Arguments
The Scientific Guide to Global Warming Skepticism
Posted on 8 December 2010 by John Cook
Scientific skepticism is healthy. In fact, science by its very nature is skeptical. Genuine skepticism means considering the full body of evidence before coming to a conclusion. However, when you take a close look at arguments expressing climate ‘skepticism’, what you often observe is cherry picking of pieces of evidence while rejecting any data that don’t fit the desired picture. This isn’t skepticism. It is ignoring facts and the science.
The Scientific Guide to Global Warming Skepticism looks at both the evidence that human activity is causing global warming and the ways that climate ‘skeptic’ arguments can mislead by presenting only small pieces of the puzzle rather than the full picture.
The Guide explains the science in brief, plain language without getting too technical. For those who wish to dig deeper into the science, more detailed treatments can be found at the following pages (often presented with varying levels of complexity from Basic to Advanced):
- Human CO2 emissions is tiny compared to natural emissions
- Global warming stopped in 1998
- It's cooling
- Climate sensitivity is low
- Climate has changed in the past
- CO2 lags temperature
- CO2 doesn't cause much warming
- The warming trend is due to microsite influences
- The temperature record is unreliable
- The hockey stick is broken
- Global warming is a good thing
- Climategate shows there's a conspiracy among climate scientists
- There's no scientific consensus
How people are using the Guide
The Guide is being used by teacher associations, museums, websites, student groups and other organisations. Read some of the examples of how the Guide is being used.
Translations
To translate the Guide into another language, there is a two-column Word document plus a PDF Overview of the Guide to mark each section for translators. Please download the Word document and email me back the document with translated text. But first contact me to ensure noone else is already working on your language.
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Skeptical Science Forum
The Guide is likely to provoke lots of questions and discussion. Rather than restrict all the discussion to a single blog post, I've created a Skeptical Science forum where individual issues can be examined in detail in their own discussion threads. If you have any questions about any part of the Guide, feel free to post your questions or comments on the Skeptical Science Forum.
Of course, the same Comments Policy guidelines apply in the forum as elsewhere at Skeptical Science - no ad hominem attacks, no politics, no profanity or inflammatory comments. And discussion is to stay on topics raised in the Guide. Down the track, I may add a general forum so any climate issues can be brought up for discussion. Whether that happens will depend on people's behaviour in this forum... so play nice! :-)
Again, a job well done and thanks to all those experts who offered their valuable time and expertise. And most of all, a sincere thanks to John Cook-- he is a true champion of science and the epitome of pedagogy.
PS: Is there anyway people will be able to view the document's content on their iPhones?
Sorry, that's the best I can do at the moment :-)
I assumne there's no restrictions ( apart from correctly attributing the material) if I print off and give away a few copies
Bob
Push it out there people.
G
Already blogged on my site: Doc alert: The Scientific Guide to Global Warming Skepticism
I have a technical question related to the guide. I don't mean to say that the guide is incomplete; it's just that I would like more information for myself. The guide, as is, is perfect.
For some reason, I'm having trouble really understanding why nights warm faster than days and winters warm faster than summers. For some reason, understanding this is eluding me.
Thanks,
Bob
The human fingerprint in the daily cycle
During the day, the sun warms the Earth's surface. At nighttime, the surface cools by radiating its heat out to space. Greenhouse gases slow down this cooling process. This is why deserts cool so much at night. Water vapour is a strong greenhouse gas and the dry desert air traps much less heat than more humid areas. A more extreme example is the moon which has no atmosphere. At nighttime, there are no greenhouse gases to trap the outgoing heat. Consequently, the difference between day and night is more extreme with daytime temperatures getting up to around 118°C and nighttime temperatures falling below -168°C. In other words, the stronger the greenhouse effect, the smaller the difference between daytime and nighttime temperatures.
The human fingerprint in the seasons
During summer, a region receives more sunlight and warms. During winter, the region receives less sunlight and cools by radiating heat to space. Greenhouse gases stop some of this heat from escaping to space so an increased greenhouse effect slows down the winter cooling. Consequently, if greenhouse gases are causing global warming, we expect to see winters warming faster than summer.
