Island states facing rising seas driven by global warming slammed on Thursday suggestions by some rich nations that a comprehensive climate deal can wait until 2018 or later.

Such proposals are "both environmentally reckless and politically irresponsible," Joseph Gilbert, Grenada's environment minister, said on behalf of the 42-nation Association of Small Island States (AOSIS).

"If we allow this to happen, global warming problems are going to worsen and the impact on a country like Grenada will be devastating," he said in a statement.

Australia and Norway have proposed setting a 2015 deadline for a climate deal that would lock in commitments from all major carbon-emitting nations.

But negotiators from Japan and Russia have said such a deadline is unrealistic, with Moscow suggesting it could be pushed out as far as 2018 or 2020, AOSIS said in a statement.

Russia's top climate official, Oleg Pluzhnikov, told Interfax news agency earlier this week that there was a strong probability "that no new agreement will be adopted in the four or five years after the expiry of the Kyoto Protocol."

Kyoto's current roster of pledges runs out at the end of 2012.

Gilbert's comments come ahead of a new round of high-level UN negotiations in Durban, South Africa, from November 28 to December 9.

Some progress has been made on "building block" issues such as finance and technology since the near-collapse in 2009 of climate talks in Copenhagen.

But sharing out cuts in the greenhouse gas emissions that stoke warming remains blocked.

"The world's climate scientists have told us that global emissions need to peak well before 2020" to keep global temperatures from rising more than the 2.0 degrees Celsius (3.6 degrees Fahrenheit) above pre-industrial levels, widely seen as a threshold for dangerous warming, Gilbert said.

"We cannot continue to delay making the decisions, to 2018 or 2020, as there will not be sufficient time for countries to take action."

The window of opportunity for staying under the 2.0 C (3.6 F) cap is shrinking rapidly, scientists say.

Many developing nations in the Caribbean, the Pacific, Asia and Africa have already experienced more frequent droughts, stronger hurricanes and rising seas, with even more severe climate impacts on the horizon, according to the final draft of a major scientific UN report to be released later this month.

The Australia-Norway proposal, submitted in September, calls for a scaling up of national carbon-cutting targets and the step-by-step construction of an international system for verification.

This could be done as an extension of the Kyoto Protocol, or a new treaty that incorporates some of its attributes, it said.

The end-point objective would be "a new, legally-binding Protocol for all Parties" -- including developed and developing countries -- in 2015.

The Kyoto Protocol currently only covers some three dozen rich nations that account for about 30 percent of global greenhouse gas emissions.

China, the world's top carbon emitter, was excluded at the outset as a developing nation, and the United States -- the No. 2 global polluter -- opted out after playing a major role in crafting the treaty.

"This is a live issue that is being discussed," Alden Meyer, top climate policy analyst at the Washington-based Union of Concerned Scientists, said of the proposal.

"But it is very political. Different countries have opposing positions, which makes getting to a 'yes' very hard on this."