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The problem is that the Sun is significantly brighter now than it used to be back then, so the amount of heating from the same amount of methane/co2 is proporti
by FreeFull 2y ago
The problem is that the Sun is significantly brighter now than it used to be back then, so the amount of heating from the same amount of methane/co2 is proportionally more now too
- edge17 2y agoWhat does that mean that "the sun is brighter"?
- dtech 2y agoThe sun is literally shining brighter, in that it produces more energy
- rawling 2y agohttps://www.forbes.com/sites/startswithabang/2018/08/28/our-sun-is-lighter-than-ever-and-the-problem-is-getting-worse/ https://www.forbes.com/sites/startswithabang/2018/08/28/our-...
- pfdietz 2y agoSince the Sun settled onto the Main Sequence after its formation, it has gradually brightened. It is now 30% brighter than it was then. The brightening is caused by accumulation of helium ash in the Sun's core. This causes the core's equilibrium state to be denser and hotter, with more energy being produced. In another billion years or so, this will drive the Earth into a runaway greenhouse effect. The oceans will evaporate and the hydrogen will be lost to space. Not long after, the Earth will be a dead planet devoid of any life, even microorganisms. You sometimes see statements about how when the Sun expands into a red giant it will destroy life on Earth, but the Earth will have long been lifeless by that time.
- naveen99 2y agoAnyone else question why astronomers are so sure about things that happened 5+ billion years ago ? I guess otherwise there’d be a probably or a maybe in every sentence ? But then how do you tell when they really are sure ?
- tomrod 2y agoScience is a powerful tool.
- wongarsu 2y agoThere is always an implied "as far as we know". But astronomy has a couple reasons to be fairly certain about many things. We can see a lot of stars, and because light takes time to travel the further away they are the older the state we are observing. We only see each star as it is right now, but from looking at a lot of them you get a good idea of how they can develop. Like how you can get a good idea of how humans age by just looking at a lot of people of different ages; you don't need to follow each of them for 90 years. The other advantage is that most of it is well understood physics that can be reasoned about and simulated. And then we can compare those simulations to what we are observing across the universe to see if our simulations make sense.
- naveen99 2y agoFeels more social than science.
- wongarsu 2y agoScience is forming a testable hypothesis and then testing it. So you hypothesize "as stars accumulate fusion products their cores get heavier and the rate of fusion increases, making them brighter" and test this both with modeling and looking if this matches the stars we can see. How is that now science?
- bloopernova 2y agoIn case others were curious about the term Helium ash: Ash is the name given to the energetic alpha-particles or helium nuclei produced by fusion reactions in a deuterium-tritium plasma, even though helium bears no physical resemblance to ash from a fire.
- pfdietz 2y agoIt should be noted that deuterium-tritium fusion is not what is happening in the Sun. The primary reaction chain involves proton-proton fusion, which yields deuterium. The deuterium immediately (within seconds) reacts with another proton to make helium-3. Helium-3 eventually fuses with another He-3 to make He-4 and two protons. There are some side chains, but the ultimate overall reaction is four protons + 2 electrons --> 4He + 2 neutrinos.
- galangalalgol 2y agoThe way I read it, it isn't a co2 greenhouse, in fact the death stroke is the increased co2 absorption at those temperatures due to weathering of rock. Driving co2 below what plants can survive. Building a parasol at l1 that can be modulated to vary what is passed and what is harvested will be necessary at some point. It could get a couple extra billion years potentially.
- pfdietz 2y agoThat destroys higher life, but tough microorganisms survive until the runaway steam greenhouse sterilizes the planet.
- baxtr 2y agoSo what are we gonna do in a billion years from now??!
- krapp 2y agoWe'll be extinct long, long before that don't worry.
- baxtr 2y agoSomeone else in the thread is saying it’s 8% brighter. So who is right?
- whinvik 2y agoDon't know how HN hivemind works but there's nothing in this question that should lead to downvotes.
- sampo 2y ago> What does that mean that "the sun is brighter"? Sun has been getting about 8% brighter (8% more energy output) every 1 billion years.
- whiplash451 2y agoDon’t know why you got downvoted. The article linked by one of your commenters is super interesting (assuming it is correct).
- Mountain_Skies 2y agoSunspot cycles are sometimes mentioned as a possible factor in climate change, especially by those skeptical of human generated causes. The downvoters might have mistaken the comment as being related to this instead of being a different solar variable.