CXRAndy
Epic Member
Life on earth has been more than capable of dealing with various CO2 levels. Current day 400ppm is extremely low compared to the past, upto 4000ppm There has been an increase in greening across the globe due to increased CO2. More plants, able to use CO2, reducing levels over time
Humans will easily adapt as will many other species.
Atmospheric CO2 levels have varied significantly from the Mesozoic Era (the time of dinosaurs, approximately 252 to 66 million years ago) to the present day, based on reconstructions from proxies like fossil plants, ice cores, and geochemical models. These estimates often have ranges due to uncertainties in proxy data, but general trends show much higher CO2 during the Mesozoic compared to recent geological periods.
Mesozoic Era (252–66 million years ago)
This was a "greenhouse" world with elevated CO2 levels, often 4–6 times higher than pre-industrial levels (around 280 ppm), supporting warm, humid conditions where dinosaurs thrived.2563ba Volcanic activity and changes in the carbon cycle contributed to these high concentrations.8c6410
Triassic Period (252–201 million years ago): CO2 levels were high, estimated at around 1,962 ppm in the Late Triassic, with some broader reconstructions suggesting 2,000–4,000 ppm.5f27b72c36b3 Levels started rising from lower values around 420 ppm early in the period.2989ee
Jurassic Period (201–145 million years ago): Concentrations remained elevated, typically 900–1,320 ppm, with averages around 1,000–2,000 ppm and peaks possibly exceeding 2,000 ppm.6429d9245c9a972608 Late Jurassic estimates from dinosaur tooth enamel suggest about 1,200 ppm.b97cfcb2c8bc
Cretaceous Period (145–66 million years ago): CO2 peaked in the Middle Cretaceous at around 1,130–2,500 ppm, then declined toward the end.8f45ce17bda1 Late Cretaceous levels were lower, around 750–1,800 ppm.6cee8ff8b48c Overall Mesozoic averages were 1,000–2,000 ppm, with excursions above 2,000 ppm.6ab552732518
Cenozoic Era (66 million years ago to present)
Following the mass extinction at the end of the Cretaceous, CO2 levels generally declined over time, leading to cooler climates and the onset of ice ages.2be371aca58d
Paleogene Period (66–23 million years ago): Early levels were high (around 1,000–2,000 ppm), but declined to about 680 ppm by 60 million years ago.8ebae2b5ddb0 By around 50 million years ago, concentrations exceeded 1,000 ppm, coinciding with warmer global temperatures.02f7ea
Neogene Period (23–2.6 million years ago): Continued decline, with levels around 300–500 ppm by 10 million years ago.6a2e26 Around 3 million years ago (Mid-Pliocene), CO2 was about 400 ppm, similar to today but with warmer conditions.9cea30
Quaternary Period (2.6 million years ago to present): During ice age cycles over the last million years, CO2 fluctuated between 180 ppm (glacial periods) and 300 ppm (interglacials).80d641f3d16d Pre-industrial levels (before the mid-1700s) were around 280 ppm.f7bd49
Present Day
As of 2024–2025 data, atmospheric CO2 is around 422–426 ppm, the highest in at least 14 million years and rising rapidly due to human activities.3ff929aa6965d3d7ff This recent increase (over 100 ppm in the last 60 years) is 100 times faster than natural changes at the end of the last ice age.1ce2e3
