A decade-long scientific debate about what’s causing the thinning of one of Antarctica’s largest ice shelves is settled this week (Wednesday 13 May) with the publication of an international study in the journal The Cryosphere.The Larsen C Ice Shelf — whose neighbours Larsen A and B, collapsed in 1995 and 2002 — is thinning from both its surface and beneath. For years scientists have been unable to determine whether it is warming air temperatures or warmer ocean currents that were causing the Antarctic Peninsula’s floating ice shelves to lose volume and become more vulnerable to collapse. This new study takes an important step forward in assessing Antarctica’s likely contribution to future sea-level rise.