Letters to the editor

Wet Earth
Erin Wayman’s article “Faint young sun” (SN: 5/4/13, p. 30), about how the early Earth stayed warm enough for liquid water, made me wonder about the effect of the temperature of the planet itself. A hotter core, thinner crust, more volcanism — wouldn’t those factors in addition to atmospheric influences affect surface temperature?
Virginia Bruce, via e-mail

“For the present-day climate, internal heat provides only 0.02