Skeptical Science Comments

Comment on Michaels Misrepresents Nordhaus and Scientific Evidence in General

Utahn

Well said. Its amazing, almost any claim I've seen Michaels make is a distortion of the truth when you actually go to the source...

Comment on Michaels Misrepresents Nordhaus and Scientific Evidence in General

dana1981

Also note that Nordhaus is one of the most conservative economists when it comes to estimating the costs of climate change, i.e. see here and here, and nevertheless supports putting a price on carbon emissions.

Comment on Medieval Warm Period was warmer

jzk

"Also, "...to a peak of warming". Really? On what basis do you claim that current temperatures are a peak? All available evidence indicates that they are just a spot on a continuing upward slope."

CB,

Peak so far. If temperatures continue upwards, then it would be fair to redo the graph. Then, there would be a new "warmest" decade to use. Compare the warmest decade currently to the warmest decade in the MWP. Using Mann's data would still yield your desired result that the MWP was cooler than today, but it would be doing it in a fair presentation of the data. The comparison in the charts presented is meaningless. As I stated, I could show the same thing by comparing any time period to a shorter time period contained in itself. What would that show? Nothing.

Comment on Michaels Misrepresents Nordhaus and Scientific Evidence in General

dana1981

Nice post Alex. You just have to shake your head when the fake skeptics insist their (mis)interpretations of the climate science/economics literature are correct, and the scientists' interpretations of their own work are wrong. Nordhaus has supported a carbon pricing system for decades, and it's a gross misrepresentation to use his work to argue against such a system.

Comment on Medieval Warm Period was warmer

jzk

Composer99,

Mann didn't take his chart and compare it to 1999-2008, skeptical science did.

Comment on Volcanic Influence on the Little Ice Age

CBDunkerson

owl905, you seem to be unable to differentiate between things that you (for whatever reason) assume I meant and what I actually meant (and/or said). This makes meaningful communication effectively impossible.

Comment on Volcanic Influence on the Little Ice Age

owl905

@CB - your response doesn't match your original claim. And your response indicating that I either agree or disagree with Miller is untrue - I disagreed with your statement that the volcanic effect lingered for centuries.

As for evidence that supports a better interpretation, read Mann - "does not require a solar trigger", but probably still requires that notorious weaker solar source. And that is not a feedback. And it makes a mess of the 'self-sustaining' phrase.

Also note that Mann's paper shows no 'four super-eruptions' in the 1375-1400 interval, and the graph posted by muoncounter properly shows a real possibility from the mystery 1458 timeframe.

Comment on Medieval Warm Period was warmer

Composer99

jzk:

The historical instrumental temperature record (those graphs of NASA GISS, UAH, HadCRUT, and the like) are compared to an arbitrarily defined 30-year climatological baseline period in order to clarify temperature anomaly information.

I am not aware of any serious valid criticism of this practice.

As long as the uncertainties and caveats due to proxy data (the differences in practice) are made clear in the applicable literature, is there some appreciable difference, in principle, between this standard practice and what has been done in Mann et al 2009 with regards to the Medieval Climate Anomaly?

Comment on Medieval Warm Period was warmer

CBDunkerson

jzk, again... the claim that the several hundred year MWP was warmer than current temperatures comes from skeptics. SkS showing a graphic proving that claim false is thus perfectly reasonable. Rather than complaining here about a graphic disproving the claim, perhaps you should be instructing 'skeptics' on how to make less ridiculous arguments.

Also, "...to a peak of warming". Really? On what basis do you claim that current temperatures are a peak? All available evidence indicates that they are just a spot on a continuing upward slope.

"Compare the warmest decade of the MWP to the warmest decade now. That would be a fair comparison"

It would not be the comparison that 'skeptics' constantly make and it is not possible with current data. We do not have sufficiently detailed geographic and temporal data to create a map of (or even conclusively identify) the warmest decade of the MWP. Though again, I find it odd that you suggest that the peak of the MWP should be compared to the not-peak of the current warming to be 'fair'. Surely, if we were really trying to determine whether modern warming is within the range of natural variability (as claimed) we should compare the peak of the MWP to the eventual future peak of the modern warming, no?

Comment on Medieval Warm Period was warmer

Tom Curtis

jzk @58: "I just want to promote good science"

No, you want to apply a cooky cutter standard without any understanding of context or purpose. Such "cooky cutter standards" cannot exist in real life, except as reduced to basic principle:

1) Do not present false information;
2) Do not make unjustified inferences; and
3) Always let readers know what you have done, so that they can check it for themselves.

If you want to argue the article represents bad science, you have to engage with the argument in the article and show how it is unjustified based on available evidence. Failing to do that, at best you can show that there are people out there easily confused by a misunderstanding the author failed to consider (possibly because it is so obviously an unjustified inference).

Comment on Medieval Warm Period was warmer

Tom Curtis

jzk @56, your claims are unjustified. To begin with, Mann et al 2009 make exactly the sort of comparison you claim to be unjustified. Specifically, figure one (intermediate article above) is a comparison of temperatures over a three century period in the Middle Ages to a thirty year period in the twentieth century.

With a bit more work, John Cook could have compressed his two figures (from Mann et al 2009) into one by showing the MWP compared to a 1999-2008 baseline. Clearly, therefore, there is no inprinciple difference between Cook's comparison and the data presentation in the original graph. If there were any merit to your claim that such comparisons are bad science, then you must reject that chart itself for not (impossibly) choosing a three century baseline in calculating the anomalies.

As it stands, I suspect editors and reviewers of Science Magazine know a little about what constitutes good and bad science. They appear to have judged this comparison of a three century interval with a thirty year interval good science for the very simple reason that, without such comparisons the mean temperature cannot be differences cannot be shown at all.

That is something you should consider seriously. Without the sort of comparison, which you in a now deleted post called "absolute fraud" the information in the anomaly map could not have been presented at all. So yours is a standard which amounts to censorship of the data.

The question with a diagram in science is always only three things: Does the diagram accurately present the information collected by the study; do the inferences drawn from the information in the graphic actually follow from that information; and is the graphic presented in a way that avoids confusion.

