A view to the possible habitability of ancient Venus over three billion years [pdf] | Hacker News Reader

A view to the possible habitability of ancient Venus over three billion years [pdf]

meetingorganizer.copernicus.org

48 pointsbookofjoe40 comments

That Venus may once have had an Earth-like climate, until it hit a "runaway greenhouse gas state", is a scary thought considering our current challenges on Earth (and melting permafrost and methane bubbles). Sometimes people say "we might pollute enough to kill all humans, but nature will continue just fine without us." - Unless we do enough damage to trigger a runaway state and turn Earth into another Venus.

We're basically as significant to the Earth existing as a mold strain is to a mountainside. If we're idiotic enough to trigger a climate catastrophe that wipes us out, this ball will keep on spinnin'...

Spinning, yes. Habitable to some kind of life, probably. Habitable on the surface, to complex multi-cellular life, we could very well ruin that.

We could, and are, rather easily. The more complex the life-form/system, the more vulnerable it is to simple attack.

"There'll still be a lifeless ball of rock left" isn't the comforting point you seem to think it is.

My intent was to illustrate how incidental we are in the scheme of things, and thus should take extreme care if our goal is to continue to exist.

Venus probably had an Earth-like climate which evolved a wide variety of lifeforms, which culminated in the evolution of an intelligent species that built a global civilization. However, they powered this civilization with hydrocarbons pumped out of the ground, left over from decayed plant matter from eons before, so they could drive around in oversized SUVs, instead of living more densely and using trains to get around. Some of their species tried to warn them that disaster was imminent if they didn't change their ways, but the rest said this was just alarmism and that there was nothing wrong with cutting down their forests to have more grassland for raising large livestock for food. We can see now how this all worked out for the Venusians.

And as we can see from the downvotes here on a "tech site" (supposedly the most intelligent of people on this planet), Earth is obviously destined for the same fate.

This is most likely the explanation for the Drake Equation. We don't see other intelligent lifeforms, because they don't become intelligent enough fast enough, and they stupidly destroy their own environment, leading to their own extinction, before they can explore beyond their own star systems.

Climate change is a big potential ecological disaster - for us. Earth has had periods of much hotter temperatures than climate change is likely to induce. During the early Carboniferous period, the average global temperature was almost 10 degrees Celsius higher than today. It would take a long time to turn Earth into Venus, or even something similar to the Carboniferous

It’s also a disaster for thousands of non human species. Many species are going extinct because of human activity. Which in my opinion is a shame. Yes, in millions of years life may come back if we don’t trigger runaway greenhouse effects, but that’s still a lot of life destroyed.

It's not clear to me that we understand the conditions under which the earth was much hotter, or specifically what conditions resulted in cooler periods. There was a article a few days ago discussing the theory that one of the ice ages was caused by inter-planetary dust. This is an honest (and unpolitical) question: how much do we know about these past climate changes are what caused them?

I seem to remember the concentration of CO2 necessary for this to be 10-100 times higher than current. Also made worse on Venus by proximity to the Sun and collapse of the planetary magnetic field. Essentially, the greater solar wind / radiation flux and holes in magnetosphere disrupts atmospheric H2O and H2 is blown off planet, and O2 oxidizes C next (which then falls into a feedback loop with CO2 and H20 vapor driven greenhouse effect)

I'm extraordinarily concerned about global warming, but it's very likely humanity will kill itself well before it can create a runaway Venusian like greenhouse. I think the concentration of CO2 alone is fatal to human life well before that level.

edit: quick cites https://www.scientificamerican.com/article/fact-or-fiction-r... (30k ppm CO2, disputed), https://www.dhs.wisconsin.gov/chemical/carbondioxide.htm (5k ppm CO2 upper limit for workplace exposure)

I think a major concern is that a small rise in greenhouse gasses from human activity may result in a large release of greenhouse gasses stored in the earths crust. It is not expected that we would release all the gasses ourselves, but that our emissions would trigger a massive release.

I think the runaway greenhouse effect article accounts for the clathrate gun hypothesis. Not sure residency period of CH4 in the atmosphere would be consistent with the level of heat buildup to get the H20 vapor feedback loop going.

Runaway states are an unrealistic scare mongering tactic that very rarely show up in nature. There are so many feedback loops, both positive and negative, but people always forget about the negative feedback loops and overemphasize the positive feedback loops. Sure, any positive feedback loops taken out of context can be scary but that’s because it’s an idealized state that doesn’t really exist.

