Fantastic Four (2005): Johnny's Supernova

Going above 4000 kelvin would cause the Human Torch to approach supernova, which could set the atmosphere on fire according to Reed

The mass of the atmosphere is about 5150000000000000000kg

I'll assume 20 celsius or 293.15 kelvin as the starting temperature, and 4000 kelvin as the temperature the atmosphere is being heated to since that's the temperature Johnny can reach

Change in temperature = 4000k - 293.15k = 3706.85k

Specific heat capacity of air is 1005J/kg

Energy = 5150000000000000000kg x 1005J/kg x 3706.85k = 1.91857288875e25 joules or 4.5854 Petatons (Multi-Continent level)