On these three counts, nothing prevents a comparison of three centuries data to a single decade. What is necessary for such a comparison is that the conclusions be appropriately restricted, and that the data be presented in such a way as to avoid unwarranted conclusions. On the first point, (accuracy of information) there is no question; on the second, as the unwarranted inference you are making is not made by either Mann et al, nor John Cook there has yet to be shown a problem. On the third point, I believe that a caution to the effect that the data presented does not show that all decades within the MWP where cooler than the 2000s. But that is not a question of poor science, but of poor presentation.

Comment on Medieval Warm Period was warmer

jzk

"a graphic comparing temperatures over those two time periods seems a perfectly reasonable response."

CB,

But that is not what you did. You compared several hundred years that contained both warming and cooling to a peak of warming. That is no comparison at all. Compare the warmest decade of the MWP to the warmest decade now. That would be a fair comparison, and if you used Mann's data, it would still confirm your case which seems to be, "yeah some warming then, but not as much as now." I just want to promote good science.

Comment on Medieval Warm Period was warmer

CBDunkerson

jzk, given that false claims that 'the MWP was warmer than current temperatures' are made on a regular basis, a graphic comparing temperatures over those two time periods seems a perfectly reasonable response.

Yes, in an ideal world we would be able to tell the deniers, 'comparing multiple centuries to a few years is "meaningless and bad science"' and they would shut up and go away. This is not an ideal world. Instead, we present a direct comparison of the exact things they cited.

If they want to change their claim to 'some decade in the MWP may have been warmer than the past decade' we can switch to pointing out that all available evidence suggests otherwise. Until then I really don't see the problem in providing direct evidence that the claim they are making is false.

Comment on Volcanic Influence on the Little Ice Age

muoncounter

A new discussion of the 'missing' volcano just popped up. Well-illustrated and sourced, including a figure from the new Mann paper.

It sure looks like these coolings are short-lived transients.

Comment on Still Going Down the Up Escalator

Dikran Marsupial

piratelooksat50 From a statistical and scientific perspective there is no fuss, it is all really quite straighforward. The fuss arises when those who don't understand the science and/or statistics argue that climate change has stopped [or other such claims] on the basis of the lack of statistically significant warming over a timescale to short to expect a statistically significant trend whether the climate was warming at the expected rate or not.

It is very much the purpose of SkS to point out such canards, and explain why they are specious. The escalator diagram is a very good example of this.

Comment on Volcanic Influence on the Little Ice Age

MangoChutney

@dana1981 #13

Thank you dana, this is as I thought and I agree "if this theory is correct".

Comment on Medieval Warm Period was warmer

jzk

Tom,

"There is, however, some justification for it in this instance."

While you may have evidence to suggest that the MWP was not that warm, that warming will continue, that the decade chosen will turn out to be a cool decade, or anything else related to this issue, comparing those two charts is meaningless and bad science. That is my only point. In fact, it detracts from the real case that you are making because it appears to be manipulation.

Comment on Still Going Down the Up Escalator

apiratelooksat50

Personally, I don't see what all the fuss is about. There are obviously periods of cooling trends (depending on the date range chosen), but overall the trend is rising (since the start date chosen). Skeptic or believer, it's as plain as the nose on your face.

Comment on Medieval Warm Period was warmer

Tom Curtis

jzk 54, a comparison between a single decade and several centuries is far from ideal. There is, however, some justification for it in this instance. In particular, very solid evidence suggests that this will be the coolest decade of the next several centuries. (How many depends on just how soon we break the fossil fuel habit.) That being the case, we know that the average global temperature over the next few centuries will be higher than that for the current decade, and hence higher also than the average over the several centuries of the MWP.

In other words, the comparison does strongly suggest that the current warming will result in greater overall warmth in this century than at anytime in the MWP.

Of course, it is not appropriate to look at a decade to century comparison and conclude that this decade is warmer than any decade in the MWP. However, a large number of studies have been done which suggest exactly that. It is more likely than not, on current evidence that this decade, and even the 1990s was warmer than any decade in the MWP. However, the evidence for that is not so strong that it can be stated categorically.

Comment on Volcanic Influence on the Little Ice Age

dana1981

Yes, the Maunder Minimum would have effectively amplified the volcano and feedback-caused cooling, if this theory is correct. However, the notion that we're just 'recovering' from the LIA is faulty, because we're currently warming much faster than the MWP warming or LIA cooling, and volcanoes and solar activity have had little influence over that warming, especially over the past ~50 years, as we showed here.

Comment on Medieval Warm Period was warmer

jzk

Rob,

Let me put this another way. I could take Mann's data from the MWP and produce that global chart based on 950 to 1250. Then I could produce another chart with the same data, but only 980-990. Then, I could put them next to each other. One would be all red, and the other would be all white. Could I make the claim "The MWP was warmer than the MWP?" How is that a helpful comparison?
Again, none of what I say contradicts the premise that the MWP was cooler than today, just the way that the charts are used to illustrate that position.

Comment on Volcanic Influence on the Little Ice Age

MangoChutney

@muoncounter #11

If volcanic eruptions were the start of the LIA, as has been suggested, wouldn't the Maunder Minimum, which occurred midway through the LIA, just have exasperated the cold period started by erupting volcanoes?

Comment on Global Warming: Trend and Variation

Dikran Marsupial

Tom & CBDunkerson - great minds think alike! ;o)

As I said, sea level observations are not my forte, but even I knew that station data are not a reliable indicator of global sea level when taken in isolation and that there were good reasons for this. I also knew that Google Scholar is a handy way of investigating whether an argument has some merit to it before I use it.

Comment on Global Warming: Trend and Variation

CBDunkerson

Disclaimer: Tom Curtis and I are not, in fact, sharing the same brain. Any similarities between our postings, choice of papers to cite, and/or wording (e.g. 'random conspiracy blog' / 'random internet guy') are purely coincidental.

Comment on Global Warming: Trend and Variation

Tom Curtis

Dikran Marsupial, Captain Ross's benchmark at Port Arthur was examined by Pugh et al, 2002. Based on that, they conclude that sea level at Port Arthur has risen 0.13 meters in the interval, or 0.8 mm per year.

