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The LIA may have been anthropogenic

calamity said:
I'm thinking someone received a grant and figured a way to make it pay his bills for two years while he force-fit some data to look consistent with his theory. Everyone needs a racket.
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I'm thinking you didnt read the abstract, have no idea what the topic is about, have a very thin understanding of grants, scientific study and publications, and decided to chime in on an unrelated ice age 10,000 years ago in a clueless manner.

The topic is about the slight cooling in the 18th century.

And, of course, the usual suspects applaud your effort.
 
flogger said:
Yes he did that to me too lately. Once the ad homs start all it means is that you've won the argument so you should take it as a backhanded compliment really :thumbs:
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By implication of course, the IPCC have "won the argument" by virtue of being called liars by Tim the Plumber in his preceding post, along with certain other folk in past threads. I suppose you didn't think that far ahead though ;)

FYI (a point which many people find difficult to grasp) there is a rather significant difference between an ad hominem fallacy and an honest down-to-earth insult. And - more relevantly in this case - there's also a difference between an insult and an observation. To illustrate, it is merely an observation to note that you are lying by regularly posting false claims about greening being "the only directly observed effect" of increased atmospheric CO2 after having been repeatedly shown otherwise; it is neither directly observed, nor the only (or even most reliably) effect detected by the method in question. You're directly contradicting your own source for the information! So there really isn't any more accurate way to describe it. But calling that observation - even if you personally feel it to be insulting - an 'ad hom' is entirely inaccurate, and unfortunately betrays a fundamental misunderstanding of basic logical principles. It would be ad hominem if I said or implied "this is a lie, so everything else you say is a lie." Do you see the difference, and understand how the latter is logically fallacious? But of course I have never said or implied that at all; merely that much of what you post is unreliable and, more to the point, not worth the effort of (often a third- or fourth-time) rebuttal.
 
Mithrae said:
By implication of course, the IPCC have "won the argument" by virtue of being called liars by Tim the Plumber in his preceding post, along with certain other folk in past threads. I suppose you didn't think that far ahead though ;)
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The IPCC is a political entity hence the term 'Intergovernmental' in the title. It is in essence a government financed lobby group

FYI (a point which many people find difficult to grasp) there is a rather significant difference between an ad hominem fallacy and an honest down-to-earth insult. And - more relevantly in this case - there's also a difference between an insult and an observation.
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I've never called anyone a liar in all my time here. To stoop to such rhetoric is simply an admission of failure

To illustrate, it is merely an observation to note that you are lying by regularly posting false claims about greening being "the only directly observed effect" of increased atmospheric CO2 after having been repeatedly shown otherwise; it is neither directly observed, nor the only (or even most reliably) effect detected by the method in question.
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It is so far the only directly measurable effect on the biosphere and its a positive one. I have no problem at all with making that claim either

So there really isn't any more accurate way to describe it. But calling that observation - even if you personally feel it to be insulting - an 'ad hom' is entirely inaccurate, and unfortunately betrays a fundamental misunderstanding of basic logical principles. It would be ad hominem if I said or implied "this is a lie, so everything else you say is a lie." Do you see the difference, and understand how the latter is logically fallacious? But of course I have never said or implied that at all; merely that much of what you post is unreliable and, more to the point, not worth the effort of (often a third- or fourth-time) rebuttal.
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You seem to need to use a lot of words in an effort to say very little. I do not need to lie to buttress my position here even though you'd like to try and impugn my integrity as having done so :roll:
 
flogger said:
To illustrate, it is merely an observation to note that you are lying by regularly posting false claims about greening being "the only directly observed effect" of increased atmospheric CO2 after having been repeatedly shown otherwise; it is neither directly observed, nor the only (or even most reliably) effect detected by the method in question.
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It is so far the only directly measurable effect on the biosphere and its a positive one. I have no problem at all with making that claim either
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I'm curious: What instrument is used to directly measure the proportion of plants' growth and reproduction in some regions which is attributable to CO2, rather than to soil quality, hydrological cycles, interactions with other species, temperature, exposure to sunlight and so on?
 
