Craig Miller

Reducing tillage is one technique farmers are trying out to cut carbon emissions.

Supporters of sustainable agriculture are looking forward to some “sustenance” of their own, after an eleventh-hour win in Sacramento. Just as the state’s last legislative session was drawing to a close, Assembly Bill 1532 passed by a vote of 51-28, sending to the governor’s desk a system for allocating cap-and-trade auction revenues, which are expected to reach into the billions of dollars by the end of next year.

AB 1532, authored by Assembly Speaker John Pérez, lays out an approach for ensuring that all proceeds from the sale of permits be used to further reduce greenhouse gas emissions. Among the eligible activities identified in the bill are farming and ranching practices that reduce greenhouse gas emissions and sequester carbon, such as reducing soil tillage, improving energy and water efficiency, and reducing synthetic fertilizer use through compost, cover crops, and crop rotation.

“A lot of these practices also have a number of co-benefits such as reducing air and water quality, reducing erosion, and improving soil quality,” said Renata Brillinger, executive director of the California Climate & Agriculture Network (CalCAN), which lobbied to have sustainable agriculture included in the bill.

In addition to promoting specific farm practices, AB 32 auction revenues could also go toward researching and developing new approaches, providing technical assistance to farmers, offering financial incentives to help them transition to climate-friendly methods, and helping to shield California’s farmland from urban development. A study released in July by the California Energy Commission and the California Natural Resources Agency and performed by researchers at UC Davis found that urban land accounts for 70 times more greenhouse gas emissions per square acre than cropland.

CalCAN has been angling to secure sustainable farming’s piece of the AB 32 pie since 2010, when Senator Lois Wolk (D-Davis) introduced a bill that offered guidelines for spending cap-and-trade revenues on agriculture. The bill got held over in committee, and CalCAN and Wolk tried again in 2011 — with the same result.

The legislature preferred to take a more comprehensive approach toward appropriating cap-and-trade revenues, said Brillinger, and that’s just what happened with AB 1532. Now Brillinger and her colleagues — along with their partners at Community Alliance with Family Farmers, Ecological Farming Association, and California Certified Organic Farmers — hope that Governor Jerry Brown will take the next step and sign it into law.

If he does, the law will go back to the legislature next year for further tinkering, then be passed along to the state Air Resources Board for implementation. Only then will we get any sense of just how much money could go to sustainable agriculture, or even begin to calculate the sort of greenhouse gas emissions that could be achieved statewide. “Everyone wants to have those hard numbers, but it’s proving elusive,” Brillinger said.” For now, the basics will have to do.

“It’s a sector that is very susceptible to climate change impacts, and has some potential that some of the other sectors don’t. It’s one of the only sectors, forestry being the other, where there’s some carbon sequestration possible. We’ll continue to plug away at that message.”

Look for in-depth reporting on how climate change is affecting California’s farm economy in the upcoming multimedia series, Heat and Harvest, a joint project of KQED and the Center for Investigative Reporting.

Molly Samuel

Trees, grasses and freshwater aquatic systems all play a part in the carbon cycle.

The U.S. Geological Survey is developing a series of reports on how much carbon and other greenhouse gases the nation’s ecosystems hold. Trees and plants, soils and rivers, farms and wetlands all sequester carbon to greater or lesser extents. But how much? And how might that number change in the future? That’s the crux of the USGS study, which was initiated by the Energy Independence and Security Act of 2007 [page 223 of the PDF]. (There’s a simultaneous study, also by the USGS, to assess geologic carbon sequestration).

The national assessment will include details on greenhouse gas sequestration nationwide: how much carbon is stored now, how that carbon sink might be altered by different land use scenarios in the future (for example, increased or decreased logging, urbanization, wetland restoration efforts or agriculture), plus impacts from other sources, such as wildfire and climate change.

To tackle this immense project, the agency divided the country into regions. The assessment on the Great Plains came out late last year. Next up is the West, including California, due out this summer.

“The diversity of California is a story in and of itself,” Ben Sleeter, a USGS research geographer who’s working on the assessment told me. The Coast Range, the Klamath Mountains, the Sierra Nevada, the Central Valley and California’s deserts all store different amounts of carbon. There are diverse land management approaches in each area. And future land use options are varied, too. “It’s enormously complex,” he said.

The USGS study won’t gloss over the details. I asked Sleeter if I’d be able to learn the amount of carbon sequestered in the Sierra Nevada, and he said I could get much more specific than that. “If you were curious about an area near (Calaveras) Big Tree State Park, we will be able to summarize the land use changes and carbon sequestration changes for that area.”

