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Sun Not a Significant Driver of Climate Change
damn_registrars writes "Scientists from Edinburgh, Scotland have recently published a study based on 1,000 years of climate data. They have compared the effects of differing factors including volcanic activity, solar activity, and greenhouse gases to find which has the most profound effect on climate. They have concluded that the driving factor since 1900 has been greenhouse gases."
In related news, angered Sun goes supernova, replies "I'm not a significant what!?"
You can hold down the "B" button for continuous firing.
c. 1350-1850 A.D. Increased volcanic activity was noted but is only one of several (possibly compounding) possible factors.
Besides, changes in solar activity levels may have a delayed impact via ice melt, changes in atmospheric circulation, etc.
Yeah, ever since Oracle bought them . . .
Schroedinger's Brexit: The UK is both in and out of the EU at the same time!
Yep. Science is now for true believers. The method has been abandoned. Anyone who disagrees or is skeptical is to be ridiculed and destroyed. Yay fascism, boo debate.
How did the world warm up and cool down before then? Perhaps that is relevant?
I don't know what that was, but it was sarcastic rather that conservative or liberal.
Now a scientific mind, if one were actually interested in science - well a scientific mind would look at this study and say, well then I guess we can conclude the low period of solar activity we are in has nothing to do with the now decade long pause in global warming.
So even though we've poured many, many tons of CO2 into the atmosphere (well, other countries anyway, the U.S. having done their part in lowering emissions already) we still don't see significant warming increases.
I wonder, is it possible you can draw a scientific conclusion from these interesting facts in combination?
Probably not, for the religious fanatics never have been able to abandon their cherished gods, no matter how bitter the Kool-Aid becomes.
"There is more worth loving than we have strength to love." - Brian Jay Stanley
I see you did not actually look at the Nature paper they published. The title is: "Small influence of solar variability on climate over the past millennium". The key word is variability. As in variations in solar activity aren't a major driver in climate change, not the Sun itself.
In other words, you are the loon.
false, the Sun and insolation drives climate and climate change, greenhouse gas effects are secondary. First thing one learns in any serious geophysics course.
Well tell that to my dog Max who only naps in the sun beams.
You'll note this study does not cover any serious fraction of the Earth's history, a couple thousand years is a sneeze.
Do you know how derivatives work? Probably not, so I'll remind you. The derivative of a function is its rate of change. The derivative of a constant is always zero, no matter how big that constant is. So if you have a small function that's rapidly fluctuating, it can have a big derivative, whereas a really large signal that's barely changing at all can have a small derivative.
Yes, almost all of the Earth's energy comes from the Sun. But that doesn't matter, because we're talking about climate change. Is the derivative of the Sun's output power big enough to explain the derivative of the Earth's temperature, and are the two at all correlated? Some people who are much, MUCH smarter than you, have looked at the data, and decided that the answer is no.
As an aside, this is why math education is important even for people not interested in STEM fields. You can't think logically when you don't understand such basic concepts.
When those who disagree or are skeptical are funded by self-interested oil companies, or blend their criticism of scientific papers with simple political baggage, then yes, they are ridiculed.
When those who disagree or are skeptical do so in a way that raises a point which has already been addressed and discounted by experts in the field, then yes, they are ridiculed.
On the other hand, you are right to feel that the 'agree' side (for lack of a better word) has a mostly politicized and unthinking membership, too. For me, that problem manifests itself in the (as I see it) idiotic opposition to non-GHG-emitting power sources like fission, fusion, tidal, etc. on environmental grounds.
But you shouldn't let the existence of that mob blind you to the fact that the evidence to date supports the theory that human greenhouse gas emissions are warming the climate, and that a warmer climate will entail significant practical problems, on a human scale at least.
false, the Sun and insolation drives climate and climate change, greenhouse gas effects are secondary. First thing one learns in any serious geophysics course.
I made a mistake and read the referenced article. When will I learn...
