What if there was no sunlight

[stipalgl]

Hey guys,

I don't know if this is the right forum but with all the scientific minds circulating about, I thought I'd give it a shot.

A young nephew asked me this and it left me baffled (kind of embarrassed to admit it):

What would happen to the planet over time if sunlight was blocked from coming in due to a ubiquitous thick cloud layer that traps heat while subsequently keeping external heat out.

I scoured Google for several minutes but most questions ask what would happen in the complete absence of the Sun. Obviously here, gravity would still be in effect and I'm assuming it would take longer for plants to die? Would life be able to persist or evolve in any way with heat trapped within?

Any biologists/chemists willing to give this a shot and help me out?

Much appreciated.

 

[CycloWizard]

The thermodynamic term you're looking for is "adiabatic." It's hard to say what would happen under such conditions, but my naive guess is that fungus and mold would go crazy while algae and green plants would wane. The temperature would go up over time due to entropy, which may favor some forms of bacteria. I'm not sure what else you are looking for, but searching for "adiabatic planet" in Google should lead you in the right direction.

 

[stipalgl]

Interesting, thanks Cyclo. I wasn't aware of the term and looked it up on Wikipedia. Unfortunately (as expected I suppose), they explain the process but nothing online goes into detail about what would happen to the biological life cycle.

I'm more interested in a scenario where the Earth becomes adiabatic in some way and how the corresponding environment adapts.

I guess we can only make inferences and suppositions since it's a relatively untouched topic.

If anyone else would care to chime in, I'd look forward to it.

 

[alkemyst]

It really depends if we lose 'heat'. Either way without the free energy the sunlight gives us, we'd be fighting a losing battle.

If the sun's heat goes away, we are doomed quickly.

 

[Gibsons]

Interesting, thanks Cyclo. I wasn't aware of the term and looked it up on Wikipedia. Unfortunately (as expected I suppose), they explain the process but nothing online goes into detail about what would happen to the biological life cycle.

I'm more interested in a scenario where the Earth becomes adiabatic in some way and how the corresponding environment adapts.

I guess we can only make inferences and suppositions since it's a relatively untouched topic.

If anyone else would care to chime in, I'd look forward to it.

Most ecosystems would collapse. No light means no photosynthesis, so all the plants and algae die. So all the herbivores, from antelope to krill, die. Then the things that eat the herbivores starve and die. Fungus and bacteria would feast on the remains for some time, but eventually die out or go very very dormant.

The chemotrophic ecosystems in deep sea vents etc. would be fine for the most part.

 

[Mr. Pedantic]

Depends. If it amplifies the greenhouse effect, we'll end up something like Venus, only slightly cooler. If not, then it really depends on the degree to which light is blocked. Some plants will die, some animals will also die, and most other forms of life will probably keep on going as they were.

 

[Jaskalas]

If you broke photosynthesis (requires sunlight) there likely wouldn’t be enough plant life remaining to convert CO2 into Oxygen so you wouldn’t be around to worry about it.

Forget the food chain, we need plant life for breathable air.

 

[CycloWizard]

Most ecosystems would collapse. No light means no photosynthesis, so all the plants and algae die. So all the herbivores, from antelope to krill, die. Then the things that eat the herbivores starve and die. Fungus and bacteria would feast on the remains for some time, but eventually die out or go very very dormant.

The chemotrophic ecosystems in deep sea vents etc. would be fine for the most part.

Evolution could start all over again using something other than photosynthesis as the fundamental process by which plants do their thing. Maybe some animal would adapt to use heat shock proteins to accomplish work since heat would be readily accessible, though the lifetime of such animals would probably be pretty limited unless they lived near a thermal source/sink to create a driving force.

 

[Gibsons]

Evolution could start all over again using something other than photosynthesis as the fundamental process by which plants do their thing. Maybe some animal would adapt to use heat shock proteins to accomplish work since heat would be readily accessible, though the lifetime of such animals would probably be pretty limited unless they lived near a thermal source/sink to create a driving force.

