多于98 inches of snowhas fallen in Boston this season, while workers have spent about 170,000 hours plowing the streets and distributed more than 76,000 tons of salt on roadways. At the same time, much of the American West, Rocky Mountains, and Northern and Central Plains have experienced温度高的温度。在史诗般的干旱中，加利福尼亚州的一月最多的1月份仅占平均降水量的15％。

So what is going on with this extreme weather, and what does it have to do with global climate change?

Due to recent analytical advancements, climate scientists are now able to more accurately determine how climate change impacts the odds of anindividual extreme event occurring。

计划在未来几年内进行更多的研究，以研究极端天气与气候事件与气候变化之间的联系，全球研究已经向我们讲述了很多有关趋势的信息，包括气候变化与极端事件之间的这三个违反直觉联系：必威官网是真的吗

1）在温暖的世界中仍然可以发生记录寒冷温度。

During 2014, cities in regions like the Midwest and Northeast enduredrecord cold months。Zoom out to the state level, however, andthree states（加利福尼亚州，内华达州和亚利桑那州）2014年的年度温度升温，而没有经历创纪录的年度年度温度。这全国平均温度was warmer than normal, and at the global scale, last year was more than just above average – 2014 was the有史以来最温暖的一年。

While portions of the eastern United States have facedhistoric snow totals和frigid temperaturesthis year, theopposite can be saidfor much of the western United States.

A growing body of research suggests that a contributing factor of this drastic east-west temperature contrast could be the accelerated warming taking place in the Arctic, which can have a weakening effect on thepolar jet stream, a west-to-east river of wind in the atmosphere where cold Arctic air meets milder subtropical air in the mid-latitudes (e.g., the United States) of the Northern Hemisphere. A weaker polar jet stream创造更有利的条件对于北极周围的“波浪状”南北的路径，这可能会增加北极空气向南渗入美国东部地区的阶段的频率，而在该国西半部，较温暖的空气向北伸出。

2) A warming planet can make some regions much snowier.

这warmer the air is,the more water vapor它可以固定。这种额外的水分会带来更强烈的降雨或降雪。另外，当海面温度为warmer than average(as they are currently in theNortheast Atlantic Ocean), the atmosphere becomes fueled with more moisture and energy.

Precipitation amounts vary by region, but in the United States, all regions except Hawaii have experienced an increase in very大降水事件since the late 1950s. However, snowfall has decreased in most parts of the country since recordkeeping began, in large part because more winter precipitation has come from下雨而不是雪。Thus, temperatures play a significant role.

逐渐变暖正在减少许多地区非常寒冷的天数，但是当温度足够寒冷时，水分增加会导致降雪事件较重。实际上，当温度刚好低于冰点而不是冷（当可用的水分减少时）时，最重的暴风雪会发生 - 条件becoming more likelyin mid-winter in a warmer world.

3）气必威官网是真的吗候变化会导致在同一地点的双重干旱和极端降水。

As mentioned above, a warmer atmosphere can hold more water, fueling more intense rain and snow events. But at the other end of the spectrum, the warming climate can放大条件有利于干旱– like heatwaves, evapotranspiration and reduced soil moisture. The combination of these two extremes in one location can increase disasters like flooding and landslides, and recent history suggests parts of the United States may already be grappling with these double-whammy impacts.

自2010年以来，像中西部这样的地区受到了许多极端干旱和洪水事件的影响每个人超过10亿美元in losses. Right now, California is in the midst of a drought that researchers have found to be its worst inat least 1,200 years。尽管没有发现是由于气候变化引起的，但科学家们确定干旱已经必威官网是真的吗由创纪录的温度驱动和reduced precipitation. These prolonged warm and dry conditions were then met with an incredible deluge of rainfall in some areas of the state last December (San Francisco收到了更多的雨在几天之内，比2013年所有的事情都造成洪水和泥石流，洗路和破坏房屋。

需要行动

A growing body of evidence shows strong connections between必威官网是真的吗气候变化和极端事件，并且曾经被认为是遥远的未来威胁的影响已经发生并普遍存在。

As decision-makers scramble to keep trains and buses running among feet of snow, make plans to save infrastructure from flooding, and revise planning to contend with drought, it’s time they pause to acknowledge the role that human-induced climate change is playing in our changing weather – and commit toambitious policy changesthat reversethese trends。