（美国有线电视新闻网）经过数月的极端干旱导致水资源短缺并引发野火，内华达山脉正在下大雪——足以打破数十年的记录。
截至周二，本月迄今为止，加州大学伯克利分校位于萨克拉门托以东的唐纳帕斯 (Donner Pass) 的中央塞拉雪实验室 (Central Sierra Snow Laboratory) 的降雪量已超过 202 英寸（近 17 英尺）。
实验室的科学家们表示，这个月现在是该地区有记录以来下雪最多的 12 月，也是总体上第三大雪月。最高月份是 2017 年 1 月，降雪量为 238 英寸，未来三天降雪量不足以挑战这一记录。这里的记录可以追溯到 1970 年。
实验室官员说，雪“很深，很难穿过”，他们花了大约 40 分钟才到达距离实验室前门仅 150 英尺的地方。
这是大量的雪，非常需要，但 Sierra 雪实验室的首席科学家兼台站经理 Andrew Schwartz 表示，他们将需要更多的雪。
施瓦茨告诉美国有线电视新闻网：“虽然到目前为止这一事件令人惊叹，但我们真的很担心未来几个月没有那么多风暴。” “如果我们再不增加一英寸，我们仍然低于我们对整个冬天的预期，这意味着我们可以为干旱做出贡献而不是解决它。”
高海拔积雪作为缓解干旱的天然水库，在冬季储存水并在春季融化季节缓慢释放。根据加州水资源部的数据，内华达山脉的积雪平均每年占加州淡水供应量的 30%。去年冬天结束时，塞拉山脉的积雪水平低得惊人，春季融雪补充的水库仍低于历史平均水平。
例如，奥罗维尔湖水库目前已满 37%，与同期 71% 的历史平均值相比较低。奥罗维尔水力发电厂由于水位低，于今年夏天被迫关闭，这是自 1967 年开工以来的第一次。
今年夏天的干旱是加州 126 年有记录以来最严重的一次，而 2021 年 7 月是自 1895 年开始收集数据以来最干旱的月份。 整个地区的干旱程度自 6 月以来一直徘徊在 90% 或以上，几个州完全在干旱中。
然后在 10 月，加利福尼亚和太平洋西北部的部分地区尝到了他们正在寻找的雨水的滋味。雨季的开始带来了强烈的风暴，从太平洋吸收水分，被称为大气河流。这些冬季风暴对于确定加利福尼亚是否会最终陷入干旱至关重要。在前两个冬天，只有一场这样的风暴带来了有意义的降水。
随着气候变化加速和冬季气温升高，预计降雪量会减少。施瓦茨说，他发现曾经下雪的东西现在变成了雨。
施瓦茨说：“最终，在气候变化方面，我们在峰会上的降水量实际上正在增加，但不同之处在于我们看到降雪量减少和降雨量增加。” . “所以这符合我们的变暖信号；随着变暖，我们实际上已经远离了一些降雪。”
科学家们发现，气候变化不仅增加了极端天气的严重性，还打断了自然模式，导致极端干旱和极端潮湿之间的剧烈波动。近年来，加利福尼亚经历了这种“天气冲击”，大气河流风暴一年会造成破坏性洪水，而极端干旱会导致下一年水资源短缺。
同样，施瓦茨说，他们看到峰顶的条件从无雪的冬天转变为下个季节的暴风雪。但他也表示，内华达山脉的降雪明显减少。
“这真的将是我们在这里看到的和我们经常看到的，”他补充道。 “因此，随着这些温度的升高，我们昨天看到的那些让我们跋涉40分钟的东西会减少很多。”
除了创纪录的降雪，施瓦茨说他已经亲眼目睹了内华达山脉气候危机的严峻后果。
“总的来说，该地区的气候变化趋势在降雪方面有点可怕，因为我们不会再持续很长时间了，”他说。 “所以当我们有这样几个月的时候，我为他们感到非常兴奋。”
The nearly 17 feet of snow in California's Sierra Nevada is crushing records. It's still not enough
(CNN)After months of extreme drought that triggered water shortages and stoked wildfires, heavy snow is falling in the Sierra Nevada -- enough to break decades-old records.
As of Tuesday, more than 202 inches of snow -- nearly 17 feet -- had fallen so far this month at the University of California, Berkeley's Central Sierra Snow Laboratory, at Donner Pass east of Sacramento.
Scientists at the lab said this month is now the snowiest December on record for the location and the third snowiest month overall. The top month was January 2017 when 238 inches fell, and it's not likely enough snow will fall in the next three days to challenge that record. Records here go back to 1970.
Lab officials said the snow was "deep and hard to get through," and it took them roughly 40 minutes to get to where the measurements are taken just 150 feet away from the lab's front door.
It's a ton of snow and was much needed, but Andrew Schwartz, the lead scientist and station manager of the Sierra snow laboratory, said they are going to need more.
"While this event has been amazing so far, we are really concerned about the upcoming months not having as many storms," Schwartz told CNN. "If we don't get another inch, we're still below what we would expect for the entire winter, which means that we can contribute to the drought rather than resolving it."
High-elevation snowpack serves as a natural reservoir that eases drought, storing water through the winter months and slowly releasing it through the spring melting season. Snowpack in the Sierra Nevada accounts for 30% of California's fresh water supply in an average year, according to the California Department of Water Resources. The snowpack in the Sierra was at alarmingly low levels at the end of last winter and reservoirs, which are replenished by spring snow melt, are still below the historical average.
The Lake Oroville reservoir, for instance, is currently 37% full, which is low compared to its historical average of 71% during the same time. The Oroville hydroelectric power plant was forced to shut down this summer, because of its low water level, for the first time since it opened in 1967.
This summer's drought was the most extreme in California's 126-year record, and July 2021 was the driest month since data gathering began in 1895. Across the region, the magnitude of the drought hovered at or above 90% since June, with several states entirely in drought.
Then in October, California and parts of the Pacific Northwest got a taste of the rain they were looking for. The onset of the rainy season brought in the strong storms that draw moisture from the Pacific Ocean, referred to as atmospheric rivers. These wintertime storms have been crucial in determining whether California is going to end up in drought. During the previous two winters, only one such storm brought meaningful precipitation.
As climate change accelerates and winter temperatures increase, snowfall is expected to decrease. Schwartz said he is finding that what used to fall as snow is now falling as rain.
"Ultimately, what's happening right now in terms of climate change with our precipitation here on the summit is that we're actually seeing increasing precipitation, but the difference is we're seeing a reduction in snowfall and an increase in rain," Schwartz said. "So that matches our warming signal; with that warming, we have actually moved away from some of our snowfall."
Scientists have found climate change is not just increasing the severity of extreme weather, it is interrupting the natural patterns, causing wild swings between dry and wet extremes. California has seen this "weather whiplash" in recent years where atmospheric river storms cause destructive floods one year and extreme drought causing water shortages the next.
Similarly, Schwartz said they see conditions at the summit switch from a snow-free winter to a blizzard next season. But he also said snow is clearly decreasing in the Sierra Nevada.
"And that's really going to be what we see and what we do see frequently up here," he added. "So as those temperatures increase, we'll see a lot less of the stuff that we had yesterday that had us trudging out for 40 minutes."
Record-breaking snowfall aside, Schwartz said he's already seeing firsthand the grim consequences of the climate crisis in the Sierra Nevada.
"Overall, the trends with climate change in the region is kind of a dire one with respect to snow, because we're not going to have it for a whole lot longer," he said. "So when we have months like this, I'm very excited for them."