Fred Staples want to ignore the peer reviewed literature because some random internet guy says he should. As I understand it, here at SkS "some random internet guy" is not considered an authority. That being the case, it is up to Staples to both present the information from Pugh et al (without cherry picking), and to show why Pugh et al's conclusion is wrong.

As it stands, Staples has not bothered to do that, and does not even bother reporting accurately the random internet guy who is his source. Specifically, as quoted by John Daly,

""My principal object in visiting Port Arthur was to afford a comparison of our standard barometer with that which had been employed for several years by Mr. Lempriere, the Deputy Assistant Commissary General, in accordance with my instructions, and also to establish a permanent mark at the zero point, or general mean level of the sea as determined by the tidal observations which Mr. Lempriere had conducted with perseverance and exactness for some time: by which means any secular variation in the relative level of the land and sea, which is known to occur on some coasts, might at any future period be detected, and its amount determined. The point chosen for this purpose was the perpendicular cliff of the small islet off Point Puer, which, being near to the tide register, rendered the operation more simple and exact; the Governor, whom I had accompanied on an official visit to the settlement, gave directions to afford Mr. Lempriere every assistance of labourers he required, to have the mark cut deeply in the rock in the exact spot which his tidal observations indicated as the mean level of the ocean."

As can be seen, Ross had not reason to believe Port Arthur was particularly stable, and such a belief did not enter into his reasons for placing the benchmark there.

As an aside, I suspect his reporting of Einstein is no more accurate than his reporting of Captain Ross. An google search of his quotation shows that Fred Staples is the only person on the internet who quotes it.

Comment on Global Warming: Trend and Variation

CBDunkerson

Or, rather than reading the ramblings of conspiracy theorists on some random blog, we could look at what the peer reviewed scientific literature says about the Capt Ross sea marker in Tasmania;

"Observations of sea level at Port Arthur, Tasmania, southeastern Australia, based on a two-year record made in 1841â1842, a three-year record made in 1999â2002, and intermediate observations made in 1875â1905, 1888 and 1972, indicate an average rate of sea level rise, relative to the land, of 0.8 Â± 0.2 mm/year over the period 1841 to 2002. When combined with estimates of land uplift, this yields an estimate of average sea level rise due to an increase in the volume of the oceans of 1.0 Â± 0.3 mm/year, over the same period."

The amount of sea level rise varies across the globe due to effects of gravity, fluid dynamics, land uplift, and other factors. However, given that the volume of water in the oceans is increasing (due to both ice melt and thermal expansion) the long term trend is upwards... everywhere. Including this site in Tasmania.

Comment on Global Warming: Trend and Variation

Composer99

Fred:

Sorry, that's still cherry-picking.

Anecdotes from television shows, quotes from famous scientists, and measurements from a single site do not refute the aggregate of tidal gauge and satellite data showing mean global sea level rise is occuring. After all, those are all, by your own standard, observations, and each singly would be enough, by your own standard, to refute a claim that global sea level is not increasing.

Comment on Global Warming: Trend and Variation

Dikran Marsupial

BTW Fred, have you performed a Google scholar search to see if you can find out whether Australia [provides] An Unstable Platform for Tide-Gauge Measurements of Changing Sea Levels or not?

If it doesn't provide a stable platform, perhaps that explains why the Tasman sea tide-guages may not give a reliable indicator of global sea levels.

Comment on Global Warming: Trend and Variation

Dikran Marsupial

Fred Staples Einstein was perfectly correct. However the the observation of sea level at one location does not refute the hypothesis that sea levels are rising or that AGW is occuring.

To see why, you need to look into both the observations and the physics in more detail. Firstly not every location is a good place to cite a tide guage, because there are other factors that affect the measurements, such as glacial rebound, silting, tectonic movements etc. Also sea level does not rise uniformly around the globe (water is a viscous liquid, the distances involved are large and evaporation is not the same everywhere), so you need to take an average over multiple tide guages, preferably ones located in geologically stable locations. Which is what the scientists actually do.

Was Captain Ross a geologist? Did Captain Ross have the scientific understanding of sea level that we have now? No. He was right about taking the measurements, they are indeed interesting and useful, but that doesn't mean you can ignore the wider context.

If it was O.K. to pick a single data record and base your argument solely on that, why shouldn't I pick temperatures at some high Arctic station to show that global temperatures were rising very sharply? Simply because it would be a cherry pick, and would be neglecting the broader picture. What is sauce for the goose is sauce for the gander. What you are doing is equally unreasonable.

The difference is that I know it is a cherry pick and wouldn't use it as the basis for a serious argument.

Comment on Global Warming: Trend and Variation

Fred Staples

Cherry Picking? As Einstein said, â10000 observations may support a theory, it only takes one to refute itâ.

Science works like that. After all, the millions of stars seem set in their courses. Navigators use them every day. The earth is clearly at the centre of the universe and every thing revolves around us. Would you let a few wandering planets, and some indistinct moons, refute so well established a theory?

Captain Ross marked that sea level because it was the most stable land he knew with the least tidal rise and fall. He thought future generations would be interested.

Now you have a theory that human CO2 emissions will cause dangerous sea level rises. If you wish to retain that theory, you are required to explain why it has not happened in the Tasman Sea. While you are about it, you can explain the Comment from the President of the Maldives Federation on the Today programme a year or so ago. He was complaining that his entire country would be inundated if CO2 emissions continued to rise. John Humphreys asked how much the sea levels had risen so far he replied, âabout a centimetreâ.

Comment on Volcanic Influence on the Little Ice Age

muoncounter

Mango#9: No and no.

It's still not established that the LIA was caused by volcanic eruption - especially if no one can point to which volcano erupted at what time. Nor can we suddenly leave out the Maunder minimum entirely.

As for 'we could cancel the LIA,' what do you mean? The very existence of the LIA, whatever its causes, shows there is not just one long warming. Even if that were so, why would the modern warming be at a more rapid pace?

