BRUSSELS, Belgium — NATO must prepare for a new era of global insecurity threatened by climate change and energy shortages, the alliance’s secretary general said.

Jaap de Hoop Scheffer insisted that the alliance must look to a new “strategic horizon” where dwindling water and food supplies, global warming, and mass migration cause international tensions.

“Climate change could confront us with a whole range of unpleasant developments — developments which no single nation state has the power to contain,” he told a conference in Brussels.

“It will sharpen the competition over resources, notably water. It will increase the risks to coastal regions. It will provoke disputes over territory and farming land. It will spur migration and it will make fragile states even more fragile.”

Mr. Scheffer urged the 26 member nations to bear climate change in mind as one of the key elements “shaping the security environment in the next decade.”

He added: “The scarcity of fossil fuels is already leading to a renaissance of civilian nuclear energy — and this poses its very own proliferation problems.

“The next decade will see continuously rising energy prices and a scramble for energy resources.

“This will put a premium on energy security. And it will also put a premium on the political stability of the world’s major oil and gas producing countries.”

The old rivalries, however, were still apparent at the conference. Russia’s ambassador to NATO, Dmitry Rogozin, attacked the alliance’s support for American anti-missile defence bases set up in eastern Europe to counter Iran.

“If NATO considers the threats are coming from the south, why are you enlarging to the east? Do you have a problem with the compass?” He added: “We can install our missile defences in Cuba or Venezuela to protect our territory against the bad guys from Jamaica.”