"The world has an obligation to ensure that 'no island is left behind,'" said Grenada's UN ambassador Dessima Williams, head of The Alliance of Small Island States (AOSIS).

"It is a cruel irony that without adequate global commitments, the countries contributing least to global warming will be the ones most affected by its consequences," she added.

At a summit in L'Aquila, Italy, leaders of the Major Economies Forum (MEF) -- a combination of the Group of Eight (G8) countries and emerging economies such as China, India, Brazil and Indonesia -- agreed to cap the rise in the Earth's average temperature to two degrees Celsius (3.6 degrees Fahrenheit) above 18th-century levels.

But AOSIS said it wants that cap set at 1.5 degrees Celsius (2.7 degrees Fahrenheit) above 18th-century levels.

"Two degrees of temperature rise is still unacceptable, because it exceeds safe thresholds necessary for the protection and survival of small islands," according to Williams.

"For the smallest and most vulnerable among us, climate change is already here, causing damage," she said.

The alliance also rebuked the MEF for failing to provide details of how emissions will be curbed, and by how much.

AOSIS called for several specific goals, including an 85 percent overall reduction in global emissions below 1990 levels by 2050.

The grouping also wanted developed nations to commit to a 45 percent reduction in emissions from 1990 levels by 2020.

"Given the decades-long time lags between accumulation of greenhouse gases in the atmosphere and changes in average temperatures, a mere temperature goal is insufficient," Williams said.

"Targets need to be specific, measurable, quantifiable and defined by reference to the 1990 baseline emissions agreed to under the Kyoto Protocol."

At the L'Aquila summit, the MEF committed "to identify a global goal for substantially reducing global emissions" by 2050, but it did not say how the reductions would happen, or specify who would be reducing emmision.