Why The Current Interglacial Might Be Coming To An End
Did you know that over the last 450,000 years there have been four Ice Ages lasting around 100,000 years each?
And five interglacial periods lasting around 12,000 years each?
Look at this graph of temperature data derived from the Vostok ice core from Antarctica.
Click to enlarge
What it means is that for around 90 percent of the last 450,000 years Earth has been in an Ice Age, where global temperatures have slumped to as low as 10 deg C colder than in the relatively brief interglacial periods.
The current interglacial period (the fifth) began about 11,600 years ago, suggesting it may not last much longer. It corresponds to the time when human beings began farming and building cities and civilizations.
It is notably cooler than the previous four interglacial periods. If we ‘zoom in’ on it (see the upper graph, below)
Click to enlarge
We can see that it has been getting progressively cooler for the last 3,500 years, ‘presumably indicating the early stages of the coming Ice Age,’ says climate scientist Ole Humlum.
We also see that it is punctuated by periods warmer than the rest, most recently the Minoan warm period, the Roman warm period and the medieval warm period.
The current warm period after the ‘Little Ice Age’ of 1300-1850 (not shown as the graph ends in 1854), which according to Humlum has currently reached around the same temperature as the medieval warm period, may well be part of this natural pattern rather than driven by carbon dioxide emissions.
The lower graph shows CO2 concentration over the current interglacial period, and there is no obvious relationship with temperature.
Over a longer period, CO2 is seen to lag temperature by several thousand years rather than lead it, suggesting higher temperatures may drive greater CO2 concentrations rather than vice versa.
However, it is true that in the past 150 years CO2 concentrations have climbed from around 280 ppm to 395 ppm, a level unprecedented in the past 12,000 years [and a mere blink in Earth’s five-billion-year history].
Furthermore, since the end of the upper graph (in 1854) the temperature has risen to around the same balmy levels last seen in the Middle Ages. (This is assuming that the recent temperature data has not been misleadingly adjusted, as some believe is the case.)
This in itself is not alarming – the reported temperature rise is hardly unprecedented in the current interglacial period, and warmer temperatures (and higher carbon dioxide concentrations) provide better conditions for life to flourish.
However, if it is the case that current levels of carbon dioxide are driving runaway warming, that would obviously be deeply concerning.
That is the question current climate science is sharply focused on, though more often than not with only one acceptable answer, it seems.
Since the cost of cutting carbon dioxide emissions is huge, and will negatively affect the environment in other ways, it is well worth being sure that this is the case before taking any significant action to reduce emissions.
Despite much alarmism about a present ‘climate emergency,’ time does seem to be on our side.
While temperatures appear to have been rising on and off over the last century by about 0.15 deg C per decade, they did fall in the 1960s and 70s, and paused between 1998 and 2013, suggesting a degree of natural variability.
If temperatures continue to rise and eventually reach levels unprecedented in this (or any recent) interglacial period, then we’ll know there’s something to consider taking concerted action about, as there may be a risk that human emissions have initiated a positive feedback loop resulting in unsustainable temperature rises.
Though what counts as unsustainable is also an open question, as on a longer geological timescale we are currently in an extended ‘icehouse’ age of around 30 million years, whereas for 91 percent of the last 550 million years the Earth had no permanent ice caps at the poles at all.
From this perspective, how warm is too warm?
On the other hand, if we find temperatures stabilizing for a while, oscillating a bit, maybe falling again, then we can be more confident that we have not left the natural cycles.
Whether that is itself a good thing is a matter of debate.
In the 1970s, scientists were warning about the onset of a new Ice Age when Iceland was blocked with ice and ‘climate change’ meant global cooling. That turned out to be a false alarm, but the reasoning wasn’t entirely unsound.
The present interglacial period, if history is any guide, may have just about run its course. And what then? Human civilization has appeared and endured only during the present interglacial warmth.
How will more than 8 billion people cope with the much harsher conditions of a climate chilled by 6-8 deg C, one much less conducive to life, abundance and comfort?
Let us watch and wait for now, then, and see how things look in 2030. In the meantime, we shouldn’t take the present warmth for granted. We’ll miss it when it’s gone.
Read more at Conservative Woman
PRINCIPIA SCIENTIFIC INTERNATIONAL, legally registered in the UK as a company 
incorporated for charitable purposes. Head Office: 27 Old Gloucester Street, London WC1N 3AX.
Please DONATE TODAY To Help Our Non-Profit Mission To Defend The Scientific Method.
Trackback from your site.
Tom O
| #
Interesting article, but far more imprecise than it should have been. I didn’t think the “average” ice age was as short as the author states, nor is the current interglacial as short as is suggested. Further, no, we are not near the maximum temperature of the middle ages warming period, and certainly not close to the Roman warm period.
