…and human civilization did just fine.
The Holocene context for Anthropogenic Global warming
Guest essay by Ed Hoskins
Our current beneficial, warm Holocene interglacial has been the enabler of mankind’s civilisation for the last 10,000 years. The congenial climate of the Holocene spans from mankind’s earliest farming to the scientific and technological advances of the last 100 years.
Summary
When considering the scale of temperature changes that alarmists anticipate because of Man-made Global Warming and their view of the disastrous effects of additional Man-made Carbon Dioxide emissions, it is particularly useful to look at climate change from a longer term, century by century or a millennial perspective.
The profile of our current Holocene epoch with temperature averages century by century set against the maximum of the past Eemian epoch and the predictions of Catastrophic Global Warming alarmists this century.
The much vaunted and much feared “fatal” tipping point of +2°C would only bring Global temperatures to the level of the very congenial climate of “the Roman warm period”.
If it were possible to reach the “potentially horrendous” level of +6°C postulated by Warmists, by the inclusion of major positive feedbacks from additional water vapor in the atmosphere, that extreme level would still only bring temperatures to about the level of the previous Eemian maximum.
The Context
The Vostok and EPICA Antarctic ice core records show that there have been 5 interglacial periods in the last 450,000 years, they have varied both in temperature intensity and duration. On occasions some earlier interglacial periods were significantly shorter than the 10,000 year norm. These climate changes can be seen in the overlaid Vostock and EPICA Ice Core records from the Antarctic.
The periods of glaciation and Interglacials show a fairly regular pattern. The Antarctic based EPICA and Vostok Ice Cores above mostly show good accord for the last 200,000 years. But earlier there seems to be a similar pattern but with some significant time displacement in the period between 200,000 and 450,000 years ago. Those two Antarctic records are not so well coordinated during the recent Holocene period.
Warm Interglacials seem to last roughly 10,000 years and the intervening periods of full encroaching glaciation persist for some 100,000 years or more in between.
Prior to the Holocene epoch a period of deep encroaching glaciation had persisted for the previous 100,000+ years. Such glaciation meant that a mile high ice sheet covering New York and much of the currently inhabited Northern hemisphere. That glaciation was preceded by the Eemian interglacial period. The Eemian epoch was at its warmest about 120,000 years ago. It was some +3°C warmer than the Holocene “Climate Optimum”, only about ~8000 years ago.
So based on this pattern of radical climate change our current benign Holocene interglacial could well be drawing towards its close.
According to longer term Northern Hemisphere Greenland GRIP ice core records, the last millennium 1000 – 2000 AD was the coldest of the current Holocene epoch, with millennial average temperatures about 1.8°C lower than its early “Holocene climate optimum” in about 6000 BC.
There has since been a comparatively minor temperature recovery since the Little Ice Age some 300 years ago.
However, it is this minor temperature recovery that has recently given rise to the “Great Global Warming Scare”.
The Holocene Epoch
The temperature progress of the current Holocene interglacial epoch for the last 10,000 years is interesting as a gauge for all the recent Warmist and Alarmist predictions that have been developing over the most recent 40 – 50 years.
The Holocene interglacial can be divided into two phases.
- the early Holocene, encompassing its highest “Climate Optimum”, was relatively stable at the millennial level showing only a modest cooling of about 0.05°C per millennium from about 8000BC up until about 1000BC.
- thereafter the more recent 3000 year phase 1000BC – 2000AD shows much more rapid cooling at a rate of 0.5°C per millennium, (i.e. about ten times the earlier rate).
Judging from the lengths of past interglacial periods, after some 10,000 – 11,000 years the Holocene should be drawing to its close. A climate reversion to full, encroaching, glaciation is therefore foreseeable, if not overdue, in this century, the next century, or this millennium.
Looked at from the point of view of the most recent 3 millennia which have experienced accelerated cooling, a continued natural climate change towards a colder climate is now more, rather than less, likely.
Cooling would lead to more intense and adverse weather: there is good reason to expect this, simply because the overall energy differential between the poles and the tropics can only be greater with cooling and that in itself would lead to less stable atmospheric conditions.
In addition to more adverse weather, any coming cooling will also lead to very serious deprivation for mankind and the biosphere as a whole. Growing seasons will shorten and less arable land will be capable of crop production.
But all current Climate Change discussion and propaganda only concentrate on short term temperature variations, often with emphasis on minor short term temperature increases. These always try to emphasise ever increasing global temperatures. But they are often measured in virtually undetectable one hundredths of a degree Centigrade.
