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Climate Change Chipping Away at the Coast

USGS: Warmer ocean temps portend more erosion along the West Coast

This week researchers at the US Geological Survey (USGS) issued a damage report that assesses how badly El Nino patterns tore up West Coast beaches during the winter of 2009-2010. Up and down the coast, the survey logged beach erosion 36% above average. The study’s authors point to the intensity of the El Nino conditions during that time, as well as a geological shift in the region of warmer water. They say high water, heavy storms and warmer waters were the culprits. And they warn that with the changing climate, these events may become more common.

“This little winter is a snapshot of what climate change may look like where we have baseline higher sea levels and more significant storms.” said Patrick Barnard, a coastal geologist with the USGS in Santa Cruz.

A sign warning of cliff erosion in Santa Cruz. (Photo: Craig Miller)

One Bay Area snapshot the authors highlighted was San Francisco’s Ocean Beach. The thin coast retreated more than 184 feet, dumping the southbound lane of the Great Highway onto the beach. It took nine months before the lane was reopened and the clean-up cost $5 million.

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Planning for the Other “Big One”

Imagine 45 days of rain brought by a series of winter storms so strong and wet that they turned the Sacramento Valley into an inland sea, making the state capital virtually inaccessible. 

Well, that happened in California in the winter of 1861-1862, and scientists say it will happen again, bringing massive flooding, landslides and property damage across the state.

To help emergency agencies plan for such an event, the US Geological Survey released the “ARkStorm Scenario” in Sacramento this week, detailing the repercussions of a storm that produces up to ten feet of rain and forces the evacuations of more than a million people.

“Vast floods would basically take out all the farm land,” said Marcia McNutt, director of the USGS. “They would destroy homes, animals would die, roads would be impassable, infrastructure would be rendered unusable, dikes would fail, levees, would fail.”

Scientists created this hypothetical storm by combining two actual storms, one from 1969 and one from 1986, and putting them back to back.  Together, they rival the 1860’s storm in magnitude, which was the last time California saw a storm this size.
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USGS: Americans More Water-Conscious Overall

Craig MIller

Lake Mead in October, 2009 Photo: Craig Miller

Despite the addition of 81 million people over the period, Americans were using less water in 2005 than they were in 1975, according to the latest numbers released from the USGS.

The per-capita decrease of 30% since 2000, down to 1383 gallons per person per day, is a level not seen since the 1950s.  Of course this doesn’t mean that each person in the United States is using more than a thousand gallons per day at home–that number is somewhere between 54 (if you live in Maine) and 190 (if you live in Nevada).  The USGS number is derived from dividing total water withdrawals by total population.  In 2005, the total withdrawal was 410 billion gallons per day (5% less than in the peak year, 1980) and the total population was approximately 310 million.

An analysis by the Oakland-based Pacific Institute finds that the changes in national water use are due to improvements in efficiency, particularly in industrial use and irrigation. However, the largest category of water use–that used for producing energy–is growing (by 3% between 2000 and 2005), and the analysis cites this as a worrying trend as the population increases, particularly in dry parts of the country.  In 2005, 49% of all water withdrawals were for cooling power plants.

“Far more water is required for nuclear and fossil fuel energy systems than for most renewable energy systems,” said Peter Gleick, president of the Pacific Institute, in a statement about the new numbers.  “Water availability will increasingly limit our energy choices as climate change accelerates and population continues to grow.” California’s two commercial nuclear plants are located on the coast and use sea water for cooling.

More efficient farming seems to be one of the bright spots in the report.  Irrigation withdrawals in 2005 declined to the 1970 level of 1.28 billion gallons per day, even though the amount of irrigated land in the nation has increased by millions of acres since 1970.  It seems that American agriculture is, in fact, doing more with less, thanks to more efficient sprinklers and drip irrigation systems. Even so, agriculture still claims about 77% of “developed” water in California, according to Ellen Hanak, water policy analyst with the Pubic Policy Institute of California.