I think what it says is that the computer models don't show significant change when the solar radiation input is modified. I don't think I'm splitting hairs here. They aren't saying that the climate is not affected by changes in solar radiation.
The computer models are just approximations for the climate. They have been proven to be bad at predicting the future (like the current 10 year lull in warming). Wake me up when the computer models account for the ice ages.
Bah!
I don't need to calculate shit. The scientists did, and they're better at this than I am.
You don't know what you're talking. Seriously, you have NO FUCKING CLUE. Do you tell the contractors what thickness screws to use in your roof? Do you tell your electrician what gauge wire he should run? Do you tell your doctor which drug he should prescribe? So why the fuck do you think you can tell scientists how to better do their job?
This idiot culture, where we glorify "folksy wisdom" and condemn "book-learnin" is going to be the death of us.
Yep. Science is now for true believers. The method has been abandoned. Anyone who disagrees or is skeptical is to be ridiculed and destroyed. Yay fascism, boo debate.
Honest skepticism is important to Science: scientific theories are considered reliable not because of the strong arguments in favor of them, but because they survive scientific challenge.
But its equally important to recognize that just because skepticism is important to Science, doesn't make all skeptical commentary equally valid, and more importantly it doesn't make all sides equally valid. Its important for scientists to continue to question General Relativity. But when the rubber meets the road, I'm trusting Relativity over any other skeptical invention intended to overturn it. Relativity has survived a lot of challenges. Upstart competitors haven't.
Climatology is an imperfect Science, and its being refined all the time. But Relativity didn't overthrow Newton: Newton is so well tested and established nothing is going to overturn Newtonian gravity because it explains too much of the world too accurately. Relativity *refines* Newtonian gravity in extreme situations Newton was never checked against. All competitors to Einstein are also competitors to Newton: we all know Newton was close enough in most cases: its extraordinarily unlikely anyone is going to discover a normal situation where Newton just plain fails. Anyone wanting to replace Einstein has to not only do better than Relativity, but also better than Newton. Similarly, Climatology is being refined, but the odds are not high that its going to simply fall apart one day. Thinking that will happen represents a complete misunderstanding of how Science itself works.
OK, so if we have a bowl of water under a heat lamp, and we turn the lamp on and off at a steady rate, say, toggle it twice a minute. Now we measure the temperature of the bowl of water, and it's average over the the week is pretty consistent. Now let's say we came in to measure it one day and there's some plastic wrap across the surface of the bowl. We measure the water and the temperature is increased. We say, Hey, the greenhouse effect caused by the plastic wrap is causing a change in temperature.
Then some morons say, "But the Steady Heat Lamp! The Heat comes from the Heat Lamp!" We're talking about an increase or change in temperature, and you're saying it doesn't make logical sense that variation in the heat lamp activity isn't a major driver of change to the climate because the heat lamp cycle is steady?
Please explain your troll logic, because I need a good laugh.
That's exactly what will happen. A while back, a friend of mine described the Five Stages Of Climate Change Denial:
1. It's not happening.
2. If it is happening, humans have nothing to do with it.
3. If it's happening and we're causing it, we can't do anything about it because that would cost too much.
4. It's happening and we're causing it, but that's a good thing.
5. If those damned liberals hadn't interfered with all their regulations, the market would have taken care of this problem!
Mostly we see #1-3 right now, but I've seen #4 too, and I'm sure #5 will be along any time.
The correlation between ignorance of statistics and using "correlation is not causation" as an argument is close to 1.
Scientists from Edinburgh, Scotland have recently published a study showing that the sun is not a significant driver of recent climate change.
Of course they think that - there is no sun in Edinburgh.
Look at it this way. The variance in solar radiation over a thousand year period is less than 0.01% of the variability seen in global temperature increase during the same period. In other words, the variability in solar radiative output (insolation) is far too small to explain the wide range of variance in global warming since the onset of the industrial revolution. In contrast, increase in carbon dioxide, as expected from the physics of its absorbtion spectrum explains cha.nge in temperature quite well (in fact it explains it rather well over the past 500 million years if isotope data is evalatuated).