Mithrae said:
I'm curious: What instrument is used to directly measure the proportion of plants' growth and reproduction in some regions which is attributable to CO2, rather than to soil quality, hydrological cycles, interactions with other species, temperature, exposure to sunlight and so on?
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There is no doubt elevated concentrations of atmospheric CO2 lead to enhanced plant photosynthesis and growth. This well-known fact has been confirmed over and over again in literally thousands of laboratory and field studies conducted by scientists over the past several decades. In recent years, however, the growth-enhancing benefits of atmospheric CO2 have been increasingly studied and observed in the real world of nature using Earth-orbiting satellites. Such instruments have the capability to remotely sense plant growth and vigor at altitudes miles above the Earth’s surface; and they have generated a spatial and temporal record of vegetative change that now spans more than three decades. And what has that record revealed?

The take-home message of the satellite data is two-fold. First, at the global level, all recent studies show there has been a significant greening of the planet over the past few decades despite the occurrence of a number of real (and imagined) assaults on Earth’s vegetation, including wildfires, disease, pest outbreaks, deforestation, and climatic changes in temperature and precipitation. Greening has more than compensated for any of the negative effects these phenomena may have had on the global biosphere during that time


CO2-induced Greening of the Earth: Benefiting the Biosphere While Lifting the Poor out of Poverty | Cato @ Liberty

Here are some studies you might find illuminating on this point.

Andela, N., Liu, Y.Y., van Dijk, A.I.J.M., de Jeu, R.A.M. and McVicar, T.R. 2013. Global changes in dryland vegetation dynamics (1988-2008) assessed by satellite remote sensing: comparing a new passive microwave vegetation density record with reflective greenness data. Biogeosciences 10: 6657-6676.

De Jong, R., Verbesselt, J., Schaepman, M.E. and De Bruin, S. 2012. Trend changes in global greening and browning: contribution of short-term trends to longer-term change. Global Change Biology 18: 642-655.

Donohue, R.J., Roderick, M.L., McVicar, T.R. and Farquhar, G.D. 2013. Impact of CO2 fertilization on maximum foliage cover across the globe’s warm, arid environments. Geophysical Research Letters 40: 3031-3035.

Eastman, J.R., Sangermano, F., Machado, E.A., Rogan, J. and Anyamba, A. 2013. Global trends in seasonality of Normalized Difference Vegetation Index (NDVI), 1982-2011. Remote Sensing 5: 4799-4818.

Liu, S., Liu, R. and Liu, Y. 2010. Spatial and temporal variation of global LAI during 1981-20006. Journal of Geographical Sciences 20: 323-332.
 
flogger said:
There is no doubt elevated concentrations of atmospheric CO2 lead to enhanced plant photosynthesis and growth. This well-known fact has been confirmed over and over again in literally thousands of laboratory and field studies conducted by scientists over the past several decades. In recent years, however, the growth-enhancing benefits of atmospheric CO2 have been increasingly studied and observed in the real world of nature using Earth-orbiting satellites. Such instruments have the capability to remotely sense plant growth and vigor at altitudes miles above the Earth’s surface; and they have generated a spatial and temporal record of vegetative change that now spans more than three decades. And what has that record revealed?

The take-home message of the satellite data is two-fold. First, at the global level, all recent studies show there has been a significant greening of the planet over the past few decades despite the occurrence of a number of real (and imagined) assaults on Earth’s vegetation, including wildfires, disease, pest outbreaks, deforestation, and climatic changes in temperature and precipitation. Greening has more than compensated for any of the negative effects these phenomena may have had on the global biosphere during that time


CO2-induced Greening of the Earth: Benefiting the Biosphere While Lifting the Poor out of Poverty | Cato @ Liberty

Here are some studies you might find illuminating on this point.