There is no suggestion that modern data has been manipulated, it is pretty much a proven fact., and the manipulation goes on and on. There is nothing in the graphs that are displayed – and why wasn’t a more complete graph displayed since we certainly have data on this side of 1854 – that suggests that there is any “human signature” in them, ONLY natural variability, and the pause doesn’t suggest it, it proves it.
The 1970s “ice age scare” wasn’t a false alarm, it was more a “pre shock” of the real thing, much like a smaller earthquake may precede a major one. There is nothing outside of the wild alarmist mind that suggests anything lies in the weeds of time, so to speak, in front of us other than population reducing cold. It’s in the solar sciences, its in the astrophysical sciences, it is in real climate sciences, and of course, it is obvious to any one that can think for themselves.
Reply
ANTHONY SIMON
| #
Based on what I learned in Pre-Colombian Cultural Anthro, it started to end 12/22/2012.
Reply
Boris Badenov
| #
So, I’m going to guess we’ll need a lot more of the dreaded warming CO2?
Reply
Andy Rowlands
| #
CO2 doesn’t affect temperature, but we could do with a lot more of it anyway to optimise plant & crop growth 🙂 Craig & Sherwood Idso seem to be suggesting 1200ppm is the ideal level.
Reply
CO2 Does
| #
“CO2 doesn’t affect temperature”
Just plot CO2 and temperature over the past million years. Do a simple statistical correlation. Oh correlation isn’t causation? How bout you learn some molecular physics, meteorology
Reply
CO2 Does
| #
“CO2 doesn’t affect temperature”
Just plot CO2 and temperature over the past million years. Do a simple statistical correlation. Oh correlation isn’t causation? How bout you learn some molecular physics, meteorology, something instead of just being a stupid cunt
Reply
Andy Rowlands
| #
All historical records show temperature moves first, followed 800 years later by CO2, therefore CO2 has no effect on temperature. That abusive reply you posted may well see you blocked from this site.
Reply
Moffin
| #
Hi Andy
You must be quite the romantic with your cupid stunt.
Andy Rowlands
| #
Oh indeed Mr Moffin, I do love keyboard warriors 🙂
Moffin
| #
Hi Andy Rowlands.
I woke up in the middle of the night, wiped my computer screen free of blood and fur from Zoe and Geran’s latest cat fight, and felt indignant that “Andy” had been the recipient of disgusting abuse as well as a gentleman I believe to be involved in the governance of this site suggesting you should not have an opinion so I rearranged two words in a clumsy attempt to put things right.
Evil Knieval pulled stunts on his motor bike and a cupid stunt could be walking hand in hand along a beach with somebody special.
That fulluh Matt made me do it but the need to explain could suggest restraint and sagaciousness walk along beaches hand in hand.
Best wishes. Moffin (Matt)
Andy Rowlands
| #
No probs Matt, I knew what you meant, and I’ve used those same reversed words many times myself. Some of the arguments, and the cat-fights you mentioned on here between certain people are just ridiculous.
geran
| #
Thanks for the encouragement, guys. But I don’t consider myself a hero. I’m just trying to get the truth out, while impeding the corruption of science.
Alan
| #
I don’t see anything new here and I don’t put much faith in proxy temperature data and the concept of a single temperature to define climate. It is perhaps the best guide we have, but we need research to understand the past climate changes and not enough is being done because of the ridiculous wasted effort being applied to the nonsense of human activity causing the climate to change. Until we begin to understand the past we cannot predict the future and even then the climate system may be too chaotic for any accurate predictions.
I think we can say with some certainty that the earth has been in an ice age for around 500,000 years with glacial and interglacial periods and we are approaching the peak of an interglacial. Assuming the same pattern of climate change continues then a decline into another ice age is inevitable but that could still be thousands of years away, but we could always have another colder period with warming after. All we can do is to be adaptable and one thing is certain and that is we need cheap energy which is being destroyed by the crazy attitude to cheap coal fired electricity generation.
The idea that we can individually determine whether the climate is changing in the longer term is ridiculous. All I have observed in the UK is that winters are warmer and I only know this because there is significantly less snow. I know there have been some very hot days in summer but that is just short periods. I have monitored my energy use for a number of years and there is little indication that it is getting warmer on average through the year. But this tells me nothing about what is happening in the rest of the world. All indications seem to be that North America is getting colder all year round.
The use of a global mean temperature must be stopped. It is meaningless. I have only seen one sensible analysis and that is by Darko Butina. He has applied a statistical analysis to maximum and minimum temperatures and has shown that most temperature are within two standard deviations of the mean and we have only a small number of extreme temperatures. Such analysis is essential if we are to avoid the media hype every time some extreme event is declared. Butina’s analysis shows that there are more low temperature extremes than higher temperature extremes. It does not attempt to predict future temperatures but basically confirms that everything is pretty much “normal”.
