The odds¹ of a "white Christmas" in temperate² parts of the northern hemisphere have diminished in the last century due to climate change and will likely decline further by 2100, climate and meteorology experts said.

Even though heavy snow this year will guarantee a white Christmas in many parts of Asia, Europe and North America, an 0.7-degree C rise in world temperatures since 1900 and projected bigger rises by 2100 suggest an inexorable trend.

"The probability of snow on the ground at Christmas is already lower than it was even 50 years ago but it will become an even greater rarity many places by the latter half of the century," said Friedrich-Wilhelm Gerstengarber, climate researcher at the Potsdam Institute for Climate Impact Research.

In the northern German city of Berlin, for instance, the chances of snow on the ground on Dec 24, 25 and 26 have fallen from 20 percent a century ago to approximately 15 percent in 2008, he said. By 2100 the odds will be less than 5 percent.

Berlin last had snow on the ground at Christmas in 2001, and even though the German capital is due a festive³ snowfall, from a statistical⁴ point of view, meteorologists say it will not be white in 2008 either.

In cities with more maritime⁵ climates, such as London, and mild continental⁶ climates like Paris, snow on Christmas is even now fairly rare and will only be a freak occurrence within 100 years, he said. No snow is expected in either city this year.

"The yearning⁷ for snow at Christmas seems to grow stronger the rarer it becomes," Gerstengarber said, noting cities at low altitudes such as Berlin (30 m above sea level) will probably almost never see snow surviving on the ground by 2100.

Betting on the fabled⁸ "white Christmas" is a pastime in some countries, like Britain, and oddsmakers will increasingly have to factor in global warming's impact, climate researchers said.

 气候和气象专家日前称，受气候变化的影响，北半球温带地区的人们过“白色圣诞”的机会在过去一个世纪中越来越少，而且这个机会在2100年之前会进一步减少。

托下大雪的福，今年亚洲、欧洲和北美洲很多地区的人们能过一个“白色圣诞”了，但现实的状况是，全球平均气温自1900年以来上升了0.7摄氏度，并将于2100年前出现更大幅度的上升，这一事实预示了一个可怕的趋势。

德国波茨坦气候影响研究所的气候研究员Friedrich-Wilhelm Gerstengarber说：“与50年前相比，踩着厚厚的积雪过圣诞的机会已经少了很多，到本世纪下半叶，这样的圣诞节就更稀罕了。”

他举了个例子说，在德国北部城市柏林，一年之中12月24日至26日这几天的降雪概率已由一百年前的20%下降到了今年的15%左右。到了2100年，这一概率将不到5%。

柏林上一次的“白色圣诞”出现在2001年。尽管从统计学角度看，今年圣诞节柏林该下一场雪了，但气象学家称，今年还是别做指望了。

Gerstengarber说，在更具海洋性气候特征及温带大陆性气候特征的城市，如伦敦和巴黎，如今圣诞降雪更加罕见，并将成为百年一遇的奇观。据气象预报，今年圣诞伦敦和巴黎也不会下雪。

他说：“圣诞节下雪越稀罕，人们就越渴望。”据他介绍，像柏林（海拔30米）这种海拔较低的城市在2100年以前可能基本看不到地面积雪了。

气候研究人员称，在英国等一些国家，打赌是否会出现传说中的“白色圣诞”是人们生活中的一大乐趣。博彩公司以后也要越来越重视全球变暖的影响了。

Vocabulary:

inexorable: relentless（无情的；残酷的）

due: expecting or ready for something as part of a normal course or sequence（该到的）

maritime climate:海洋性气候

pastime:消遣；娱乐