I feel this a useful reference. It is just collation of data from a variety of resources, as in the table below, and then mapped onto one year, to give perspective of ‘how long through the year’ various events are.
The timeline is based on the life of the Sun from formation through the inevitable ‘red giant’ phase when the Sun will expand to either engulf, or almost engulf the Earth. The ‘green’ section indicates the short time during the ‘life’ of the solar system that the Earth can support ‘life as we know it’ on land. The orange section is the time before the atmosphere could support life on land, and the red section represents the time when CO2 levels can no longer support plant life, and the earth is set to become like Venus. On the one year time line, we need to find another home by tomorrow, and that is without climate change or any problems created by people.
Key Timeline Observations & Discussion Points.
- Life On Earth Began Early and without oxygen.
- It took around half the time there has been life, to evolve to, but Evolution started slowly.
- The Brief Burst of Life on Land.
- Cyanobacteria: The first photosynthesis.
- Thermal Runaway.
First On Earth Began Early: But Evolution started slowly.
Life began within 500 million years, which may sound like a long time, but considering the Earth was formed as a result of a sequence of collisions, and would have taken time to become even close to stable. Life had to form in the oceans given that land was inhabitable at the time, and we have evidence of life going back as far as we have evidence of oceans.
Given how quickly life arose, it seems surprising that it took another 2 billion years to single celled organisms, and 3 billion years to get to multicellular organisms. For 3/4 of the time there has been life, all life was single cell life, and there were no animals at all. Evolution was slow to get started!
The Brief Burst of Life on Land.
On the ‘annual calendar’ life on land provides only three weeks to live on land. Life on land becomes possible in early June, and ends before the month is over. This is become by the time the plants have transformed that atmosphere to have enough Oxygen to form ozone to block deadly radiation reaching the Earths surface, the CO2 supply is running low. Plants keep compensating for the ever increasing heat from the Sun by consuming CO2 and reducing greenhouse gas during the first half of the life of the solar system, but once CO2 levels are two low for plants to continue, all life will end as the planet enters thermal runaway, unless the Earth finds a new solution to controlling the temperature for the second half. The Earth will join Venus as a planet with temperatures beyond the temperature where water boils.
The Earth will have supported life on land for less than 1/20th of the life of the solar system.
Cyanobacteria: The first photosynthesis.
The current building block of life, photosynthesis, was not even present during the first billion years of life, and green plants were not present during the first 3 billion years, evolving only 1 billion years ago.
You may have heard of the ‘goldilocks zone‘. The distance from a star that is ‘not too hot’ and ‘not too cold’. The Earth is now at the very edge of that zone, as the zone continues to move away from the sun and will soon encounter thermal runaway, where temperature increases add more water vapour to the atmosphere. Since water vapour is a greenhouse gas, the Earth then heats further, adding more water vapour as a result. The end result: Earth will become another Venus with temperatures rapidly soaring beyond those where life is possible.
Given the rapid pace of technological advancement, 25 million years should be more than enough time to find a solution, but in geological time 25 million years is not that long. All things considered, humans only just managed to evolve in time!
|Years Relative to Now||date||Source|
|Sun Formed||-4,600,000,000||1/01/2020||Discover Magazine|
|Earth Formed||-4,500,000,000||4/01/2020||Discover Magazine|
|o2 – Oxygen||-2,400,000,000||24/03/2020||Great Oxygen Event|
|Eukaryotic (modern) cells||-2,000,000,000||8/04/2020||New Scientist|
|First Animals||-800,000,000||24/05/2020||Natural History|
|Plant Life On Land||-470,000,000||6/06/2020||New Scientist|
|First Dinosaurs||-231,000,000||15/06/2020||BBC Science Focus|
|Sun Is A Red Giant||5,000,000,000||31/12/2020|