* Rising population, development put more in harm's way

* Policymakers urged to act in next few decades

* Less emphasis on mitigation, more on cutting risk

By David Fogarty and Deborah Zabarenko  

March 28 (Reuters) - A future on Earth of more extreme weather and rising seas will require better planning for natural disasters to save lives and limit deepening economic losses, the United Nations said on Wednesday in a major report on the effects of climate change. 

Some 32 social scientists and researchers from around the world, including a Senior Sustainability Scholar at Arizona State University, have concluded that fundamental reforms of global environmental governance are needed to avoid dangerous changes in the Earth system. The scientists argued in the March 16 edition of the journal Science that the time is now for a "constitutional moment" in world politics.

In 2008 and in 2011, the world was rocked by riots and by revolutions coinciding with spikes in food prices. Now researchers are projecting that by 2013, food prices will soar to unparalleled heights, causing widespread hunger in the most vulnerable populations and social unrest, with an enormous potential for loss of human life.