Comment on Volcanic Influence on the Little Ice Age

CBDunkerson

owl905, I don't know if we are having some sort of semantic breakdown or if you really believe things to be exactly the opposite of my understanding.

The Miller 2012 paper absolutely does suggest that volcanic eruptions caused cooling, which in turn was amplified by climate feedbacks, which resulted in the centuries of cooler temperatures generally known as the LIA. I mean, the bloody title of the paper is, "Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks".

If you disagree with the above then you are going to need to explain what you think the Miller paper is about. If you don't have some radically different understanding of the paper then you must somehow be reading my original post to mean something other than what I said above. At which point I'd suggest that, as a general principal, it would be wise to consider all possible meanings of words and phrases you read and then not assume that interpretations which conflict with reality were the ones intended.

Comment on Medieval Warm Period was warmer

jzk

Rob,

I refer only to the two chart chosen by Skeptical Science to contrast todays warming with the MWP. The Mann chart shows a several hundred year period that includes, according to his data, both years of warming and years of cooling. The Skeptical Science chart shows only a decade at a warming peak. It is it any wonder one shows "red" and the other not?
It may very well be that the MWP was cooler than today, or not. Let the science show us that.

Comment on Volcanic Influence on the Little Ice Age

MangoChutney

If the LIA was caused by erupting volcanoes and we could cancel out the LIA, is possible that the current warming is just one long continuation of the Medieval Warming Period, Roman Warming Period, all the way back to ..... ?

Comment on Still Going Down the Up Escalator

Tristan

Interesting!

BTW DM, is your identity 'outed', or was it something you never bothered to hide?

Comment on Still Going Down the Up Escalator

Dikran Marsupial

In case anyone is interested, I tried recomputing the credible interval on the regression taking into account the stated uncertainties in the estimates of GMST provided by BEST (I didn't use the last two values due to the lack of coverage of the stations used). Here again is the Bayesian regression analysis using the estimates themselves:

Here is the Bayesian regression analysis taking into account the uncertainty in the BEST estimates.

As I suspected, the 90% credible interval is a little wider, but the difference is barely detectable, which suggests Brigg's criticism of the handling of uncertainty is not much of a cause for concern.

The expected trend for the BEST estimates is 0.0257 (95% credible interval 0.0048 to 0.0464) and when the uncertainties in the estimates are accounted for it becomes 0.0255 (95% credible interval 0.0026 0.0486). Note that the credible interval does not include zero or negative values whether the uncertainty is accounted for or not.

Technical note: The Bayesian regression is performed by sampling from the posterior distribution of regression parameters (including the variance of the noise process). To incorporate the uncertainty in the estimates, I just sampled from the distribution of the responses assuming that the BEST estimate is the mean and the stated uncertainty is the standard deviation (RATS, reading the documentation it is the 95% confidence interval, so it is actually twice the standard deviation, so my analysis overstates the uncertainty by a factor of two - and it still doesn't make much difference!).

Comment on Medieval Warm Period was warmer

Rob Painting

And as if to complicate the situation once again - Last Millennium Climate and Its Variability in CCSM4 - Landrum (2011) suggest something else again.

Comment on New research from last week 5/2012

Ari Jokimäki

One difference with Younger Dryas seems to be that Younger Dryas event might not have occurred globally at the same time (Antarctica seemed to be warming when Northern Hemisphere cooled).

Comment on Major Study of Ocean Acidification Helps Scientists Evaluate Effects of Atmospheric Carbon Dioxide on Marine Life

Doug Mackie

Not quite William. Buffering describes the process by which additions of acid and/or base cause minimal pH changes to a solution (compared to if the acid and/or base had been added to an unbuffered solution).*

When oceanographers refer to alkalinity** they mean the acid neutralising capacity of the water with respect to pure carbonic acid (H₂CO₃). That is, you use H₂CO₃ as your base unit. It is sort of like currency trading and referencing everything to the $US.

Seawater is not usually thought of as a multi-buffered system. Yes, there are other things that function as buffers but they present at low levels and generally poorer buffers; buffering is thus dominated by the carbonate system.***

As for measuring alkalinity, it doesn't really matter what you measure: As we detailed in our OA series (see the button, left side, main page) the CO₂ system can be fully described (i.e. calculated) from any two of pH, total alkalinity (A_T), pCO₂, and total dissolved carbon dioxide (C_T).

Researchers thus can freely convert between any of those parameters. It comes down to the particular apparatus used. For example, A_T and C_T are easily measured with good precision and good accuracy but require discrete samples â as opposed to continuous measurement like using a pH electrode. (See the OA series for more on this).

*The mechanism by which this is achieved is really cool and we'd be dead without our carbonate buffered blood. The details are senior high school chemistry and if there is sufficient interest I will write up a post about it and try simplifying.

**There are several shades of 'alkalinity', including 'total alkalinity'. In the interest of brevity, I am going to concatenate them all here but in later posts I will be more precise.

***Details of this are enchantingly subtle and complex. Read the OA series and come back with questions.

Comment on Volcanic Influence on the Little Ice Age

owl905

@KR-No idea what your response is about - dropped years is years without rings = missing rings (Mann even uses the term p.3). Your statement about tree-line is straight off both RealClimate and the Mann paper.

Dana introduced the Mann paper, so it is part of this thread. And no, it's not "quite frankly unrelated". Both papers focus on different aspects of the forcing effect and timing of volcanic events. Miller's case is boosted if Mann's suggestion of a stronger forcing effect is true.

As for the "language you seemed concerned about", no again. It's Mann that's putting up the warning flags not too leap too far too fast with the suggestion. Part of Mann's requirement is to find other tree-types in the same region as controls.

Comment on Hiding the Incline in Sea Level

Bernard J.

...that it would have...

Comment on Global Sea Level Rise: Pothole To Speed Bump?

Gillian

Thanks for this. I didn't realise that sea levels would vary with El Nino and La Nina. It makes sense.

