Climate change is transforming the way we think about security. "This will not be the first time people have fought over land, water and resources, but this time it will be on a scale that dwarfs the conflicts of the past", said the Congolese representative at the UN Security Council debate in April 2007. The French called it the "number one threat to mankind".

The representative from Papua New Guinea said the dangers that small island States and their populations faced [from climate change] were "no less serious than those faced by nations and peoples threatened by guns and bombs". An increase of just half a metre in sea level would put at risk the very survival of the human population of many Pacific Island nations.

UN Secretary-General Ban Ki-moon said the scenarios facing us were alarming. Scarce resources -- whether energy, water or arable land -- could lead to a breakdown in established codes of conduct, and even to outright conflict. He cautioned Member States to focus more clearly on the benefits of early action. Our increasingly unstable climate is no longer seen as primarily an environmental or economic issue. Over the past two years, the threat we face has grown larger in scale and sharper in outline.

Recent scientific evidence has reinforced, and in some cases exceeded, our worst fears about the physical impacts facing us. It has become increasingly clear that climate change has consequences that reach the very heart of the security agenda: flooding, disease and famine, resulting in migration on an unprecedented scale in areas of already high tension; drought and crop-failure, leading to intensified competition for food, water and energy in regions where resources are already stretched to the limit; and economic disruption on the scale predicted in the 2006 Stern Review on the Economics of Climate Change, and not seen since the end of the Second World War.

This is not about narrow national security, but about collective security in a fragile and increasingly interdependent world. And tragically, once again, it will be the most vulnerable and the least able to cope who will be hit first. There is no choice between a stable climate and the fight against poverty -- without the first, the second will certainly fail.

Anyone still convinced that climate change is purely an environmental problem should read the report published on 16 April by the Military Advisory Board, a group of highly respected retired Admirals and Generals in the United States. During these retired military officers' 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. And yet they categorically state in their report that projected climate change poses a serious threat to America's national security. They say it is "a threat multiplier for instability in some of the most volatile regions of the world". In other words, an unstable climate will create the very kind of tensions and conflicts that the Security Council deals with, day in and day out, yet more frequent and even more severe.

It was those concerns that lay behind the United Kingdom's decision to use its presidency of the Security Council to instigate an unprecedented debate on 17 April 2007 on energy, security and climate. And it was those concerns that prompted 55 countries -- a record number for a thematic debate -- to sign up to speak and take part. However, taking it to the Council was not an alternative to action elsewhere within the United Nations or across the international community. British Foreign Secretary Margaret Beckett herself commented that as the United Kingdom's lead negotiator at the United Nations Framework Convention on Climate Change for over five years, she was the last person who would wish to undermine those other vital multilateral efforts.

The UN General Assembly and the Economic and Social Council have key roles to play as well. The Security Council, however, charged as it is with the maintenance of international peace and security, can make a unique contribution in building a shared understanding of what an unstable climate will mean for our individual and collective security. The decisions we make and the actions we take, in whatever forum, as we begin to build a low-carbon global economy will be better, stronger and more effective because of the fullest possible understanding of all the implications of climate change, including security imperatives. Equally, failure to address these issues in the relevant fora will exacerbate the security implications of climate change.

The Security Council debate on 17 April was a landmark event, as it marked the recognition of climate change as a core security issue. It also demonstrated that the majority of the international community sees an unstable climate as an unprecedented threat that must be met with greater urgency and ambition. If we succeed in this shared endeavour, we will all enjoy a better prospect of security. As Foreign Secretary Beckett said, "climate change is a threat that can bring us together if we are wise enough to stop it from driving us apart".

The Council debate was only part of a long process that will come to involve every aspect of the United Nations work in almost every fora. We are committed to climate change for the long term and we will work to build trust and capacity through a newly-established "Friends" group, through future events both inside and outside the United Nations and, of course, by working closely with Gro Harlem Brundtland of Norway, Han Seung-soo of the Republic of Korea and Ricardo Lagos Escobar of Chile -- the Secretary-General's Special Envoys on Climate Change.