The increasingly unstable climate is no longer seen as primarily an environmental or economic issue. As the threat we face has grown larger in scale and sharper in outline over the past two years, as recent scientific evidence has reinforced, and in some cases exceeded, our worst fears as to the physical impacts facing us, so it has become clear that climate change has consequences that reach to the very heart of the security agenda.

Flooding, disease and famine and from that migration on an unprecedented scale and in areas of already high tension. Drought and crop-failure and from that intensified competition for food, water and energy in regions where resources are already stretched to the limit. Economic disruption on the scale predicted in last year’s Stern Report and not seen since the end of World War II. This is not about narrow national security — it is about collective security in a fragile and increasingly interdependent world. And tragically, once again, it will be those who are most vulnerable and least able to cope that will be hit first. There is certainly no choice between a stable climate and the fight against poverty. Without the first, the second will certainly fail.

Anyone wanting to trace the links between what science is telling us about physical impacts and the broader ramifications for our security would do well to read a startling report that appeared Monday. The Military Advisory Board are a group of the most respected retired Admirals and Generals in the US. During their careers they have stood face to face with everything from containment and deterrence of the Soviet nuclear threat during the Cold War to the more recent struggle against terrorism and extremism. They are about as far as you can get from the old stereotype of a tree-hugging environmentalist. And yet in that report they state, categorically, that projected climate change poses a serious threat to America’s national security. In other words, an unstable climate will make the very kinds of tensions and conflicts that the Security Council deals with, day in day out, yet more frequent and even more severe.

It is those concerns, then, that lay behind the UK’s decision to use its Presidency of the Security Council to instigate this unprecedented debate Tuesday. And it is those concerns that prompted 53 countries to sign up to speak and take part.

The Security Council can make a unique contribution in building of a shared understanding of a what an unstable climate will mean for individual and collective security. And the decisions we come to and the action we take as we begin to build a low carbon, global economy will be better, stronger and more effective because it is informed by the fullest possible understanding of all the implications of climate change — including the security imperative.

Tuesday’s deal marked the recognition of climate change as a core security issue. It demonstrated that the vast majority of the international community now see an unstable climate as an unprecedented threat that we must meet with much greater urgency and ambition. If we succeed in that shared endeavour, we will all enjoy a better prospect of security. Climate change is a threat that can bring us together if we are wise enough to stop it from driving us apart.

Beckett is British Foreign Secretary