It should be noted that there is no 18 years pause in global warming of sea temperature records. In fact, if one uses the arbitrary 18 year intervals to assess global atmospheric climate change, the record still shows global warming. Its just that within the last 18 years it has not been increasing as fast as the average over the last 100. Consequently, no one should be surprised that November 2013 proved to be the warmest November in recorded human history.
"They aren't saying that the climate is not affected by changes in solar radiation."
That's what they're saying. But they're offering absolutely nothing new here. This is merely a review of others' past (perhaps too long past) work.
What they do say (section 6.4, "climate change", which is their conclusive paragraph) is:
"Extensive climate model studies have indicated that the models can only reproduce the late twentieth century warming when anthropogenic forcing is included, in addition to the solar and volcanic forcings [IPCC, 2007]. The change in solar radiative forcing since 1750 was estimated..."
Here is a plain English translation. (This bit is pretty important.)
"Climate model studies by other people can only reproduce the late twentieth century warming when anthropogenic radiative forcing is included."
This paper actually claims no new evidence that Anthropogenic Global Warming (CO2 AGW) is actually occurring. Their own statements (their own concluding paragraph above if you read the whole thing) says that they are relying on past studies to come to that conclusion. Other people concluded that. And they cite as a reference, an old IPCC report. The newer IPCC report is much toned down from the 2007 version they cite.
Not much to see here, and certainly nothing new, by their own admission. Move along now.
I should also point out that the entire concept of "radiative forcing" this is based on was refuted a few years ago, and so far that refutation has not been successfully challenged.
The Sun is a primary energy source that is more constant than what the deniers are saying. When the Sun was supposed to reach a high in the 11 year cycle it missed it's mark this last cycle max. Still the climate data continues to show a steady rise in global temperatures. Even elevated CMEs (Coronal Mass Ejections) are not affecting climate change as most of the energy misses our little spit ball compared to the size of the energy wave. Even a direct CME impact would be a short term effect. The slow elevation of solar emissions would take Milena to affect the climate to the levels we are seeing.
What is left is the rise in carbon and other GHGs we are filling our thin gas envelope with. I don't need to go into the particle physics side of how much energy the element carbon stores Watch the Exxon commercial about the energy output of petroleum products.
actually, even 1000 years ago in the "medieval warm period", the average global temperature may well have been as warm or warmer than the recent 15 years, the errors in estimation of magnitude are quite large.
There's a great video by Bill Nye performing this very experiment.
Check it out at result of carbon dioxide in atmosphere
What the deniers are claiming is that somehow the bulbs really aren't of equal intensity, which in this experiment is easily shown false since one can place a second pair of thermometers on the top of the vessels at equal distances from their respective lamps and readily demonstrate that for these two thermometers the temperature outside the vessels are the same. Not surprisingly the deniers ignore the findings of the scientific article, which demonstrates that at least for the last 1000 years (of which the last 100 has seen the most warming) solar output has been relatively stable by comparison, with very little variation outside of the usual solar cycles that amounts to less than 0.01% difference in output from maximum to minimum.
The UK getting record snowfall despite AGWers claiming the UK wouldn't see snow after 2008.
It goes back and forth. In 2000, they were saying that AGW would get rid of snow. In 2008, they were saying the snow was a result of AGW.
No doubt you will see a reversal again when there is no snow.
"First they came for the slanderers and i said nothing."
And one more. Apologies for the multiple posts. Re: the argument about "radiative forcing" in atmospheric gases.
Arguments refuting this idea are available HERE and HERE (pdf).
Don't get me started on volcanoes. Even up to 5 years ago, many in the climate science said that volcanoes play no significant role in the present climate changes. This year they finally began to retract that belief, based on actually beginning to look at the data..
