The Real Climate

November 21, 2007

Rather than waste energy explaining why the UN and its climate satraps are dishonestly predicting our doom, here’s a summary of what the climate has actually done over the last few hundred thousand years, and how that effected humanity.

I can’t find a book that directly deals with the connection between climate and history, so have constructed a summary for this post, using data from this book and its sources, this book and its sources, and Wikipedia.

Ice Ages

At least for the past half million years these happened every 100,000 years and lasted about 90,000 years – leaving just 10,000 years on average between ice ages. The last one finished about 10,000 years ago, so based on history, we’re due for another one soon!

The numbers (based on ice core analysis) are here and plot out as follows:

creative commons

Temperature is the top, blue, line with axis at left.

During ice ages, the sea level drops hundreds of feet, glaciers cover most arable land (which is in the northern hemisphere), and there are massive droughts, since less sea water is evaporated to form clouds and then rain.


Is 0.038% of the atmosphere. Animals exhale it and plants convert it into growth. Plants release their CO2 when they die (which is why the trendy carbon offsets are nonsense).

CO2 is absorbed by water, the amount depending on temperature. If you heat sea water it will outgas some of its CO2. That’s why the CO2 line (colored green) above lags behind the red temperature line -the earth warms first and then the sea outgasses CO2. So temperature rise is a cause not an effect of CO2 increase.

UN Climate Models

These are so complex they need supercomputers to run them – I think three in the US and one in the UK.

None of the models correctly predict recent past climate. That’s because the physics is not fully understood, and the computational problem is very hard.

Predicting climate is much harder than predicting currency exchange rates, which lots of clever and highly motivated people have also failed to do, in spite of massive computing resources.

Human History

Modern Homo Sap is thought to have appeared about 130,000 years ago, so our species has spent most of its time in an ice age. Life at first will have been very nasty, brutish, and short, with lifespans of 20 years.

There were advantages – the massive sea level fall facilitated migration, for example opening a land bridge from northern Russia to north America. A small group crossed it about 18,000 years ago and populated the both north and south America within just 2,000 years.

During this ice age, the UK was connected to France.

Interglacial Period

That started about 10,000 years ago and is we’re still in it, waiting for the next ice age. As you’ll see from the graph above, interglacial periods have temperature ups and downs, and those for the current period have substantially shaped our history, as follows.

Early Interglacial Period: 10,000 to 9,000 years ago

As temperatures rose, our numbers and longevity increased, because:

– We’re much less prone to die from heat than cold (by a factor of 10).

– As glaciers retreat, more land becomes available for hunting and farming.

– The CO2 liberated by the warming oceans fertilizes trees and crops.

– It gets rainier as the climate warms (more water evaporated from the sea), and that further boosts plant and hence animal life.

So life started looking up 10,000 years ago, and we soon invented farming, which enabled us to build larger and longer-lived populations.

Holocene Climate Optimum: 9,000 to 5,000 years ago

The temperature rose several degrees over current levels and stayed that way long enough for us to invent civilization, starting with cities, about 7,000 years ago.

It’s possible our many legends about Gardens of Eden look back to this time of warmth and plenty. Towards its end the Minoan civilization emerged, which lasted an extraordinary 1,500 years.

Pre-Roman Cooling: 5,000 to 2,200 years ago

In this and all subsequent cooling phases, island or archipelago nations have become dominant. In this case, Greek civilization emerged, laying all the foundations of western art, science, and politics.

Roman Warming: 2,200 to 1,400 years ago

This was several degrees warmer than now – much of the bread part of Bread and Circuses was produced in north Africa. The Romans completed the edifice of Western science, art, and politics on the foundations inherited from the Greeks.

In the UK, the population reached about 5 million, a level it was not to reach again until the late 1700s.

During this period China became a single nation, and the Classic Mayan Empire flowered.

Dark Ages: 1,400 to 1,100 years ago

Temperatures plunged, taking crop levels and population down. The Roman empire collapsed, in part because of multiple invasions by hungry barbarians.

Disease was rife everywhere.

The Mayan Empire collapsed.

Islam got started when a warlike desert people conquered and enslaved the weakened Christian population around the Med.

The island/archipelago warriors of this phase were the pathologically nice Norwegians and Swedes, who became the Viking pillagers – the English prayed “From the wrath of the Norsemen protect us.”

Medieval Warm Period: 1,100 to 700 years ago

Food and populations recovered.

The Vikings were whacked by the recovered Brits, and Europe came back to life, starting to push Islam back in Spain. Most of our grandest cathedrals were built then.

The diverted Vikings founded Iceland, Greenland, and settled in north America (Vinland).

The Little Ice Age: 700 to 150 years ago

Temperatures plunged again, and the weather became unsettled. Malaria was rife in Europe (it needs sun on stagnant water, not high temperatures), featuring often in Shakespeare’s plays as “the ague”.

The island-based conquerers in this cold period were the mild-mannered Brits, who were helped by being safe on an island warmed by the Gulf Stream. Plus they were used to lousy weather.

Hence the nation which has “mustn’t grumble”as its motto came to build the world’s greatest empire, invented modern agriculture and industry, and (via the US) modern democracy.

Incidentally, the late Little Ice Age is the climate of Dickens’ novels – snowy Christamasses, freezing houses, etc.

Modern Warm Period: 150 years to ?

This latest cycle is as natural as all the previous ones – the best current theory is they’re caused by fluctuations in the solar wind.

The now-warm Brits relapsed back into not grumbling and other nations overtook them. Lifespans and populations grew massively across the world.

The graph above shows the past interglacials were a degree Centigrade warmer than we are now, so there’s more to come, and that will enable the 5 million outside our first world to match our standards of living.

That warming and prosperity will also help us prepare for the coming ice age – by settling other worlds, improving food production, and building cheaper power sources.

If man-produced CO2 is enhancing this warming, that’s entirely good – both for the 5 billion people still in poverty, and for all of our descendants who must inherit, and master, a freezing world.