The predictions of Catastrophic Global Warming by alarmists should be set in the context of the temperature picture of the current Holocene interglacial
The much vaunted and much feared “fatal” tipping point of +2°C would only bring Global temperatures to be at the level of the very congenial and productive “Roman warm period”. A further rise of +2°C could only bring positive economic benefits to the bulk of the Northern hemisphere.
Catastrophic Global Warming alarmists postulate that temperature rise will reach the “potentially horrendous” level of +6°C by from the inclusion of major positive feedbacks from additional water vapor in the atmosphere. The +6°C temperature level would still only bring global temperatures only to about the level of the previous Eemian maximum.
The Eemian interglacial ~120,000 years ago, was a warm and more plentiful period in the worlds recent history: hippopotami thrived in the Rhine delta. As ice sheets substantially receded in the Eemian, resulting sea levels were about 3 meters higher than found at present. But that ice sheet disintegration process would have taken millennia to be fulfilled.
But according to the Alarmists all this radical and destructive temperature increase is supposed to occur over a span of less than 100 years in this century 2000 – 2100AD. And it is solely attributable to Man-kind’s burning of fossil fuels and emission of extra Carbon Dioxide into the atmosphere.
Over the past 20 years:
- Man-made Co2 emissions have risen by ~14%
- CO2 concentrations in the atmosphere have increased by almost ~8%
but there has been no perceptible increase in Global temperature.
Global Warming Alarmists including:
- the Intergovernmental Panel on Climate Change
- the United Nations
- many Western Governments
- Green NGOs, etc.
aggressively assert catastrophe with excessive temperature rises. But is extreme hubris to expect that mankind could achieve a complete reversal of the world’s climatic progress of the last 3000 years and achieve an additional positive +6°C change over the course of the current century.
When the postulated warming in the coming century as promoted by the IPCC and other Global Warming alarmists is collated against the progress of actual Holocene temperatures, the absolute implausibility of the Man-made global warming hypothesis becomes obvious.
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‘If it were possible to reach the “potentially horrendous” level of +6°C postulated by Warmists, by the inclusion of major positive feedbacks from additional water vapor in the atmosphere, that extreme level would still only bring temperatures to about the level of the previous Eemian maximum …’
==================================
And why didn’t every past warming episode, with the accompanying far more important water vapour feedback, follow the ‘worst case’ temperature trajectory produced by the IPCC predictions/projections?
Ed Hoskins – you have used ice core data as a proxy for global temperature, which is incorrect. There is a well know “polar amplification” effect whereby the temperature variations at the poles is much greater than the globe overall. Customarily one divides the ice-core data by two (or more) to discount for polar amplification. This changes the basic premise of you argument, sadly.
Some may find a brief overview of ice core temperature (T) data useful.
Most such T data are derived from fractionations in isotopes of O and H. Fractionation occurs when water evaporates (e.g. from the sea surface) into the atmosphere, again when some of that water precipitates as rain over, e..g. southern Greenland, and again when it falls as snow on the upper GL ice plateau. The derived ice core T is a product of all such fractionations, after calibrations are applied (e.g. downhole T mentioned above). That is why one cannot combine ice core T directly with surface measured T. Now envision how the north Atlantic (the source of much of the moisture that falls as snow on GL) via the AMO and Gulf stream changes its T over time. (Antarctica has less variation because of the circum-Antarctic ocean current.)
Ice core T data may be precise, but they in part reflect changes in ocean currents and T.
“But all current Climate Change discussion and propaganda only concentrate on short term temperature variations, often with emphasis on minor short term temperature increases.” If the people prominent in the political side of the alarmist movement could find a way to achieve their ends because of an impending ice age they would probably switch back to alarm over that.
GISP does not represent the rest of the Northern Hemisphere. Around 1200 BC which is erroneously called the Minoan warming, was a very cold period for the mid latitudes, and caused the demise of many cultures including the Minoans. While the 8th century was as warm or warmer than now in Europe, during a decidedly colder period in GISP.
There are lots more supplementary data to the GISP ice core from around the world to validate the overall premise that the Holocene is winding down. Quibble all you like about such trifles as when exactly the Minoan optimum ended or the post Roman cooling began. The evidence indicates the best years of this interglacial are behind us and the next max will begin sooner than we’d like. Enjoy it while it lasts.