Andela, N., Liu, Y.Y., van Dijk, A.I.J.M., de Jeu, R.A.M. and McVicar, T.R. 2013. Global changes in dryland vegetation dynamics (1988-2008) assessed by satellite remote sensing: comparing a new passive microwave vegetation density record with reflective greenness data. Biogeosciences 10: 6657-6676.

De Jong, R., Verbesselt, J., Schaepman, M.E. and De Bruin, S. 2012. Trend changes in global greening and browning: contribution of short-term trends to longer-term change. Global Change Biology 18: 642-655.

Donohue, R.J., Roderick, M.L., McVicar, T.R. and Farquhar, G.D. 2013. Impact of CO2 fertilization on maximum foliage cover across the globe’s warm, arid environments. Geophysical Research Letters 40: 3031-3035.

Eastman, J.R., Sangermano, F., Machado, E.A., Rogan, J. and Anyamba, A. 2013. Global trends in seasonality of Normalized Difference Vegetation Index (NDVI), 1982-2011. Remote Sensing 5: 4799-4818.

Liu, S., Liu, R. and Liu, Y. 2010. Spatial and temporal variation of global LAI during 1981-20006. Journal of Geographical Sciences 20: 323-332.
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I always go to Libertarian think tanks funded/founded by oil company billionaires when I want unvarnished scientific truth on fossil fuel emissions.

:roll:
 
Threegoofs said:
I always go to Libertarian think tanks funded/founded by oil company billionaires when I want unvarnished scientific truth on fossil fuel emissions.

:roll:
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Do you really ?

Well whatever works best for you :wink:
 
You didn't answer my question. Or rather, you showed that your earlier claim was... ah... misleading and false (still!). What is directly measured regionally or globally is changes in vegetation cover. The relative contributions of CO2, soil quality, hydrological cycles, ecosystem interactions and so on to regional changes in vegetation cover are not directly measured at all.

If you think that they are, please answer my question: What instrument/s are used to directly measure them? Not to measure greening or browning, but to directly measure CO2 and other factors' relative contributions to it?
 
Mithrae said:
You didn't answer my question. Or rather, you showed that your earlier claim was... ah... misleading and false (still!). What is directly measured regionally or globally is changes in vegetation cover. The relative contributions of CO2, soil quality, hydrological cycles, ecosystem interactions and so on to regional changes in vegetation cover are not directly measured at all.

If you think that they are, please answer my question: What instrument/s are used to directly measure them? Not to measure greening or browning, but to directly measure CO2 and other factors' relative contributions to it?
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Reference the studies themselves. CO2 levels are easily measured and you've been given plenty else to look at so what other factors is it you are alluding to ? Are you trying to claim those studies and observations got it wrong and that the Earth is not greener as a consequence of extra CO2 ?

If so what is your contrarian evidence for this ?

https://www.newscientist.com/article/mg21829204-400-carbon-emissions-helping-to-make-earth-greener/

Why is it so difficult for you to accept that extra CO2 may well be a far more positive thing for us than a negative or do you have some other agenda in play here ?
 
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flogger said:
Reference the studies themselves. CO2 levels are easily measured and you've been given plenty else to look at so what other factors is it you are alluding to ?
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So changes in vegetation cover are measured, CO2 levels are measured, therefore the effect of CO2 on vegetation changes is 'directly measured.' Blatantly fallacious and still false, but for the sake of argument let's go with it.

Then changes in temperature are measured, CO2 levels are measured, so the effect of CO2 on temperature changes is directly measured.

Unless you'd care to actually answer the question, and explain how the former is directly measured in contrast to the latter?
 
Threegoofs said:
Interesting theory - here's the paper.

The concept is that the native population of the new world were managing the land in North America, clearing most of it with fire. Then, in the 1500s and 1600s, disease wiped out 90% of natives, thus allowing massive forest regrowth in the now-depopulated US.

