Bronze Age Climate Restoration

Those who followed my blog last year saw me work at tracking and isolating the various likely factors responsible for the temperature variation experienced throughout the ten thousand year Holocene. A big question mark was the existence of a two thousand year or more Bronze Age optimum that ended with the Hekla event in 1159BCE. We ran down a lot of factors and in fairness none appeared up to the task of explaining that particular optimum.

Since then, the climate has precipitously cooled and then warmed slowly over decades approaching the former optimum but actually coming nowhere close. The Rhine has been frozen several times throughout history and each time local climate took a long time to recover.

Yesterday’s item finally provides a creditable mechanism to operate this engine.

We have a layer of freshened water that is between one to two hundred meters thick lying on top of the underlying ocean waters. The temperature of these underlying waters is about two degrees over the freezing point of fresh water ice. That is a huge supply of available heat that if actually mixed with the overlying ice would eliminate it.

The upper layer is a degree or so below the freezing point. This means that a sustained warm spell and plenty of help from winds could remove this layer. If this layer is removed, it becomes decidedly harder for sea ice to form at all and its breakup the next summer will simply put it back to the way it was.

With surface temperatures a couple of degrees above freezing during the summer, the land will warm up and as happened during the Bronze Age, the permafrost will disappear.

It is pretty obvious that the Hekla event gave twenty years without crops and that means the gain of at least a couple of meters of sea ice each of those years. Over twenty years that likely added up to a beginning round of forty meters. The process likely continued at a slower pace for centuries longer until the sea ice approached a thickness of even a hundred meters or more.

What happens with sea ice is that as it ages the salt is slowly removed and this salt mixes into the surrounding ocean were normal circulation takes it eventually out into the Atlantic.

Thus the post Bronze Age cold spell produced a fresh water layer sitting directly on top of the polar sea. The lack of severe storms failed to produce any mixing since it was way too thick anyway.

The present situation and some fortuitous winds appear to have thinned this layer and have led to the present gross reduction in sea ice thickness. I do not think that the remaining sea ice is any more than part of a two year cycle of ice passing through the gyre and if not that yet, is about to be.

The big question now is whether the winds or normal seasonal warming, sufficient to remove this fresh water cap anytime soon. We are at the point in which it can do a lot of good. Yet I am aware we have been here before for decades even only to have it abruptly end.

And that mechanism is now a little clearer. For some reason we get a summer or two without any melting and suddenly we have a lot of ice. One Alaskan Volcano could do that. It really is that quick. If this mass of left over freshened water from Hekla could be eliminated though, we could return to Bronze Age conditions.

Chronology Incognito

The one issue that keeps cropping up in our ongoing perusal of the literature is that dating the past is fickle. A consensus slides into the literature and when overturned, taints all the prior work. I find myself constantly rechecking sources to get some comfort, and yes, making mistakes. We need to think about this.

For the past several thousands of years we are dependent on carbon dating. This method must be corrected by tree ring matching and that has been improving since its first discovery. That is why we know Hekla blew up in 1159 BC. Thank god we know something! On the other hand, the acknowledged error factor is significant in its own right and the wood itself can easily be decades old. This means that one sample can throw you all over the map.

Imagine dating Hekla on the basis of an ash collapsed roof. This sounds very straight forward. The assay will come back based on the apparent age of the wood which must be younger than the event. The house stood for a hundred years and the assay accounts for an error factor of one percent for ninety five percent of the time. That suggests that the date lies between 1300 BC and 1200 BC. You see how easy this is.

Now imagine trying to convince your peers that on the basis of other weaker evidence that the date is a hundred years too old.

The problem is that data does get written up and made to look convincing. This is hard to overcome. We have just reviewed the Vostok Ice Core. A marvelous chart lays out the apparent sequence of the data in clear chronological order. We have no way of confirming the reliability of the corrective factors used, if any, and thus are susceptible to been misled.

It is clear that hotspots occurred that were clearly significant and briefly countered the effects of the general ice age. The spacing is such that we can say that this is a periodic event that has yet to reoccur because the curve shape of the Holocene is radically different. The Holocene is the first stable climate regime in the past one million years because the Northern Ice Cap has been eliminated.

So what are these hotspots? They appear periodic. If they are periodic, then the probability exists that the cause is both cosmological and strongly periodic within a narrow predictable time range. If it is a solar event then it will be say 100,000 years plus or minus 10,000 years. If it is orbital then it will be say 100,000 years plus or minus 1000 years.

