If a supernova occurred one light-year away, what effect would the initial light surge likely cause on Earth?

Instantaneous superficial burns or solar flare-like effects, largely shielded by the atmosphere.

When a supernova occurs just one light-year away, the initial visible light and thermal pulse arrives first. While this surge would be many times brighter than the Sun, Earth's atmosphere provides a significant degree of shielding against the thermal radiation component. The text suggests that this intense but brief energy input might cause superficial burns or effects similar to very powerful solar flares on the sunlit side of the planet. However, the atmosphere absorbs the most severe thermal damage, preventing immediate, widespread ignition or mass fatality that would occur closer in (e.g., within 25 to 50 AU).