I argued with my brother tonight about the reality of mans negative impact on a global scale. It was a long debate over quite a few beers, but beers or no, he believes no significant impact can be traced to man. I conceded that the prosecution must prove beyond a reasonable doubt and so I suggested he watch An Inconvenient Truth. He argued that a politicians goals make him less than a reliable witness to which I said Global Warming rests on science, true science is fact not perspective. He said he’ll watch An Inconvenient Truth, but I already smell his aversion to Gore. So, Dopers I need a website that’s irreproachable, irrefutable, and above all, short (he’s not much of a reader). Please help.
You’re not going to find an ‘irrefutable proof’. Global warming is likely happening, and likely manmade, but there’s no ‘proof’ of it. Evidence for man-induced climate change is found through empirical observation, modeling, comparison with past data, etc. There’s no mathematical proof, and there is still a non-insignificant minority of climate scientists who are skeptical.
There is, however, a preponderance of evidence, growing stronger as time goes on. That’s not likely to impress your brother.
Sam doesn’t quite have it. There is no proof. There is even no evidence. There is suspicion, no more. All we know is that the world’s temperatures have increased over the past two hundred years and that man has released vast quantities of CO2 - a greenhouse gas - into the atmosphere. No link between the released CO2 and global warming has yet been proven and there is much effort being expended to prove it. One of the big problems for many is that CO2 levels are right down in the ‘noise’ level - less than 0.04%.
I suggest you read one of the discussions between jshore and intention.
Me, I’m sceptical of AGW, but sceptical in the proper sense.
You and your brother need to clearly define what you are arguing about. It’s one thing to say that man is warming the atmosphere – just lighting a cigarette will warm the atmosphere a bit. It’s another thing entirely to claim that man’s CO2 emissions will warm the atmosphere to the point where it will have a large negative impact on mankind. The latter can be referred to as the CAGW hypothesis.
Unfortunately, there is no such thing. At this point, CAGW is just a hypothesis, and a shaky one at that. The science is NOT settled.
What I would suggest you do is this: Study a couple skeptic’s web sites. I found that a good place to start is to read A Skeptical Layman’s Guide to Man-Made Global Warming
Also study a couple pro-AGW sites, like realclimate
Pay close attention and read with an open mind. At the end, if you can satisfy yourself that CAGW is valid, then you ought to be able to make a compelling argument to your brother. On the other hand, you might change your own mind.
If you want to say that that’s not proof, then I think we’re going to be having some problems with things like saying that gravity or the stars exist for certain, as well. Outside of the world of math all scientific proofs are simply a preponderance of evidence.
Copying and pasting from a previous post:
That I know of, there are three categories of evidence lending to the conclusion that global warming is anthropogenic.
- The upturn of the average global temperature (AGT) from the end of the 19th Century (the weakest evidence, and hence the most debated.)
- The link between CO2 in the atmosphere and how it tracks with the AGT over the last 650,000 years. How much CO2 is being released into the atmosphere by humanity is very quantifiable. You can look up the numbers yourself by visiting the Department of Energy’s website.* According to the IPCC report, the historic high point for CO2 in the atmosphere is ~300ppm and we’re at 379ppm, where the range was always between 180-300. To be 79ppm above the historical maximum where the total spread itself was only 120ppm difference (180-300) is pretty impressive.
- Computer modelling of the reaction of sunlight in the atmosphere with varying levels of CO2 (and other gasses), which have been verified against history when sudden releases of CO2 by volcanos to provide reasonably predictive results, come to a result of increasing global warming with the amount of CO2 being released by humanity and none or significantly less without it.
A semi 4th item is that any other theories as to why the Earth appears to be warming don’t seem to bear through to follow what we are seeing. There is evidence that the Earth was also naturally warming up, but that’s an “also.”
Personally, I think that the most telling thing is that the United States government itself agrees with the IPCC results:
http://www.epa.gov/climatechange/science/recentcc.html
- Their CO2 group is here: http://cdiac.esd.ornl.gov/ and the files are here: ftp://cdiac.ornl.gov/pub/ndp030/CSV-FILES/
Science is all about testable prediction. Even when predictions come true, one cannot really call anything “proven”, only strongly supported.
