It would be very interesting to have sci-fi stuff showing our planet lacking the ozone layer due to deterioration of biodiversity and pollution.

I read that Earth could not have life if there wasn't an ozone layer to filter the uv radiation from the Sun. If the ozone layer was distroyed, what would happen to Earth's biodiversity and appearance? Would Earth no longer have forests and fauna even if rainfall continued to exist?

And what would happen to Earth's sky? Would it still be blue or would it change its color and brightness? Would sunlight look brighter or dimmer?


closed as off-topic by L.Dutch, Vincent, StephenG, Cadence, Ash Jul 8 '18 at 11:04

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  • $\begingroup$ Did you research the changes that occurred as a result of the Arctic and Antarctic ozone holes? A link to that claim that UV run amok will kill all life would be quite fun reading. $\endgroup$ – user535733 Jul 8 '18 at 0:07
  • $\begingroup$ in short, it would kill everything. The Earth would be blasted with constant UV radiation that would drive all plants extinct, maybe some deep water organism could survive. $\endgroup$ – Sasha Jul 8 '18 at 0:13

In the short run, there would be survivable problems. In the long run, it would have little effect.

UV is dangerous because it creates free radicals in the outer layers of skin (or leaves or paint or whatever.) Those free radicals are very reactive and attack most materials. The free radical attacking DNA is the route that UV causes skin cancer and more generally the cells reacting to the free radical attacking most organics causes the inflammation of sunburn.

The immediate effect of the loss of ozone would be a major increase in skin cancer and serious problems for animals without fir or feathers (like us) i direct sunlight.

Nonetheless, this can all be adapted to and life would evolve to live in the high-UV environment. There are several ways this can happen.

First, UV doesn't penetrate very deeply and a thicker layer of dead cells on the skin would have good protective power. Shells, fur, feathers all help and would evolve to be thicker.

Second, an increase in free radical scavengers -- chemicals which preferentially react with free radicals yielding harmless products -- would quickly evolve. All animals and plants have some now, so selection for an increase would happen pretty quickly. These scavengers are frequently dark colored, so animals in general might move towards darker hues.

Thirdly, improved repair mechanisms would evolve. DNA mutates a lot and we already have very effective mechanisms to repair those mutations. There's not a lot of evolutionary pressure to improve them now, because must cancers strike after we're don raising a family, so there's not much of a selection effect. In a higher cancer environment, there's certainly be some improvements evolving. This would be slower, though.

Finally there'd be behavioral adaptations: More nocturnal animals, for instance.

Plants likewise would evolve better coping mechanisms.

How fast the ozone loss happens would have a major impact: If it's essentially instantaneous, there'd be no time to evolve better defenses and there'd be a substantial impact until evolution had a chance to operate. In general the impact would be greatest for things with long lifetimes and slow reproduction: Trees for instance might be very hard hit if the decline was quick. People lacking technology might have trouble surviving a quick decline. Me, I'd buy some SPF 100 sunscrean and wear a hat and proper UV-absorbing glasses and try to stay out of the sun.

But life would persist and evolve -- it's good at that. (Though times would be tough for a while, and I'd expect to see a significant impact on longevity.)

As far as the color of the sky goes, the effect would be negligible. The sky is blue because of Raleigh Scattering and ozone is uncolored so it's not clear there's be any noticeable visual effect. You might detect the odor of ozone formed by the UV at ground level.

  • $\begingroup$ So you mean Earth would not become a desert planet like the Atacama? $\endgroup$ – user18428 Jul 8 '18 at 0:50
  • $\begingroup$ Could genetic engineering be used to make people immune to the high UV radiation? $\endgroup$ – user18428 Jul 8 '18 at 0:50
  • $\begingroup$ @user18428: "Tolerant" maybe. "Immune" is unlikely, though. And genetic engineering is hard if you're looking for something more complicated than simple biochemical pathway changes. Evolution might well beat us to it! (I'd much prefer the genetic engineering approach, as evolution is hard on the generations it takes to evolve.) $\endgroup$ – Mark Olson Jul 8 '18 at 1:00
  • $\begingroup$ @user18428: The Atacama is a desert mainly because it is the driest place on Earth. See the Wikipedia article for details: en.wikipedia.org/wiki/Atacama_Desert $\endgroup$ – Mark Olson Jul 8 '18 at 1:02
  • $\begingroup$ I know that.But I was thinking about the impossibility of life on Earth if our planet didn't had the ozone layer.So I thought if Earth would become an extremely empty lifeless desert in the short term.Could this happen? $\endgroup$ – user18428 Jul 8 '18 at 1:21

There was life on Earth before the ozone layer existed.

There was life on Earth even when there was no oxygen in the atmosphere.

Such life still exists deep down in the rocks. So the worst thing that can happen is that Earth will be like it was 2.5 million years ago, but with a chance to recover faster. See https://en.wikipedia.org/wiki/Life

It is also quite likely that the ozone layer temporarily disappeared at the K-T extinction event, because the huge asteroid impact, and the resulting fires changed the composition of the atmosphere. It was not nice. But we know that life survived. https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_extinction_event

It happened 65 million years ago. That means, in geologic time, quite recently.


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