Always puzzles me when looking for evidence of extraterrestrial life on exoplanets we always try to look for oxygen - life existed for a long time without it
A policeman sees a drunk man searching for something under a streetlight and asks what the drunk has lost. He says he lost his keys and they both look under the streetlight together. After a few minutes the policeman asks if he is sure he lost them here, and the drunk replies, no, and that he lost them in the park. The policeman asks why he is searching here, and the drunk replies, "this is where the light is".[1]
Science very thoroughly follows the drunkard principle, because there is no sense in looking at places were you unable to find anything. Science is looking for what it can possible see. It cannot see a bacteria under ice of Enceladus, so it doesn't even try. But it can see sometimes gases around Enceladus, so it looks for them.
We don't just look for oxygen. For instance, there was some excitement a few years back when there was a tentative observation of phosphine in Venus's atmosphere.
To have a good biosignature, you want a signal that cannot be explained by anything other than life. Of course, that means that there might be planets with life that we do not notice, because all of the observables we have access to have an abiotic explanation. Not much you can do about that other than a bunch of science.
Detecting that a planet might barely support life is impossible to do remotely for our next door neighbor Mars, and we have rovers and orbiters sending high resolution images every day. For exoplanets, we're working with 1 pixel images. Not 1 megapixel, 1 pixel. So for now we can only look for things that would make scientists say whoa, how can that possibly happen?
I wouldn't say the planet "barely" supported life before the oxygenation event. Otherwise we wouldn't have as much fossil evidence as we have.
I'd rephrase what you wrote with our current technical limitations make it more feasible to detect life by finding something that would make astrobiologists say woah, how can that possibly happen?
> I wouldn't say the planet "barely" supported life before the oxygenation event. Otherwise we wouldn't have as much fossil evidence as we have.
I believe you're talking about Earth, and the person you're responding to was talking about Mars. At least I don't think Mars had an oxygenation event or fossils?
Really, really weird that the article doesn't even mention nitrogen, nostoc or heterocysts. I'm not sure you can have a conversation about the great oxygen holocaust without at least bringing up one of the primary reasons we know "something" about the conditions before the event, specifically that there are still bacteria around today who are putting out a pretty significant amount of effort to create anoxygenic environments specifically for nitrogen fixation; that nitrogen as a terminal electron receptor basically 'cant happen' in the presence of oxygen.
Its just weird to not discuss the evolutionary lineage that still uses pre-oxygenation event hardware (with some extreme bug fixes to deal with oxygen) to fix nitrogen.
99%+ of species were driven to extinction, first from their environments becoming bathed in oxygen they were powerless to resist, and then from the whole planet freezing over for an eon (except maybe some equatorial refugia). Volcanism eventually restored enough CO2, with the oxygenators frozen, so the ice could melt.
The Great Oxygenation event wasn't due to the consumption of CO2 but rather the reaction of methane with the newly introduced oxygen, which reduced the greenhouse effect (aka raditative forcing). Since we already have lots of oxygen in the atmosphere they cannot help us the same way.
It's helpful to recognize that we're not the first organism to risk undermining the conditions that made us successful by altering the gas mixture in the atmosphere, and that 400 million years of ice is the sort of consequence that we're playing with.
Coordination is even harder when a decent fraction of the population cares so little that they actively shut out any attempt to point them in a better direction
It would only take a very small fraction of the population to care and change everything. The small fraction that profits from the polluting industries and uses those profits to maintain the status quo.
Lets start with best country of the world that is made of 300 million consumers and 1000 factory owners (also known as polluters) each of which has identical share of the market.
To reduce pollution, factory owners would need to use less polluting means (i.e. less profit) and produce less (again less profit).
What happens if 999 factory owners do adhere to pollution-reduction, while 1 of them is polluting a bit more than others? (Answer: The polluter increases his share of the market, as more profits can be reinvested; and with more market share the profit will grow even more)
The point: consumers incentivize factory owners to polute, if consumers buy stuff despite polution.
This exercise ignores legislation, but law will not change until enough of consumers/voters start to care of the topic and will be ready to pay more for less and demand for it.
Why are owners of capital deemed to be innocent when subject to the invisible hand and not the consumer? Answer is probably due to media influence paid for by the profits I alluded to earlier
I would like to label guilt/innocence as irrelevant.
The scenario above, describes the dynamics of how incentives work.
As long as consumers expect stuff to be cheap, somebody will step up to provide that (reaping profits). Only highly conscious society or totally authoritarian one can make these changes (though probability of dictator caring about environmental effects is low, and probably not sustainable).