Fortunately, your document is clear enough that perhaps even the politicians might understand and they are my current target. I won't try to convince the MP for my riding in Canada, John Baird who is probably the worst possible choice for the job in our parliament.
At the COP15 in Bali when he had the substantive role rather than the current "temporary" one, he left a high-level meeting and was seen minutes later drinking a cocktail at a party. There is no way that he's getting my vote.
But it appears very likely that votes alone won't help us to deal with the issue. I guess that it's time to "get in their faces".
Thinking about it as why nights cool more slowly helps, maybe, since the cooling all takes place through the radiation of LWIR?
Langenfelds et. al. (1999), GRL 26:13, 1897-1900.
This is a laypersons understanding of the night/winter issue, so please excuse and correct any misstatements or misconceptions, but I'll give a try at explaining my understanding as maybe we are on a similar level scientifically. Think about daytime being when the earth absorbs heat from the sun and nighttime as when heat is radiated back out through the atmosphere. That's why it's almost always coldest in the early morning just before dawn after an entire night of losing heat.
The warming effect of CO2 is related to how it interferes with the heat radiating back out through the atmosphere. Since there is more radiating of heat during the night it is the nighttime temperatures that will be most affected by the increasing CO2.
Although I'm sure there is some radiation of heat occurring during the daytime, I imagine it must be less because the gradient in the temps between the earth and the atmosphere is less than at night. Also the temperature moderation during the daytime from radiating heat would be relatively small compared to the temp moderation driven by heat absorption.
With regards to winter temps I think the concept would be the same since you have less insolation, longer nights etc during the winter so the effect of the CO2 would show up more.
One question that occurs to me from writing this up is why doesn't CO2 have an equal effect in blocking the heat coming into the earth as it does on blocking the heat leaving? My guess is it has to do with the radiation coming in (sunlight) being of different wavelengths compared to the heat radiation going out.
there's a mistake in the figure on page 8 where the captions at the top "Likely" and "Very Likely" are the wrong way round :-(
I'd vote for "Its frigging cold" being included in the next edition, if only because where I am, it is - at the moment. And whilst I'm on the subject - any plans for a blog post on this "WACCo"(Warm Arctic, Cold Continent) weather modeling ?
Though not highly technical, this might help. I pay attention to night time dew, because it can effect my work. What I have observed is that there is less dew on overcast or cloudy nights. On clear nights, heat radiates out into space faster, causing more dew.
Similarly, greenhouse gases slow the radiative cooling at night, hence warmer night time temps.
If the sun was the cause of warming, you would expect to see more daytime warming, when the sun is out. But instead, night temps are rising faster than day temps.
Bacisally the same idea for summer / winter.
Now I'm wondering if the overcast nights being warmer has more to do with mixing between layers of the atmosphere, in which case, the analogy is not as good. Anyone?
Dang yes you're right. I think there's something about the sequence
"Most Likely", "Likely", "Very Likely" that looks wrong, but yes when you think about it more ... Sorry for the false alarm
I think what you are saying makes sense. To paraphrase, the earth warms up during the day and cools off at night. So it seems logical that there would be more outgoing radiation after it has heated up and outgoing radiation is what is blocked.
Regarding your comment about heat coming into the earth - Infrared does not come in from the sun; at least nothing appreciable if anything at all. Ultraviolet comes in, impacts and warms the ground and the ground radiates the Infrared.
sailrick - 20
You got me thinking. It seems to me that because of the warmth of the day, you will have more moisture in the air than you would at night. Water vapor is a greenhouse gas.
CO2 would be more appreciable with less water vapor. During the day, for the sake of argument only because I have no idea what the numbers are, CO2 may represent 20% of the greenhouse gases while at night it may represent 80%
Is this what you are saying?
Also, I suppose whatever argument we come up with for the night/day issue is going to apply to the winter/summer issue.
Bob Guercio
To be precise, it's primarily visible light that warms the Earth's surface. UV light is mostly absorbed by the ozone layer.
why doesn't CO2 have an equal effect in blocking the heat coming into the earth as it does on blocking the heat leaving?
