinced it is all bunk.
Never mind that the climate change could indeed lead to some regions of the world to actually become colder.
Maybe the problem is that everybody thinks they are experts on the weather, too, after all, they can sense it with their own senses - not.
Diamond or not, that's a cool discovery. The author though is making a mistake when he says that "The scientific method is universal. If we selectively ignore it in certain disciplines, we do so at our peril."
Science is broader than those disciplines where the hypothetico-deductive method is appropriate ("the natural sciences"). Science is the quest for knowledge, and epistemology, or the "science of knowledge", informs us of another particular method, the axiomatic-deductive, appropriate for "the social sciences".
The first rule of "the scientific method" is there is no scientific methoD. There are scientific methodS. The author has fallen victim to the all-too-common "scientism" that has swept the globe from the 19th century onward.
Should it be enough that there is wide agreement in peer reviewed journals to really make something so? In a similar situation, there's wide agreement from economists on what makes the world tick, yet these folks with little job prospects outside of government or academia manage to repeatedly fail to create models which display predictive power.
In the case of economics, the 'scientific method' chosen, that of mathematical economics, is inappropriate since human action "plays by different rules" than pulsars. Climate scientists similarly have the ability to influence politics.
At least they are using the correct type of method, but to say that X number of peer reviewed journals establishes the anthropocentric warming hypothesis as true is a logical error. Climate scientists need to exhibit predictive power and the fact is they haven't been able to do that. Historical evidence also doesn't lend itself to the idea that small amounts of warming will lead to disaster. It's a great story to put people into a panic and manipulate them but there is just not the necessary proof.
For more details see Howard Hayden's one-letter disproof of global warming claims: http://www.stephankinsella.com/wp-content/uploads/2009/10/Ha...
I've had friend doing his biology PHD say effectively the same thing as this to me.
It is frustrating that science communication is such a PR game to the detriment of the general public's understanding of what science is in reality.
The author states, "...that suggests man-made activities are responsible for changes in concentrations of CO2 in our atmosphere."
Notice the difference between that statement, and "OMG we're all going to die a giant heat death 5 years from now if we don't give up all our liberties!"
There are no pure carbon white dwarfs. There are carbon-oxygen dwarfs. Crystalline C/O doesn't sound as sexy as diamond. Scientists shade the truth for publicity all the time.
"I take the hard view that science involves the creation of testable hypotheses" - Michael Crichton
A computer simulation is not a testable hypothesis, never has been, never will be. There are millions of variables that go into our climate, to say that a computer simulation can capture all of them is naive at best.
In regards to the diamond planet, nobody is suggesting we radically alter the world economic system over a guess about a "diamond planet". The "climate change" crowd has an entire legion of people dedicated to killing the world economy over a bunch of un-testable computer simulations.
Going to throw this in the mix - this is definitely something to think about when considering global warming.
Consult Google for these numbers - I checked a couple sources to find rough estimates. Please correct me if I made an error. Obviously, this is a gross simplification...
The atmosphere has 5×10^18 kg of mass. That is 5,000,000,000,000,000,000 kilograms of mass for people who like to see the zeros.
Just by breathing, the human race produces about 2.2 trillion kilograms of CO2 annually. However, humans are only a fraction of the earth's CO2-producing biomass, about less than 1/1000 by some estimates. So that means that earth's creatures probably produce over 2 quadrillion kilograms of CO2 annually! Human technology (cars, power plants, etc) produce 27.2 trillion kilograms of CO2 annually. Let that sink in for a second - just by breathing, we produce a magnitude greater amount of CO2 than fossil fuel ever will. Wow. So where is it all going? My guess is photosynthesis is doing a pretty good job of keeping things in balance, but I am open to suggestions.
In case you haven't seen this, here's one programmer's perspective on working in climate science:
Unlike astrophysicists, climate science has some very vocal members trying to form policy decisions. The result of these decisions can mean spending Trillions of dollars.
So we don't get to have dispassionate debate in the facts, as the stakes are extremely high and incorrect conclusions can have enormously expensive consequences.
Also, unlike astrophysicists, climate science has some very vocal critics trying to keep current policy decisions intact. The result of these decisions can ensure billions in corporate profits over the coming years.
And so, as you say, we don't get to have dispassionate debate in the facts, as the stakes are extremely high and incorrect conclusions can have disastrous consequences.
Well, it's an unfortunate fact that diamonds in space are not as politically charged. In a vacuum it's unfair to give more scrutiny to climatologists, but given that it is politically charged, there's reason to question people's motives (and to be fair, people who will go overboard in the questioning).
The funny thing about climate change is how people treat it like a RELIGION.
I have nothing against religion, but I do not like it when people treat science like a faith - that is, take the facts for granted, and assume they are true, rather than trying to do what REAL scientists do, and prove their hypotheses false.
I see a lot of scientists trying to prove that humans are a major cause of global warming. I see very few of them looking for holes in their arguments, or trying to prove their hypotheses wrong.
Do humans warm the earth? Absolutely, no question about it. The question is whether or not we have a significant impact.
The earth has had dramatic warm and cold periods long before we even existed, what makes us think that we are the catalyst for everything? Is it not a bit concerning that many so-called scientists tried to hide data that went against their research?
> I see very few of them looking for holes in their arguments, or trying to prove their hypotheses wrong.
Where have you been looking at the scientists' work? Have you been following their peer-reviewed publications to reach the conclusion that they don't question these theories?
You sound like a creationist. Those stubborn evolutionists also allegedly take the facts for granted and never question them (never mind that for example usually creationists dwell on completely irrelevant 'facts').
for those interested, i interviewed several climatologists with some questions i had about global warming. The results are on my blog:
Ok, long discussion, i cannot add much given my non-familiarity with climate change science, but will point out this quote, i wrote some time back. "One generation's science is the another generation's religion"
If they want some "People on the fringe of science" to be quoted as "opponents of their work", they should try saying that the existence of a diamond planet 4000 light years away from the earth is a proof that God did not create the universe or some such.
But to me, it does not seem a well-thought blog. Who says a "scientific-method" that works for identifying the structure of a planet 4K light years away would also work for climate on earth?
My perspective on this is that, at least for people like myself, believing or disbelieving in human caused climate change is completely an act of faith.
We can look at the situation, try to wade through the journal magazines, blogs etc to find a reality behind it. But what we get, unless we have massive time to invest, is basically all we get. We pick a perspective on it that we feel defines us somehow, or fits with our worldview, and then dig in, surrounding ourselves with media that fits the image.
I believe in global warming because it seems that the interests backing the antiglobalwarming campaign have massive financial motivations for doing so. Also, as an avid urban cyclists anything that gets more cars off the street or at least regulates emissions, and pushes people towards smaller cars.
I trust the government and universities more than I trust big corporations and I know corporations are absolutely willing to pay people to find/make science that fits their preconceptions.
So in short I don't know. I took a guess, and I did so after weighing what I assume to be the motivations of the actors, and the outcomes if either side is wrong. If we prepare for global warming it will turn the world into a better place whether or not there is such a thing as global warming.
So in short I don't know. I took a guess, and I did so after weighing what I assume to be the motivations of the actors
Well, that's precisely the wrong thing to do.
The right thing to do, when you don't have enough evidence, is to say "I don't know". You can then go on to say "I think the preponderance of evidence is on one side or another", but you certainly shouldn't go round believing things.
Wovon man nicht sprechen kann, darüber muss man schweigen.