LONDON – Thirty years ago, the Cold War was at its height and the United Kingdom had just clawed its way out of recession. Perhaps those factors explain why, this week in 1982, when 119 government delegations chose to sign the United Nations Convention on the Law of the Sea (UNCLOS), the UK was not among them. According to Donald Rumsfeld, Britain’s then-prime minister, Margaret Thatcher, declared UNCLOS to be “nothing less than the international nationalization of roughly two-thirds of the Earth’s surface.”

Fifteen years later, when the UK finally acceded to UNCLOS under a Labour government, the convention was applying, for the first time in history, an internationally agreed legal framework to the majority of coastal waters around the world. Countries’ rights to fish, minerals, and other resources were enshrined in law, with recourse to international adjudication should disputes arise. The right of free passage on the high seas was assured.

Britain and other countries must now learn from, rather than repeat, the Thatcher government’s mistake. A new debate is emerging about how we govern and exercise stewardship over the high seas – the 45% of the Earth’s surface that lies beyond national jurisdictions.

We know that a resource crunch of unprecedented scale is coming. Non-oil commodity prices have risen precipitously in the last decade. The high seas can provide food, minerals, and novel resources for technology and medicine. But the weaknesses of the current governance regime, epitomized by rampant illegal, unregulated, and unreported fishing, threaten to undermine the global security and sustainability to which well managed oceans can contribute.

UNCLOS is a symbol of global cooperation, compromise, and international law that was more than 20 years in the making. The failure of the US Senate to ratify it serves only to strengthen the case against