Chess Puzzle

Today's puzzle:


White found a neat way to exploit the insecure situation of Black's king in this position, bringing the game to a quick end. How did he do so?


Solution to the last puzzle:
R.F. Griffiths - J. Wolpert
SA Championship, Pretoria 1963
Griffiths came out with 2.Rc3! Now if 2...a2 there follows 3.Qxe5+ Ka7 4.Qc5+ Kb8 5.Qf8+ Ka7 6.Ra3+ Kb6 7.Qd6+ Kb5 8.Qa6+ followed by 9.Rxa2 and wins. So Black played 2...Qb1+ 3.Kh2 Qf5 4.Rxa3 Rb2 5.Qa7+ Kc8 6.Rf3! and resigned. A fine piece of adjournment analysis by Griffiths. Going back to the diagram, any move by White's queen allows 2...Qxc1+ 3.Qxc1 a2 and the pawn queens, while any other move, other than 2.Rc3, allows 2...a2. Hence White's optimism!