Heat would be readily accessible, but I'm not sure how you could turn that into work? You need a heat differential to do that, right? Cells seem a bit too small to do that.

Even in thermal vents, where it's very hot, energy is derived from chemicals, not through a heat engine sort of process.

 

[pw38]

If you broke photosynthesis (requires sunlight) there likely wouldn’t be enough plant life remaining to convert CO2 into Oxygen so you wouldn’t be around to worry about it.

Forget the food chain, we need plant life for breathable air.

That's what I was thinking.

 

[Kristijonas]

I wonder how much time would have to pass until the oxygen would be "breathed out", considering there are no plants and no pollution from factories/planes/cars. Only what's left in the atmosphere. If it would be several hundreds of years, perhaps animal life could somehow adapt and start using something else instead of oxygen?
Also I doubt photosynthesis is the only process that generates oxygen. Perhaps other processes could be genetically engineered into certain species (fungi?) if there would be a need?

 

[Mr. Pedantic]

I wonder how much time would have to pass until the oxygen would be "breathed out", considering there are no plants and no pollution from factories/planes/cars. Only what's left in the atmosphere. If it would be several hundreds of years, perhaps animal life could somehow adapt and start using something else instead of oxygen?
Also I doubt photosynthesis is the only process that generates oxygen. Perhaps other processes could be genetically engineered into certain species (fungi?) if there would be a need?

Nowhere near enough time. Maybe for primitive animals and fungi, but nothing approaching the complexity of mammals.

As for sources of oxygen, there are only so many sources of oxygen available, and only so many energy sources. I can see other sources of metabolic 'currency' being used, they already are in some primitive life. However, for higher-order organisms, if our oxygen supply disappears, then so do we.

 

[CycloWizard]

Heat would be readily accessible, but I'm not sure how you could turn that into work? You need a heat differential to do that, right? Cells seem a bit too small to do that.

Even in thermal vents, where it's very hot, energy is derived from chemicals, not through a heat engine sort of process.

Yes, that's what I meant by saying they would need to be near a heat source or sink as the temperature away from those places would become increasingly uniform. I'm not sure how work would be produced either, except that heat shock proteins can undergo conformational changes due to changes in temperature. Those changes are converting heat to work on a very tiny scale. Perhaps DNA would evolve that would produce some auto-polymerizing heat shock protein that is like actin in the present world, which goes from globular to fibrillar when stress is applied. Just speculating wildly.

 

[sm625]

If the earth was covered in a black cloud then we wouldnt have a greenhouse effect. In order to get a greenhouse eefect the light has to actually penetrate the outer layer. There is a reason greenhouses are not covered in black. What we would have is a giant solar water heater. Determining the actual average temperature of that system is beyond my paygrade.

 

[Gibsons]

Yes, that's what I meant by saying they would need to be near a heat source or sink as the temperature away from those places would become increasingly uniform. I'm not sure how work would be produced either, except that heat shock proteins can undergo conformational changes due to changes in temperature. Those changes are converting heat to work on a very tiny scale. Perhaps DNA would evolve that would produce some auto-polymerizing heat shock protein that is like actin in the present world, which goes from globular to fibrillar when stress is applied. Just speculating wildly.

hm, I guess we could have a critter that crawls to some hot spot, then moves back to a colder spot. Or longish one, that basically works like a heat pipe...

 

[Jeff7]

If the Sun goes out, life on Earth would have only a few sources of power available:
- Tidal energy from the Moon, which would slowly diminish as its orbit changes due to the energy transfer.
- Residual geothermal energy leftover from its formation.
- Chemical energy.

Some life exists now that could survive on geothermal and chemical energy alone, such as tube worms around hot vents at the bottom of the ocean.

But what you've got left is a ball of warm rock and metal, radiating heat out into the surrounding Universe. The rate of heat loss would be affected significantly by how well the atmosphere can keep the planet insulated.

