Wednesday, August 26, 2015

New Research Says Global Warming a Factor in California Drought

A new study says the risk of extremely low precipitation years in California is increasing due to global warming.  Researchers from Columbia University found that unusually hot temperatures attrributable to anthropogenic climate change have intensified the current drought attributed to natural varibility in rainfall. Warming is responsible for between 8 and 27% of California's water debt according to the study. Baseline conditions have shifted as a result of climate change. The Palmer Drought Severity Index indicates a mild drought as -1. The more severe a drought the larger the negative number. Warming has shifted the Index from zero to about -0.5. The shift means in practical terms that it takes less of a natural dip in precipitation levels to cause drought conditions. It gets worse in the future. If warming continues the Index's value will shift towards -1, meaning that even if California gets normal amounts of rain, it will teeter on the brink of drought conditions because it is hotter. By 2050 mild drought conditions will prevail 54% of the time. The study's results are consistent with other recent research that found the probability of drought in California has doubled compared to the previous century. As one scientist put it, "the warning signal has definitely emerged from the noise." But will it be heeded in time?

California's politicians are revisiting an old debate about whether efficiency or more water storage is the answer to California's now severe water shortages. The debate recently surfaced in headlines when Governor Brown refered to a state Repugnant leader as "ignorant" when she claimed water shortages should be blamed on liberals who refused to build more dams. The debate is triggering momentum for several water storage projects in the Central Valley. An enlargement of Shasta Dam at the northern end of the valley, discussed for three decades, passed a major regulatory hurdle when the Bureau of Reclamation released its final feasibllity study. Shasta could feasibly be enlarged by increasing its height eighteen feet. That would add 634,000 acre-feet of water for use. The proposal has lanquished in regulatory limbo with changing political administrations and environmental conditions. The study says the enlargement would cost $1.2 billion, but the federal government will not foot the bill. Senator Diane Feinstein has introduced a bill in the US Senate that could be an answer to the funding problem. Environmentalists are generally opposed to higher reservoir levels because they would inundate upper stretches of the McCloud River, protected under the Scenic River Protection Act. Nor is it undisputed that salmon would benefit from cold water releases since last year the Fish & Wildlife Service found that an enlargment of the reservior would not significantly improve water temperatures enough in the Sacramento River to benefit salmon.