As Russian lawmakers ratified the Kyoto protocol on climate change on Friday after years of dithering, grim scenarios like these may have been on the minds of some.

A growing number of analysts argue that global warming linked to greenhouse gas emissions is not just a "green issue."

They argue it might eventually top terrorism on the global security agenda, provoking new conflicts and inflaming old ones.

"The biggest security problem from global warming would be forced migrations, the dislocation of people because of flooding or drought," said Steve Sawyer, climate policy adviser for environmental group Greenpeace.

"Or drastic ecosystem change could change the resource base and uproot rural people. Forced migrations of people almost always cause problems."

Former Canadian Environment Minister David Anderson said earlier this year that global warming posed a greater long-term threat to humanity than terrorism because it could force hundreds of millions from their homes.

Russia's ratification of Kyoto cleared the way for the long-delayed climate change pact to come into force worldwide.

Kyoto obliges rich nations to cut overall emissions of heat-trapping carbon dioxide to 5.2 percent below 1990 levels by 2008-12, by curbing use of coal, oil and natural gas and shifting to cleaner energies like solar or wind power.

The United Nations projects that temperatures may rise by 1.4-5.8 Celsius by the year 2100. That could raise sea levels, swamp low-lying states, and bring desertification or floods.