Thursday, Sept. 18, 2008 | Nothing in San Diego County contributes more carbon dioxide to global warming than the cars and trucks people love. Passenger vehicles account for almost half of the carbon dioxide San Diegans create. Their driving habits emit carbon dioxide at a rate nearly 50 percent higher than the rest of the state.
If San Diego addresses the challenges posed by the globe’s warming climate, change will come in the transportation sector, the largest local source of carbon, according to an inventory of San Diego County’s carbon-dioxide emissions compiled by the Energy Policy Initiatives Center at the University of San Diego Law School.
The report offers the first up-close glimpse of the contribution that San Diegans’ energy consumption has on a global problem. It makes clear just how small a role San Diego’s carbon plays in contributing to the nation’s emissions. The United States in 2006 produced nearly 6 billion tons of carbon dioxide, according to the Energy Department. The same year, San Diego produced 34 million tons — about one half of one percent of the country’s total.
Cars aren’t just responsible. Flights out of Lindbergh Field created 5 percent of the region’s carbon dioxide. Electricity generation produced a quarter; burning natural gas in home heating and stoves produced 9 percent. While per-capita emissions have been steady since 1990, the population has grown and driven emissions up. (San Diegans on average emit half the carbon dioxide that their counterparts do across the nation, the researchers found.)
Local climate and energy experts said the inventory’s established baselines for emissions will be vital for measuring progress as California launches carbon-reduction efforts called for by Assembly Bill 32, the landmark state legislation that mandates a return to 1990 atmospheric carbon-dioxide levels by 2020. They also said understanding San Diego’s contribution drives home the scope of the climate problem facing mankind — not just San Diegans.
“It’s critical because the science tells us that to reduce the risk of damaging climate change, you have to make a large reduction percentage-wise in emissions — we’re talking about 50 or 60 or 80 percent by mid-century,” said Richard Somerville, a theoretical meteorologist at Scripps Institution of Oceanography. “It’s a very large number. You can’t do it by token acts or symbolic acts. You have to wean the world away from fossil fuels or you have to find a way to capture or sequester the carbon from the atmosphere.”
To understand how much carbon dioxide cars contribute, consider this: An average car driving 15,000 miles a year releases five tons. (The pollution is measured in pounds or tons because the particles have weight.)
Inventories are not new. San Diego, Chula Vista and the state of California have all inventoried their emissions. But the researchers’ county-wide accounting offers a strategic roadmap, quantifying the carbon-reducing impacts of a host of existing and proposed state and federal initiatives.
“All too often there are no metrics for us to gauge success,” said Irene Stillings, executive director of the San Diego-based California Center for Sustainable Energy. “What [the report] has done for the community is give us those metrics. The knowledge is invaluable to the community, so we know where to put our efforts.”
Want to know how much carbon will be saved locally if San Diego Gas & Electric meets state-mandated goals for obtaining 20 percent of its electricity from renewable sources? (Two million tons a year.) Or if that goal is raised to 33 percent? (Another million tons.) Or how the state’s $1 billion solar-panel subsidy will cut carbon dioxide emissions here? (Two hundred thousand tons.) The report gives regulators, bureaucrats and politicians an idea of where the most effective reductions can be made.
The biggest gain (2.3 million tons) will come from the federal government’s decision to increase car fuel-efficiency. In fact, nearly half of the reductions needed to return to 1990 levels will come from cars.
“We’re addicted to our cars,” said Andrea Cook, climate change program manager at the San Diego-based California Center for Sustainable Energy. “Very few of us live in communities we walk and shop and stay in. We don’t necessarily work where we live or shop where we live. We’ve got a culture that’s dominated by getting there in the car.”
The report does not estimate how much it will cost to effect those changes. “It’s clearly an important question,” said Scott Anders, director of the Energy Policy Initiatives Center and an author of the report. “You can’t just say we need to get to X at whatever cost.”
A majority of the strategies identified to reduce carbon dioxide come from state and federal regulatory initiatives. That stokes a debate in San Diego, where Mayor Jerry Sanders has questioned the city’s role in fighting climate change, pointing instead to the state and federal government as being best-equipped to combat carbon dioxide.
The researchers acknowledge the significant role of state and federal agencies. But they also point to a significant role for local governments. “They can play a more direct role in locally and regionally based strategies,” the report says, from reducing how much residents drive to promoting solar-power programs to capturing potent methane gas from decomposing waste at landfills.
Kassie Siegel, climate program director for the Center for Biological Diversity, an environmental group, said inventories should serve as helpful planning tools for local governments.
“You can’t rely on voluntary action to solve the problem, because the scale is so great,” Siegel said. “We can’t do it without government planning: federal, state and local.”
Nearly all of San Diego’s emissions have a connection to energy use, the researchers found. Some do not. The report estimates that the 2003 wildfires increased emissions that year by 20 percent (nearly 8 million tons of carbon dioxide were released when shrubs and trees burned).
Cook said that surprising finding is reason to protect habitat across the county from fire. Carbon isn’t just sequestered and reduced by the far-off Brazilian rainforest — the region’s sage-smelling hills do it, too. “It’s just another source that needs to be managed,” she said, “like smart growth or transportation or renewables or water. The ecosystems are another significant source or sink, a carbon reduction or a big emitter.”