Grasping at straws indeed. This is the map for November, and you're telling me that the AGW folks are grasping at straws?
http://www.ncdc.noaa.gov/sotc/service/global/map-percentile-mntp/201311.gif
Well when you go looking for evidence, you tend to find it. Both sides in any debate like this will present veritable mountains of evidence in favour of their position, we've seen it time and again. It doesn't make you right.
Citation? Also localized event, also short dips do not contradict long-term trends, also potentially not all that remarkable if it's only the ninth or tenth coldest on record (the statement is pretty non-specific).
Who said that? Someone whose opinion actually matters in this debate or just some newspaper reporter on a slow day?
Well how cold does it usually get in that part of Antarctica? If it gets within a few degrees most years, then that's not news.
As opposed to a typical winter, which sees... how many? Really, this needs to be placed in context.
Who said that? The people who made the report or someone else? If someone else, then I bet they're disagreeing with the people who did make the report. So what is the point of disagreement? What part of the IPCC methodology was flawed? Who reached this conclusion and how did they reach it? There are no details to go on here.
Lies. Lies and deceptions. If it were so 'obvious' there would not be such protracted debate over the issue. Truth of the matter is, most people don't know what to think any more. Both sides seem to have so much evidence that trying to sift through it all is an exercise in futility. We've got to the point where it's a handful of 'true believers' on both sides who are absolutely convinced they are right, and a majority of confused individuals who don't know what side to take if they should even be taking a side at all.
Yep.
Nope. You're very clearly one of the true believers, you're going to find what you want to find and believe that it was just coincidence that all the evidence reinforced what you thought already.
Don't believe me? Look at what you just typed. You are not looking for the truth because you believe you already found it, so what would be the point of looking further?
"What is left is the rise in carbon and other GHGs we are filling our thin gas envelope with."
There are LOTS of things "left". In fact there are so many variables, creating so much "noise", than any "signal" from AGW has been extremely difficult to detect (and indeed, might not even exist).
The Exxon argument is a straw-man. We know that burning fuel adds heat to the environment completely aside from any "GHG" forcing. One is not evidence of the other.
Neither one of the fine articles linked to in the summary mention radiative forcing. Neither do either of the two references you cite as proofs that radiative forcing has been debunked. The Wikipedia describes radiative forcing as:
In climate science, radiative forcing is defined as the difference of radiant energy received by the earth and energy radiated back to space.
There is no mention of it being refuted (or even controversial); not in the Wikipedia article and not in the two references you cited. In fact, since radiative forcing is a rather simple definition it is hard to imagine how it could be refutable.
Furthermore, this reference of yours, despite having pretty pictures, seems to be based on utter nonsense with the main point being:
Internal [actual greenhouse] temperature cannot exceed maximum strength of solar heating input.
This is utter nonsense because it makes a direct comparison between heat and temperature. It would be helpful if the article mentioned what the temperature limit of the strength of solar heating was. But if they did that, the utter nonsense would be apparent because the temperature of a solar furnace can be many thousands of degrees (either Celsius or Fahrenheit) so if there is limiting temperature, it must be so high as to be meaningless in discussions of global warming.
Another way to see it is that if you can trap solar energy in a box that has perfect insulation (energy comes in but it does not go out) then the temperature of the box will rise without limit. Of course there is no such thing as a perfect insulator so there are limits to how high a temperature you can achieve but these limits are not a direct property of the solar radiation. There is a temperature limit, of a sort, to solar radiation but the limit is the temperature of the surface of the Sun, which again has no bearing on discussion of global warming.
We don't see the world as it is, we see it as we are.
-- Anais Nin
Agree that the Sun is the source of all the energy in the climate. The composition of the earth's Atmosphere, oceans and crust, have been likened to the "thermostat" in that they can absorb or reflect that energy to varying degrees.