Your guess is correct: the sun, being a black body at ~5000 K, radiates mostly in the "visible" region, with a peak near 500 nm. The earth, also a black body, but at ~290 K, radiates in the infra-red, with a peak near 10,000 nm (10 um). Nice graphics here and here.
Greenhouse gases (CO2, H2O, CH4, etc) are transparent in the visible region, so absorb very little radiation from the sun. However, they do absorb strongly in several regions of the infra-red. Another nice graph there.
BTW, have you sent out press releases to the various media organisations? Might be worth it to get the guide a bit more widely disseminated.
Your usage of the "Human Fingerprint" in one of your replies leads me to reflect that it certainly is not the planet that is broken but rather humanity itself. The planet is quite capable of taking care of itself, and will on geologic time scales (say roughly another ~250Myr).
But it is true, her work looks damn good. :-)
For example, see Larry Gonick and Woollcott Smith's immortal book, The Cartoon Guide to Statistics? They open the chapter on testing hypotheses with a legal example about racial bias... I'm skipping the calculations here... in which the cartoon lawyer concludes triumphantly that the chances of getting an 80-person jury panel with only 4 African Americans work out to about .0000000000000000014.
"Is that a small number or a big number?" says the judge. The lawyer explains, It's less than the chances of getting three consecutive royal flushes in poker. So the judge rejects the hypothesis of random selection, confiding to the reader, "If I was in that poker game, I'd a started shootin' after the second royal flush..." Yeah.
Keep up the good work. Elise
I'd like to secong Phil's request for an article on the "Warm Arctic, cold continents" weather pattern. Cold weather is rapidly becoming the latest denier meme in the UK as we face our second (or third, depending on your location) really severe winter in a row. There are some interesting research articles around on WACCo (like the acronym Phil!) and on the hypothesis of reduced autumnal sea ice causing cold mid-latitude winter conditions, see for example the Arctric Report Card 2009 - Atmosphere or Petoukhov and Semenov 2010. But additionally some suggest that the remarkably low solar activity may be the cause, e.g. Lockwood et al 2010, at least for Europe. Given the Russian winter of 2005-06 (a focus of the Petoukhov paper) and the widespread nature of the 2009-2010 cold, maybe the Lockwood example doesn't work hemispherically? I know it seems strange to ask an Aussie about Pommie weather, especially during the Ashes :), but this is the best site on the Web for resources linked to debunking false skeptic arguments, or providing links to the good science.
I recommend that you switch the color of the primary text from blue to black. I just printed the document and the blue text is not easy to read. In addition, it would be less costly for everyone to print the docuemnt if the primary text were black.
I'm now posting the following note on comment threads to media articles that address climate change and encourage you to do follow suit.
"All of the anti-AGW poppycock posted on this comment thread is thoroughly debunked on the SkepticalScience website: http://www.skepticalscience.co.../ "
"To each his own."
Interesting concept Eric! That you 'refine' your arguments to make them harder to debunk. Surely the point of 'debunking' in this context is to illustrate faulty logic,reasoning and evidence, not just less artful 'arguments'. Since we are discussing physical phenomena in the real world, 'refinements to the argument' won't tip the physics in or against your favour.
This isn't a debating club where we 'win' if our sophistry is cleverer. This is the real world.
In the solutions threads in particular, the real world takes top priority and I agree with the consensus opinion in those threads. I think the difference is that it is much easier in the real world to test a solution than to test a model.
“Climate Scientist Warns World of Widespread Suffering If Further Climate Change Is Not Forestalled”
“ScienceDaily (Dec. 8, 2010) — One of the world's foremost experts on climate change is warning that if humans don't moderate their use of fossil fuels, there is a real possibility that we will face the environmental, societal and economic consequences of climate change faster than we can adapt to them.”
http://www.sciencedaily.com/releases/2010/12/101208125801.htm
In this case, the foremost expert is Lonnie Thompson, distinguished university professor in the School of Earth Sciences at Ohio State University.
Kudos to Dr. Thompson for telling it like it is!
