by Ann Thomas

MCL’s Water and Watersheds Committee hosted a talk at its November meeting on climate change science and efforts by water utilities to prepare their systems for an uncertain future with warmer temperatures, rising ocean waters and more variable precipitation.

David Behar (pictured), Climate Program Director for the San Francisco Public Utilities Commission and staff chair for the national Water Utility Climate Alliance (WUCA), spoke about the wide range of global climate forecasts and models that utilities use to try to predict changes that may take place. He cautioned that the models can only predict probability, not what will actually happen, and should be used “with a clear eye that they are problematic.”

WUCA comprises ten major water utility districts that deliver water to a combined 43 million customers. Members include the San Francisco PUC, Metropolitan Water District of Southern California and San Diego County Water Authority, among others. WUCA’s goal is to assemble information, analysis and forecasts sufficiently reliable to be the basis for capital investments needed to maintain systems and adapt to a changing climate.

Behar is also a member of the Marin Municipal Water District Board, but his discussion with the committee focused on broad climate issues.

Forecasting and models—uncertainties exist

Behar expressed concern that California’s official projection for sea level rise, “up to 55 inches by 2100”, doesn’t accurately portray the science behind the models. “Make no mistake,” he stressed, “there is no disagreement on whether or not the world is warming and ocean levels are rising.” However, he contends that it would be more accurate to say that sea level is estimated to rise from 21 to 55 inches by 2100, with wide variation in the projections of scientists wrestling with the issue.

The future, he added, can no longer be understood in the context of the past and there is incomplete understanding about how many factors affecting climate will evolve. The sensitivity of the climate to carbon dioxide, for example, is not well understood, and a National Academy of Sciences climate study does not include land ice modeling because it is so complicated.

He listed three main uncertainties in climate projections:

1. Emissions (how well will we get a handle on greenhouse gas emissions?)
2. Internal variables (natural changes)
3. Model uncertainty (the degree to which models can predict the future)

For the water utility industry, he said, this is a time for assessment and planning. In particular, districts need information downscaled from global models to a watershed level in order to plan changes in reservoir operation, transportation and distribution systems that will be needed to meet users’ needs. Downscaling from global climate models to a resolution that shows what is happening locally is needed because adaptation will take place on a regional level.

Rising waters and rising costs—where the rubber hits the road

“Money is where the rubber hits the road for the water utility community,” Behar said. Over the next 20 years, $335 billion will be needed to keep drinking water systems in good repair nationwide. Adapting systems to respond to climate change could potentially cost U.S. water utility ratepayers $1.7 to $2.2 trillion dollars between now and 2050.

His employer, the San Francisco PUC, will spend $40 to $60 million to boost its resiliency to backflow in anticipation of increased inundation from rising bay waters. Only six to ten inches are needed, he noted, to make the situation worse.

The Wild West of modeling—many initiatives, no coherence

Behar listed numerous initiatives providing data and models on changing climate. These include the following: U.S. Fish and Wildlife’s landscape conservation cooperatives, EPA’s Climate Ready Utilities, National Oceanic and Atmospheric Administration’s (NOAA) climate services, the U.S. Global Change Research Program (a 13-agency effort), and the White House Office of Science and Technology’s National Climate Assessment. He expressed some dismay about the lack of consistency among initiatives.

NOAA’s Regional Integrated Science and Assessments (RISA) he said is “a good program.” RISA supports research that addresses complex climate sensitive issues of concern to decision-makers and policy planners at regional levels.

“Ultimately,” he said, “adaptation starts with science, or else you have mal-adaptation…If we can invest now in data storage and computing power we should do so.”

MCL’s Water and Watersheds Committee currently meets on the fourth Thursday of the month at 4:30 PM in the MCL office. MCL members and guests are welcome.

The next committee meeting, on January 26, 2012, will feature an update by Jack Curley, the county’s project manager for Flood Control Zone 9, on the Ross Valley Flood Control and Watershed Program.

This long-term $129 million plan to help control flooding and improve watershed function in the Ross Valley is partially funded by a storm drainage fee on property within the Flood Zone 9 district that was approved in 2007.

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