Tower to gauge climate success

Scientists charged with determining if progress is being made under California's new anti-global warming law on Monday unveiled one way they will gather crucial independent information.

Government and university scientists will rely on sensors along a 2,000-foot television tower rising from the tomato fields near Walnut Grove.

The recently placed sensors will analyze the amount of carbon dioxide, methane and other greenhouse gases in the air. The data will help determine whether the state – or the Sacramento Valley at least – is reducing emissions fast enough. The new landmark state law requires that greenhouse gas emissions be reduced by 25 percent over the next dozen years.

"Climate change is becoming a mainstream issue, and California is taking a leading role," said Marc Fischer, a scientist with the Lawrence Berkeley National Laboratory who helped conceive of the pilot program. "And without an objective measure, it will be difficult to tell if our goals are being met."

This state pumps about 550 million tons of greenhouse gases into the atmosphere every year, according to the California Air Resources Board. That's more than any other state and about one-eighth of the country's total.

Passed last year, AB 32 calls for reducing those emissions 25 percent by 2020 and an additional 80 percent by 2050.

But the law isn't clear about how those goals will be met.

Regulators will likely rely on gasoline sales records, factory emissions reports and other sources to determine whether factories, farms and power plants are doing their part.

Verifying that information is another matter.

That's where towers like the one in the tomato field can help – at least according to this group of scientists, which is backed by the National Oceanic and Atmospheric Administration.

Arlyn Andrews, a NOAA scientist on the project, said the research is unique because the scientists aren't studying global atmospheric patterns.

Instead, they are trying to analyze the air composition of a particular region. The agency has also installed monitors on the Sutro Tower in San Francisco, as well as in Wisconsin, Maine, Texas, Colorado and Iowa.

Gauging a region's emissions is a tough task, especially since pollutants can travel vast distances. For instance, UC Davis researchers recently detected pollution from China at research stations at Lake Tahoe.

Andrews said researchers would examine weather patterns to determine whether the pollution detected at the Walnut Grove tower is occurring locally or blowing in from elsewhere.

"We're not looking for exhaust from a single factory or parking lot," Andrews said. "But by getting up on these very tall towers, we can get a representative picture of the Sacramento Valley."

Across the globe, scientists, policymakers and companies are grappling with the enormous challenges presented by the prospect of global warming.

Scientists say the rise in global temperatures has multiple causes, but is driven chiefly by society's increasing emissions of greenhouse gases, particularly carbon dioxide from the burning of fossil fuels.

Future temperature increases – and their consequences – can be softened by reducing emissions of greenhouse gases, scientists believe.

The issue gained even more prominence last week when former Vice President Al Gore and the United Nations Intergovernmental Panel on Climate Change were awarded the Nobel Peace Prize for helping sound the alarm.

Another challenge for California regulators will be determining whether the greenhouse gases are coming from human activity or nature.

Andrews said researchers would rely on "tracer" indicators to make that call.

For instance, auto exhaust releases various chemical compounds in addition to carbon dioxide. So if the sensors detect large amounts of those compounds, Andrews said, scientists can more safely assume the carbon dioxide is coming from cars and trucks.

In its more traditional role, the Walnut Grove tower broadcasts the signal of Channel 31. The monitors were installed last month at 100, 300 and 1,600 feet. They will make continuous observations of the region's air. Once a day, researchers will capture an air sample in a flask. Those flasks will then be sent to a NOAA lab in Boulder, Co., for more thorough analysis using a computer program called CarbonTracker.

About the writer:

• The Bee's Todd Milbourn can be reached at (916) 321-1063 or tmilbourn@sacbee.com.