Why might Antarctic melting add less to sea level rise?

Bedrock rebound could slow projected ice loss

New analyses suggest that some estimates of future sea-level rise from Antarctic ice loss may be too high because many ice-sheet models omit a key feedback: the rise of bedrock once ice thins. As ice mass decreases, the solid Earth underneath rebounds upward, changing how ice rests on and slides across its bed.

That uplift alters the physical contact between ice and the ground, which can reduce the rate at which ocean water undercuts and melts grounded ice. When models include this viscoelastic response of the crust, the pace of ice retreat and the resulting contribution to global sea level in many scenarios is reduced—an effect that recent work quantifies as potentially cutting projected melt by a nontrivial percentage in some cases.

Why this finding matters

• It affects near- to mid-century projections used for coastal planning and risk assessments.
• Including bedrock dynamics narrows uncertainty around Antarctic contributions to sea-level rise, though it does not negate the overall threat from warming.
• Policy-makers and adaptation planners need projections that capture coupled ice–solid-earth feedbacks to make robust decisions about infrastructure and flood defenses.

Caveats and next steps

Researchers caution that bedrock rebound is one of many interacting processes—ocean warming, ice-sheet geometry, and ice-shelf dynamics remain critical. The dampening effect found by recent studies does not eliminate the need to reduce greenhouse gases or to prepare for significant sea-level rise in vulnerable regions. Improving models will require better geophysical data beneath ice sheets and longer-term observations to validate how uplift alters ice flow in practice.