CO2 has been a major factor in climate for a looooong time, at least as far back as the Cambrian explosion since CO2 is what melted "snowball" earth prior to the Cambrian explosion. CO2 can be both a "feedback" (melting permafrost) or a "forcing" (volcanos, human emissions). When acting as a feedback it always amplifies the direction of the change. We have known about CO2's major role since the 1950's when improved spectrometers finally pinned down it's role in the ice ages, ( Milankovich cycles alone cannot account for the magnitude of the changes observed in the ice ages).
Our best estimates of an important metric called "climate sensitivity" come from Fourier's formula and paleoclimatology (aka-geology). Fourier's formula alone gives ~1.5C rise for a doubling of CO2 but that assumes Earth is an ideal black body, which it is not. Adding geological evidence to estimate the feedback component brings it up to ~3.0C, the error bars are between 1.5c and 4.5C for a doubling of CO2, with the upper limit being far less certain then the lower. The uncertainty at the upper end is due to the lack of knowledge on things like frozen methane in deep ocean beds. The recent IPCC report downgraded the risk from sudden "tipping points" so the current high end estimate of climate sensitivity (whatever it is exactly) has a smidge more certainty than the previous report.
Disclaimer, IANACS, just a layman with a 30yr interest in the subject, don't rely on what my aging neurons tell you, WP is your friend for climate facts and trivia and I'm more than happy to be (politely) corrected.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
You have some catching up to do. Because there are not sufficent permanent temp stations in the Arctic, the amount of warming seen there has been seriously underestimated.
Rapid Arctic warming is one of the features of global warming / climate change and it should have struck the doubters as very strange that the most staggering decrease in the volume of Arctic ice was occurring during a period where there was SUPPOSEDLY no warming.
And, it's always been grossly inaccurate to say "no warming for 17 yrs" as temps have been slowly rising in places where there are adequate numbers of stations.
The correct statement is "no statistically significant warming". That is NOT the same as saying "no warming" or "we're in a cooling period".
Pain is merely failure leaving the body
God I love how you guys (both sides) goes totally ballistic about some minor detail of a post. No point in trying to deduce what someone said, if there is the smallest amount of unfactual commentary or the slightest error, they will be bombed back to kingdom come.
Mars used to have plenty of water, a comfortable atmosphere, and perhaps some living microbes.
Mars had undergone a very nasty climate change, and the peculiar thing is, Mars has no human.
Anyone care to explain what happened to Mars (without the involving the Homo Sapiens Sapiens) ?
Muchas Gracias, Señor Edward Snowden !
Frankly, that "Climate Sophistry" page is absurd. Never mind that two fifths of the article is a section entitled "Modern Philosophical Analysis", the basic premise of the article displays a basic misunderstanding of fact.
The article claims (in the most obtuse way imaginable) that the way the so-called "greenhouse effect" does not mirror the actual observed behaviour of greenhouses here on Earth.
If the authour had even a basic grounding in science he would know that "the greenhouse effect" is NOT how greenhouses retain heat. The greenhouse effect was so named in 1824 by analogy to the effects observed in a greenhouse, not because the mechanism was the same.
Is "greenhouse effect" therefore a bad name for way radiation is trapped in a planet's atmosphere? Maybe, but in almost any introductory text on the subject you will see phrases like "would have a sort of greenhouse effect" that clearly show the term to be descriptive, not prescriptive.
Regardless, I cannot understand how any reasonable person could make that leap from "bad name" to "ALL CLIMATE SCIENCE IS LIEZ OMG".
If it's in you sig, it's in your post.
A perfect example of Dunning-Kruger at play.
The "hockey stick" was from actual data! D'oh!
Temperatures have risen, and the changes in atmospheric radiative properties have been observed and confirmed for ever.
There was a major prediction about global warming in a Nature article in 1980. The understanding then was substantially less mature and there was no clear-cut observed signal in the data at that time (as we know now, fossil fuel soot was temporarily counteracting increased greenhouse forcing). Since then, observed data have turned out the way that it was predicted then, and the understanding of the fundamental physics then is the same as now.
The predictions are not groundless, and the models aren't wrong.
