If you’re tired of feeling guilty about driving a gas-guzzling car or cranking up your air conditioning, you could just try hanging your head in shame about that bottle of spring water you are sipping instead.

Yes, the foes of bottled water are at it again, this time in the form of an advertising campaign that aims to promote tap water and underscore the environmental costs of producing and disposing of plastic water bottles.

Tappening, a group that opposes bottled water, is spending $250,000 on a media campaign to promote its cause. Tappening is a joint venture of ad agency DiMassimo Goldstein and public relations firm Ericho Communications. It most recently launched a campaign called “Message in a Bottle” that aims to deliver one million empty water bottles to incoming Coca-Cola CEO Muhter Kent.

The campaign is the latest of many recent attacks on bottled water, including the urging of boycotts by the mayors of cities including London, San Francisco and Seattle.

“We can use our advertising and public relations abilities to un-sell bottled water hype,” said Tappening’s Mark DiMassimo.

The ads will appear as “wild postings” on construction sites in ten U.S. cities as well as in magazines and community newspapers, the group said. The ads claim that last year, plastic bottles generated more than 2.5 million tons of carbon dioxide and that every year, 38 million bottles end up buried in the ground.

Can the running shoes we buy really help protect the environment?

According to a new list by nonprofit group Climate Counts, Nike ranked first among the world’s most climate-friendly companies.

In its second annual report, Climate Counts ranked companies based on efforts to reduce greenhouse gas emissions, support of global warming legislation, public disclosure of their efforts to address climate change, and whether they measure their impacts on the environment.

Nike ranked well in all those areas, garnering a score of 82 out of a possible 100 points. Stonyfield Farm, IBM, Unilever, Canon, General Electric, Toshiba, Procter & Gamble, Hewlett-Packard and Sony rounded out the list’s top 10.

Google, Anheuser-Busch and Levi Strauss logged the largest score improvements, each jumping over 20 points since last year. The average company score improved 22 percent over last year, when Canon was the top scorer.

Who were the losers? In a word, restaurants.

Olive Garden and Red Lobster owner Darden Restaurants, Wendy’s and Burger King each scored zero out of 100 points, while KFC and Taco Bell owner Yum Brands registered a single point for encouraging reduction of energy consumption.

Jones Apparel Group was the only other company to receive a score of zero.

For Climate Counts’ full list, click here.

Solar power companies have been working around the clock to drive down the price of clean electricity from the sun so it can one day be as cheap as the energy we get from dirtier sources, like coal plants.

Until we get there, however, some solar panel installers have come up with a solution that they say will give more people access to solar energy. How are they doing it? By allowing customers to lease, rather than buy, the photovoltaic solar panels for their roofs.

It’s the same idea, really, that has enabled some people to get behind the wheel of a luxury car they could otherwise not afford — low or no upfront costs followed by a monthly bill.

SolarCity, based in Foster City, California, is one company that recently started offering leases to its customers. Chief Executive Lyndon Rive told Reuters he wanted to do away with the hefty cost of buying solar panels — on average about $20,000.

“Even those who really want to make an environmental change can’t part with $20,000… the solution is just too costly for them.”

Under SolarCity’s lease program, customers with a small home could pay as little as $70 a month for a 2.4 kilowatt system, Rive added. The company is also allowing customers who sign up before July 31st to put no money down on their system. After that, upfront costs should be between about $1,000 and $3,000, Rive said.

“We can essentially make it so that everybody can now afford clean power,” Rive said.

The leased projects will be financed through Morgan Stanley, and SolarCity said it will serve as a one-stop shop for both installation and financing.

Right now the program is only available in California, but SolarCity is expanding to Oregon, Arizona and has plans to go to the East Coast.

Looking for clean air and lots of greenery? Los Angeles is probably not the first place that comes to mind.

Still, the city as famous for traffic and smog as it is for sunshine and celebrities is working hard to earn the mantle of the greenest big city in America.

In its latest move, the L.A. City Council this week passed a law that will require all new building projects bigger than 50 units or 50,000 square feet to comply with the Leadership in Energy and Environmental Design (LEED) building standards. The city claims the move will cut its carbon dioxide emissions by 80,000 tons by 2012 — the equivalent of taking 15,000 cars off the road.

Mayor Antonio Villairagosa says the goal is the most aggressive of any big U.S. city. It is part of a broader plan the mayor laid out last year to reduce L.A.’s carbon footprint by 35 percent below 1990 levels by 2030.0

Still, critics point out that L.A.’s plan is not as aggressive as the one being pursued up North, in San Francisco — a debate the “Los Angeles Times” chronicled on Tuesday. In the story, advocates said L.A.’s move will have more of an impact on the environment because it covers so much more ground than San Francisco.

In the meantime, L.A. might have to take on an even bigger challenge — convincing the public that it can really go green.