There are certain gases, called greenhouse gases (GG), which absorb the infra-red wavelengths radiated by the Earth, as discovered by Joseph Fourier two centuries ago. It is undeniable that carbon dioxide absorbs radiated heat and that the concentration of CO2 has risen by over 30% in mere decades compared to its much much longer-term natural average of around 280 ppm. (This is not to say that CO2 concentrations have always remained at 280 ppm, but the rate of the current increase is unprecedented.)
Now, that does not prove that humans have raised the global temperature, it merely provides a strong correlation. But even skeptics accept that if the GG concentration continues to rise at today’s astonishing rate, sooner or later it will affect the climate.
So what about those predictions I talked about? Well, it seems that we will measure a cooling this year due to the way heat is dissipated by La Nina. But the few years after this will provide a telling signature regarding the reality or otherwise of Global Warming. Personally, I side with the experts referenced in that article in predicting a new record high sometime in the next 5 years. A skeptic might predict no record high, or even a continued drop.
Assuming you will know your brother for another 5 years, perhaps a bet is in order, to be called in either in 2013 or whenever a new record were to be announced?
But the vast majority of the atmosphere, ie. oxygen (ca. 20%) and nitrogen (ca. 80%), are not IR-absorbing gases but blue gases. When you look at the proportion of gases which do absorb IR wavelengths, CO2 accounts for a significant proportion of the greenhousing properties of the atmosphere. Really, I’ve lost count of how many times this has been stated here.
And your point is? Correllation does not imply causation. To whit, you might recall that there have been ice ages with higher CO2 concentrations. Therefore higher CO2 levels do not necessarily mean an increased greenhouse effect.
It’s very tempting to look at the match, but the evidence just isn’t there. Yet.
Hence my words “only a strong correlation”.
In which case, the 0.04% isn’t the “problem”, but the possibility of other effects which might mitigate those significant IR-absorbing properties.
Conclusive evidence? Perhaps not. But neither can one say that there is no evidence whatsoever that the vast reserves of undeniably IR-absorbing gases released by human activity has affected climate. Correlation can be evidence of causation in some cases, and a red herring in others.
And I should have included an example here: those high CO2 ice ages you bring up might be explained by periods of high volcanic activity. Yes, this pushed up the CO2 concentration, but it also massively increased the amount of ash and dust (and therefore reflecting cloud) in the atmosphere. We have no evidence yet that cloud cover will mitigate the IR-absorbance of the current emissions (and even if it did, that would still constitute a significant global climate change even if global warming was averted.)
Actually, correlation does imply causation - if it were not so, the scientific method would be impotent.
Correlation alone doesn’t conclusively demonstrate causation, but it does imply it, quite often.
You’re right. A poor choice of words on my part.
Here’s the thing. Throughout geological history there have been periods of global warming alternating with periods global cooling.
It was quite warm around AD 1000. Then the average temperatures fell for a few hundred yesrs, bottoming out around 1650, known as The Little Ice Age The era finished arounf the mid 19th century, and temperatures have been rising ever since.
There is little doubt that we are currently in a period of global warming. The dispute is about the cause of the current warming. Some people think that carbon emissions are contributing to the rise. Others think its just the natural cycle. Some people think the rise will cause distster in a few decades time, other people think that the world has survived global warming before, and will again.
But if you want to convince your brother, try using a variant of Pascal’s Wager.
Case 1: Believe in global warming, and take action against it. If you are right, you gain everything. If you are wrong, you lose nothing.
Case 2 : Don’t believe in it, don’t take action against it. If you are right, you gain nothing. If you are wrong you lose everything.
Case 1 is the best option to take.
( I think it’s valid in this case. It fails in matters of theology because there are several different Gods to choose from. No such problem here)
This is a pet peeve of mine: of course the Earth will be fine - it’s a big ball of rock, and whatever species get wiped out, others will take their place. The danger of rapid climate change is to billions of human beings.