It is hardly a trifle to be assuming that GISP proxy temperatures through the Holocene move in unison with the rest of the northern hemisphere when they actually move in opposition. The temperature trends from the Antarctic would be more valid than from the Arctic.
ulriclyons June 2, 2015 at 2:53 am
As I said, the GISP core is supplemented by many other data from around the world. The general trends are accurate, even if specific details vary region to region. The Holocene is gradually petering out, punctuated from time to time by steadily decreasing temp spikes. That’s why I refer to your points as trifles. Just as the current (as of 1998) picayune spike in temp since 1850 is a trifle. We live in the coldest millenium (except for the Younger Dryas) of one of the three coldest eras in geologic history, to at least 600 million years. I’m not going to worry about whether the eastern Mediterranean was a degree or two warmer than Greenland in 1200BC or 800AD. My advice still remains: Enjoy it while it lasts.
The Minoan WP was indeed followed by a severe cold snap which disrupted the Mediterranean world, the Greek Dark Ages CP.
Here’s a NH temperature proxy that’s reasonably reliable….
http://www.independent.co.uk/news/science/veni-vidi-viticulture–remains-of-roman-vineyards-found-in-uk-738723.html
Greg,
Wine from north Britain during the Medieval WP was of such high quality and volume that French exporters suffered.
Thanks, Ed Hoskins. Excellent article.
Reblogged this on The Next Grand Minimum and commented:
“Looked at from the point of view of the most recent 3 millennia which have experienced accelerated cooling, a continued natural climate change towards a colder climate is now more, rather than less, likely.”
As far as global warming alarmists belief system is concerned, the past climate changes never happened. It has to be that way for their climate con to have a chance of being believed. But that’s the problem … theirs really is a climate con, pure and simple.
A few years ago, I tried my hand splicing smoothed HadCRUT3 to the self-corrected historical temperature proxy by Loehle, published in Energy and Environment, and favored by Dr. Roy Spencer. My results: Global temperature during the current pause of modern warming has been slightly warmer than the warmest 30 year period of the MWP.
The successful Norse dairy farms of SE Greenland a thousand years ago say you’re wrong. The experimental dairy herd is not yet ‘living off the land’ entirely as during the MWP.
Greenland ice core records appear to me as showing that Greenland had a significant meltdown during the Eemian interglatial.
‘So far the ice cores can only provide us a glimpse into the Eemian warm period. But we can already tell that Eemian climate was significantly warmer than the climate of the current Holocene interglacial – probably about 5°C warmer. As ice from the Eemian period (albeit disturbed) has been found at all drill sites, we also know that the Greenland ice sheet did not melt away entirely during the warmth of the Eemian. Close analysis of δ18O values in the Eemian ice does indeed suggest that the Eemian Greenland ice sheet was not dramatically smaller than today’, link:
http://www.iceandclimate.nbi.ku.dk/research/climatechange/glacial_interglacial/eemian/
Chris,
Excellent link, showing that the high Northern Dome was not affected even by greater and longer Eemian warmth. The Southern Dome and lower elevations of the Northern were however affected.
It does however appear that during the interglacials of about 400,000 and 800,000 years ago, the Southern Dome did melt away in places, but they were even warmer and longer than the Eemian.
Due to its lower peak warmth, the Southern Dome would probably survive even if the Holocene lasts as long as those two previous super interglacials.
Donald,
The CET shows you’re wrong.
Also, the Southern Dome of the GIS did indeed diminish during the Eemian, but that interglacial was a lot warmer than this one and lasted 5000 years longer, so far.
Ultimately, we have no more reason to believe the planet will cool going forward than that it will warm. We have no first principles. We don’t know why there were ice ages in the Proterozoic, we don’t know why there was one in the Ordovician, and between the Carboniferous and Permian. We don’t know why it got very hot in the Triassic, and again in the early Eocene. We don’t know why it has cooled ever since, culminating in our current ice age.
Until we know this…
BTW, whoever plotted that graph upstream that showed the Tertiary maximum in the Oligocene got it wrong.
Considering that we are still in the Pleistocene, I’d say the most likely outcome is the end of the Holocene interglacial followed by another 100,000 year max. I’d like to be wrong, but will be long gone – hopefully!
Well, all of the prior cold periods ended so we can presume the Pleistocene will end as well. Since our understanding is zero, it surely remains possible that the Pleistocene is ending now.