Plants would start to die off fairly quickly; some may enter some kind of hibernation type of phase. From there, your food chains start to collapse from the base up. Bacteria might have a field day with the decaying stuff everywhere, but even they will start to have problems as the temperature continues to fall.
You might end up with a few small pockets of bacteria here and there, or a few extremophiles that are able to survive in harsh environments.


So, you can tell your inquisitive little nephew that humanity would go extinct before too long if the Sun were to suddenly go away.

 

[CycloWizard]

hm, I guess we could have a critter that crawls to some hot spot, then moves back to a colder spot. Or longish one, that basically works like a heat pipe...

Yes, the world would probably be much less exciting. However, it sounds like a fun topic for a few comics targeted at the extreme dork fringe... :whiste:

 

[Mr. Pedantic]

Yes, that's what I meant by saying they would need to be near a heat source or sink as the temperature away from those places would become increasingly uniform. I'm not sure how work would be produced either, except that heat shock proteins can undergo conformational changes due to changes in temperature.

Proteins (all proteins) change shape when heated or cooled. This is due to the fact that the tertiary and quarternary structure of proteins is dependent on hundreds if not thousands of bonds, of varying degrees of strength. Because heating something is just adding to its kinetic energy, when a protein is heated all its atoms gain energy. Some gain enough energy to break bonds; generally, the weaker the bond, the less heat is required to break it. Breaking bonds causes the structure of the protein to change.

In this regard heat shock proteins are no different to any others; they are called such because they are produced in response to heat (e.g. caused by inflammation), among other things; not because they react differently to changes in termperature. They can be denatured like any other protein.

If the earth was covered in a black cloud then we wouldnt have a greenhouse effect. In order to get a greenhouse eefect the light has to actually penetrate the outer layer. There is a reason greenhouses are not covered in black. What we would have is a giant solar water heater. Determining the actual average temperature of that system is beyond my paygrade.

Oh dear.

See, the thing about black is that it doesn't mean 'impenetrable to radiation'. I see no reason why X-rays, UV, infra-red, or radio waves wouldn't be able to penetrate a black cloud layer in sufficient quantity to heat the Earth.

Also, the reason we don't paint greenhouses black is because that defeats the whole purpose of building it to house photosynthetic plants. Not because it's horrible at holding heat energy (it's not).

 

[CycloWizard]

Proteins (all proteins) change shape when heated or cooled. This is due to the fact that the tertiary and quarternary structure of proteins is dependent on hundreds if not thousands of bonds, of varying degrees of strength. Because heating something is just adding to its kinetic energy, when a protein is heated all its atoms gain energy. Some gain enough energy to break bonds; generally, the weaker the bond, the less heat is required to break it. Breaking bonds causes the structure of the protein to change.

In this regard heat shock proteins are no different to any others; they are called such because they are produced in response to heat (e.g. caused by inflammation), among other things; not because they react differently to changes in termperature. They can be denatured like any other protein.

I understand that protein shapes change due to heating because of increased influence of thermal fluctuations driving them away from their equilibrium conformation. My point was that, under a completely different evolutionary pathway, different proteins might exist that acted as I described. Some heat shock proteins (e.g. alpha crystallins in the ocular lens) aren't produced in response to temperature - they absorb heat from temperature increases to protect the other proteins in the vicinity, then release the energy slowly and return to their natural conformation. The lens is a special case, but it's a proof of concept anyway.

 

[piasabird]

Astranauts in space manage to stay alive with no sunlight, at least for a while. So probably warmth is more important than sea light. Another example might be deep sea divers. The human body seems to act like a furnace as long as it has fuel. Sure there are the obvious arguments of sunlight makes a planet liveable and plants grow. Without the sun to provide heat and warmth things could get kind of difficult. many people in large cities could live most of their lives indoors and manage to survive with no windows and no sunligt.

