President Obama gave his first major speech on climate change today at the United Nations, part of a special session convened by U.N. Secretary General Ban Ki-moon. The reason for the session? Lack of speed in international negotiations to address climate change.

You can see the president's speech here:

In addition to reaffirming the U.S. commitment to addressing climate change, the president listed some recent accomplishments: new efficiency standards for all vehicles, billions of dollars for renewable energy development, and the nation's first mandatory greenhouse gas reporting system. He even noted a plan to work with the world's other largest economies, known as the G20, to "phase out fossil-fuel subsidies so that we can better address our climate challenge."

The Obama administration unveiled a plan to boost fuel efficiency standards for cars and trucks to an average of 35.5 miles per gallon by 2016—four years ahead of current schedule and up from an average of just 25 miles per gallon today.

The new standards (pdf) will also impose—for the first time ever—a limit on greenhouse gas emissions from vehicles at 250 grams per mile in 2016 under the new proposed rule. (That’s about 5.5 ounces per kilometer, for those of you who like your units mixed differently.)

There are very few vehicles capable of meeting the new standards today, which would mean more hybrids and possibly even electric or other alternative vehicles would have to hit the road within seven years for automakers to comply.

In the newly released budget, the U.S. Department of Energy cuts $100 million from the hydrogen fuel cell program in fiscal year 2010 and transforms its name to "fuel cell technologies." Hydrogen, of course, is just the fuel of a fuel cell—a device that recombines hydrogen and oxygen to produce water and electrical current. Still, the name change distances the Obama administration from the "hydrogen economy" goals of their predecessors.

"We asked ourselves, 'Is it likely in the next 10 or 15, 20 years that we will convert to a hydrogen car economy?' The answer, we felt, was 'No,'" said energy secretary Steven Chu in a briefing on the budget for reporters yesterday, citing the need for better fuel cells and a near complete lack of infrastructure.

The President and Congress may not be in agreement about how best to deal with climate change, but it appears that they do agree on at least one thing: they'd like to give you money to trade in your old (polluting) car.

Under the terms of a provisional agreement between the president and Democrats in the House of Representatives, a "Cash for Clunkers" program would look something like this: Anyone who owns a car that gets less than 18 miles-per-gallon could trade it in for a voucher to offset the purchase of a more fuel-efficient car. Depending on exactly how fuel-efficient that new car or truck is, that voucher could be worth as much as $4,500—at least for the lucky first one million trade-ins.

Medical marijuana advocates are up in arms over yesterday's federal raid of a marijuana provider in northern California, claiming that the action is at odds with a policy change announced last week by U.S. Attorney General Eric Holder.

Wednesday afternoon, U.S. Drug Enforcement Administration (DEA) agents arrived at Emmalyn's California Cannabis Clinic in San Francisco's South of Market district, confiscating marijuana plants, lights, and other cultivation equipment as about a dozen people protested outside, the San Francisco Chronicle reports.

Emmalyn's had reportedly been operating under a temporary permit issued by the San Francisco Department of Public Health. A DEA spokesperson told the Associated Press that the clinic may be in violation of federal and state laws, but refused to provide any other details of the case.

The Senate yesterday gave its nod to President Obama's picks for key science slots in his administration. Both appointees are leading advocates of aggressive government action to stem and reverse climate change.

Lawmakers confirmed Harvard physicist John Holdren as director of the White House Office of Science and Technology Policy, and Jane Lubchenco as chief of the National Oceanic & Atmospheric Administration (NOAA). Lubchenco, 61, a marine biologist, becomes the first woman to head the agency, which oversees the National Weather Service and ocean and atmospheric research.

Holdren is well-known for leading the charge to reduce the threat of global warming as well as to prevent the spread of nuclear weapons. As Obama's top science adviser, he will help sculpt science and tech policy.

President Obama and United Nations (U.N.) Secretary General Ban Ki-moon saw eye to eye on fighting climate change when they met at the White House yesterday. Ban said that he and Obama agree that climate change is an “existential threat” to mankind, according to a U.N. press release. The leaders have high hopes for when the U.N. convenes in Copenhagen, Denmark, in December to work out a successor to the Kyoto Protocol, the 1992 international climate change treaty that expires in 2012.

Just over 50 days in office now, Obama has made clear his intentions to get the U.S. on better climate footing. Obama wants to institute a carbon cap-and-trade system, such as the one in practice by the European Union since 2005. This regulatory scheme sets a countrywide statutory limit, or “cap,” on greenhouse gas (GHG) emissions. Companies then buy credits from the government that represent their portion of total emissions toward the cap. These credits are then sold amongst companies – the “trade” – creating a GHG credit marketplace. This system allows businesses who lower their emissions to profit from selling their credits to companies that need to up their allotted emissions – or face stiff financial penalties – thereby encouraging emissions-lowering practices.

WASHINGTON, D.C. (March 10, 2009)—If you're 17 and visiting our nation's capital, it's probably enough that your hotel room at the Saint Regis, steps from the White House, has a television in the bathroom.

But if that weren't enough, you're here as one of the 40 whiz kids selected as finalists in the storied Intel Science Talent Search. You've got a shot at $100,000.

But for some kids, that might not be enough. Better throw in a meeting with the president.

The 40 finalists—who have been strutting their scientific stuff for several days, as we've been on hand to live-Twitter and to profile a few projects, everything from Splenda in drinking water to whether parents should discuss their drinking with their kids to cellulosic ethanol—had a hastily scheduled trip to the White House yesterday. That included a chance to meet President Obama.

WASHINGTON, D.C. (March 10, 2009)—Stem cells have long been touted as potential cures or treatments for a variety of ailments from paralysis to Parkinson's disease. After all, these cells (found in bone marrow, for instance, and also in human embryos, making their use a subject of much controversy) can potentially turn into a wide variety of cells with specific functions. Or, they can throw off proteins—such as growth factors—that help other cells grow. Stem cells injected into a paralyzed patient’s spine, for instance, might help regenerate nerve tissue.

But while the flexibility of these cells is the key to their usefulness, they might not be quite as flexible as we once thought, says Julia Dory Ransohoff, 17, one of 40 finalists in the Intel Science Talent Search here in Washington this week for the competition’s final rounds. (We've been on hand to live-Twitter and to profile a few projects, everything from Splenda in drinking water to whether parents should discuss their drinking with their kids to cellulosic ethanol.)

The generation-long debate surrounding the dumping of the nation’s radioactive nuclear waste under Nevada’s Yucca Mountain may finally be drawing to a close. As ScientificAmerican.com reported yesterday, the plan to turn the mountain – some 100 miles (160 kilometers) from Las Vegas – into a nuclear repository appears to be dead in the water: President Obama’s proposed 2010 budget removes major funding needed to complete the project – and it faces opposition from powerful Senate Majority Leader Harry Reid, a Nevada Democrat, who doesn't want the country's spent nuclear fuel dumped in his state.