If you look at the glacial/interglacial fibrillations within the Pleistocene it seems apparent that the planet bounces very quickly out of glacial episodes like a perturbed system returning to its normal state, but has to be dragged kicking and screaming back into a glacial.
We’ll all be gone either way.
gymnosperm June 2, 2015 at 7:18 am
There is zero geologic evidence that the Pleistocene has ended. The planet still has two icecaps and many other glaciers. In fact, there’s a disheartening amount of ice on the planet. The geology of 2.6 million years ago is pretty much identical to the geology of now. Plates have moved a few inches, but the Isthmus of Panama remains closed and Antarctica remains an island. Those two facts, and the interruptions/changes in ocean currents they produced along with minor changes in orbital eccentricity, seem to be the most likely causes of the current period of glaciation.
So the most like scenario is the Holocene is just another brief warm period bracketed by 100,000 year glacial maxima. Until the geology changes significantly, there is no reason to think otherwise. Wishing it weren’t so doesn’t make it so.
Gymno,
The Pleistocene has been only the NH extension of the ice house that began in the Oligocene, with the formation of the Antarctic Ice Sheet, due to the opening c. 34 Ma of deep oceanic channels between that continent and South America and Africa, ie the creation of the Southern Ocean. Northern ice sheets were added after the closure of the Inter-American Seaway, c. three Ma.
The Carboniferous-Permian ice house lasted tens of millions of years (by one measure 100 my), so the current one probably has a lot longer to go. However, the actual ice age during the Ordovician ice house period was shorter in duration, so who knows?
Over the past several ~100 kyr glacial cycles, there has been reasonably good correlation between temperature and the various Milankovitch orbital parameters. Most students of the ice ages believe these cycles act as triggers for glaciaiton. (But they are not the only drivers, as changes in albedo, ocean currents, and cloud cover must also play significant roles.) The shortest-term orbital variation (the ~21 kyr precessed obliquity cycle) has been cooling the northern hemisphere (NH) for some 9 kyr, the period of the Holocene. That will end in a couple kyr and the NH will start to warm again. But the ~100 kyr eccentricity cycle, which defines the ~100 kyr major glaciation periods, is also near a minimum. The combination of these two cycles predict that solar irradiance and thus NH temperature variations over the next few tens of kyr should be much smaller than over the past few glacial cycles. Major glaciation is not in Earth’s near future.
The Quaternary Period splits into two separate Epochs – Pleistocene and then Holocene.
I can be chastised for this, but I believe we are still in the Pleistocene and the Holocene is just an interstadial. It seems to me that the Holocene epoch was created due to human civilization (language, tools, writing), and not due to temperature. Since the average interstadial is 10,000 – 15,000 years and the Holocene is already within the range for a turn back to cold.
The Holocene is a perfectly ordinary interglacial, not interstadial.
On the other hand, the most severe population crisis the genus Homo is documented to have survived was the reduction of the world population (bottleck) about 70-100,000 years ago, contemporaneous with a marked *cooling* spike in the ice core data.
During a more primitive time, we did not understand that the current interglacial was not some special interglacial. We incorrectly deemed the Pleistocene to be something different from where we were at. We imagined that “The Ice Ages” had ended. Now, with better understanding, we can see how erroneous this concept of “The Pleistocene” and “The Holocene” being different things is. It is a grave error. It has infected the thinking of the hubris laden humans and made them feel overly optimistic. There is going to be a harsh reckoning when “The Pleistocene” stands up and dances, singing “I never died!”
I quote:
“Over the past 20 years:
Man-made Co2 emissions have risen by ~14%
CO2 concentrations in the atmosphere have increased by almost ~8%
but there has been no perceptible increase in Global temperature.
Global Warming Alarmists including:
the Intergovernmental Panel on Climate Change
the United Nations
many Western Governments
Green NGOs, etc.”
Precisely. I would not expect anything else since 18 of the 20 years were a warming halt known as the pause/hiatus or whatever else it is called. As I have said before, the absence of this warming invalidates the the Arrhenius theory of greenhouse warming.
It follows that
THE GREENHOUSE THEORY OF GLOBAL WQARMING IS DEAD.
And with it dies AGW, the anthropogenic global warming.
History is not now. There are too many unknowns in the past to make comparisons to the present.
What everyone keeps missing in the equation is the level of vegetation in these time periods, the particular geographical formations over history (Gondwanaland, volcanoes, meteor strikes, CO2 levels in oceans and deviations in the average 11 year solar minima/maxima cycles).
