<p>I would say, that with our current atmosphere and magnetic field there's not a &quot;direct&quot; threat to life as they shield the Earth.</p>
<p>The atmosphere is <a href="http://gsp.humboldt.edu/OLM/Courses/GSP_216_Online/lesson2-1/atmosphere.html" rel="nofollow noreferrer">opaque to X-ray radiation</a> that can come from outside. It seems that much of that opacity comes from water vapor, and <a href="https://earthobservatory.nasa.gov/global-maps/MYDAL2_M_SKY_WV" rel="nofollow noreferrer">the amount of that in the atmosphere changes</a> depending on different factors. X-ray radiation has also effects on the ionosphere and can change its size, which affects communications but I don't know whether life is affected for that.</p>
<p>Earth's magnetic field is disturbed by a CME and that has also various effects like inducing currents that, as you said, pose a risk to power grids and telecommunications. However there's another effect that's also associated with CMEs and solar flares: <a href="https://en.wikipedia.org/wiki/Solar_energetic_particles" rel="nofollow noreferrer">Solar Energetic Particles</a>, these types of events are, I believe, the one that could have a more direct effect to life. If they are happening together with the disturbance of the magnetic field produced by a CME, then our shield is weakened. The maximum flux of the chain reaction they produced when they reach Earth happens at 18km above the sea level, and at the altitude of a commercial flight is ~300 times more than at sea level. However, only seems to pose a &quot;risk&quot; to frequent flyers (crew and passengers) as the cumulative effects could produce cancer. I've extracted these numbers from the <a href="https://www.raeng.org.uk/publications/reports/space-weather-full-report" rel="nofollow noreferrer">Extreme Space Weather report by the Royal Academic of Engineering</a> and references therein.</p>

CC BY-SA 4.0
2020-07-11T20:00:30.363Z
2020-07-11T20:00:30.363Z
dvdgc13
<p>Abrevaya et al. (2020) in &quot;The UV surface habitability of Proxima b: first experiments revealing probable life survival to stellar flares&quot; (<a href="https://ui.adsabs.harvard.edu/abs/2020MNRAS.494L..69A/abstract" rel="nofollow noreferrer">abstract</a>, <a href="https://ui.adsabs.harvard.edu/link_gateway/2020MNRAS.494L..69A/EPRINT_PDF" rel="nofollow noreferrer">PDF</a>) say:</p>
<p>&quot;Our results show the impact that a typical flare and a superflare would have on life: when microorganisms receive very high fluences of UVC, such as those expected to reach the surface of Proxima b after a typical flare or a superflare, a fraction of the population is able to survive. Our study suggests that life could cope with highly UV irradiated environments in exoplanets under conditions that cannot be found on Earth. &quot;</p>
<p>That suggests that total-extinction conditions aren't found on Earth, either.  The paper has a lot more detail of their assumptions and modeling, but that's my quick takeaway from the abstract.</p>

CC BY-SA 4.0
2020-07-11T20:00:06.213Z
2020-07-11T20:00:06.213Z
Eric Jensen
<p>I know a repeat of the <a href="https://science.nasa.gov/science-news/science-at-nasa/2014/02may_superstorm/" rel="nofollow noreferrer">1859 Carrington Event</a> (coronal mass ejection) would pose a severe risk to power grids and telecommunication networks but wouldn't pose an immediate threat to life.</p>
<p>If a large solar flare can release <a href="https://hesperia.gsfc.nasa.gov/sftheory/flare.htm#:%7E:text=Large%20flares%20can%20emit%20up%20to%2010%2032,are%20typically%20three%20stages%20to%20a%20solar%20flare." rel="nofollow noreferrer">10e32 ergs</a> of energy, is there an energy level where a solar flare or CME would pose an immediate threat to any life on the Earth that doesn't live below sea level.</p>

CC BY-SA 4.0
2020-07-11T16:50:53.273Z
The power grid being affected *is* an immediate threat to lives.
StephenG - Help Ukraine
CC BY-SA 4.0
2020-07-11T17:02:12.617Z
@StephenG I didn't specify human life in my question. I believe the failure of the power grid would not be an immediate threat to much of the animal kingdom.
Bob516
CC BY-SA 4.0
2021-08-31T14:45:43.100Z
Possibly useful:  https://physics.stackexchange.com/a/258093/59023 and https://physics.stackexchange.com/a/568946/59023 and https://physics.stackexchange.com/a/202229/59023
honeste_vivere
<earth><solar-flare><coronal-mass-ejection>
Solar flares/CME dangers to life?
Bob516
# Solar flares/CME dangers to life?