The hypotheses HAVE been reinforced and confirmed by observable facts, over and over and and over and over and over.
Since postscripts seem to be popular in this thread, I will add one here containing direct quotes from that article.
(I will not get into the maths here to keep this article readable for non-math people.)
Judging by the contents of the article, I would suggest that the exclusion of the maths was also to keep the article writable for non-math people.
The climate science version of the greenhouse effect, [is an] example of the creation of a simulacrum [...] And just like the Matrix, only a few people are able to see through it.
If it's in you sig, it's in your post.
I'm sitting right now in Karlsruhe, germany. The temperature according to the yahoo weather app is 13 degrees centigrade. (Yahoo is usually wrong, that means weather is a bit better and a bit warmer actually, but I'm to lazy to dig up an accurate number, as it is not important). Just for future reference if this gets digged out by climate researchers or idiots like you in a few hundret years: today is 24th of december, the year is 2013 (christian time). I repeat he fucking temperature outside is +13 degrees centigrade. ... more snow, snow storms, blizzards and sledges? Ha? What do you think, why that is so? BECAUSE europe is supposed to be covered with snow, from north italy, north spain over france and germany and poland into siberia in the east up to the north pole. With only exceptions being parts of ireland, island and wales and perhaps england. It is supposed to be covered in snow like it always was around christmas, except for the last 20 - 30 years. ... according to the climate of 30, 50 or 100 years ago. But it is, depending on your region: 13, 20 or MORE degrees (centigrade) to warm!
For you morons who don't get it to the slightest: TODAY IS CHRISTMAS! What do you think why every christmas story on the world involves snow? Snowy regions, coldness and snow, snow
HOWEVER: there is no snow! It is fucking 13 degrees to warm for it. It is supposed to have something like -10 degrees here, going down at nights to -15 to -20. But it is not. It was not happening to be that cold since 25 or more years.
With the raw exception of a winter where it actually is a little bit below zero. And then all scream: seeeeee! It is cold! There is no global warming!
I repeat in case you did not get it: right now northern europe should be under a snow cover
(And yes, there are plenty of negative effects for not freezing, like having a mosquito plague every summer)
Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
You must have missed that whole no warming in 17 years thing.
You must have fallen for the climate deniers' play on public ignorance. The full and correct statement is this: "There has been no statistically significant warming in the past 15 years."
Notice that the word "statistically" is emphasized because it makes all the difference. If you remove it, the statement will be about plain average temperature. But as it is written above with the word "statistically" in place, the statement is about error bars around the average. The longer timespan you measure, the smaller the error bars become. 15 years timespan is just barely too short to make definite conclusions. But 16 years or more is enough and the conclusion is that warming is still ongoing.
You're probably just trolling, but you're currently modded +3, so I'm going to reply.
Such as the US just had one of the 10 coldest years on record.
Minima and maxima are by definition outliers. While there is an entire body of statistical literature on outliers, they're not used to determine trends or draw conclusions, because they are essentially (bad) luck.
The UK getting record snowfall despite AGWers claiming the UK wouldn't see snow after 2008.
Sources please. Because no serious scientist would ever make such a definite statement. A mathematician might, but science, including climate science, is all about statistics and probabilities. In any field. Perhaps you mean this article in the Independent? The scientist quoted says that in 20 years time, snowfall will become a rare and exciting event. So I think that we can consider him proven wrong if it snows in southern England for say, five out of ten years from 2020 onwards?
Antarctica getting within .5 degrees of the coldest recorded temperature on earth.
Antarctica is a huge and largely unexplored continent. Finding a new minimum in a situation where very little information was available is hardly suprising, and certainly shouldn't be used to draw any conclusions.
Along with 2000 record low temperatures recorded over the last couple of months.
Among how many measurements? Record since when? And see above about outliers.
Add that to the IPCC report showing no warming for 17 years.