I’d actually like to see Friends of the Earth change their name to “Friends of the Poor Bastards Who Will Lose Their Houses And Lives”.
That’s a very weak argument. First of all, there most definitely is a cost to taking action against Global Warming. A HUGE cost. A cost great enough that it could cause economies to go into recession and slow global economic growth dramatically. There is also opportunity cost. Money spent on global warming is money not spent on research into cancer, paying for Medicare, doing other science, or paying for the damage that global warmining might cause.
The right question to ask is, “What are the range of cost estimates for global warming, and how do they compare to the cost estimates of trying to stop it?”
The IPCC says for warming below 2.5 degrees over the next century, the net cost to the globe will be zero. There will be added costs in equatorial zones, but this will be offset by longer growing seasons, lower heating bills, and the opening up of northern land for development. So you could address that problem by simply transferring wealth from the rich northern countries to the poorer equatorial countries.
Above 2.5 degrees, there will be a net cost to the global economy. But what’s the cost of trying to prevent that 2.5 degree rise? Currently, Kyoto is so costly that even the countries which have ratified it are not implementing it, and Kyoto would not come close to reducing the global temp by 2.5 degrees in 100 years.
I’m not taking a side in the debate here, I just wanted to point out the fallacy of pretending that doing something about global warming was cost-free. If it was, we wouldn’t be arguing about it.
The Stern report suggested that continuing to release IR-absorbing gases at the current rate could cost up to 20% of GDP, while only 1% of GDP would be required to ameliorate such a worst case scenario.
In any case, I reject the argument that reducing emissions voluntarily (as opposed to involuntarily, as in 1990’s Russia) will be economically damaging. That is simple hysterical doom-mongering with no evidencial basis, from people who don’t understand how complex the system in question is.
You could say I am an Economic Global Cooling skeptic.
Indeed. It’s rather silly that the debate is over the existence rather than the cost. My mom, at least if you corner her, will eventually admit to agreeing that AGW is happening, but you have to argue for an hour that global warming itself exists before you even get to anthropogenic, but then she’ll finish it with “But I don’t think it’s clear that it’s worth paying to fix.” which is a reasonable position to take given that it’s not real clear how the cost will play out. But she’ll make you prove the existence all over again every time, starting from simply stating it it’s all made up by scientists trying to justify their profession.
But, in the end, the suggested solutions are to cut pollution, improve technologies to be more efficient, save forests, and cut oil dependency. None of those are bad things, and can be justified for reasons entirely independent of global warming.
Cut pollution - Littering is illegal. Technological hurdles aside, it seems like you should always be trying to push for getting over those hurdles.
Improve technologies - One of the key points of capitalism is to give power to new technology for the betterment of our lives. Monopolies are legal to split because they have a naegative impact in the capitalistic model, there being no motive to develop new technologies. But you could easily say that for something that has such an expensive infrastructure already built in (oil/gas based engines), it’s not clear that alternative technologies have any hope without government backing.
Save forests - They’re pretty. It would be a shame to lose them, while as halting mankind’s expansion into them really doesn’t hurt anything (in the US. Obviously in Brazil this might be different, but I could just as easily see that introducing modern farming techniques there would ultimately be a boon the economy.)
Cutting oil dependency - It gives a bunch of local warlords in the Middle East more power over the rest of the world than they should really have as well as funding their tyranny of the locals.
High costs, but you could just as easily view all of it as being investment spending and not cleanup.
I disagree. For example, suppose that I claim that according to my calculations, the dreaded mumba-gumba monster is likely to destroy the worlds’ economy costing us up to 50% of GDP. Fortunately, there is a simple solution. etc. etc.
Whatever you think about the CAGW hypothesis, Pascal’s wager doesn’t really answer the question about how to act. And even if it did, it wouldn’t answer the question about whether CAGW is valid.
One thing I’ve noticed: A lot of these prophecies contain plenty of weasel language.
Oooh. The irony.
Exactly what policy would you propose?