In this link in comments on WUWT:
Is a wonderful comment by RBGatDuke. I’ve edited things a little bit. I included the preceding and responding comments, and there was a correction by RBGatDuke that I’ve ‘inlined’ for easier readability. (You can always hit the link to see the actual unchanged version if this bothers you).
First up, the lead in:
Abram March 25, 2015 at 8:21 am
Here’s a guy who thinks he’s the worlds #1 climate scientist, but his experience is in dendrochronology. Really, there shouldn’t be a link between these two as the tree rings give an approximation of the “sum of conditions” not necessarily climate, but he already knew that.
emsnews March 25, 2015 at 8:30 am
Quite so, Abram. Mann thinks he is #1. Tree rings show not just temperature but also rain amounts and incidentally, insect attacks. Yes, we have regular years every 20 or so in the Northeast where we have all the trees stripped of their leaves simultaneously by caterpillars who come out of the ground where they hibernate.
So on these years, the tree rings are smaller than other, normal years.
Tree rings most certainly do not show us cooling or heating alone.
Steve Oregon March 25, 2015 at 8:42 am
Good one. Imagine what Mann would do if he had any power or authority.
He’d be the Pol Pot of Climate Science.
I think that the spacing indicates that the reply is about the “truth” of what Abram says, that tree rings integrate all limits, but I find it amusing that it also seems appropriate to the Pol Pot comparison ;-) At any rate, here’s the reply about tree rings:
rgbatduke March 25, 2015 at 8:58 am
IIRC this is literally the truth. In one of the directories released with the original tree ring data, there was a record of email conversations where some of the goals of the work were clearly discussed with colleagues, and dealing with the MWP and LIA were on the list, as they were clearly visible on (IIRC) Jones and Briffa’s reconstructions that were also published in AR3/TAR. But the JB result wasn’t a hockey stick, and hence didn’t tell the right story. IIRC there were climategate emails that said almost exactly the same thing. The simple fact of the matter is that there was a body of climate scientists — a substantial body — in direct communication with one another and at the very least displaying their utter lack of scientific objectivity as they were “gunning” for the MWP and LIA in order to support their assertions of catastrophic warming (and the funding cornucopia gold rush that followed, where they were regularly interviewed on radio and TV and became “famous” — and who can resist the seduction of all that?).
But my favorite thing is this:
Note well — for the trees used by Mann as proxies, we expect to see roughly 12% increased growth rates of tree rings from 1850 to the present due to the increase in atmospheric CO_2 itself, not due to increased temperatures at all! Indeed, the growth rate due to temperature increases is also documented in this short review as being expected to be around 10% over the same interval.
The problem with this is that it means that the tree ring proxies were almost certainly incorrectly selected and normalized across the overlap using Mann’s procedure of only using trees that were in good correspondence with the temperature data and then extrapolating the ring widths observed into the past. In the past there would have (possibly, even probably) much less variation in CO_2 level, so that they underestimate warming by roughly a factor of two by attributing growth due to two factors in the recent present to only one of the two, but not correcting for the absence of variation in the other in the remote past.
Tree rings based climate estimates probably underestimate past warming by a factor of roughly two, outside of the additional confounding of heat with or without adequate water under the conditions of lower CO_2. That is, hot dry low-CO2 conditions actually decrease plant growth rates as they are water-limited in growth and (as the article points out) have large stoma through which water loss occurs, experiencing a very severe increase in plant stress. As CO_2 increases, plant stoma sizes needed to maintain CO_2 perfusion decrease, water loss decreases, and in addition to growing faster in response to the otherwise rate limiting CO_2, the plant grows faster still in warmer conditions even when less water is present, as they lose less water to respiration through the smaller stoma.
This additional confounding factor could make tree rings underestimate past temperatures by an additional factor of 2, or it could cause tree rings to infer cool conditions where in reality the conditions were hot, but CO_2 stressed and dry.
I first realized this when I saw a paper (probably linked through this site) that was trying to make inferences about tropical storms and temperatures using growth rates of certain tropical trees (in the Phillipines, maybe? Can’t remember.). The trees have showed a systematically increased growth rate that the article (naturally) attributed to global warming even though the data they presented did not show any sort of good correlation with global average temperature in detail. It did, however, follow a curve I had recently worked out for probable well-mixed CO_2 content in the atmosphere over the last 1850 years, and the numbers — 15% overall, IIRC — worked out almost perfectly for the increase in growth expected from the increase in CO_2 alone.
