From climate change to volcanoes and earthquakes, the world's growing challenges have leaders in earth science proposing a merger of agencies that study the planet.

Creation of a new Earth Systems Science Agency is urged in this week's edition of the journal Science, by merging the National Oceanic and Atmospheric Administration and the U.S. Geological Survey.

Included in the group making the proposal are former heads of both agencies as well as others who have held science policy positions in government.

"The United States faces unprecedented environmental and economic challenges in the decades ahead. Foremost among them will be climate change, sea-level rise, altered weather patterns, declines in freshwater availability and quality and loss of biodiversity," the group warned.

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D. James Baker, NOAA administrator from 1993 to 2001, said the group felt the divided responsibilities among agencies made it harder to get things done.

"We felt that laying this [idea] on the table would have a lot of positive aspects," said Baker, who now works on deforestation concerns with the Clinton Foundation.

With a $4 billion budget and 12,000 employees, NOAA, a part of the Commerce Department, studies the atmosphere and oceans.

USGS, part of the Interior Department, with a $1 billion budget and 8,500 workers, focuses on fresh water and the Earth, including such threats as volcanoes and earthquakes, and has a biological arm.

The group proposing the new agency had long been concerned that science programs that are part of regulatory or management agencies tend to be downplayed at budget time, said Charles Groat, a former director of the Geological Survey and now interim dean of geosciences at the University of Texas.

"Given the challenges the country faces in the environment and energy," he said, the two agencies could make a significant contribution to science, he said.

The combined agency would provide a strong group on behalf of science, he said, working in collaboration with the National Science Foundation, NASA, the Environmental Protection Agency, Department of Agriculture, Department of Energy and National Institutes of Health.

Creation of the new agency also would revive the name ESSA. Before 1970, NOAA was known as the Environmental Science Services Administration.

In addition to Groat and Baker, signing the proposal were Mark Schaefer, former acting director of the Geological Survey; former White House science adviser John H. Gibbons; Donald Kennedy, Food and Drug Administration commissioner from 1977 to 1979; Charles F. Kennel, former associate administrator of NASA and director of its Mission to Planet Earth, and David Rajeski, who formerly served in the White House Office of Science and Technology Policy and the Council on Environmental Quality.