Comment on NASA scientists expect more rapid global warming in the very near future (part 2)

Rob Painting

Muon - here's a couple of papers:

Response of global upper ocean temperature to changing solar irradiance - White 1997. Who state:

"For penetration depths of 80-160 m(etres) observed in this study, back radiation anomalies come into balance with solar insolation anomalies over equilibration timescales of approximately 1.5-3 years, yielding model phase lags of 40Â°-75Â° that are similar to those observed"

And:

Temperature responses to spectral solar variability on decadal time scales - Cahalan (2010). Whom write:

"We find surface atmospheric response â¼1 K, about twice as large as the mixed layer response. The surface air response lags the TSI variation by â¼1 month, while the ocean mixed layer response lags the surface air response by â¼2 years for both inâphase and outâofâphase SSI (spectral solar irradiance) forcings."

No doubt there's a great deal more literature on this, but that's the extent of my search. No real surprise here, scientists from NASA are right about the ocean thermal lag, and people on the internet are wrong.

Comment on New research from last week 5/2012

chirhophoros

A very well assembled compilation - it's great being able to have a look at the papers minus a pay wall. Wrt Lundqvist et al, Does anyone have any idea to what extent the 19 -20 century warming shift resembles or differs from the apparently abrupt termination of the Younger Dryas?

CC

Comment on NASA scientists expect more rapid global warming in the very near future (part 2)

Rob Painting

Don 9000 & Pirate - I've received a reply From Dr Hansen, he does not consider that the omission of "implies" changes the meaning of that passage. And as Pirate points out, Dr Hansen is revising the paper anyway.

Comment on Volcanic Influence on the Little Ice Age

owl905 - Mann's paper is about accounting for 'dropped years' from minimal/no growth at marginal tree environs. The trees chosen for tree-ring paleo data are deliberately in marginal regions so that they more clearly show the effects of temperature, rather than fertilizer, local bear populations, insect infestations, etc. In other words, the Mann paper is about improving the time accuracy of tree-ring data.

The Miller et al paper discussed in this thread, on the other hand, is about considering an ocean circulation tipping point caused by a series of strong volcanic eruptions, leading to the LIA period lasting hundreds of years. That's a different question entirely, and quite frankly (aside from year-resolution of tree-ring data) unrelated. Identifying the volcano(s) would be very interesting, although they did not show much data for that other than the near-equatorial location due to both hemispheres being affected.

The Mann paper is quite interesting - and the language you seem concerned about (your "...warning flag" comment) is entirely reasonable for an initial effort that should be followed up with additional work.

Comment on Volcanic Influence on the Little Ice Age

muoncounter

Here is a large eruption database, from a comment by David Benson on the RC thread. There's only one VEI 6 volcano (Krakatoa class) in the 13th century.

Comment on Global Sea Level Rise: Pothole To Speed Bump?

barry

Steve, a 5 meter rise by 2100 is a worst case potential discussed in the paper. Uncertainties and negative feedbacks that mitigate against this potential are clearly discussed by Hansen and Sato. The graph is a simple model of an ice-sheet loss doubling regime derived from paleo-records, and is not meant to represent an actual scenario for the year-by-year rate of sea level rise acceleration (Hansen says this explicitly in the 2007 paper the graph is modelled from). As mentioned above, the more likely realization of such a potential would come with short periods of massive inundations rather than a smooth rate increase.

Hansen is not saying that he believes the 5 meter rise by 2100 is the likeliest outcome, just that it is not implausible and shouldn't be discounted. His general theme in this and other papers is that the official projections, like those in the IPCC, are too conservative presenting upper bounds. And even though we should be wary of focussing on short-term data, as you have done, it's worth pointing out that global sea level rise (and Arctic sea-ice decline) have so far been underestimated by the IPCC. Hansen may have a point; and he is aware of the limits of and arguments against his thesis, and has called for more study to test it. Whether consciously or not, you have misrepresented his argument here.

Here's the monograph underpinning the graph that's got your attention:

Hansen (2007): Scientific reticence and sea level rise

Read the whole thing for comprehension and context. It's not long.

Comment on Volcanic Influence on the Little Ice Age

muoncounter

It's troubling that neither the Miller (paper discussed here) nor Gao et al 2008 say which volcano was the likely source of these eruptions. Statements like Miller's "two of the most volcanically perturbed half centuries of the past millennium" are too vague even for geologists.

Emile-Geay et al 2006 suggest that ... a tropical location is likely, given the
worldwide presence of the ashes and simultaneous presence of its signal in ice cores from both poles. El Chicon is possible.

However, Timmreck et al 2008 found that this eruption, wherever it was located, wasn't much of a cooler-offer:

The large AD 1258 eruption had a stratospheric sulfate load approximately ten times greater than the 1991 Pinatubo eruption. Yet surface cooling was not substantially larger than for Pinatubo (â¼0.4 K).

Incredibly, Miller does not cite either of these papers, which are clearly relevant.

Another relevant source is Environmental History resource page on the impacts of volcanoes on European climate history. Mention is made of severe climate change during the mid 6th century "dust veil event," but nothing about 1258.

Comment on Volcanic Influence on the Little Ice Age

owl905

@CBDunerson - the paper's thesis in no way suggests the volcanic effects lingered for centuries. Nor does it in any suggest that the long-term effect was "self-sustaining". There is an event co-incidence of volcanic activity, aerosols, and a temperature drop in the Alantic northern border. The LIA was global, long-term, and uneven in its onset. And the recap notes that the timeframe is not only localized, but earlier than usual dates associated with onset.

A problem with the paper is identifying the volcano. It isn't huge (the 1258 super-eruption is still unsolved). But if the source is actually close to the coast of Iceland, the grouping of proxies could limit bigger implications.

@Dana - that Mann link is a subtle game-changer. He forwards a very tentative case for missing rings, ... the disclaimers Mann himself puts into the article is a warning flag.

Comment on Global Sea Level Rise: Pothole To Speed Bump?

Norman

Forgot to include a link to the Ari Jokimaki article found using the Search option.

Ari Jokimaki article I used.

Comment on Global Sea Level Rise: Pothole To Speed Bump?

Norman

DB @ 40,

I followed your instructions to use the Search function to look for more current information on deep sea heat content.