Inlined correction:rgbatduke March 25, 2015 at 9:03 am
Sorry, I meant that that Malaysian trees didn’t follow the known local temperature but were in good agreement — really excellent agreement — with the CO_2 curve itself, a thing that eluded the authors of the study as it has eluded the entire discipline AFAICT. My bad. end inline update. -EMS
This may be the next big shoe to come crashing down on the global warming dendroclimatologists. AFAIK, they have all to a Mann completely, utterly, totally neglected the effect of CO_2 itself on growth rates of the very plants they are using as proxies. In many cases — notably this case in the Phillipines or Malaysia or wherever it was — consideration of CO_2 completely eliminates any correlation with temperature at all in the residuals (that is, after taking CO_2 increase into account, there is nothing left to explain via temperature variation). In any event, correcting for it will, without question, substantially lower the anomaly these methods report when it is taken into account.
This is the one thing that the catastrophists don’t want to draw attention to, but even my friends in Environmental Sciences are perfectly aware of — the increased CO_2 alone is responsible for over 10% of the crops harvested worldwide every year. If one takes the increased drought resistance and increased growth rates due to warming (whatever the cause) into account, the number goes up closer to 20%. We feed, clothe, and shelter somewhere between 1 and 1.5 billion people a year with this food mass, with the plant fiber mass, and with the trees mass that we know, quite reliably and on the basis of literally hundreds if not thousands of greenhouse experiments, is available only because of the increased CO_2 in the atmosphere.
This is why even some otherwise rabid ecologists are starting to change their stance on CO_2. Yeah, maybe it will cause a global catastrophe in 100 years, maybe not, but up to now its effects have been so overwhelmingly positive that the world would almost certainly have voted to burn enough carbon to take the atmosphere to 400 ppm regardless if they were actually informed of its benefits.
1 to 1.5 billion people.
That’s how many people would potentially starve if we waved a magic wand and dropped CO_2 right back to 280 ppm tomorrow. At the very least, to prevent the worst catastrophe humanity has ever even dreamed about we’d all have to tighten our belts and equitably distribute the food we have to the world’s poorest 2 or 3 billion people, as naturally the hardest hit would be the poorest and most populous nations, nations that can only feed their own populations because of the CO_2 benefit.
Here’s the really, really sad thing. The climate news this week has been fabulous. Seriously! A paper is being published that through careful work reduces aerosol cooling uncertainty by over a factor of two and reduces the probable cooling itself to a mere 0.5 C! This in turn invalidates 80% of all of the climate models — 100% of the ones predicting catastrophe. This in turn requires one to re-tune the surviving ones so that they work at all with the much smaller aerosol cooling, which eliminates almost all of the positive water vapor feedback which is the only thing that could cause a real catastrophe. The probable implication of this paper is that the “crisis” is decisively over! ECS from 1 to 2 C is simply not likely to be catastrophic even in RCP8.5, and most probable ECS is on the low side of this range, with basically no net feedback on top of CO_2-only forcing!
Throw in the observation that the hockey stick neglected direct CO_2-driven growth and hence is incorrectly normalized. Throw in on top of that the simple observation that the CO_2 increase in the industrial era is feeding one person in five who is alive today (and not just humans — this effect pervades the entire biosphere!). If we had anything like objective reporting on this issue, anything like non-politicized science addressing it, anything like simply human selfishness in analyzing it, this would be headline news.
And in 1 to 2 years, if the aerosol result holds up, it will be. It is simply inevitable. If the strict upper bound of aerosol cooling is only 1 C, it will simply no longer be possible to maintain the illusion that the GCMs are useful in some way. The modelers will be forced to recalibrate the models, and the recalibrated models will, without any doubt at all, show far, far less warming than the old ones.
There will be two important social results from this. It will become common knowledge that the claims for precision and accuracy in these models and their suitability for purposes of “projecting” future climate have been from the beginning sheer bullshit. Numerous papers will appear proving what is and really always has been perfectly obvious, that there is no statistical basis for any claim for predictivity for the entire procedure that has been used to “project” a future climate, that every single assertion of “confidence” in documents presented to policy makers has been a deliberately deceptive misuse of a statistical term in a political context. Pitchforks and torches may appear as it becomes clear just how much public money has been wasted and stolen and misdirected as a result of this deliberate, self-interested deception. Second, it is barely possible that we will stop demonizing coal burning power plants and gasoline burning cars long enough for science and technology to do its job and actually invent better alternatives without the panic and without the incredible misdirection of resources into climate research on the hypothetical effects of a hypothetical catastrophe that will no longer be hypothetically likely at any level worth the money.
All good, from my point of view.
[A strong comment, thank you. .mod]
davidmhoffer March 25, 2015 at 10:09 am
Long ago, before I discovered WUWT, I brought up the issue of CO2 fertilization disrupting tree rings in terms of both temperature and precipitation response in what I soon came to understand was a “science” forum in name only. I was patted on the head and told not to worry about the issue, and to leave the science to the “scientists”. Kinda forgot about it until your comment just now.