As one LAT reader commented: “Los Angeles green? Only with paint.”

Solar power company First Solar may be worth $19.6 billion, but its CEO is still tickled by the latest “green” consumer products.

Take solar backpacks, for instance. The trendy totes boast photovoltaic solar panels that generate power for consumers to recharge their iPods, digital cameras or other electronic devices.

“Things like the solar backpack, things that are off-grid… that can be intermittent or even charging a small battery, that stuff’s kind of cool. And there’s a real functional use to that,” Ahearn said in an interview with Reuters.

Some things, however, even solar executives are skeptical of, such as cars with solar roof panels that can recharge their batteries.

“I’ve seen cars in Germany with solar roofs on them. We haven’t looked at them as a product. Off the cuff, it seems more gimmicky to me than real,” Ahearn said.

Turns out Arnold Schwarzenegger’s bodybuilding past may be helping California fight global warming.

The state’s governor, and former Mr. Universe, on Friday likened the push to reduce greenhouse gas emissions to the fight to lose weight, saying people — and countries — will only achieve their goals if they are forced to.

“There are some states and there are some countries that shoot for certain goals in reducing greenhouse gas emissions, but they will never get there, I think. Unless you put a serious cap on it you won’t get there,” Schwarzenegger said at a Wall Street Journal conference near Santa Barbara, adding that most people who want to lose 20 lbs. to look good on the beach “will not get there.”

“But if a fighter has to meet a certain weight category,” he will, Schwarzenegger said, “because that’s the rule… you cannot fight if you are not that particular body weight.”

Last year, California joined a coalition of European countries, U.S. states, and others by signing a partnership to slow global warming through an international carbon trading market.

Schwarzenegger said he preferred a market-based cap-and-trade system to a carbon tax, saying “the people of California have sent me to Sacramento to be the tax Terminator.”

When Wal-Mart decided it needed an environmental strategy, it asked for help from some of its biggest critics.

The only thing is, the non-governmental organizations it looked to for advice on building a sustainable business didn’t want to ruin their green cred — or jeopardize their relationships with their donors — by admitting that they were working with Wal-Mart.

“We had to guarantee them that we would not ever tell anybody that they were there,” Wal-Mart Chief Executive Lee Scott said during an appearance at the Wall Street Journal ECO:nomics conference in Goleta, California.

Since then, Scott said NGOs have been critical to helping the company understand issues such as sustainable fisheries and carbon dioxide emissions as well as pushing it to go farther in thinking green.

“They are more aggressive than we are, and they push us to go further, but they also have not been as judgmental about our failures as I was afraid they would be,” Scott said.

Next, Scott said Wal-Mart will call on NGOs to help its Chinese suppliers clean up their act.

General Electric’s chief executive may be reconsidering his political loyalties.

At the Wall Street Journal’s ECO:nomics conference on business and the environment on Wednesday, Jeffrey Immelt fielded some sharp questions about GE’s bullish green strategy and support for government tax credits for sources of renewable energy. Finally, he shot back.

“I came here tonight because I was invited, but really I don’t need to be lectured by anyone in this room on how to compete,” Immelt said.

He added: “I always thought I was a Republican until tonight.”

Regardless of his party affiliation, Immelt derided the presidential candidates for suggesting that the United States should work toward “energy independence” — a concept he said was “naive.”

“People shouldn’t even be able to say those words because we are so far away from that.”

“Where’s the beef behind this decision?” U.S. Senator Barbara Boxer asked, waving an empty white box labelled “EPA Documents” in front of California state officials and reporters at Los Angeles City Hall on Thursday.

The California Democrat, who chairs the Senate’s environment and public works committee, lashed out at Environmental Protection Agency (EPA) Administrator Stephen Johnson during a field briefing for his decision last month to deny California’s attempt to set tough new standards for auto emissions.

“I know this is a little bit showbusiness, but I don’t know how else to make my point,” Boxer said as she turned the box upside down.

The showbusiness was lost on Johnson, since he declined to come to California to answer questions from the Senator and hear testimony from her allies. Boxer nevertheless insisted that an empty seat be left in the middle of the room to symbolize the absence of any EPA representative.

“The bottom line is the chair is empty, there is no excuse for this decision,” said Boxer.

Johnson has agreed to testify before the Senate Environment and Public Works Committee in Washington on Jan. 24, Boxer said.

During the briefing, Boxer heard testimony from California Attorney General Jerry Brown, California Air Resources Board Chairman Mary Nichols, Natural Resources Defense Council Senior Climate Advisor Fran Pavley, and Sierra Club Executive Director Carl Pope, all of whom side with Boxer on the issue.

Brown, who along with 15 other state attorneys general is suing EPA over its decision, said he couldn’t be sure whether the courts would act swiftly to decide the case.

“It wouldn’t surprise me if the case is till pending as Bush leaves town,” Brown said.