The greatest threat to global security: climate change is not merely an environmental problem.

• Author: Parry, Emyr Jones

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...