My understanding of climate change is that it is the consequence of a complex system of physical interactions influenced by everything that exists. The radiation from the sun, the movement of the planet on its axis, plate tectonics, volcanic activity, glacial activity, meteor impacts, changes in the level of the sea and its chemical composition, the structure of the atmosphere, the evolution of life, the development and destruction of environments and ecosystems, are all important contributory factors.

One thing is clear, the climate does not stand still. The geological history of the planet, some 4.6 billion years of it, proves that. Throughout all of that time change has been a constant. It is still going on today and it will continue tomorrow and the day after that.

In light of these facts I argue that it is a mistake to consider possible outcomes of climate change from an entirely anthropocentric (human-centred) position.

Unfortunately, the current debate seems to be entirely focused on that very standpoint. As a result, it often appears to ignore all other factors, like those mentioned above. I am going to explore the subject of climate change in a calm, considered, and (hopefully) informed manner. I am not a professional scientist, I am an enthusiastic amateur at best, a layperson at worst. I am trying to take the view of the average person who is not an expert. I have no agenda other than to understand the subject better.

Let us begin at the beginning with a brief history of the planet Earth and its ever-changing climate.

In what scientists call the Hadean Eon, which lasted from 4.6 to 4 billion years ago, the planet Earth came into existence. It was formed from an accretion disc revolving around the sun until it spiralled into a central gravitating body. The Sun’s solar luminosity was only some 70% of what it is today.

The Giant Impact hypothesis suggest that another planet collided with the newly forming Earth and from the resultant debris the Moon was formed. Its orbit was some 64,000 km from the Earth and its presence stabilised the planets fluctuating axis of rotation. An Earth day was only 7 hours long. Tidal locking resulted in the Moon always presenting the same face to the Earth. This is because the Moon takes as long to rotate on its own axis as it does to revolve around the Earth.

The planet was in a molten stage at this point, its entire surface incredibly hot and constantly moving.

Around 4 billion years ago the Greenstone Belts, the oldest known rocks, were formed as the molten stage ended.

By about 3.9 billion years ago the Earth has acquired an atmosphere of mostly Carbon Dioxide (CO₂), Methane (CH₄), Ammonia (NH₃), and water vapour (H₂O). An Earth day is now some 14 hours long and the Moon has moved to 282,000 km away.

The Isua Greenstone Belt, an ancient rock formation found in southwestern Greenland today, formed about 3.8 billion years ago. It is important because it contains some of the earliest evidence of life so far discovered.

Vaalbara, the first supercontinent forms around 3.6 billion years ago. The Congo craton also appears at this time. A craton is a stable area of the Earth’s crust that forms the mass of a continent or the central basin of an ocean.

Life begins to evolve. Prokaryotes, microscopic single-celled organisms, are flourishing. There is 75% more Nitrogen (N) and 15% more CO₂ in the atmosphere than today. Solar luminosity has increased to 80%.

3 billion years ago Cyanobacteria develop the ability to produce Oxygen (O) as a by-product of photosynthesis.

From 2.9 to 2.7 billion years ago the Pongola Ice Age occurs. During this time Vaalbara, the supercontinent, also broke up. It is followed by the first known mass extinction event, which occurred 2.5 billion years ago. It is called the Great Oxygenation Event and was caused by the increase of Oxygen released into the atmosphere by primitive plant cells using photosynthesis. Oxygen was poisonous to anaerobic bacteria of that time. As a result, free Oxygen appeared in Earth’s atmosphere for the first time.

The Huron Ice Age began 2.4 and ended 2.1 billion years ago. Intensive mountain building, called orogeny, followed and Nena, the North Europe-North America, cratonic land-mass formed. Solar luminosity increased to 85% of today’s levels.

From 1.85 billion years to 541 million years ago an awful lot happens. Organisms with a nucleus enclosed within membranes, Eukaryotes, appear and lead to the development of meiosis, cell division essential for multicellular life forms, and sexual reproduction. Land plants appear resulting in an increase in Oxygen and a decrease in CO₂ in the atmosphere. There are four ice ages and continued continental creations and destruction. The Earth day is now 20 hours long and the Moon has moved to 357,000 km from the planet. The first large complex multicellular organisms are swimming through the seas. There is a mass extinction event that kills 70% of sea plants. The accumulation of Oxygen in the atmosphere allows for the development of the Ozone Layer, which reduced ultraviolet light sufficiently so as to allow life to colonise the land. Invertebrates with shells also appear.

It is difficult for us to imagine the span of time from 4.6 billion to 541 million years ago. It is huge. The average human life span is only some 70 years, which is nothing in geological terms. I believe that this is one of the problems that many people have when considering the subject of climate change. The planet simply does not function on our timescale.

In the next part I will look at the Paleozoic Era, a geological period of some 300 million years, when life both exploded with variety and complexity and yet also very nearly disappeared altogether.