To help present the data, the USGS is collaborating with UC Berkeley’s Geospatial Innovation Facility, the group that developed Cal-Adapt, to create a similar tool, which will make the information in the assessment more accessible.

Lisa Collins, a lecturer at the USC Dornsife College, spent four years studying samples from floating sediment traps in the San Pedro Basin as a way to determine what’s falling through the water column and how deep it’s getting.

“We have a pretty good idea of how much biomass is produced in the ocean, but we don’t have a great idea of how much of that biomass actually gets down through the water column and ultimately to the sediment,” said Collins.

One reason that matters, she says, is that phytoplankton, which make up much of the biomass, live and grow by taking up sunlight and carbon dioxide, just like plants on land do. When the phytoplankton die, they sink, taking that stored carbon down the water column with them. If they make it all the way to the mud at the bottom of the ocean, Collins says, that carbon will be sequestered there for hundreds or thousands of years or more.

“San Pedro Basin is a sink for carbon,” said Collins.

She said there’s more carbon getting sequestered there than in other areas of the world where similar studies have been conducted. The reason, she said, is the relatively cool water temperatures in the region.

“The microbes that are chewing up and eating up that carbon are utilizing that carbon as particles are sinking,” said Collins. “In the warmer waters, they can work faster, and so are able to eat up more of the carbon. So the net result is that less carbon makes it to the bottom.”

Once microbes eat the carbon, they then “breathe” it out said Collins, releasing it back in the water and the atmosphere.

Within the San Pedro Basin, Collins found differences in the amount of carbon making it to the sea floor depending on the season and the weather across the four years. She said she’s hoping this kind of detailed information can help climate modelers make more accurate predictions about how the ocean is going to respond to climate change.

“When we think generally about how the world is warming up and is predicted to continue warming, it’s something we should pay attention to,” said Collins, “because not only is it going to affect us on land, but if we’re talking about temperatures getting warmer in the ocean as well, what we’ll probably see is that the oceans won’t be taking up as much carbon.”

The study is published in the August issue of Deep-Sea Research I.

California's forests provide water, habitat for animals, lumber and tourism dollars, and they sequester carbon. (Photo: Molly Samuel)

For decades the federal government has touted the nearly 200 million acres of national forests and grasslands under its control as a “land of many uses.” But one “use” that’s seldom discussed is as a huge repository for carbon.

But clearly it’s on the minds of officials and scientists as the Forest Service seeks comments on its proposed new planning rule. National Forests and Grasslands are managed individually, but the planning rule guides how those management plans are developed. This new one is replacing a Planning Rule from 1982.

According to the Forest Service press release, some of the highlights in this new Planning Rule include

• Improved ability to respond to climate change and other stressors through provisions to restore and maintain healthy and resilient ecosystems
• Increased protections for water resources and watersheds
• More effective and proactive requirements to provide for diverse native plant and animal species

The Forest Service manages just under half of the forest land in California. Below is a handy map from their website (If you want to see all the federal land in California — not just National Forest — nationalatlas.gov offers this PDF map).

In celebration of the UN’s “International Year of Forests,” I recently went down the rabbit hole of trying to understand how much carbon California’s forests hold. Figuring that out is, according to Forest Service research forester Jeremy Fried, “An accounting problem. And like any accounting problem, you need to have accurate data.”

That’s been a challenge. Fried works on the Forest Inventory and Analysis Program (FIA), which is the Forest Service’s annual census of the nation’s trees. Unlike the census of the nation’s people, the goal isn’t to count every individual, but to count and measure plots of trees all over the country. But the sizes and locations of those plots have changed over the years, and that makes for unreliable data.

In fact, last year was the first time that Fried and other researchers were able to go back and re-measure the same plots. What he found was that on the 15 million acres of forested lands that the Forest Service manage in California, trees sequester somewhere on the order of 1.8 teragrams of carbon a year (almost two million metric tons).

Going forward, Fried says, as long as the funding holds up, the FIA will continue measuring the same plots, and not just in National Forests, but plots in all kinds of public and private forests.

One last note. Fried explained that carbon generally makes up half of the biomass of a tree. To calculate the biomass of a tree, researchers measure its width and height. But a tree isn’t a box, so you have to add in the branches, maybe you measure the stump separately, and what about the bark versus the stem? The list goes on. Just to give me a sense of how complicated this is, he gave me this number: 102,905. That’s how many ways there are of calculating the carbon content of a Douglas Fir. 102,905.