WASHINGTON -- The Bush administration is drastically scaling back efforts to measure global warming from space, just as the president tries to convince the world the United States is ready to take the lead in reducing greenhouse gases.

A confidential report to the White House, obtained by The Associated Press, warns that U.S. scientists will soon lose much of their ability to monitor warming from space using a costly and problem-plagued satellite initiative begun more than a decade ago.

Because of technology glitches and a near-doubling in the original $6.5 billion cost, the Defense Department has decided to downsize and launch four satellites paired into two orbits, instead of six satellites and three orbits.

The satellites were intended to gather weather and climate data, replacing existing satellites as they come to the end of their useful lifetimes, beginning in the next couple of years.

The reduced system of four satellites will now focus on weather forecasting. Most of the climate instruments needed to collect more precise data over long periods are being eliminated.

Instead, the Pentagon and two partners -- the National Oceanic and Atmospheric Administration and NASA -- will rely on European satellites for most of the climate data.

"Unfortunately, the recent loss of climate sensors ... places the overall climate program in serious jeopardy," NOAA and NASA scientists said in the report to the White House.