Planning to retire in the next few years? Please reconsider: The economy needs you more than you know.

Economists have long expected an aging population to hamper growth for the simple reason that it means a smaller labor force. But new research has identified a potentially more powerful impact: Rapid retirements deprive companies of critical experience and knowledge, which undermines productivity across the entire economy. Demographics may thus be a critical factor in why the current economic expansion, which began as the...