Numerous meteors have hit earth which some propose caused the extinction of dinosaurs when a strike hit earth and increased its rotation speed – stronger gravity.
We are in a solar minima now since 2008 which explains the pause (not decrease) in warming. Yet recently India experienced extreme heatwaves during the months of April May, while Australia had record national monthly averages and Queensland a record March day maximum.
The real flat-earthers are deniers who cling to dinosaur fossil fuels and support out-dated theories of Omnipotent Mankind, able to conquer all – a mindset indicative of the arrogant 1950s. Nearly as bad as the AGW Creationist slur. Creationist do not believe in science so why would they postulate on man-made CO2 causing warming by referring to devil scientists.
Deniers refuse to accept that mankind is as influential as they like to think they are but in a negative way.
Every action has an opposite and equal reaction.
Mankind pumps heat into the atmosphere, from a billion vehicles, from Coal and nuclear power stations (coolant water effluent), wars (troop movements, explosions), wargames and training, space shuttles (dinosaur SUV rocket) blowing out and up in the atmosphere, two a-boms, and 2000 nuclear tests.
Add to that the rapid increase in Urban Heat Islands (Dubai, a desert city in an already extreme climate made worse by energy hungry AC and Desalinisation systems).
Nature expels and absorbs C02 in a near balanced cheque book. Mankind adds CO2 and does not remove it. Nature is adapting to Mankind and causing Climate SYSTEM Change.
I agree with:
Jtom – June 1, 2015 at 1:47 pm
‘Sounds to me like you’re saying less stable atmospheric conditions would lead to greater energy differential between the poles and the tropics.’
‘Either way, I suspect the correct wording would be, greater energy differentials lead to less stable atmospheric conditions. Period. ‘Cooling’ is a relative word. If the tropics and the poles both heated up or both cooled down, but by vastly different amounts, it would still produce greater atmospheric instabilities.’
Removal of up to 50 percent of equatorial rainforests in the past 50 years has created an imbalance in hot/cold transference.
Rainforests cool the hottest part of the planet (as well as absorb CO2) by transpiration and cloud attraction. Reducing this volume of vegetation also changes the water cycles.
Warmer air is more energetic air (ice, water, gas) and increased molecular temperatures mean increases in molecule vibration.
Increased tropical air temperature causes more air to be drawn down from the equator at more volatile speeds such as we saw with the Jet Stream being dragged down below the UK in 2009.
David Linton
Your exaggerations and extrapolations and false claims would make more sense if any single sentence in the above was technically accurate from its first word through the period.
Wow. Impressively rant David.
“Mankind pumps heat into the atmosphere, from a billion vehicles, from Coal and nuclear power stations (coolant water effluent), wars (troop movements, explosions), wargames and training, space shuttles (dinosaur SUV rocket) blowing out and up in the atmosphere, two a-boms, and 2000 nuclear tests.”
I’m not sure how any of these things “pumps heat into the atmosphere”. The heat was already here on earth, no?
Do you use any energy? If so, then you are part of the problem. If your footprint is bigger than the average human…and it most likely is… then you are one of those really bad humans. What do you propose we do about all this? How will you lead by example? What steps would you take if dictator of the world? How much would those steps cool the earth? Describe the cost/benefit analysis of your plan. What is the optimal temperature of the earth?
Mary Brown (replying to David’s earlier rant (er, post) about CO2’s effect on all things global.)
I am hoping he will reply; stating that only he but all of his immediate and extended family has been sterilized. 8<) If not, he is only contributing to the future energy problem, isn't he?
David,
Concur with RACook on this. Sorry, but every single sentence, as nearly as I can tell given their composition problems, is not just false but hilariously so.
The impact [which] demonstrably led to or hastened the demise of non-avian dinosaurs did not do so by affecting earth’s rotation or gravity, but by its catastrophic effects on planetary vegetation and phytoplankton, which killed off the herbivores and in turn the carnivores with relied upon them. Lots of land and sea creatures were also wiped out by those effects directly, of course.
For “with”, please read “which” I’m obviously typing impaired.
Yes David, please tell us the answers.
What is optimum CO2 level?
What is optimum earth temperature?
And please document with peer-reviewed papers.
We’re all waiting for this vast knowledge transfer.
I don’t care about peer reviewed papers. Lots of smart people don’t have the time or inclination to wade through the peer review tedium. This site IS peer review. Good ideas fly. Bad ones get ripped up. Doesn’t matter where they come from.