Reply
Rob Williamson
| #
Again we see people …even “Climate Scientist” Ole Humlum…confusing Glacial Periods and Ice Ages.
Perhaps calling a Glacial Period an “Ice Age” is common…. a colloqialism. But using a colloquialism when discussing scientific topics is wrong and mistaken…. and confuses people and leads them astray. This is what the socialist Climate Alarmists love. Please stop it and get your terms right.
We are in an Ice Age right now that began 2.6 million years ago. What this article is talking about is a returning Glacial Period. We call what we are in now an “Interglacial Period” for a reason. We do not call it an Inter Ice Age Period.
We are in an Interglacial Period, between Glacial Periods, during the current Ice Age.
The current Ice Age we are in has been going on for more than two and a half million years and is called the Quaternary Glaciation.
As long as we have polar ice caps and glaciers and ice sheets… we are in an Ice Age.
Reply
Andy Rowlands
| #
Agreed Rob, and well said.
Reply
Rob Williamson
| #
Thank you Andy… Take care..
Reply
Matt
| #
Hi Rob.
The ambiguity could arise from the current ice age being called the Quarternary Glaciation.
I appreciate your apparent informed information on differentiation between “glaciation” and “ice age” but ambiguity is one cause of loopholes and here we appear to have one.
Forewarned is fore armed.
Regards Matt
Reply
Rob Williamson
| #
Hi Matt: What I’m bringing attention to is the difference between Glacial Periods… and Ice Ages.
You’re correct that the ambiguity is because the current Ice Age is called the Quaternary Glaciation . The word Glaciation is so similar to Glacial.
But they have to get the terminology correct… because how many people are there that incorrectly believe the last Glacial Period was an Ice Age?
How many people fail to realize… that we are in an Ice Age right now ? ?
It’a all part of the deception and confusion that the Alarmists depend on.
Reply
Matt
| #
Hi Rob: I stand corrected and a little more informed.
Thank you.
Reply
THOMASWADAMS
| #
Cosmic Cycles, not Carbon Dioxide, Control Climate.
by: Viv Forbes, 5th February 2016.
Please feel free to publish, forward, post or quote from this.
“Projections are difficult! Especially about the future.”
Those who think the political war on carbon will lower Earth’s temperature or keep climate stable need to study climate history.
Temperatures on Earth dance to a cyclic rhythm every hour, every day, every month, every season, every year, and to every beat of the sun-spot and glacial cycles.
The daily solar cycle causes continual changes in temperature for every spot on Earth.
It produces the frosts at dawn, the mid-day heat and the cooling at sunset. It is regulated by rotation of the Earth.
Superimposed on the daily solar cycle is the monthly lunar cycle, driven by the orbit of the Moon around the Earth. These two cycles interact to produce variations in atmospheric pressure and tides, and currents in the oceans and the atmosphere.
These are the daily weather makers.
The yearly seasonal cycle is caused as the tilted axis of Earth’s rotation affects the intensity of solar energy received by each hemisphere. This produces spring, summer, autumn and winter for every spot on Earth.
Then there is the 22 year sun-spot cycle, which correlates with cycles of floods and droughts. Sunspot cycles are indicators of solar activity which causes periods of global warming and cooling.
Variations on the sun also affect the intensity of cosmic rays reaching Earth’s surface – cosmic rays create nuclei for low level cloud formation, and the shading from such clouds reduces surface temperatures.
Earth’s climate is also disrupted periodically by the effects of changing winds, ocean hot spots and submarine volcanism that produce the El Nino Southern Oscillation.
The least recognised but most dangerous climate cycle is the glacial cycle. We are fortunate to live in the Holocene Epoch, the latest warm phase of the Pleistocene Ice Age.
The climate history of the Holocene, and its predecessor the Eemian, are well documented in ice core logs and other records in the rocks. Each cycle consists of a glacial age of about 80,000 years followed by a warmer age of about 20,000 years, with the peak warming occurring over about 12,000 years.
Our modern warm era commenced 12,000 years ago and peaked during the Medieval Warming, so it is probably nearing its end.
The Holocene Warmth as revealed by the Greenland Ice Cores.
The Eemian Warm Period was warmer than today.
There have been eight warm eras separated by long glacial winters over the last 800,000 years of the Pleistocene.
In every beat of this cycle, the vast ice sheets melt, sea levels rise dramatically, coral reefs and coastal settlements are drowned, and forests and animals re-colonise the higher land released from the ice.
Reply
THOMASWADAMS
| #
One stand alone fact should forever resolve this discussion. It is a fact: The Earth, in it’s great celestial orbit, for the last one thousand years, has been imminently arriving in that location, wherein the Earth has always endured an “Ice Age”, and nothing has occurred that will change that destiny.
Reply