A glacier front is not a balance sheet

A glacier's terminus, velocity, surface height, and total mass are examined as related but non-interchangeable measures. Hypothetical examples show how a nearly stationary front can coexist with upstream thinning, or an advancing tongue with redistribution rather than sustained mass gain. The essay distinguishes surface balance from total balance, retaining refreezing and discharge within the appropriate accounting boundaries. Greenland's published 2025 assessment provides a concrete case of reduced annual loss that remains net loss, with its period and uncertainty intact. Gravimetry, altimetry, and input-output methods are compared by what they measure and omit, including discharge-gate boundaries. Image timing and geolocation also matter to retreat claims. The conclusion matches each question to its measurement instead of making one dramatic front photograph represent the whole ice sheet.