The massive carbon sequestration from tree growth dropped CO2 levels, thus triggering a Little Ice Age.

An Error Occurred Setting Your User Cookie
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Worth exploring, although I doubt the population collapse could have been quite so complete or the reforestation quite so rapid.
 
Mithrae said:
So changes in vegetation cover are measured, CO2 levels are measured, therefore the effect of CO2 on vegetation changes is 'directly measured.' Blatantly fallacious and still false, but for the sake of argument let's go with it.
Then changes in temperature are measured, CO2 levels are measured, so the effect of CO2 on temperature changes is directly measured.
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The big difference being the effect of CO2 on vegetation growth is well known and has been for decades its effect on temperature is not and is as yet speculation but don't just take my word for it

Plants Need CO2 - Carbon Dioxide Emissions - Global Warming Climate Change Facts

Unless you'd care to actually answer the question, and explain how the former is directly measured in contrast to the latter?
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Read the studies I'm not the one who did the measuring I just linked the results. If you don't want to believe those then whats your theory ?

Then perhaps you can answer the question about why you are in such denial about all this despite the long established correlation between increased CO2 and plant growth and overwhelming evidence of this effect seen in the real world ?
 
Jack Hays said:
Worth exploring, although I doubt the population collapse could have been quite so complete or the reforestation quite so rapid.
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Well, several sources point to the population collapse being so complete - 95% or so. And reforestation was certainly rapid. I'm mostly familiar with the situation in North America, but there is certainly evidence of large settlements in the Amazonian basin that have only recently been discovered.

I recommend reading Charles Mann's book, 1491, for a good overview of these basic facts.

The question really is if these basic factual pieces of information could have impacted the climate.

The Pristine Myth: The Landscape of the
 
flogger said:
The big difference being the effect of CO2 on vegetation growth is well known and has been for decades its effect on temperature is not and is as yet speculation but don't just take my word for it

Plants Need CO2 - Carbon Dioxide Emissions - Global Warming Climate Change Facts



Read the studies I'm not the one who did the measuring I just linked the results. If you don't want to believe those then whats your theory ?

Then perhaps you can answer the question about why you are in such denial about all this despite the long established correlation between increased CO2 and plant growth and overwhelming evidence of this effect seen in the real world ?
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Love how he proclaims 'overwhelming evidence' and 'direct evidence' and then never actually provides any when directly questioned.
 
Threegoofs said:
Well, several sources point to the population collapse being so complete - 95% or so. And reforestation was certainly rapid. I'm mostly familiar with the situation in North America, but there is certainly evidence of large settlements in the Amazonian basin that have only recently been discovered.

I recommend reading Charles Mann's book, 1491, for a good overview of these basic facts.

The question really is if these basic factual pieces of information could have impacted the climate.

The Pristine Myth: The Landscape of the
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Thanks, but I'm aware of a great deal of the discussion of pre-Columbian Native American populations. I don't think the evidence justifies a sweeping generalization of an extreme outcome. Extraordinary claims, after all, require extraordinary evidence. But leaving that aside, timing of the onset of the LIA is even more problematic. A sample:

For this reason, any of several dates ranging over 400 years may indicate the beginning of the Little Ice Age:

  • 1250 for when Atlantic pack ice began to grow
  • 1275 to 1300 based on radiocarbon dating of plants killed by glaciation
  • 1300 for when warm summers stopped being dependable in Northern Europe
  • 1315 for the rains and Great Famine of 1315–1317
  • 1550 for theorized beginning of worldwide glacial expansion
  • 1650 for the first climatic minimum.[SUP][17][/SUP][SUP][18][/SUP][SUP][19][/SUP]

[h=2]
[/h]
 
Jack Hays said:
Thanks, but I'm aware of a great deal of the discussion of pre-Columbian Native American populations. I don't think the evidence justifies a sweeping generalization of an extreme outcome. Extraordinary claims, after all, require extraordinary evidence. But leaving that aside, timing of the onset of the LIA is even more problematic. A sample:

For this reason, any of several dates ranging over 400 years may indicate the beginning of the Little Ice Age:

  • 1250 for when Atlantic pack ice began to grow
  • 1275 to 1300 based on radiocarbon dating of plants killed by glaciation
  • 1300 for when warm summers stopped being dependable in Northern Europe
  • 1315 for the rains and Great Famine of 1315–1317
  • 1550 for theorized beginning of worldwide glacial expansion
  • 1650 for the first climatic minimum.[SUP][17][/SUP][SUP][18][/SUP][SUP][19][/SUP]

[h=2]
[/h]
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So you're aware, but had no clue of the population decline estimates of 95%.

Sure.
 
flogger said:
Then perhaps you can answer the question about why you are in such denial about all this despite the long established correlation between increased CO2 and plant growth and overwhelming evidence of this effect seen in the real world ?
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I've never disputed or denied the finding of a CO2 fertilization effect in recent decades in some regions; on the contrary, I've specifically noted more than once that increases in generally darker foliage cover is a positive albedo feedback to CO2 warming, certainly during the major deglaciation periods and probably in the present also. Yet more... um... blatantly incorrect information from you, it seems.

But perhaps you can answer the question about why you are in such denial about the CO2 greenhouse effect despite the long established correlation between increased CO2 and temperature change and overwhelming evidence of this effect seen in the real world?



See also Shakun et al 2012, Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation, Nature

flogger said:
The big difference being the effect of CO2 on vegetation growth is well known and has been for decades its effect on temperature is not and is as yet speculation but don't just take my word for it
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Of course, you still have not explained how the effect of CO2 on regional or global vegetation growth is directly measured and, as noted earlier, have in fact posted references which show precisely the opposite. So if nothing else on that score at least your claim that it's "the only directly measurable effect" remains proven to be a... well... let's just settle for calling it a constantly-repeated false propagandistic claim in direct contradiction of your own sources and my repeated efforts to point out the obvious. I'm sure there must be a shorter term for that cumbersome phrase, but I can't imagine what it would be.

On the other hand, you pretend that the effect of CO2 on temperature change is not equivalently proven - or even better and more directly proven, since longwave radiation fluxes can be directly measured - simply by denying even more fundamental proven scientific facts which have been known since the 19th century! (EG, John Tyndall 1861, On the Absorption and Radiation of Heat by Gases and Vapours, and on the Physical Connexion of Radiation, Absorption, and Conduction; Philosophical Transactions of the Royal Society of London.) In that light, I suppose I'll have to concede that this could potentially be more a case of determined self-delusion than anything else.
 
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Mithrae said:
I've never disputed or denied the finding of a CO2 fertilization effect in recent decades in some regions; on the contrary, I've specifically noted more than once that increases in generally darker foliage cover is a positive albedo feedback to CO2 warming, certainly during the major deglaciation periods and probably in the present also. Yet more... um... blatantly incorrect information from you, it seems.
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No you are simply in denial now given what you've already been shown

But perhaps you can answer the question about why you are in such denial about the CO2 greenhouse effect despite the long established correlation between increased CO2 and temperature change and overwhelming evidence of this effect seen in the real world?
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Because the correct value for the climate sensitivity of CO2 has never been established unlike its plant fertilization properties so there is no such overwhelming evidence. What we do have evidence of is a modest natural warming phase (like dozens of others since the last glaciation)which may well have peaked and which started long before humans could have influenced it. The invokation of CO2 as a culprit is without any empirical foundation whatsoever

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Yes the Milankovitch cycles are well known but hardly relevant to just the discussion of the last 30 years of satellite observation

Of course, you still have not explained how the effect of CO2 on regional or global vegetation growth is directly measured and, as noted earlier,
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I may be an engineer but satellite sensor technology is not part of my resume. I suspect the compilers of the studies are the people you should take up your complaint with

have in fact posted references which show precisely the opposite.
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No your references are actually completely irrelevant to the discussion given they are studies of natural processes spanning hundreds of thousands of years not man made ones spanning a few decades