 

[Mr. Pedantic]

I understand that protein shapes change due to heating because of increased influence of thermal fluctuations driving them away from their equilibrium conformation. My point was that, under a completely different evolutionary pathway, different proteins might exist that acted as I described. Some heat shock proteins (e.g. alpha crystallins in the ocular lens) aren't produced in response to temperature - they absorb heat from temperature increases to protect the other proteins in the vicinity, then release the energy slowly and return to their natural conformation. The lens is a special case, but it's a proof of concept anyway.

Do you have a study or article to support this? All I can find in support of this is summarized by two studies*, which just say that they change conformational structure in response to heat to prevent aggregation of protein fragments - nothing about actually releasing energy. You are right in that some Hsps are produced all the time in certain tissues, with the small Hsps in the lens being an example. But their overall function is still the same - to prevent cellular damage from protein aggregates induced by stress.

Another thing is, if they release energy over time, what would they release it as? And how would that translate into useful energy storage/production for the cell?

What I was thinking is a photosynthesis homologue - because the sun primarily emits in the visible spectrum, life on Earth has evolved to capitalize on this fact. However, the sun emits a significant portion of its energy in other forms as well, In the absence of visible light these other spectra will become more important, and I don't see why new processes would not develop to mimick photosynthesis but adapted to use IR or UV instead of visible light.

* Maulucci G, Papi M, Arcovito G, De Spirito M. The thermal structural transition of a-crystallin inhibits the heat induced self-aggregation. PLoS One. 2011 May 9;6(5):e18906.
Ganea E. Chaperone-like activity of alpha-crystallin and other small heat shock proteins. Curr Protein Pept Sci. 2001 Sep;2(3):205-25.

Astranauts in space manage to stay alive with no sunlight, at least for a while. So probably warmth is more important than sea light. Another example might be deep sea divers. The human body seems to act like a furnace as long as it has fuel. Sure there are the obvious arguments of sunlight makes a planet liveable and plants grow. Without the sun to provide heat and warmth things could get kind of difficult. many people in large cities could live most of their lives indoors and manage to survive with no windows and no sunligt.

No sunlight equals no photosynthetic plants. No photosynthetic plants equals a) no oxygen, and b) no feed for primary consumers. No feed for primary consumers equals, in various direct or indirect ways, no food for us. No food for us equals we die. What no oxygen means should be fairly obvious.

 

[CycloWizard]

Do you have a study or article to support this? All I can find in support of this is summarized by two studies*, which just say that they change conformational structure in response to heat to prevent aggregation of protein fragments - nothing about actually releasing energy. You are right in that some Hsps are produced all the time in certain tissues, with the small Hsps in the lens being an example. But their overall function is still the same - to prevent cellular damage from protein aggregates induced by stress.

Another thing is, if they release energy over time, what would they release it as? And how would that translate into useful energy storage/production for the cell?

* Maulucci G, Papi M, Arcovito G, De Spirito M. The thermal structural transition of a-crystallin inhibits the heat induced self-aggregation. PLoS One. 2011 May 9;6(5):e18906.
Ganea E. Chaperone-like activity of alpha-crystallin and other small heat shock proteins. Curr Protein Pept Sci. 2001 Sep;2(3):205-25.

I'm not going to open my binder of alpha-crystallin papers and try to find one that answers your specific question, but what I said is definitely well known and available in the literature. You'll probably have to go pretty far back to find the details of it. I'll offer a thought experiment instead though that might convince you.

Heat is a mechanism for moving energy around. Heat flux is generally proportional to the temperature gradient (Fourier's "Law" of heat conduction). The eye, owing to avascularity in the transparent tissues (cornea, aqueous, lens, vitreous), is exposed to temperature gradients much larger than any other part of the body except skin on the fingers and toes. Thus, alpha crystallins prevent aggregation of proteins in the lens which would otherwise cause cataracts during brief exposure to extreme temperatures. Hopefully we can agree on this bit as I don't think any of it is controversial.

