California's attorney general sued Southern California Gas Co on Tuesday over a huge methane leak near Los Angeles, escalating legal action sparked by an underground pipeline rupture that has forced thousands of residents from their homes since October.

The latest civil complaint accuses the utility, a division of San Diego-based Sempra Energy of violating state health and safety laws by failing to promptly control the escaping gas and report the leak to authorities.

The lawsuit also cites environmental damage caused by the uncontrolled release of 80,000 metric tons of methane, the prime component of natural gas and a far more potent greenhouse gas than carbon dioxide.

The leak stems from an underground pipeline rupture at the company's 3,600-acre (1,457-hectare) Aliso Canyon natural gas storage field. The largest such leak ever in California, at its height it accounted for a fourth of all methane emissions statewide.

"The impact of this unprecedented gas leak is devastating to families in our state, our environment and our efforts to combat global warming," Attorney General Kamala Harris said.

The lawsuit in Los Angeles County Superior Court amends a civil complaint brought in December by the Los Angeles city attorney and later joined by Los Angeles County. It seeks unspecified civil penalties and court orders requiring the utility to immediately take all steps necessary to mitigate the leak, repair the damage and prevent future discharges.

Several attempts to halt the methane release have failed, but the company said it hopes to finally plug the leak by the end of the month through a relief well now being drilled.

The company said in a statement it would "respond to the lawsuit through the judicial process."

Last week, the South Coast Air Quality Management District filed a separate lawsuit against SoCal Gas seeking civil penalties of up to $250,000 a day for each of six pollution-related health and safety code violations.

The stench of methane fumes has sickened scores of people and was prompting the relocation of more than 6,600 households from the Porter Ranch community at the edge of the crippled underground gas storage field.

More than 20 private lawsuits have been filed on behalf of some of those residents.

The company also had accelerated removal of surplus gas stored beneath the site to diminish underground pressure on the ruptured well, then halted those withdrawals to maintain a minimum reserve needed to keep reliable supplies for customers.

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MEANWHILE, Popular Resistance reports that a new high-level study concludes chronic methane leakage from natural gas producers could sorely undercut U.S. emission reduction targets and climate goals:

New analysis from PSE Healthy Energy and University of California at Berkeley finds that increased deployment of renewable energy is the best way to meet or even surpass Clean Power Plan targets, as recent scientific measurements of methane leaks from natural gas systems have found higher rates of leakage than those recorded in official inventories. States that plan to depend on switching their electricity generation from coal to natural gas under the Clean Power Plan risk failure to achieve meaningful greenhouse gas reductions.

As the Obama Administration develops new rules for methane, such as last week’s Bureau of Land Management regulations applied to the release of methane from new and existing oil and gas production sources on federally-managed lands, the study – using updated assumptions of methane leakage – underscores the need to further address methane leakage in order to meet climate targets.

The study, The Impact of Methane Leakage on Achieving Clean Power Plan Emission Goals, analyzes whether America will meet electric generation sector emissions reductions targets under the Clean Power Plan with different mixes of energy resources on the electric grid, while taking into account a range of upstream methane leakage rates similar to those found in recent studies.

The study shows that the U.S. is likely to miss emissions reductions targets if states rely on switching from coal to natural gas for electric generation as a primary means of emissions reductions in their implementation plans.However, it finds that by supporting the adoption of renewable energy and energy efficiency in state plans at rates already proven easy, practical and possible, the nation can not only meet its emissions reductions targets, but possibly even exceed those goals.

Dr. Elena Krieger, director of the Renewable Energy Program at PSE Healthy Energy and co-author of the report, said, “Our research shows that the nation can easily meet its carbon pollution reduction goals by deploying clean, renewable energy and energy efficiency projects across the country at rates that we are already seeing on the ground in many places. This is an easy way for states to ensure that America will truly achieve the emissions reductions that will help our country meet the climate targets agreed to in Paris last December, and decrease the risk that methane leakage will undermine emission reduction efforts in the power sector.”

The Clean Power Plan calls for 32% emissions reductions below 2005 levels by 2030. The plan allows each state to determine how best to reduce their power sector emissions in that timeframe, and suggests three pathways: switching electric generation from coal to natural gas, improving the efficiency of coal power plants, and replacing fossil fuels (coal and natural gas) with renewable energy sources like wind and solar generation.

U.S. EPA calculations state that nearly half of those reductions have already occurred due to historic coal-to-gas switching between 2005-2013. But recent science has found that this calculation does not reflect the full climate impact of methane leakage across the natural gas system, which erodes the climate benefits of switching to gas.This new study released today updates these historic emissions reductions to reflect lifecycle emissions of methane.

The study co-author, Zeke Hausfather of University of California, Berkeley, said “Methane is a very potent greenhouse gas, and a strong contributor to climate change. The most recent scientific studies show that methane leakage is variable, but can be quite high in some areas of natural gas production.Without taking into account the full lifecycle of natural gas, it is impossible to know the true climate impact of our energy decisions.”

Methane is a much more powerful greenhouse gas than CO2 (over 30 times more powerful over 100 years, and over 80 times more powerful over 20 years), and numerous recent scientific studies have found leakage rates to be much higher than the 1.5% leakage estimated by the EPA in its Greenhouse Gas Inventory. This study considers the impact of methane leakage rates on achieving the plan’s targets. In the Clean Power Plan, the 32% greenhouse gas emission reduction target is achieved by 2030 when calculated using the U.S. EPA’s low leakage rate of 1.5%.

However, the study shows that if states adopt the likely energy mix projected by EPA, which relies heavily on natural gas, emissions are reduced overall nationwide by only 28-29% on a 100-year timeframe, and 22-23% on a 20-year timeframe at a methane leakage rate of 4%. At a 6% methane leakage rate, the upper limit of the methane leakage range in the study, greenhouse gas emissions reductions are only 25-26% on a 100-year timeframe and well below 20% on a 20-year timeframe.

However, the study also analyzed two energy mixes that include future growth in the deployment of renewable energy and efficiency at levels on par with current and historic annual renewable energy growth in the US. The study finds that even if methane leakage rates are at the higher end of the analyzed range, the Clean Power Plan targets can not only be achieved but even surpassed by adopting such high-renewables energy mixes.

This finding suggests that to reduce the climate impact of electricity generation in the U.S., there must be a greater focus on curbing upstream methane leakage rates from across the entire natural gas production, transmission and distribution chain, and, even more reliably, states should develop Clean Power Plan implementation plans that continue to support the rapid growth of renewable energy and energy efficiency rather than promoting the increased use of natural gas.

Originally published by Reuters