So if nothing else on that score at least your claim that it's "the only directly measurable effect" remains proven to be a... well... let's just settle for calling it a constantly-repeated false propagandistic claim in direct contradiction of your own sources and my repeated efforts to point out the obvious. I'm sure there must be a shorter term for that cumbersome phrase, but I can't imagine what it would be.
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Good grief fella you've been given the observed evidence of what is actually happening in the real world but you still refuse to believe it and worse still are now calling it propaganda. And they call us skeptics the 'deniers' :shock:

On the other hand, you pretend that the effect of CO2 on temperature change is not equivalently proven - or even better and more directly proven, since longwave radiation fluxes can be directly measured - simply by denying even more fundamental proven scientific facts which have been known since the 19th century!
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Obviously not given the results of the speculation to date

STILL Epic Fail: 73 Climate Models vs. Measurements, Running 5-Year Means « Roy Spencer, PhD

This is what is called guessing and getting it spectacularly wrong.

One could try using simple common sense here too. If the CO2 level is higher than at any time in the last 10,000 years then why isn't the temperature anywhere near being so ? Surely if CO2 had the significance they are telling us it has then this must come to pass ? Could it be (shock horror) CO2 has nothing like the importance they want us to believe it has viz temperature. If that is so it would really put the skids under your new world order agenda wouldnt it ?
 
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flogger said:
Because the correct value for the climate sensitivity of CO2 has never been established unlike its plant fertilization properties so there is no such overwhelming evidence.
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What is the correct value for plant fertilization from CO2, exactly?
 
Mithrae said:
What is the correct value for plant fertilization from CO2, exactly?
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I expect it will vary depending on the species and latitudes but as you were linked the optimal level for plant growth is around 1200 - 1300 PPM or around three times that of today. Even your commercial greenhouse owner will confirm such benefits so they are not scientifically contentious in any way nor have they been for decades

CO 2 climate sensitivity however has never been quantified in this manner meaning we have no way of telling what the impact of an extra 10, 50 or 100 PPM will have on temperature. Remember we are talking percentages of extra CO2 in our atmosphere equivalent to 0.0001% (100PPM) of total atmospheric volume from a relatively weak greenhouse gas so this inability to quantify its significance is unsurprising
 
flogger said:
I expect it will vary depending on the species and latitudes but as you were linked the optimal level for plant growth is around 1200 - 1300 PPM or around three times that of today. Even your commercial greenhouse owner will confirm such benefits so they are not scientifically contentious in any way nor have they been for decades

CO 2 climate sensitivity however has never been quantified in this manner meaning we have no way of telling what the impact of an extra 10, 50 or 100 PPM will have on temperature. Remember we are talking percentages of extra CO2 in our atmosphere equivalent to 0.0001% (100PPM) of total atmospheric volume from a relatively weak greenhouse gas so this inability to quantify its significance is unsurprising
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CO2's effect on temperature has been quantified in precisely the same manner: In controlled circumstances, value X for CO2 will produce value Y for variable in question, be it plant growth or temperature increase.

You do not have a precise "correct value" for plant growth from an additional 120ppm of CO2 in the real world, do you? At best, you might find a range of possible values depending heavily on other variables.


You know, the more we discuss this the more I think that I have to eat my words: You really couldn't be lying. Incorrect you certainly are, but no informed intelligent person could possibly forge ahead with constantly emphasising such an obvious and strong comparison if their purpose was to paint one of the known effects of atmospheric CO2 in a good light and the other bad, because it accomplishes precisely the opposite. The methods and conclusions of climate science are entirely comparable to any other scientific enquiry. I can't fathom why you've been unable to comprehend this after so many threads and so many posts explaining it to you, but I do apologize for my earlier comments. You really deserve pity, not censure.
 
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