Science: Iceland volcano pulse check; Planetary climate evolution; Etc.

Those darned tectonic plates just keep moving around.

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Insolation = incoming solar energy

Some new modeling data indicates that Earth’s life-compatible climate is quite unusual. A more common evolutionary path for planetary climates in life zones around stable stars looks like lifeless Venus or hot variants thereof. Of the 5,566 exoplanets discovered as of Dec. 19, 2023, only Earth has a potential to have liquid oceans. Astronomy & Astrophysics comments about planetary climate evolution: 

First exploration of the runaway greenhouse transition 

with a 3D General Circulation Model

Climate modeling is a key step to understanding their characteristics, atmospheric composition, and possible histories [of planetary climates]. If a surface water reservoir is present on such a terrestrial planet, an increase in insolation may lead to a dramatic positive feedback induced by water evaporation: the runaway greenhouse. The resulting rise in the global surface temperature leads to the evaporation of the entire water reservoir, separating two very different population of planets: 1) temperate planets with a surface water ocean and 2) hot planets with a puffed atmosphere dominated by water vapor. Therefore, the understanding of the runaway greenhouse is pivotal to assess the different evolution of Venus and the Earth, as well as every similar terrestrial exoplanet. .... Our simulations were comprised of two phases. First, assuming initially a liquid surface ocean, there is an evaporation phase, which enriches the atmosphere with water vapor. Second, when the ocean is considered to be entirely evaporated, there is a dry transition phase for which the surface temperature increases dramatically. Finally, the evolution ends with a hot and stable post-runaway state. By describing in detail the evolution of the climate over these two steps, we show a rapid transition of the cloud coverage and of the wind circulation from the troposphere to the stratosphere.

This paper is the first to model the transition from an ocean planet Earth-type climate to a hot, lifeless Venus-type. The researchers are asking how delicate is the Earth's pro-life equilibrium? Specifically, what would it take to tip the Earth into a climate like Venus? The answer is that it doesn't take much.

The model indicates that there is a positive feedback loop where increasing surface temperature increases water evaporation. Water vapor is itself a greenhouse gas that increases warming. That causes further water evaporation. Within a certain range of temperature, a range that Earth is within now, this process leads to a new equilibrium point of temperature. This is because the planet is still able to cool itself by radiating heat away into space. The hotter the planet becomes the more heat radiates away, until that equilibrium point is reach.

With continued heating and water evaporation, the blanket of water vapor around the planet is so thick that the planet no longer loses heat in this way and there is nothing to stop the heating process. This is the “runaway” heating point doesn’t stop until all the surface water has evaporated. 

The question is, how much does the Earth have to heat to reach the uncontrolled heating feedback loop? The data indicates that if the Earth’s surface temperature by a few tens of degrees, then we would tip over into runaway heating. That’s good news, but the range of temperatures that keep a planet in a habitable state is fairly narrow.

At worst, AGW is projected to lead to a few degrees of warming, maybe 6ᵒ C with tipping points and positive feedbacks. This the model used increased solar radiance as the initial cause of heating, not the burning of carbon fuels. They plan on doing a follow up study to see at what temperature we would hit runaway heating if the cause of initial heating were increased CO₂. 

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Wood has long proved a sturdy, reliable construction material — for perhaps as long as half a million years. Carved, interlocking logs uncovered in Zambia date to about 476,000 years ago, making them the oldest known wooden structure. The structure — possibly a remnant of a walkway, seating area or storage unit — hints that some human relatives may have led a less nomadic lifestyle than previously thought.

The earliest known example of modified wood is a polished plank from Israel dating to around 780,000 years ago. Wooden tools don’t appear in the historical record until about 400,000 years ago. Before this new study, the earliest known example of a wooden structure was much more recent: around 9000 B.C.

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Tyrannosaurus rex’s menacing grin may have been less toothy than previously thought. Artistic renderings commonly depict the ravenous reptile as lipless, constantly baring its pearly whites. But T. rex may actually have had a pout that kept rows of pointy teeth covered, similar to Komodo dragons, an analysis of the skulls and teeth of dinosaurs and modern reptile suggests.

Brunch

By Germaine: Science guy