A draft of the Senate's version of a climate bill has been released. The official version is scheduled to be unveiled officially today in the Senate.

The move comes on the heels of President Obama's speech to the United Nations in which he called for action on climate change. A House climate bill passed back in May, but since then climate change has taken a back seat to health care reform. There's been some concern that no climate change legislation will be passed before a meeting in Copenhagen this December where world leaders are supposed to work out a new climate change treaty. With no law in hand, U.S. negotiators may find it hard to sell other countries on strict emissions reductions.

The draft bill tightens emissions caps somewhat compared to the House bill, calling for a 20 percent reduction in emissions by 2020 compared to 2005 levels, rather than a 17 percent reduction. It also contains sections devoted to reducing emissions specifically from transportation sources, as well as incentives for emissions reducing technology such as carbon capture and sequestration, nuclear power plants, and renewable energy.

But much work remains before the bill can become law. For example, some parts of the bill have only placeholder language, awaiting action from committees. Nevertheless, Senate Majority Leader Harry Reid (D-NV) has reportedly said that the bill is on track to be passed by the Senate before the Copenhagen meeting. That's not to say it will become law by then, of course, as it will still have to be reconciled with the House Bill.

The massive energy bill that would set a cap on carbon dioxide emissions and provide other incentives and requirements for clean energy has passed the U.S. House of Representatives by a slim margin.

It's far from becoming law, though. Passing the bill in the Senate will be more difficult: many Democrats voted against the bill in the House, something that can't happen in the Senate if it is to pass. What's more, President Obama isn't entirely happy with the bill and will be pushing to get some changes made, including removing a provision designed to encourage other countries to set up emissions goals of their own, according to the Washington Post.

Some experts hope that the bill's passage in the House will prove a strong bargaining chip later this year when world leaders meet to discuss international caps on emissions.

The good news is that the United States has plenty of natural gas, according to a new report described in the New York Times. The bad news is that the carbon-emissions targets in the energy bill working its way through the United States House of Representatives didn't take this into account.

According to the report, there's 35 percent more accessible natural gas in the ground than previously thought, in large part because new technologies have made it possible to get at more of the gas. This tech has led to a boom in natural-gas supplies, and that seems to be why oil and gas tycoon T. Boone Pickens has been talking up using natural gas for powering vehicles: he could be looking for a new market for all of this gas to keep prices from plummeting in the future.

The fact that there's a lot of natural gas is good for reducing carbon dioxide emissions. Natural gas produces about half of the carbon emissions of coal when used to make electricity. Switching to natural gas could provide a relatively cheap way to meet emissions targets, especially in the near term. And that's a great thing. Except for this: natural gas can't take us all the way to an 80 percent emissions-reduction target, which is where scientists say we should be by 2050, if not sooner. Some experts are concerned that natural gas will allow utilities and others to put off investments in research and development needed to meet the stricter emissions goals.

There are a couple of potential solutions. One is to mandate more use of renewable energy, but economists argue that such mandates are expensive: it's better to let a market sort out which technologies to use. Another potential solution is to make the early-emissions targets in the bill more challenging, pushing investment, but this could be politically tricky. There are a lot of uncertainties about this natural gas; some experts warn that we shouldn't count on it. The best solution is probably increased federal funding for research, especially basic research into things like the physics of excitons in solar-cell materials. Then even if companies fail to plan ahead, the breakthroughs that they need to meet later targets could be ready for them.