I also left in the kudos from the moderator and the reply from DavidMHoffer, mostly as I had a similar experience on a different question when I first started out. The “There there little boy, don’t tire out your tiny little mind with the hard stuff, just trust use wise ones” from a site that insisted on deleting any followup comments of the form “But what about THIS that seems to conflict?”… It was a bit of snark about “I must hang out at WUWT” that gave me a clue about where to go to get real information and reasonably polite treatment when asking questions…
At any rate, it is a very good comment and deserves to not be lost in the flood of a half dozen articles and 1000 comments a day at WUWT, so I’m putting a copy here.
FWIW, this is my comment on the same thread. Not nearly as moving, but more technical, IMHO:
E.M.Smith March 25, 2015 at 12:06 pm
The AMOC is the far north / European end of the Gulf Stream (North Atlantic Drift) AND the return current below the surface. Now Mann was all “unprecedented” all over this slow down, and absolutely certain that it is an unusual and human caused thing.
Unfortunately, it is highly precedented and happens to even greater degree with very significant tendency to ‘regularity’. (I note in passing that we just had a ‘super tide’ event with folks coming out to see it as there will not be another one for decades… yet there will be another one as tides are driven by lunar / solar orbital mechanics.) My speculation is that much of the cyclical change is related to water flow changes directly driven by tide cycles in both water and air and that’s why we have what looks like 1500 ish year cycles along with sub cycles at 750 and about 300 years, along with a 5000 ish year cycle on the long end.
But far from speculation. This paper looks at Florida weather and how it relates to changes in the Gulf Stream and through it AMOC (by implication).
While it mostly looks at Hg concentration and transport with sea level and temperature changes, there’s an interesting chart of changes in the ratio of oak to pine pollen (which shifts with temperature and rainfall).
Figure 3. Lake Tulane Hg flux in relation to organic matter and selected plant taxa over the last 60 000 years. Horizontal green bars indicate Tulane Pinus periods (TP0 through TP6), which correspond to YD and Heinrich Events H1 through H6.14 Sea level in the Gulf of Mexico since 25 000 years BP is based on ref 17.
The second of the dramatic peaks of the accumulation rate of Hg (ca. 13 000 and 5000 years BP, Figure 3) is slightly before the sharp increase in Pinus pollen, which lags a few hundred years. The Pinus rise is interpreted as a change in water regime, with increasing warmth and higher summer precipitation. If correct, the result would be an acceleration of the rise in regional water table, creating conditions for increased reductive dissolution of secondary Fe (and release of Hg). The soil, nearly at its present groundwater state, apparently was then rapidly depleted of stored Hg.
So we have periodic peaks of warmth and rain (Florida “summer pattern” today) happening when there are increases in Hg accumulation (leaching into the lake) in sync with the Younger Dryas and Heinrich Events. Heinrich Events being a rise in ice rafted debris on ocean floors https://en.wikipedia.org/wiki/Heinrich_event
Heinrich events appear related to some, but not all, of the cold periods preceding the rapid warming events known as Dansgaard-Oeschger (D-O) events, which are best recorded in the NGRIP Greenland ice core. However, difficulties in synchronising marine sediment cores and Greenland ice cores to the same time scale cast aspersions on the accuracy of this statement.
So they are during cold events, preceding the rapid warming spikes of D-O events.
What’s the point? While there is a lot of speculation that Heinrich Events are caused by some kind of fresh water flow or ice dam collapse leading to a slow down or halt of the AMOC, that isn’t known. IMHO it could just as easily be a natural shift of the current under extreme tidal forces (and would explain the quasi-periodic nature of D-O events that happen on the same schedule as Bond Events during the Holocene and their Heinrich Event fellow travelers). But what is clear:
When the AMOC slows and shifts, and Europe goes cold, the solar heat backs up in the Gulf of Mexico and Florida gets warmer and wetter. This is not at all unusual, and has been happening for tens of thousands (and perhaps hundreds of thousands) of years. The pine and the oak trees are clear testimony to that. The Mercury is a bit more complicated, but also suggests the same.
So all you folks in the frozen north and tundra Europe, Florida is the place to head when the ice doesn’t leave “on time”… but you already knew that ;-)
This is also indirectly testimony for the W. Thunderstorm Thermostat Thesis. Florida gets warm, and wet, and fires up a whole lot more thunderstorms to hold total heat flow constant (less from the Arctic, more via thunderstorms and convection / precipitation). Even now during full on interglacials, it is very clear that the heat can only build up so far before the thunderstorms kick in and take it to the stratosphere for direct radiation to space. Hard to get much over about 88 F in Florida for very long before a thunderstorm cools things off again. Even when the Gulf Stream backs up and the AMOC shuts down; it just goes to “Summer Mode” and rains out the heat…
So, IMHO, this is pretty direct evidence that Mann has no clue about what real science has been done showing natural variability far more extreme than any proposed human caused changes. And just how much the AMOC is an oscillator and not a steady state.