Sure:
Mass of air affected * Specific heat of air * ∆T = Energy
Mass of air affected:
Volume of air affected * Density of air
Specific heat of air:
~1,003.5 J/°C (does vary a bit, but would be negligible here)
∆T (Change in Temperature):
20°C
Density of air:
1.225 kg/m³
Normally for "affecting the climate", I use 609.6m for height of air, though it can be different in some cases.
So:
Volume of air:
204,709.733 x 609.6 = 1,247,910,532.368 m³
Mass of air:
1,247,910,532.368 x 1.225 = 1,528,690,402.1508 kg
So, the formula would be:
1,528,690,402.1508 x 1,003.5 x 20 = 30,680,816,371,166.556 Joules
Or around 7.33 Kilotons of TNT (7-C; Town level)