I have a very disturbing conundrum to put to you, but more on that later.

Before I go into the conundrum, I wanted to give you some background into the history of our planet Earth since it’s birth 4.6 billion years ago…

The Blue Marble -Nasa

The Earth has been through some very disturbing upheavals during it’s long existence, with wide swings from one extreme to another, but let’s not get ahead of ourselves.

Ancient Times

The oldest rocks found on Earth are 4.1 billion years old, so we know that geological processes similar to today were operating at this time. The atmosphere is another story though, because this was composed chiefly of carbon dioxide and nitrogen, but devoid of oxygen.

The temperature at the Earth’s surface must have been within 10°Celsius of today since there is evidence of sediments. Sediments are the product of weathering and deposition, which means there must have been water vapour in the atmosphere and liquid water at the surface, i.e., between 0°C and 100°C.

This all points to an Earth settled into what we know today; a core, mantle, and crust with tectonic plate movement.

Early Life On Earth

The earliest photosynthesising organisms are found in rocks 3.6 billion years old, and resemble stromatolite structures. Stromatolites can be seen today in the shallow waters around the coast of Australia. They are composed of layers of blue-green algae and calcium deposited by the algae.

The geological fossil record shows us that life, thriving on oxygen as we do today, was well established by 2.5 billion years ago.

By 540 million years ago (end of the Proterozoic eon), there was a wide range of animal types and shapes without skeletons in the seas known as the Ediacaran faunas. These were jellyfish, worms, sea-urchins, sponges, and shrimpish creatures.

The Paleozoic era, 542 – 251 million years ago, saw a huge increase in the diversification of skeletal creatures typified by trilobites, shellfish, corals, and fish in the sea. On land we had the development of fauna and trees, beetles, and reptiles.

A Cambrian Trilobite

Mass Extinctions

During this era, the massive explosion of life was interspersed with 4 great extinction events. By far the worst came at the end of the era in an event known as the late Permian extinction, when around 96% of species were wiped out.

Glaciation And The Greenhouse

Previous to the Permian extinction, the Carboniferous period was a time of huge tropical forests that are responsible for the world’s major coal deposits. This was followed by glaciation, in the late Carboniferous and early Permian periods, almost assuredly brought on by the massive draw-down of CO₂ from the atmosphere by the explosion of plant growth.

In addition we have the formation of the super-continent Pangea that caused mountain uplift, and thus weathering, which is also a major cause of CO₂ draw-down from the atmosphere.

Thus we see evidence of the direct link between plants, weathering, atmospheric CO₂, and glaciation.

Moving on to our more recent geological history, the last 2.5 million years have seen the Earth in the grip of an ice age, which continues to the present day.

Yes indeed, today we find ourselves in an inter-stadial, that is a warm period within an ice age. Over the last 600,000 years especially, a glaciation period of around 100,000 years, is followed by an inter-stadial of around 10,000 – 15,000 years, before slipping back into another glaciation, and so on.

Our present inter-stadial started 11,000 years ago.

Orbital variations of the Earth around the sun are the major forcing factor behind this phenomenon.

Let me explain…

The Earth orbits the sun not in a circle but in an elliptical shape. The shape of the ellipse varies over 110,000 years, from barely more than a circle, to maximum eccentricity, and back to just more than a circle again.

Elliptical Orbit Variations

It is when the Earth’s orbit is in it’s most circular phase that maximum glaciation occurs, because the Earth remains further from the sun for a longer period.

At the present time our orbit is moving towards minimum eccentricity, which it will reach in approximately 50,000 years time.

There are other orbital variations which affect the distribution of incoming solar radiation across the planet. It is however, the elliptical cycle that affects the quantity of solar radiation to reach the Earth’s surface, and is at present the more dominant cycle.

Human Intervention

It has been shown that in past inter-stadials, the Earth’s mean surface temperature gradually falls as we near the beginning of glaciation proper. This time however, we are seeing a rise in mean temperature due to rapid global warming caused by us humans.

There is no doubt that another glaciation period, over the northern hemisphere in particular having the worst ice-up, would devastate the human population. In the previous glaciation, ice sheets reached latitudes further south than the American great lakes, with tundra extending down as far as southern Greece, Italy and Spain.

Human activities are having an effect on the climate to the extent that rising temperature is melting polar ice shelves and glaciers around the world. The north polar regional ice cap is shrinking and thinning at an alarming rate.

The reduced surface area covered by ice has a knock-on effect on planetary albedo, where less ice reflects less solar radiation back out to space, thus more radiation is absorbed by the atmosphere and planet surface.

This is part of a positive feedback loop that enables mean surface temperature to rise even further, and at an ever increasing rate.

The Conundrum

Herein lies the disturbing conundrum.

We may just avert, delay, or weaken the next glaciation directly because of anthropogenic generated global warming, thereby saving us from the worst rigors of a freezing planet.

But this may well come at the expense of displaced populations from low lying island and coastal territories. Because make no mistake, should the polar regions ice melt, we are talking about a sea level rising in the 10’s of metres.

If however, the planet’s entire population were to be displaced to the tropical latitudes because of glaciation, we would have complete meltdown of civilization, and most likely another mass extinction of 96%+ of the world’s species as the pressure for space told.

As it stands…

With our lack of collective progress towards combating climate change, and the predicted increased planetary temperature resulting from the fossil fuels we have already burned, I am not sure we are not now passed the point of no return.

We may just have inadvertently, averted the next ice-up and saved billions of lives, at the expense of the loss of millions of square miles of precious land.

On the other hand, if by some miracle we do manage to pull back rising surface temperature, stop the ice melting, and prevent the sea level rising, we may just bring on the next ice age.

Sincerely,

P.S. What the future holds no one knows, which way the pendulum swings is unpredictable. Can we afford to sit around and wait to see the global warming effects? That’s a question for the entire world. Don’t ring me, phone the president!

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