John's Book
If you're interested in finding out the truth, you have to argue TO THE POINT, not just to avoid the point. Looking for a causal basis for global warming in cosmic rays is a lost cause.
Eric, I'd love for you to fully explain how that actually works (not how it could work or might work). But it belongs here.
(a) The example of positive feedback on page 3 has a caption saying “Warming causes oceans to give up more CO2”. Elsewhere we are told that the oceans are getting more acidic - i.e. more dissolved CO2. So which it? Is CO2 in the ocean going up or down or both? Is it different in different places? Is one from the deep sea and the other not? Why is it so paradoxical, if so?
(b) The graph of Build-up in Earth’s total heat content. My problem here is a bit harder to explain. I’m fascinated by that graph of increasing ocean heat energy. I’m also confused by its seeming variability. Why is it going up in such a stagger? Where is the heat going when it seems to level off every decade or so? So I look at the reference at the back and I
see it is from Murphy et al in 2009. Hmmm. 2009 that’s good - recent. But wait. Hang on. It says: “Figure redrawn on data from paper supplied by Murphy.” Hmmm. It would be better to get a graph taken from an actual paper. So I check around the site here doing searches for ocean heat content and I can’t find this graph or anything similar. I know it used to be here somewhere. Has it disappeared? All I can find are rebuttals of claims that the ocean cooled during the last decade. Not quite the same thing, though, is it? Why isn’t there more information on this graph? How reliable is it given that ocean temperature data are supposedly so vexatious and that reliable temperature measurements, we are told, are almost non-existent until recently? How is heat content calculated, roughly? Does it include the whole ocean or is it just a part? I really feel that this graph needs more explanation. It is probably the most interesting graph I’ve seen illustrating global warming. If it is reliable, why isn’t it shown more often? You can see how suspicions arise in the mind just following this line of thought.
I would really appreciate it if someone could provide satisfactory answers to these questions for me - pointing elsewhere if necessary. I would be even more delighted if my queries give rise to improvements to the clarity of the site and the guide too. Please keep up the good work, it is greatly appreciated.
CO2 in the ocean is going up. The ocean is building up CO2 because it's absorbing much of the CO2 we're emitting. But as the ocean warms, it's ability to absorb CO2 is lessening. So we are seeing more of our CO2 emissions remain in the atmosphere each year (the airborne fraction). The trend in the airborne fraction is slight, teetering on statistical significance.
"I’m fascinated by that graph of increasing ocean heat energy. I’m also confused by its seeming variability. Why is it going up in such a stagger?"
I haven't discussed this with Dan Murphy, author of the paper where that graph came from, but my speculation is the variability in the ocean heat graph is because he calculates total ocean heat from the upper ocean heat content. Upper ocean heat shows more variability compared to the total ocean heat calculated to greater depths because the upper ocean exchanges heat with the deeper layers. This is why when you see graphs of heat over 0 to 700 metres, the heat content jumps up and down while graphs of heat down to 2000 metres deep show a more monotonic increase in heat.
To calculate ocean heat back to 1950, Murphy had to use ocean data calculated from measurements of the upper ocean. To extrapolate this to deeper waters, he used studies that found the heat accumulating in the deep ocean was around 30% of the heat accumulating in the upper ocean. Thus if he'd have had access to direct ocean heat measurements down to the abyssal depths, I'm guessing the ocean heat graph would've shown less year to year variability. That's just speculation on my part.
The following graphic from NOAA gives an idea of John what is talking about:
A simplified version is that CO2 is less soluble in the oceans at higher temperatures. You can see the band of CO2 flux to the atmosphere around the tropical regions, where water temperatures are higher, and the absorption of CO2 in cooler waters (Note the obvious warming around Antarctica & flux of CO2 to the atmosphere).
So you can see that both absorption and release of CO2 from the oceans can occur at the same time, it's a matter of temperature, the net effect at the moment is seeing CO2 build up in the ocean, as also evidenced by increasing ocean acidification measurements and declines in carbonate saturation states. So there's no contradiction.
Now as the oceans continue to absorb more heat their ability to store CO2 will diminish, and we'll see the red regions in the graphic start to rise.