If the ozone layer of planet Earth was completely depleted (to near-zero concentrations), what would the average summer UV-index rise to in New York City?

If relevant, other changes anticipated are the complete melting of the ice caps (raising water levels 260 feet and submerging nearly all of the city), and I anticipate violent dawns as unblocked solar radiation sweeps the globe. (Among other things.) I'm looking for a ground-level answer on the index, though.

  • $\begingroup$ Hooray for hard-science questions! $\endgroup$
    – Samuel
    Commented Jun 18, 2015 at 22:51

1 Answer 1


It would be over 30 in the summer.

The UV index typically goes to 11, which is considered extreme, especially for mid-latitude cities.

enter image description here

This site provides the above graph which includes: The solar spectrum above the atmosphere (A), and at the ground level (B, C), ozone absorption (D), and the erythemal action spectrum (E).

The vast majority of radiation, especially for the more dangerous shorter wavelengths, is absorbed by the ozone layer. The ozone is responsible for absorbing all the UVC and 90% of the UVB.

This simulation explores what would have happened if we hadn't banned ozone depleting chemical use. It shows how the UV index would change for mid-latitude cities as the ozone depletes. It actually bottoms out at just under 30% our current ozone, so the UV index for 0% ozone would be much higher. The correlating decrease in ozone for this UV index increase is provided here.

enter image description here

So New York, which sits in the middle of this latitude range, would be sitting at a UV index of 30+ without ozone.


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