When do tidewater glaciers become unstable and retreat rapidly?

Tidewater glaciers become unstable and retreat rapidly primarily when they experience significant melting due to warming ocean temperatures, which undermines their ice fronts. This process is often exacerbated by increased calving rates, where large chunks of ice break off into the sea, and by the melting of glacial ice from below due to warmer water currents. Additionally, changes in ice dynamics, such as the loss of support from the glacier's grounding line, can further accelerate retreat. These factors combined can lead to a rapid and dramatic loss of ice mass.