Privileged Planet: wandering CO2 levels (Introduction)

by David Turell , Monday, March 11, 2024, 21:07 (258 days ago) @ David Turell

Disastrously low at one point:

https://wattsupwiththat.com/2024/03/10/how-co2-starvation-caused-the-greatest-extinctio...

"Around 400 million years ago during the Devonian, carbon dioxide concentrations were over 2000 ppm, 5 times higher than today’s level. That allowed evolving land plants to rapidly spread across the land. Plant species diversified and increased so rapidly it was called the Devonian Explosion. Marine species likewise multiplied enabling greater fish speciation, so the Devonian was called the Age of Fishes. However, by the end of the Devonian, the increase in photosynthesizing plants had greatly reduced CO2 concentrations to near dangerous levels. (my bold)

"During the following geologic period known as the Carboniferous, great forests of primitive Lycopod trees now covered the earth’s wetlands. Trees buried in the swamps were slow to decompose, creating some of the earth’s greatest coal deposits. That further sequestered CO2. Some research suggests CO2 levels fell as low as 150 ppm, plant starvation levels. That led to the Carboniferous Rainforest Collapse around 305 million years ago. Low CO2 levels also correlated with a die-off of ocean algae known as the “Phytoplankton Blackout”. This dramatic collapse in primary production on land and in the sea, disrupted the earth’s Permian food web and set in motion a series of long-drawn-out extinctions known as “Dead Clades Walking”. (my bold)

"The vigorous photosynthesis of the Carboniferous had also generated the earth’s greatest levels of oxygen. Compared to our atmospheric oxygen of 21%, oxygen levels reached 30 to 35%. High levels of oxygen allowed giant arthropods to evolve. It also enabled amphibian ancestors, that breathed by absorbing oxygen through their skin, to better colonize the land. However, as forest species and phytoplankton went extinct, oxygen levels plummet. As a result, the giant arthropods, as well as primitive amphibians like Euryops, adapted to more abundant oxygen, were the first to go extinct by the early Permian around 295 million years ago. Falling oxygen concentrations also reduced land animals’ ability to use high altitude ecosystems.

"Starting with the Olson Extinction land plants experienced >60% extinction rates, rates lasting into the middle Triassic period. Plant eating reptile-like species, such as Diadactes and Edaphosaurus, went extinct by 272 million years ago, along with the Dimetrodon predators, further restructuring ecosystems. Mid-Permian extinctions continued culminating in another mass extinction event known as Capitanian orLate Guadalupian extinctions between 262 and 259 million years ago with some regions indicating extinction of 74-80% of all vertebrate genera. Driven by the phytoplankton blackout, 35-45% of marine invertebrate species went extinct during this time, and all caused a cascade of biological disruptions.

"The subsequent Great Dying or end Permian Extinction 252 million years ago was simply the culmination of “dead clades walking” that began with CO2 starvation, the rain forest collapse, and phytoplankton blackout. The end Permian saw 81% of the remaining marine species and 70% of remaining terrestrial vertebrate species go extinct. The loss of forests and their ecosystem continued throughout the entire Permian as reflected by the absence of coal deposits.

"However, biased by the rapid extinction event 66 million years ago when a meteor struck earth, many researchers looked for a similarly rapid extinction event, like a volcanic eruption. Despite the life-promoting benefits from high CO2 and increased biodiversity during the Devonian, researchers were biased by recent narratives suggesting rapidly rising CO2 is a deadly killer. So, several researchers blamed end Permian extinctions on a series of volcanic eruptions, the Siberian Traps, narrowly centered around 252 million years ago for the release of copious amounts of CO2. If history teaches us anything, because that release raised CO2 concentrations back to over 2000 ppm, it more likely enabled the new expansion of life on earth, like it did during the Devonian, now with the rapid spread of flowering plants, the Age of Dinosaurs, and the further evolution of birds and mammals.

"And again, if history teaches us anything, we must ensure that attempts to reduce CO2 concentrations do not result in devastating CO2 starvation ever again." (my bold)

Comment: This article shows us the massive extinctions of species that helped produce Roup's estimated loss of 99.9% of all organisms that ever existed during all the evolution until the present. This is not to diminish the leading roles of CO2 and oxygen in directly influencing and creating the driving forces of evolution. Viewed this way, pruning twigs along the way was a minor contributor.