California\u2019s snowpack is supposed to reach its peak April 1, so today, state surveyors hold their final Sierra snow survey of the year. <\/p>\n
But instead of peak snow, there\u2019s almost none. <\/p>\n
Snow across California\u2019s Sierra Nevada measured just 18% of average Monday \u2014 among the smallest in decades. A month of record-shattering heat thawed the snow and sent runoff coursing into streams and rivers, leaving only minimal water in the mountains as the state heads into dry season.<\/p>\n
The early melt is a symptom of global warming that scientists say is becoming more pronounced.<\/p>\n
\u201cThis particular year is as clear an indication of the influence of climate change as anything we\u2019ve seen,\u201d said Peter Gleick, a leading water scientist and co-founder of the Pacific Institute. \u201cClimate change is influencing California\u2019s water system quickly and severely.\u201d<\/p>\n
This year the Sierra snowpack peaked on Feb. 25 at 73% of average.<\/p>\n
The summerlike heat in March broke monthly records<\/a> in many areas of the Western U.S., accelerating the melting of snow in the Rocky Mountains as well. <\/p>\n Precipitation in California has been about average since October, but more of that precipitation is falling as rain, less as snow.<\/p>\n The warmth and premature melt mean the state\u2019s forests will dry out a month or more earlier than usual, Gleick said, which increases the risk of wildfires.<\/p>\n \u201cIt also means rivers and streams are going to dry out sooner, and that has bad implications for natural ecosystems and our fisheries,\u201d he said.<\/p>\n Cities and farms should still have have ample water because major reservoirs in Northern California are nearly full. That\u2019s because this winter brought decent rain and the three years prior years were wet, too.<\/p>\n \u201cWe were lucky this year in the sense that even though we have so little snow left, we had an average amount of rainfall,\u201d Gleick said. \u201cThere are going to be years, inevitably, where we not only have almost no snow, but we don\u2019t get the rain either.\u201d<\/p>\n California traditionally had relied on the Sierra snowpack to hold about 30% of its water, on average.<\/p>\n \u201cWe\u2019re losing that storage,\u201d Gleick said. \u201cIf we can\u2019t depend on reliable long-term snowpack and snowmelt later in the year, we\u2019re going to have to do other things to make our water system more resilient.\u201d <\/p>\n When Gleick wrote his dissertation at UC Berkeley in the 1980s, he examined a range of climate scenarios and analyzed how rising temperatures would likely change the timing of runoff in Northern California.<\/p>\n \u201cCurrent trends precisely match scientific projections from decades ago,\u201d he said. \u201cMore and more of our annual runoff is occurring in the winter months, and that\u2019s because it\u2019s more rain, less snow and faster snow melt.\u201d<\/p>\n Adapting to these changes requires new thinking and new approaches, he said, including efforts to use water more efficiently<\/a>, recycle more wastewater<\/a>, capture more runoff to replenish groundwater<\/a>, and change how reservoirs are operated<\/a>.<\/p>\n Though California isn\u2019t in a drought, dry conditions have spread in parts of the state. It\u2019s now abnormally dry in about one-fourth of California, largely in the northeast, according to the U.S. Drought Monitor<\/a> website.<\/p>\n At UC Berkeley\u2019s Central Sierra Snow Laboratory, near Donner Pass, only patchy snow remains.<\/p>\n \u201cThis year is a perfect example of warm snow drought,\u201d said Andrew Schwartz, the lab\u2019s director. \u201cWe\u2019ve seen a lot of rain that would have been snow if we had cooler temperatures.\u201d<\/p>\n There have been worse years, Schwartz noted, including during a severe drought in 2015, when the sparse snow disappeared around the lab even earlier.<\/p>\n