Indeed. They also investigated why, but you're conveniently leaving that out since it doesn't fit your agenda. I'll give you a hand as to the causes according to the IPCC: an exceptionally quiet sun (there's another of those outliers), several smaller volcanic eruptions increasing the amount of dust in the upper atmosphere, and an increase in dust in the lower atmosphere, probably due to industrial pollution. According to the IPCC, the discrepancy is partially explained by these three causes (which weren't put into the models when the prediction was made), and the remaining difference is small enough to fit within the natural variation (stochasticity) of the models, or be attributed to errors in the models.
Its become pretty obvious which side has been lying. Now they are grasping at straws to report ANYTHING that shows their side "might" be right.
Sorry, this is not the 18th century anymore. Science is a quantitative affair, and necessarily so, because our world isn't binary. The question is not whether there is human-induced climate change, the question is how strong an effect humans are having on the biosphere. Maybe it's small enough to be negligible (probably not, according to what we currently know), maybe it's huge and a danger, but it's a quantitative question.
I'm going to ignore the alarmists and look at the evidence myself. If AGW was real, they wouldn't have to lie as often and at least ONE of their predictions would have happened.
Excellent idea. Try reading the IPCC report instead of The Drudge Report and you might find some.
You wrote (emphasis mine):
The Earth's orbital changes around the Sun varies from more circular to more elliptical and its axis wobble changes and the net effect is that the different solar inputs are what causes the major climate shift on about a 110,000 year cycle.
From the /. summary (emphasis mine):
They have concluded that the driving factor since 1900 has been greenhouse gases.
From the U of Edinburgh press release (emphasis mine):
Research examining the causes of climate change in the northern hemisphere over the past 1000 years has shown that until the year 1800, the key driver of periodic changes in climate was volcanic eruptions.
These tend to prevent sunlight reaching the Earth, causing cool, drier weather. Since 1900, greenhouse gases have been the primary cause of climate change.
Now let me tie it all together for you. Let's say we assume:
(1) Over the course of hundreds of thousands of years, variations in solar radiation are the strongest determinants of global temperature.
(2) Over the course of the last thousand years, volcano eruptions have been the strongest determinants of global temperature.
(3) Over the last hundred years, anthropogenic greenhouse gasses are the strongest determinants of global temperature.
Here's the important point: you can believe ALL THREE of these things without the least contradiction. Denialist arguments seem to assume that any dominant factor must be dominant in every past period and over every timescale. This is why people scratch their heads at the denialists' "gotchas!", e.g. "Gotcha! There were no SUVs in the medieval warm period." So what? It's a straw argument. Nobody ever claimed that *all* past climate variation was due to greenhouse gasses, much less *anthropogenic* greenhouse gasses.
Post may contain irony: discontinue use if experiencing mood swings, nausea or elevated blood pressure.
Solar output has been gradually increasing for a long time, and some "skeptics" claim this is the real reason for the climate changes we've observed (ie: not greenhouse gas emissions). But the emerging consensus is that this increase in solar output is nowhere near enough to account for the warming we've seen in the last century.
XML is like violence. If it doesn't solve your problem, you're not using enough of it. --AC
Water vapor doesn't last enough to be a forcing so it's a feedback. When there a long-lived GHGs, that can raise the temperature enough to evaporate sufficient amounts of water, then its effect becomes large enough that it's dominant.
From http://en.wikipedia.org/wiki/Global-warming_potential
Although water vapour has a significant influence with regard to absorbing infrared radiation (which is the green house effect; see greenhouse gas), its GWP is not calculated. Its concentration in the atmosphere mainly depends on air temperature. There is no possibility to directly influence atmospheric water vapour concentration
Pain is merely failure leaving the body
After Willard Watts' Junior Woodchucks went around identifying good and bad stations, researchers used the "good" stations to derive the temps and got almost exactly the same results - indicating that the correction factors that's been used for decades by the USHCN are reliable.
Pain is merely failure leaving the body
Mann's hockey stick was created with adjusted data. The unadjusted data looks entirely different. There was nothing actual about it.