Here is what I found. Ari Jokimaki: "From 1993 to 2008 the warming of the upper 700 m of the global ocean has been reported as equivalent to a heat flux of 0.64 (Â±0.11) W mâ2 applied over the Earthâs surface area (Lyman et al. 2010). Here, we showed the heat uptake by AABW contributes about another 0.10 W mâ2 to the global heat budget. Thus, including the global abyssal ocean and deep Southern Ocean in the global ocean heat uptake budget could increase the estimated upper ocean heat uptake over the last decade or so by roughly 16%."

The "could" is important. Also in the same article by Ari: "The warming below 4000 m is found to contribute 0.027 (Â±0.009) W mâ2. The Southern Ocean between 1000â4000 m contributes an additional 0.068 (Â±0.062) W mâ2, for a total of 0.095 (Â±0.062) W mâ1 to the global heat budget (Table 1)."

Look at the range of error so the total could be as small as 0.033 or as large as 0.157. Of the 0.64 heat flux in the 0-700 meter section of the oceans the deep ocean may contribute as little as 5% or as much as 25% more. It seems the method of determining the deep ocean heat content is not so well established and remains in the very high error bar range of possibilities. More research will need to be done before any declarative statements can be made about total ocean heat content. The graph you posted in #4 showing the ocean heat content may approach this value or again it is just as possible it may be much less and closer to the total energy found in the first 2000 meters of ocean water (which has much smaller error bars).

Comment on New research from last week 5/2012

muoncounter

Global cloud height decreased between 2000 and 2010

I like this one a lot:

... a decrease in global effective cloud height over the decade from March 2000 to February 2010

Yet this was a decade of record high cosmic ray flux.

More GCRs makes clouds decrease in height? Have to bury this paper under a flurry of obfuscation: In the same vein as The Escalator, down means up and up means down.

Comment on Examples of Monckton contradicting his scientific sources

pbjamm

Peter Hadfield's (aka potholer54)response to Monckton has been posted up on WUWT. Good dismantling of Monckton. Read the comments section only if you have a strong stomach.

Comment on Medieval Warm Period was warmer

Rob Painting

jzk - yes it would be neat if we had a whole bunch of global proxy data with sufficient resolution (detail), say at the annual (yearly) scale, but AFAIK there's not a great deal - and we know how worked up the fake-skeptics get about the tree-ring data.

You just have to work with what you have.

The real dagger to the heart of the MWP (to my mind) is the global circulations. Mann's reconstruction agrees very well with how we expect the circulations, and their teleconnections to operate. Not perfectly of course, but a warm MWP wouldn't agree at all.

For instance ENSO (La Nina/El Nino) was weaker (lower amplitude) then, and the natural oscillation in ENSO was longer (around 80 years?). This is consistent with a cooler tropical Pacific than today.

Additionally, the Amazon rainforest was wet - consistent with a more southward displacement of the ITCZ (inter tropical convergence zone) than exists today. Again suggesting a cooler global climate back in medieval times.

Comment on We're heading into an ice age

scaddenp

"The degree" varies wildly however. You can predict sunrise etc with very high degree of accuracy. You can also predict the changes in insolation due to the Milankovitch cycles which drive the ice cycle with a very high degree of accuracy, but climatic effect of that change also depends on other factors - especially level of GHGs.
On the other hand, volcanoes are unpredictable with no known physical basis to a "cycle". A statistical recurrance period should never be confused with a prediction. Saying we are "long overdue" for an eruption smacks of pop-sci documentaries, and I would be interested if you have a science paper that says that.

The basis for saying that there wont be an iceage soon is a/ Berger, A. and Loutre, M. F. (2002) which consider that orbital drivers, and b/ our GHG levels are getting to Pliocene levels - too high for an iceage.

Comment on Volcanic Influence on the Little Ice Age

dana1981

Mann has a new paper out which discusses volcanic eruptions in the 13th Century too. RealClimate discussion here.

Comment on Volcanic Influence on the Little Ice Age

dorlomin

IIRC that region in Canada has been invoked as a likely key to triggering glacial periods, as snow lies on the Canadian archipelago and around Hudson Bay later during the summer as the summer sun weakens it reinforces the cooling trend allowing Hudson Bay to remain frozen all year round. This allows a very slow southward creep of summer snow which forms the begining of the glaciers. Norwegian Mountains and then the Scottish Highlands also play a role.

That is that they are very close to the point where all summer snow can lie with a small amount of cooling.

It is possible these volcanos did not cause the little ice age but their impact was enough to allow the build up of cold summers with snow all year round to drop the temperaturtes that was not able to clear fully before a slight drop in solar output refinforced the millenia long dropping solar energy in mid summer at high nothern latitudes.

It is far from a done deal with this at the minute but it is a very interesting study and seems to just catch a point where the climate is valnrable to reinforcing changes.

Comment on Global Sea Level Rise: Pothole To Speed Bump?

Doc Snow

#45--"Perhaps the planet's accelerating toward c with respect to your reference frame...?"

OK, that was an LOL. "(Polite) Snark Of The Day" award.

Comment on We're heading into an ice age

pingpong2727

OK this is stupid, we can predict things, but only to a degree. Apparently we are also long overdue for a super volcano eruption under yellow stone park, but it hasnt happened yet. The only thing that we have actually proved right from prediction, is that there is 365 days in a year, not counting leap years, So everyone can calm down, I dont think we will be in an ice age in any time soon.

Comment on Medieval Warm Period was warmer

jzk

Comparing 1999 - 2008 to 950 to 1250 is simply not a fair comparison. According to the Mann data, 1100 - 1250 was colder than average. (See his data set A for NH mean). How is that a relevant comparison? No such comparison occurs in Mann's paper.

Comment on Global Sea Level Rise: Pothole To Speed Bump?

william

If the Arctic ocean becomes ice free, we may see some real acceleration in sea level rise. A giant solar collector (the open Arctic ocean) beside a large block of ice (Greenland) may see a coupling of warm air rising from the collector to be sucked down by katababic cooling over the ice block. Basically a Foen Wind over a very large glacier. When a Foen wind hits ice, all the energy is concentrated right at the ice surface and is being imported from somewhere else, unlike solar radiation which can only supply so much energy per given area.