The Pacific Institute commentary added some sobering notes:

The United States, although relatively water-rich, faces a range of threats to its vital supplies of freshwater. Overuse has turned the Colorado River into little more than a trickle. Overuse and contamination threaten the massive Ogallala aquifer, which runs from Texas to South Dakota and is an important source of irrigation and drinking water. Political and economic conflicts are growing between Alabama, Florida, and Georgia over water use. And other serious threats to our water resources – including climate change, environmental destruction, and population growth – remain unaddressed.

Household water use across the country is growing proportionately to U.S. population growth.  While people are becoming more water-efficient at home, these behavioral changes are being balanced out by a shift in population to hotter, drier areas, such as the Southwest.

The Pacific Institute’s Circle of Blue Water News has interactive maps showing which states have decreased their water withdrawals between 2000 and 2005 and total water withdrawals by state for this time period, as well as charts tracking U.S. water withdrawals since 1950.

11/18/09 Update:
Listen to audio of Peter Gleick discussing the report’s findings on today’s broadcast of NPR’s Morning Edition.

Is the Climate Killing Our Trees?

Aerial_Shasta forestsA new collaborative study suggests that warming temperatures are taking a toll on trees in old-growth forests across the western US.

The study concluded that the near doubling in the mortality rate over several decades transcends forest types, elevation, tree size and species. The study will by published in Science this week.

Phil van Mantgem, who co-led the research team at USGS, said the spike in dying trees could lead to habitat destruction for forest wildlife. And while living trees absorb greenhouse gases, dying trees actually release carbon dioxide into the atmosphere, furthering the effects of global warming.

Usually, van Mantgem said, a small number of trees in a forest die each year and are replaced by new growth. However he’s observed that trees are dying so quickly that new growth is having trouble keeping up. He said one of the causes could be the West’s rising average temperature. While it rose only 1 degree (F) during the past few decades, he said it’s been enough to reduce the snowpack and melt the snow earlier, causing longer periods of dry weather and distressing forests.

Warm weather might also nurture insects and diseases that attack trees. Some reports have already tied destructive bark-beetle outbreaks to higher temperatures.

Nate Stephenson, another research team co-leader with the USGS, said the deaths, over time, could reduce the age of the western forests. “Tree death rates are like interest on a bank account – the effects compound over time,” Stephenson said. Stephenson worries that the increasing rate could lead to a bigger and more abrupt change in forests, similar to sudden and extensive die-backs observed in the southwest, Colorado and British Columbia.

Scientists from the U.S. Forest Service, and six universities collaborated on the study. Van Mantgem appeared on KQED’s Forum program today, along with host Dave Iverson, Climate Watch Sr. Editor Craig Miller and Inez Fung, author of a new study on seasons shifting from rising temperatures. Van Mantgem then popped up on NPR’s Science Friday. New York Times correspondent Andrew Revkin, author of the widely followed Dot Earth blog, also appeared and responded to recent polling on attitudes toward climate change.

Climate Linked to "Silent Streams"?

Memo to anglers: If you’re wondering why they’re not biting, it may be because they’re not there. Little noticed this week was a report from the U.S. Geological Survey, detailing the staggering losses that freshwater fish species have suffered across the U.S. The report describes nearly 40% of North America’s freshwater fishes as “imperiled.” The figure represents a 92% increase over a similar survey done in 1989 by the American Fisheries Society, which participated in the new report. USGS director Mark Myers cited loss of habitat and invasive species as primary causes for the decline but noted that “climate change may further affect these fish.” The news is worse for California, as topping the Survey’s at-risk list are “salmon and trout of the Pacific Coast and western mountain regions.”

Release of the report followed by one day Terry Root’s keynote presentation at the California Climate Change Conference, in which the Stanford researcher warned of a catastrophic loss of trout habitat in California, due in part to climate change.