The California Global Warming Solutions Act of 2006 mandated statewide reductions in greenhouse gas emissions to 1990 levels by 2020. To reach this goal, the California Cap-and-Trade system was established under which companies are given annual allowances for greenhouse gas emissions and if they exceed those allowances, they may purchase carbon offsets or pay a fine. Carbon offsets are avoided emissions or sequestered greenhouse gases that are sold by the ton.
Researchers have been taking advantage of this system to finance projects that not only reduce greenhouse gas emissions, but also serve other important functions including protecting freshwater resources in California.
Perhaps the best example of this is in the Sacramento-San Joaquin River Delta, a region that provides drinking water to 22 million Californians.
Restored wetlands in the Sacramento-San Joaquin River Delta are natural carbon capturing systems. In flooded wetlands, carbon is locked into the soil, preserved in a low oxygen environment and allowed to accumulate over time.
Prior to 1850, vast wetlands occupied the Sacramento-San Joaquin River Delta, accumulating up to 50 feet of peat soil over the course of 7000 years. Around 1850, farmers drained the wetlands and started growing crops. However, continued farming of peat soil has slowly released carbon to the atmosphere sinking the islands in the Delta further and further below sea level.
Today all of the islands in the Delta are 10-25 feet below sea level and maintained by an extensive network of levees. These levee systems are under intense strain due to continued farming, rising sea levels and the threat of massive earthquakes.
When asked about the potential failure of levees in the Delta, senior hydrologist Steve Deverel with over 20 years of experience working the Sacramento-San Joaquin River Delta said, “There is skepticism about the ability of the improved levees to withstand a major seismic event.”
But here is where the risk lies: if the levees were to fail, saltwater contamination would be almost instantaneous, with dire consequences for millions of Californians. Many counties in California, such as Contra Costa, Alameda and Santa Clara counties, rely heavily on Sacramento-San Joaquin River Delta water for municipal use, meaning that saltwater contamination could lead to millions of people without water to drink.
By restoring wetlands in the Delta, this process is reversed. Soils are re-built resulting in less strain on the levees, making the wetlands a natural buffer against saltwater intrusion and sea level rise. They also provide critical habitat for migrating birds in the Pacific Flyway.
Unfortunately, building wetlands is not cheap. And without their crops, landowners in the Delta will need an alternative to replace the lost income. To help replace the farmers’ lost income, a team of experts, including myself, was recently assembled to write a methodology for Delta wetland restoration that will be submitted to the California Air Resources Board for approval in California’s Cap-and-Trade system.
The methodology outlines the steps that need to be taken to build a wetland and monitor the amount of greenhouse gas that it captures every year. Currently the methodology is being vetted in the global voluntary carbon market under the stewardship of the American Carbon Registry, the organization in charge of all carbon offset projects in California’s Cap and Trade System.
In addition to carbon offset methodology development, the California Air Resources Board is using funds acquired through the Cap-and-Trade system to invest in wetland restoration in the Delta. Recently, a 10 million dollar grant was awarded to a large wetland restoration project in the Delta, backed by a diverse team of collaborators including myself and other scientists at UC Berkeley, the California Department of Water Resources, and Hydrofocus, a hydrological consulting firm.
By stalling Senate Bill 32, the future of greenhouse gas capturing projects is uncertain. As unsustainable land use in the Delta threatens one of the largest freshwater resources in California, we greatly need legislation that will allow financing for wetland restoration in the Delta. The well being of millions of Californians reliant on Sacramento-San Joaquin River Delta water hang in the balance.
 Drexler J, De Fontaine C, Deverel S (2009) The legacy of wetland drainage on the remaining peat in the Sacramento — San Joaquin Delta, California, USA. Wetlands, 29, 372-386.
 Ingebritsen S, Ikehara M, Galloway D, Jones D (2000) Delta subsidence in California: the sinking heart of the state. Geological Survey (US).