Comment on Volcanic Influence on the Little Ice Age

CBDunkerson

This theory that effects of the volcanic eruptions lingered for centuries after the events themselves seems like a new sort of 'tipping point' argument. That is, volcanic aerosols usually fall out of the atmosphere within a few years and have no significant long term effects... but this study is suggesting that a large enough set of volcanic events could introduce sudden sharp cooling which then becomes self-sustaining for hundreds of years. If that eventually proves out it would indicate that there are some major climate feedbacks that can be triggered on very short timescales... Arctic ice and ocean circulation for the study in question. There has long been concern about potential tipping points in these same areas with the gradual GHG warming we have been seeing, but this suggests it is possible that an otherwise temporary warming spike (e.g. El Nino) could result in a similar self-sustaining change.

Comment on Public talk: Global Warming - The Full Picture

Michael Whittemore

Tom Curtis @25 I have finial found the right information, it would seem they are still debating the actual compensation scheme but due to caps on the amount the carbon tax can increase by and the some what "predictable" Internationale price of carbon will be, they have concluded that "Tax cuts will increase over time with a second round of tax cuts in 2015-16 that will further raise the tax-free threshold to $19,400, matching the impact of the carbon price to 2020." (http://www.cleanenergyfuture.gov.au/clean-energy-future/securing-a-clean-energy-future/#content05) It looks like I was wrong, John Cook was right to explain that compensation will cover most of the costs.

Comment on Global Sea Level Rise: Pothole To Speed Bump?

andylee

Time is an enabler for change, for without it nothing can change.
Time simply allows processes to take their course, not cause them.

Comment on NASA scientists expect more rapid global warming in the very near future (part 2)

muoncounter

RP#50: Maybe Scafetta and West 2005:

The climate sensitivity to the 22-year cycle, Z8, is approximately 1.5 times stronger than the climate sensitivity to the 11-year cycle, Z7, and, on average, the 22-year climate response lags Hale solar cycles by approximately 2.2 Â± 2 years. These effects are predicted by theoretical energy balance models. In fact, the actual climate response to cyclical forcing is stronger at lower frequencies because the damping effect of the ocean inertia is weaker at lower frequencies.

They show a relatively poor quality graph (their Fig. 4) illustrating this lag. 2.2+/- 2 years seems like very high uncertainty; 18 months is well within that window.

The 'damping effect' statement makes sense, but could be more clearly stated: ocean thermal inertia reduces climate response to short-term drivers. If the response to a 22 year cycle is much greater than the response to an 11 year cycle, such short period events like ENSO cannot be causes for climate change. The gradual buildup of GHGs, on the other hand, is a long period driver.

Comment on Public talk: Global Warming - The Full Picture

Michael Whittemore

Tom Curtis @25 Of course you say, I would like a link to that fact?

Comment on NASA scientists expect more rapid global warming in the very near future (part 2)

Rob Painting

Muon @ 48 - the peer-reviewed literature doesn't make it clear, but these are two separate issues. Firstly, the lag in surface air temperature response to a change in solar irradiance is about a month, but the ocean response is on the order of 18-24 months. Still trying to track down a paper that deals with this issue specifically. It's mentioned in a few papers, but only in passing.

Comment on NASA scientists expect more rapid global warming in the very near future (part 1)

Pete Dunkelberg

Link needed for IanC's # 16.

Comment on Global Sea Level Rise: Pothole To Speed Bump?

John Hartz

Dumb questions (perhaps):

Does time cause climate change?

If not, why all the consternation about time-series plots of surface temperatures?

If so, how exactly does time cause climate change?

Comment on New research from last week 5/2012

Biophilia

Do you think Von Deimling talked to the Russians...?

http://www.skepticalscience.com/arctic-methane-outgassing-e-siberian-shelf-part2.html

Comment on Public talk: Global Warming - The Full Picture

Tom Curtis

Michael Whittemore @24, it is of course 50% given back to the people, and most of the remaining funds used to compensate trade exposed industries, schools, hospitals etc, or to fund research on renewables.

Comment on Still Going Down the Up Escalator

Tom Curtis

Tamino (Grant Foster) has an excellent new post explaining how you can make a reasonable estimate of the uncertainty of a trend without knowing the uncertainty of the data, ie, why Briggs is wrong. Interesting read.

Comment on Public talk: Global Warming - The Full Picture

Michael Whittemore

Tom Curtis @23 Will there you have it, %50 of the revenue given back to the people sounds good to me. I have been thinking about it and they would be able to do it with increased tax rebates at the end of each year. But I worry that he is only talking about the next couple of years before the ETS starts? I also have concerns that they will not be making as much as they do from a tax as they will from an ETS. But for now I will agree that an adjusted compensation rate of %50 of the revenues sounds fair. It would be good if they had that in writing though.

Comment on Public talk: Global Warming - The Full Picture

Tom Curtis

Michael Whittemore @22, it seems that I need to withdraw that the compensation will be increased "... by requirement of law". Never-the-less, it is the governments stated intention to do so:

"Speaking after a Swan speech at the National Press Club, the Climate Change Minister, Greg Combet, said the macro-economic outcomes from the modelling proved carbon pricing was a ''manageable reform'' which would not bring about the ''end of the world''.

Mr Combet said household compensation - to be funded with 50 per cent of the revenue from the tax - would be regularly reviewed to make sure the real level of assistance was maintained as the carbon price rose.
Meetings of the multi-party climate committee will continue today to negotiate demands for compensation and extra spending that add up to more than the revenue the carbon tax will raise."

(My emphasis)

There is, of course, "many a slip twixt cup and lip", particularly where government promises go. Never-the-less the return of adequate compensation is fundamental to the logic of the scheme, and is unlikely to be tampered with.

Comment on Global Sea Level Rise: Pothole To Speed Bump?

Bernard J.

SteveChase at #41:

Dr. Hansen's graph isn't sigmoid, it's an asymptotic progression and he didn't say when it would end.

Erm, I think that you mean geometric (although that too is a clumsy term), not "asymptotic".

