Is it possible to create an endothermic reation on the same scale as an atomic explosion?

Question

What is the biggest endothemic reaction we ever produced?

Answer 1

Melting of ice is an endothermic reaction. So I guess, When a whole glacier melts, a huge endothermic reaction is happening. On a much more grander astronomical scale, imagine a comet that vaporizes as it approaches the perihelion of its orbit. The heat absorbed would be much more than the heat released from any single atomic explosion made by man.