The data is showing three precisely similar events with a high degree of probability and clear apparent periodicity. So within the confines of our data we have clear unique and similar events that are separable from the ice age data. The probability of real periodicity is also very high and certainly approaching ninety percent plus.

If for example, the orbit were most of 150,000 years, then simple stretching of the data will preserve the near term data chronology and fit in the remainder handily giving us a 600,000 year chart. I would suspect that our weak present knowledge puts such an orbit well within the probability range. Right now we merely know that we are traveling in the right general direction and at a relative velocity that certainly supports an orbit hypothesis. We do not really know were we are on the curve of the orbit let alone a refined knowledge of the path of perigee.

Returning to the issue of carbon dating, we have illustrated just how controversial any single carbon dated data point must be. It also reaffirms the need for careful methodology and multiple samples to pin down chronologies. It also tells us that the documentary record needs to be disciplined by facts on the ground. This is slowly happening in the Mediterranean and other selected regions around the globe.

On the other hand there is still far too much ‘terra incognito’. Had the Maya built only in wood, what would we know? Millions lived in the Amazon and we have only just discovered them. And that is all within the past several thousands of years. Deeper and older, we have barely turned a spade.

When we dig down though a couple hundred feet of mud and discover man made stonework from seventy thousands of years ago, how will we explain it? Certainly our endeavors have raised the possibility.

Volcanic Climate Forcing

Anyone who has followed my investigations regarding the climatic temperature ranges experienced during the Holocene or since the end of the Ice Age should be aware of two things. The first is that the case for apparent solar variation as a forcing mechanism is weak. Part of the reason for this is that we have one apparent correlation in the Maunder minimum and no other really convincing data that cannot be attributed to noise.

My major concern though is that a one degree shift in Global temperature is perhaps measuring a tenth of a percent of the actual influx of energy. That means that the temperature should be way more responsive to solar variation if it is truly responsive. Instead we have a sea of energy flowing in that the atmosphere sheds handily to maintain an equilibrium that varies one degree per century over a two degree range. This is pretty amazing. It is a good bet that the attempts to link climate variation to solar variation may be a lot weaker than thought. Never underestimate researchers’ ability to cherry pick data.

The other side of this argument is that the capacity of the earth to offset climate variation is also grossly underestimated. It is as if we have protective barriers that cost more and more effort to over come. They are not linear at all. Even CO2 runs into a wall of diminishing returns as the percentage rises.

The second very clear fact is that every major temperature drop that we have been able to identify save the Little Ice Age has been associated with known major volcanic activity. This is the one certain way in which to lower global temperatures. In most cases, this effect lasts for a couple of years. Hekla gave us a generation of foul weather in the northern hemisphere after 1159 BCE. Thera was even bigger and caused a general collapse in Mesopotamia centuries earlier.

We have already commented on the loss of global heat as a result of the conversion of the Sahara into desert during the Bronze Age. The wrecking job was completed with the 1159 BCE blast and our northern climate has since varied between the Bronze Age optimum and the various temperature declines induced by volcanism since. We have seen that it takes about two centuries to recover to the optimum from a major low. Obviously restoring the Sahara would likely shorten this recovery time.

That returns us to the Little Ice Age. All the evidence to date is arguing forcefully that the only engine capable of lowering global temperatures is volcanism. It is also arguing that the engine for a cold northern climate is northern volcanism. It is obvious that a major injection of dust and sulphur dioxide into the polar air mass would be several times more effective than Mount Pele on the equator. In fact a major volcano that performed for a century would be able to keep the arctic several degrees colder for decades and cause a resultant buildup of polar ice, to say nothing of providing Europe with a much colder climate.

Hekla has already shown us such a result in 1159 BCE, and in a much smaller way in the late eighteenth century.

The only remaining question left is where is the volcano(es)? Here we have no problem whatsoever. The volcanic belt in the Aleutians and Kamchatka is home to the scariest set of explosive volcanoes outside of Indonesia. There are forty in Alaska, and they are active as hell. There is one going of every couple of years and we are likely in a quiet period.

Even more importantly, they are well positioned to inject gas and dust into the polar air mass and surprise! It has been a hundred years since we have had a major eruption up there that blew away twenty cubic kilometers of dust. Perhaps our northern warming trend reflects the moderate level of eruptions over the past one hundred years.

The point that I want to make is that while no Europeans even knew these volcanoes existed, they were quite capable of producing all the climatic effects experienced in Europe while not causing a measurable effect over the rest of the globe. Maybe we even have a Thera out there unrecognized and undated.