Edit: guilt/innocence are irrelevant in the sense that they do not change the outcome. If human gets into a tigers cage and gets eaten (or seriously injured), outcome was predictable without the need to know who is at fault (tiger or human).
Whatever policy you implement, end result must be that stuff costs more and people live with less: virtually no personal cars, no for-fun-flights (vacation), force people to wear same pants for years and repair them when they get damaged.
That is hard pill to swallow for many, even for somewhat environmentally-aware beings.
Assuming no free energy is invented.
Related: exponential growth (x % each year) is not sustainable (approx 2500 years to consume whole universe converted to energy on 5% yearly growth); effectivity increases only multiply exponential function by a constant.
> Whatever policy you implement, end result must be that stuff costs more and people live with less: virtually no personal cars, no for-fun-flights (vacation), force people to wear same pants for years and repair them when they get damaged.
> That is hard pill to swallow for many, even for somewhat environmentally-aware beings.
You’re not wrong but I think adding some context would be helpful here.
That appears to be the situation now but it didn’t necessarily have to be this way. If effort in earnest was started earlier to develop the technologies necessary for transitioning off hydrocarbons, develop renewable energy generation, and so on the transition may not necessarily be so severe. And the policy which enabled this delay did cost consumers any way due to the active funding of a pro hydrocarbon influence campaign. Though I would guess the total cost of that policy is still much lower than actually trying to transition.
I think transitioning is a much easier pill to swallow if you realize that the decision will be made one way or another eventually and that it’s better to be proactive rather than reactive when trying to solve such an existential issue. That is, if one believes the science and cares about the future beyond just one’s self. Unfortunately that influence campaign I was mentioning earlier did a good job of denying the issue, used bad science to deceive, delayed climate action, degraded efforts of those fighting against it, etc. However I do acknowledge the ability to care beyond just one’s self is, to a certain extent, a financial privilege.
Incentivizing having less children is also another long term approach to limit emissions as technology becomes more efficient. Though it seems this has already been accomplished unintentionally in many places.
I’ve gone on kind of a rant but my point is yes the necessary policy decisions are more severe today but it absolutely did not have to be this way. And that is important to keep in mind because that campaign is still actively at play today.
Right, our incentive system (money) is non-binding if you have enough money to spend on avoiding consequences.
We need something different (or perhaps something additional) which can motivate those people to pull their heads out of the sand and quit chasing profit for profit sake and change the status quo.
Yeah, it's really a shame that geo-engineering projects keep getting shut down. We either control the climate, or it kills people. It's that simple. Without controlling the climate you don't get to pick and choose who lives and who dies because of "nature". It's not even a coordination problem. It's a regulation problem. People don't all need to agree before progress can happen and errors can be corrected. We just need any organization to show some backbone and stop kowtowing to the suicidal environmentalists.
"Suicidal environmentalists"? What kind of preposterous position is that?
There is no known CO2 removal or capture technology currently capable of reducing levels faster and with less energy inputs than simply shutting down the current emitters.
Geo-engineering is essential, but stopping emissions is even more so.
More to the point, geo-engineering is guaranteed to fail if emissions are unchecked. Whatever gains the former can offer, the latter may easily overwhelm. Our only hope is for emitting processes to become much more expensive than non-emitting alternatives. Fortunately we are on that path, although entrenched interests force emitting processes to continue well beyond economic rationality. E.g., new coal burning infrastructure being built even now.
I mean, if we actually last another 400m years, or even 1 million it's completely possibly that we could slowly shade the Earth with solar shades orbiting the planet. It does not take 'much' energy to reduce the energy input to the planet when you can move things on very long timescales.
With any luck, it will happen in just a few centuries as waste heat from industrial processes grows without bound, unless industrial expansion moves off-world before then.
FWIW, looking at my flagged history, I can only presume that in 2012 I thought "flag" meant "mark as important / put it in my favorites" (similar to the little flag icon you could put on email messages back in whatever email client I had used decades earlier).
Not sure what is controversial about the Great Oxygenation Event. Some submissions are auto-flagged for any reason like having astroturfing history, some people don't like the source (I flag a lot of The Register articles as it's a low quality tech tabloid prone to posting manipulative flamebait, in my opinion), some people think it's against the HN guidelines or not front-page-worthy for any reason.
pretty sure it's only comments you get the ability to downvote once reaching a certain threshold. Stories you can flag or upvote, but I've never seen a downvote for them.
† https://press.princeton.edu/books/hardcover/9780691145020/ox...