If a progression were "asymptotic" to the independent variable (time), you'd have the interesting phenomenon where the progression wouldn't reach a particular moment. Perhaps the planet's accelerating toward c with respect to your reference frame...?

If a progression were asymptotic to the dependent variable (temperature), and if it's initially accelerating or 'geometric' (as Hansen's trajectory is), then I'm not-so-sorry to tell you that the trajectory will be approximately sigmoid.

Hansen's trajectory appears to be continuously exponentially increasing only because it's extrapolated to 2100, and no further. You may like to re-interpret what this means, but simple physics dictates that the overall curve (that is, when extended beyond the 2100 upper x-axis bound that was shown on a simple graph) will be sigmoid.

And one day, when current society is merely a layer in the fossil record, that trajectory may even head downward.

None of this changes the fact that with the appropriate âT/ât, âSR will approach (for a relatively brief period) the order of magnitude of millimetres per day. Your argument can only be whether âT and/or ât are likely to be of the values that would result in Hansen's predicted 2100 rate of sea level rise.

Comment on NASA scientists expect more rapid global warming in the very near future (part 2)

apiratelooksat50

Tom Curtis at 10
Looks like we were both right in a way. Kind of like kissing your sister.

I contacted Mr. Hansen and asked him for clarification on his intent of using "implies" in the paragraph. In an excerpt from his e-mail:

"That's a good point -- not a very precise word -- what I meant was that we could conclude -- of course that is a pretty strong statement -- we will see if referees agree with my assertion, when I submit the paper for publication in ~ a week or so."

It will be interesting to see the language used in the final version if the paper is published after peer review.

Comment on Public talk: Global Warming - The Full Picture

Michael Whittemore

Tom Curtis @21

Can you show me where it states income tax will decrease/increase with the amount the government makes from the ETS? Because if the price of carbon is floated then it will fluctuate, and I don't see how they can keep on adjusting income tax. The reason they started the carbon tax at $20 a tonne was so they would not have to compensate people as much as when it becomes an ETS. Also to be clear I am not saying the government will run out of compensation funding, I am saying they will pocket it. I read they will be setting up some sort of bank that will determine what to do with the funds, but with a fluctuating ETS it will not be income tax they use to distribute the funds.

My point regarding a green power system, is that they would not need to buy carbon fuels or carbon credits. I agree with your point regarding the use of solar panels, but with such a mass push for green power the costs of the panels would come down. My not very well thought out plan of forcing the power network to become green, has me thinking that with large scale wind farms and huge solar plants they would not require much money to run. The cost to the customer would surely be low. Many towns are now buying wind farms to supply them power because in the long term its very cheap.

Your point about people reducing their energy consumption is right, but its not nice. People dont waste energy, its expensive as it is, making it cost even more is sad. I get it though, a carbon tax is a good option, I just would rather the government step in and assist making the power network green. That way we wont all have to become energy saving hippies.

Comment on Global Sea Level Rise: Pothole To Speed Bump?

Steve Case - "Were I to live to 2101 I would be surprised to see the ocean creep up that fast."

Then you are putting forth either the Argument from Common Sense (recommended link - very relevant) or the Argument From Personal Astonishment. Both are logical fallacies - when your personal opinions are contradicted by actual data, the data wins.

As to asymptotic versus sigmoid - ice loss will taper off, but possibly only when we run out of ice... It depends on what our future emissions are.

Comment on Global Sea Level Rise: Pothole To Speed Bump?

CBDunkerson

Steve, the IPCC AR4 values you claim as 'contradicting' more recent studies explicitly exclude accelerating land ice export because it was only slightly documented at the time;

"Further accelerations in ice flow of the kind recently observed in some Greenland outlet glaciers and West Antarctic ice streams could increase the ice sheet contributions substantially, but quantitative projections cannot be made with confidence"

While it is amusing to see a 'skeptic' using modeled results from the IPCC to 'refute' direct measurements from GRACE, the simple fact is that the IPCC AR4 estimates are now known to be significantly conservative. There is no "conflicting evidence" here. Just a past incorrect estimate vs current measurements.

Comment on NASA scientists expect more rapid global warming in the very near future (part 2)

muoncounter

"global temperature change caused by solar variability lags solar irradiance by about 18 months."

The spamboy did raise a valid point: FR2011 determined a lag between TSI change and temperatures (they used both satellite and surface records) of 1 month. This was in agreement with results of Lean and Rind 2008. Putting an 18 month lag into FR's data (available at you-know-who's blog) destroys all semblance of fit.

Comment on Global Sea Level Rise: Pothole To Speed Bump?

Daniel Bailey

@ Steve Case:

What part of "Decadal Doublings" (from your Hansen quotes) don't you understand? You continually post here with handwaving assertions based on linear thinking when the records are fraught with evidence of exponential change.

In that you cite Hansen, quote Hansen, then cherry-pick the parts that support your agenda & elide the rest, your "argument" devolves to straw.

Comment on Global Sea Level Rise: Pothole To Speed Bump?

Steve Case

RE: #38 Bernard J. at 16:14 PM on 7 February, 2012

I get the very same numbers you get, and if you continue the progression out to 2101 it is indeed one millimeter per day.

Were I to live to 2101 I would be surprised to see the ocean creep up that fast. Comparing Pulse 1A to today or 2100 is apples and oranges. We currently don't have continental ice sheets in the temperate zones waiting to melt. There is certainly enough water locked up in the Greenland and Antarctic ice sheets to cause such a rise if they were to melt. However there's conflicting evidence of such melting. Table 10.7 in the IPCC's AR4 tells us that the contribution of Greenland and Antarctica to sea level rise by 2100 will be negative. Elsewhere The GRACE studies say the opposite.

Dr. Hansen's graph isn't sigmoid, it's an asymptotic progression and he didn't say when it would end. He only plotted it out to 2100. I extended it by one year to get the one millimeter per day number. My mathematical "Straw man" as you've put it merely puts Dr. Hansen's curve in actual numbers that can be understood by ordinary people who can decide for themselves whether or not such a scenario is likely to come to pass.