(Asked by: username_0 on 2020-07-11)

I know a repeat of the [1859 Carrington Event](https://science.nasa.gov/science-news/science-at-nasa/2014/02may_superstorm/) (coronal mass ejection) would pose a severe risk to power grids and telecommunication networks but wouldn't pose an immediate threat to life.

If a large solar flare can release [10e32 ergs](https://hesperia.gsfc.nasa.gov/sftheory/flare.htm#:%7E:text=Large%20flares%20can%20emit%20up%20to%2010%2032,are%20typically%20three%20stages%20to%20a%20solar%20flare.) of energy, is there an energy level where a solar flare or CME would pose an immediate threat to any life on the Earth that doesn't live below sea level.

**Tags:** earth, solar-flare, coronal-mass-ejection
> **Comments:**
> **username_1**: The power grid being affected *is* an immediate threat to lives.  
> **username_0**: @StephenG I didn't specify human life in my question. I believe the failure of the power grid would not be an immediate threat to much of the animal kingdom.  
> **username_2**: Possibly useful:  https://physics.stackexchange.com/a/258093/59023 and https://physics.stackexchange.com/a/568946/59023 and https://physics.stackexchange.com/a/202229/59023  

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## 2 answers

### Answer by username_3 on 2020-07-11. Score: 1

I would say, that with our current atmosphere and magnetic field there's not a "direct" threat to life as they shield the Earth.

The atmosphere is [opaque to X-ray radiation](http://gsp.humboldt.edu/OLM/Courses/GSP_216_Online/lesson2-1/atmosphere.html) that can come from outside. It seems that much of that opacity comes from water vapor, and [the amount of that in the atmosphere changes](https://earthobservatory.nasa.gov/global-maps/MYDAL2_M_SKY_WV) depending on different factors. X-ray radiation has also effects on the ionosphere and can change its size, which affects communications but I don't know whether life is affected for that.

Earth's magnetic field is disturbed by a CME and that has also various effects like inducing currents that, as you said, pose a risk to power grids and telecommunications. However there's another effect that's also associated with CMEs and solar flares: [Solar Energetic Particles](https://en.wikipedia.org/wiki/Solar_energetic_particles), these types of events are, I believe, the one that could have a more direct effect to life. If they are happening together with the disturbance of the magnetic field produced by a CME, then our shield is weakened. The maximum flux of the chain reaction they produced when they reach Earth happens at 18km above the sea level, and at the altitude of a commercial flight is ~300 times more than at sea level. However, only seems to pose a "risk" to frequent flyers (crew and passengers) as the cumulative effects could produce cancer. I've extracted these numbers from the [Extreme Space Weather report by the Royal Academic of Engineering](https://www.raeng.org.uk/publications/reports/space-weather-full-report) and references therein.


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### Answer by username_4 on 2020-07-11. Score: 1

Abrevaya et al. (2020) in "The UV surface habitability of Proxima b: first experiments revealing probable life survival to stellar flares" ([abstract](https://ui.adsabs.harvard.edu/abs/2020MNRAS.494L..69A/abstract), [PDF](https://ui.adsabs.harvard.edu/link_gateway/2020MNRAS.494L..69A/EPRINT_PDF)) say:

"Our results show the impact that a typical flare and a superflare would have on life: when microorganisms receive very high fluences of UVC, such as those expected to reach the surface of Proxima b after a typical flare or a superflare, a fraction of the population is able to survive. Our study suggests that life could cope with highly UV irradiated environments in exoplanets under conditions that cannot be found on Earth. "

That suggests that total-extinction conditions aren't found on Earth, either. The paper has a lot more detail of their assumptions and modeling, but that's my quick takeaway from the abstract.


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