New York Times – In his final term as California’s governor, Jerry Brown has made the battle against climate change a signature issue: He is fighting to vastly reduce the state’s emissions of greenhouse gases, to accelerate the move to electric cars and to rewire the state’s electrical grid. In December, he had a star turn with world leaders at the United Nations climate change conference in Paris.

But despite all his efforts, California’s emissions rose modestly over the first three years after he took office in 2011, the last years for which data is available. The latest blow came from Porter Ranch, a Los Angeles suburb where a breach at an underground natural-gas storage site in October released 107,000 tons of climate-changing methane and ethane — the largest such leak in terms of climate impact in American history — before it was capped late last month.

California Gas Leak Threatens Jerry Brown’s Image as a Climate Change Hero - 04 MarchA report in the journal Science last week concluded that the Porter Ranch breach, at its peak, effectively doubled the amount of methane emitted daily in the Los Angeles Basin, highlighting how such accidents can set back even the best-intentioned climate policies.

Speaking on behalf of the Brown administration, Mary D. Nichols, the chairwoman of the California Air Resources Board, said her agency had been working on regulations for methane as a short-lived climate pollutant when the leak occurred.

She said that the environmental policy makers – not just the Brown administration – had only not too long ago began to concentrate on the effects of pollutants like methane, and that the Porter Ranch leak had added a sense of urgency to address that.

“It’s been a jolt for everybody, realizing what potential for really major harm can come from this sector, which we have tended to take pretty much for granted,” Ms. Nichols said. New studies have shown that, even aside from the leak, “there’s more methane escaping into the atmosphere than we previously thought,” she added.

The leak not only snarled the state’s climate-change efforts but also prompted complaints that the governor was slow to address the problem and that his regulators had failed to prevent it.

Food & Water Watch, a group that works to ban hydraulic fracturing and protect the water supply, sometimes brings a papier-mâché likeness of Mr. Brown to its rallies to decry what it sees as his support for the oil and gas industry. The governor has shunned calls to move toward reducing the state’s oil production, and while he has supported strict regulation of hydraulic fracturing, commonly called fracking, he has opposed a ban on the technique.

“Just believing climate change is real doesn’t mean he’s doing anything about it,” said Adam Scow, California director at Food & Water Watch. “He hasn’t done anything that constitutes real leadership.”

Referring to some of Mr. Brown’s climate goals, like reducing greenhouse gas emissions in California to 80 percent below 1990 levels by the year 2050, Mr. Scow said: “That’s a politically convenient approach. We need to be planning for a 100 percent renewable future in California, and we’re not doing it.”

Ms. Nichols of the California Air Resources Board defended the governor, saying he had made addressing climate change a priority across state government. “He is not going to get a perfect score from environmentalists,” she said. “Environmental advocates are always looking to push for more.”

In the final year, Mr. Brown has pushed by way of legislation accelerating a shift to renewable power, and struck clean-energy agreements with a host of states and cities. California now gets 26 percent of its power from renewable sources, compared with an typical of ten percent in other states.

Ms. Nichols said that the governor “has a broad view of what the state needs to be doing on these issues, and it’s now been incorporated into the work of every relevant agency.” For example, the Department of General Services now considers the environment when buying fleets, she said, and the Department of Transportation includes greenhouse gas emissions in its plans.