Now, by the paper you linked, we see that alpha crystalllins self-aggregate to absorb energy ("heat shock"). These are very large molecules to begin with (MDa range, IIRC). If we integrate this effect over time as the eye is exposed to more and more thermal shock, then light transmittance would be compromised in short order as more and more aggregates of increasing size would form. Moreover, the short range order by which crystallins maintain transparency of the lens would break down as the electrostatic interactions of the crystallins were fundamentally altered by this aggregation. Thus, the fact that some people have clear lenses after the age of 5 would seem to support my theory that these crystallins absorb the thermal energy quickly, then gradually give it off (also as heat) via random thermal fluctuations which result in drag losses. Indeed, reversibility of the short-range order has been demonstrated by a lack of hysteresis in rheological testing. In the latter case, mechanical strain energy was imparted as a mimic for thermal energy, yet the fluid rapidly recovered to its native mechanical properties over short timescales.

What I was thinking is a photosynthesis homologue - because the sun primarily emits in the visible spectrum, life on Earth has evolved to capitalize on this fact. However, the sun emits a significant portion of its energy in other forms as well, In the absence of visible light these other spectra will become more important, and I don't see why new processes would not develop to mimick photosynthesis but adapted to use IR or UV instead of visible light.

I think the original question said no light got through, not just no visible light.

 

[infoiltrator]

Look for "Nuclear Winter" and " Volcanic Eruptions". Volcanic eruptions have put enough ash in the air to effect climate.
Nuclear Winter was a scenario of the cold war if enough bombs went off.

 

[Mr. Pedantic]

I'm not going to open my binder of alpha-crystallin papers and try to find one that answers your specific question, but what I said is definitely well known and available in the literature. You'll probably have to go pretty far back to find the details of it. I'll offer a thought experiment instead though that might convince you.

Heat is a mechanism for moving energy around. Heat flux is generally proportional to the temperature gradient (Fourier's "Law" of heat conduction). The eye, owing to avascularity in the transparent tissues (cornea, aqueous, lens, vitreous), is exposed to temperature gradients much larger than any other part of the body except skin on the fingers and toes. Thus, alpha crystallins prevent aggregation of proteins in the lens which would otherwise cause cataracts during brief exposure to extreme temperatures. Hopefully we can agree on this bit as I don't think any of it is controversial.

Now, by the paper you linked, we see that alpha crystalllins self-aggregate to absorb energy ("heat shock"). These are very large molecules to begin with (MDa range, IIRC). If we integrate this effect over time as the eye is exposed to more and more thermal shock, then light transmittance would be compromised in short order as more and more aggregates of increasing size would form. Moreover, the short range order by which crystallins maintain transparency of the lens would break down as the electrostatic interactions of the crystallins were fundamentally altered by this aggregation. Thus, the fact that some people have clear lenses after the age of 5 would seem to support my theory that these crystallins absorb the thermal energy quickly, then gradually give it off (also as heat) via random thermal fluctuations which result in drag losses. Indeed, reversibility of the short-range order has been demonstrated by a lack of hysteresis in rheological testing. In the latter case, mechanical strain energy was imparted as a mimic for thermal energy, yet the fluid rapidly recovered to its native mechanical properties over short timescales.

Ah, I see what you're getting at. The organism would still need a separate mechanism to convert heat energy to mechanical energy, though; these proteins would only function as an energy store to allow the organism to survive in between energy sources.

I think the original question said no light got through, not just no visible light.

I generally take sunlight (and light in general) to mean visible light.

 

[CycloWizard]

Ah, I see what you're getting at. The organism would still need a separate mechanism to convert heat energy to mechanical energy, though; these proteins would only function as an energy store to allow the organism to survive in between energy sources.

The conformational change is actually work, though it's reversible. I'm just saying that proteins which were based on this principle but driven by natural selection might have developed that were capable of more impressive feats. Let's say something like neutrophils, which can produce "tethers" capable of moving them along a surface or pulling them towards some other object. I think (though I'm not sure) that in neutrophils, their self-mobility is governed by chemical potential energy, but another mechanism is theoretically possible.