Al Gore made his debut in the 2008 presidential campaign Monday night, encouraging voters to back Barack Obama because ''take it from me, elections matter.'' The former vice president's speech at the Joe Louis Arena was part endorsement and part blistering attack on the man who denied him the White House eight years ago. ''After eight years of incompetence, neglect and failure, we need change,'' Gore said. ''After eight years when our Constitution has been dishonored and disrespected, we need changes.''

Salt crunches underfoot like frosty soil on this bare stretch of land in western Uzbekistan. Cotton, to be used to make a mattress, is stacked in a home. The status of Uzbekistan as the world's second-largest cotton exporter is in danger because of environmental destruction. "Thirty years ago, this was a cotton field,' said a 61-year-old farmer who has lived near this city all his life. "Now it's a salt flat.'

European Union trade officials have launched an investigation into whether imports of U.S. biodiesel break international trade rules because of subsidies, the EU's executive Commission said on Friday. A European Commission statement said examination of complaints lodged by European industry found an investigation was warranted. "Sufficient evidence was provided of subsidies to the U.S. biodiesel sector, as well as dumping of biodiesel in the European market," the statement said.

The most obvious lesson to be learned from the Senate's failure to mount any sort of grown-up debate on climate change last week is that the country needs a new occupant in the White House. Read Full Comment

An American military supercomputer, assembled from components originally designed for video game machines, has reached a long-sought-after computing milestone by processing more than 1.026 quadrillion calculations per second. The Roadrunner supercomputer costs $133 million and will be used to study nuclear weapons. The new machine is more than twice as fast as the previous fastest supercomputer, the I.B.M. BlueGene/L, which is based at Lawrence Livermore National Laboratory in California.

Before the anticlimactic demise on Friday of legislation to combat global warming, the Senate majority leader, Harry Reid, Democrat of Nevada, called climate change "the most important issue facing the world today.' Senator George V. Voinovich, Republican of Ohio, a critic of the bill, nonetheless called it "the most significant piece of legislation to ever come out of the Environment and Public Works Committee.' Senator John W. Warner winked at Senator Joseph I. Lieberman as he was met by Senators John Kerry, left, and Barbara Boxer.

Its reservoir levels receding and its grounds parched, California has fallen officially into drought, Gov. Arnold Schwarzenegger said Wednesday, warning that the state might be forced to ration water to cities and regions if conservation efforts did not improve. A farm near Bakersfield has been put up for sale for commercial development. There is tension between city residents and farmers, who consume most of California's water.

Prison Yard as a Planet Green TV Ad On Wednesday, Discovery will introduce Planet Green, a new cable brand promoted as the first 24-hour channel dedicated to eco-friendly living. It is the highest-profile cable channel introduction of the year, and an equally risky one. By wrapping itself in the planet, Discovery is betting that "eco-tainment' will appeal to viewers.