Unfortunately, net positive feedback loops for climate are clearly evident in the geological record. A great presentation of the evidence is in Hansen's Storms of My Grandchildren.

He also says it's basically impossible for the Earth to reach a Venus-like state. But we could easily get runaway warming sufficient to add several extra degrees.

It's very unlikely that we can cause enough environmental damage to cause that: https://en.wikipedia.org/wiki/Tipping_points_in_the_climate_...

It would be nice if a probe would find on Venus an ancient poster "Climate change is not real, they all are lying to you!" or a record of an ancient comic speech "It's only Venicians who have problem, Venus is going to be fine".

I believe the Demonym for Venus is Venusian, or perhaps Cytherean. Venician sounds like Venetian, that is, somebody from Venice.

You are probably right. I was going to use Venusian, but it sounds terribly wrong to me, I can't explain why.

“Coal is the future of life on Venus!”

A great sci-fi movie idea. In the far future, when Earth is suffering massive effects from a 5-degree warming, NASA launches more probes to Venus. One uncovers evidence that Venus not only once had life, but had civilization. After studying large number of artifacts, it is found they too had a climate crisis created by their civilization, one thats started with a run-away 6 degree rise, but failed to address it, which ultimately destroyed them.

The movie ends with a potentially gloomy message that we may already be too late.

A better movie: We use geoengineering to make Venus habitable and maintain Earth's climate in its current state. We double the effective surface area of the human race and all of Earth's species, while the idea of terraforming Mars is reduced to a silly joke.

Instead of making a movie, we could actually do it. It sure beats the hell out of Mars.

You'd need a heck of an umbrella to block all that sunlight. Seriously, cooling it down via solar blockage is about the only way you could ever make Venus livable. Followed by massive removal of CO2 on the now-icy surface.

Mars has the advantage that it's easy to make something hot- just use energy- while making something colder is more complicated. Also- here me out here- basketball on Mars will be insane. Venus still has, what, 80% of earth's gravity? Boring.

> You'd need a heck of an umbrella to block all that sunlight. Seriously, cooling it down via solar blockage is about the only way you could ever make Venus livable. Followed by massive removal of CO2 on the now-icy surface.

This is part of a plot point in Kim Stanley Robinson's Mars trilogy, definite recommend if you want some reading about terraforming.

> Also- here me out here- basketball on Mars will be insane. Venus still has, what, 80% of earth's gravity? Boring.

Even better, lunar water polo.

> Major overturn events,or a proliferation of Large Igneous Provinces over millions of years could have turned Venus’ once stable temperate climate into the CO2dominated hot house of today.

https://en.wikipedia.org/wiki/Large_igneous_province

There may be fossilized Sleestaks et al. ready for us to discover. However, it's almost 900 degrees on the surface. Making a multi-day fossil-hunting bot that can handle 900 degrees would be a huge technical feat: big AC with a powerful/big fuel source.

the 'global resurfacing event' they refer to probably rules that out as wikipedia describes this as '[covering] most or all of the planet with lava'

I'm starting to get annoyed at papers like this that are all about simulations. How is anyone to evaluate the paper without access to the models and simulations? Archive that material or don't permit publishing.

Seems like there are too many orders of magnitude more CO2 for Venus to be the result of some sort of ecosystem issue, if it was originally like Earth.

It would have to be more like the entire crust and a substantial layer below was turned over and combusted, wouldn't it?

And we know that Venus has a flagrantly unusual rotation.

So wouldn't the obvious explanation be a giant impact, with parameters that didn't lead to a big moon like Earth's?

So if I'm not mistaken then it's likely that 3 billion years ago earth, mars and venus all might have been suitable for sustaining life. A science fiction work based on this premise could be interesting.

Very readable two-pager. Not sure I like the styling of the graph though.

I found that plot strange as well. I wonder why they didn't take a few minutes to redo it rather than sketch it out if it were going to be published?

It's itching me the wrong way as well. I prefer academic publications "dry" and austere, keeping distractions at a minimum. Stylish, cutesy graphs are better suited for other forms of dissemination

It's a poster abstract, it's ephemeral, the piece research is waiting to be written up and sent to a proper journal. Meanwhile, a scan of a quick sketch is enough to get the point across.

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