Above: The geologic time scale of the Earth. It shows the following:
- 4600-4000 mya: The Hadean Eon
- no life
- 4000-2500 mya: The Archean Eon
- 2500-541 mya: The Proterozoic Eon
- 541-252 mya: The Paleozoic Era
- 252-66 mya: The Mesozoic Era
- 66-0 mya: The Cenozoic Era
- first Hominins
Above: Estimated atmospheric oxygen over the last 3.8 billion years, on a linear time scale, with upper and lower bounds shown.
The chart shows 5 stages:
- Stage 1: 3.85-2.45 Ga
- Stage 2: 2.45-1.85 Ga, the Great Oxidation Event
- Stage 3: 1.85-0.85 Ga, the Boring Billion
- Stage 4: 0.85-0.54 Ga
- Stage 5: 0.54 Ga to present
There was very little atmospheric oxygen in stage 1, with a gradual increase in stage 2, to a plateau in stage 3, a rapid increase in stage 4, continuing to a peak in the middle of stage 5 until finally levelling out to the present value of 0.21 atm.
Above: Global temperature over the last half billion years, on a roughly logarithmic time scale (more detail closer to the present).
Earth's temperature has mostly been well above the present, with 2 exceptions: the Carboniferous period about 300 million years ago, and the Quaternary period which began over 2 million years ago and continues. A quarter billion hot years in between. Humans only know a world with ice caps.
Above: Global temperature over the last half billion years, on a linear time scale, with glacial periods shown at the bottom.
Above: Atmospheric CO₂ in parts per million by volume (ppmv) over the last half billion years, on a linear time scale.
The datasets vary widely, but they seem to agree there was less CO₂ about 300 million years ago, and since the Dinosaurs went extinct, with much higher CO₂ otherwise.
Above: Biodiversity (in thousands of genera) over the last half billion years, on a linear time scale.
This shows biodiversity generally increasing, with a lull around the Triassic roughly 200-250 million years ago.
Above: Global temperature since the dinosaurs went extinct, on a linear time scale.
This shows temperature generally decreasing from a peak about 50 million years go, with the Antarctic freezing, thawing, and freezing again since.
Above: Global temperature over the last 5 million years, on a linear time scale.
This shows temperature generally decreasing, with rapid oscillations between warm and cool periods, and the amplitudes increasing (maximum and minimum temperatures spread farther apart over time).
This time scale is still too large to see recent trends.
Above: Global temperature over the last half million years from 3 different sources, on a linear time scale.
This shows repeated cycles of freezing, with 5 peaks above the 20th century global temperature average in the last 450,000 years, the present epoch being the most recent peak.
Above: Sea level in meters (relative to the 20th century average) over the last 20 thousand years, on a linear time scale.
This shows sea level increasing rapidly from 15 to 7 thousand years ago, leveling out since then.
Above: Graph of human population from 10000 BCE to 2000 CE. It shows exponential rise in world population that has taken place since the end of the seventeenth century.
Above: Global temperature over the last 2 thousand years, on a linear time scale.
This shows global temperature mostly flat with a slight bump for the Medieval Warm Period and a dip for the Little Ice Age, with the temperature going up steeply in the last century.
Above: Atmospheric CO₂ in parts per million by volume (ppmv) since 1750 CE. Also, atmospheric CO₂ from fossil fuels vs. all CO₂ flux in trillions of kg.
Above: Global temperature change since 1900 CE due to these factors: sulfates, volcanoes, ozone, sunshine, and greenhouse gases.