A special meeting of the United Nations Security Council is due to consider whether to expand its mission to keep the peace in an era of climate change.
Small island states, which could disappear beneath rising seas, are pushing the Security Council to intervene to combat the threat to their existence.
There has been talk, meanwhile, of a new environmental peacekeeping force — green helmets — which could step into conflicts caused by shrinking resources.
The UN secretary general, Ban Ki-Moon, is expected to address the meeting on Wednesday.
But Germany, which called the meeting, has warned it is premature to expect the council to take the plunge into green peacemaking or even adopt climate change as one of its key areas of concern.
"It is too early to seriously think about council action on climate change. This is clearly not on the agenda," Germany's ambassador to the UN, Peter Wittig, wrote in the Huffington Post.
"A good first step would be to acknowledge the realities of climate change and its inherent implications to international peace and security," he wrote.