BBC.地平线.2012.全球怪象

has become known as the Little Ice Age.
事实上 有记录的最冷的冬天
In fact, the coldest winter ever recorded
是在1683-84年间
was in 1683-84.
看到人们记录天气之认真
It's interesting to see the care
是非常有趣的
with which things are recorded,
还有当时华丽的语言
but also the colourful language people use
我们现在已经不再用了
that we don't actually use nowadays.
例如"深刻的冷"这种措辞
"Profound cold" things like that is sort of wording
在现代的科学论文中是不能使用的
that we can't use in a modern scientific paper,
但是其实意义丰富
but actually means quite a lot.
那太阳黑子为什么会消失五十几年呢
So why did the Sun's spots disappear for 50-odd years?
为了回答这个问题
To answer that question,
迈克还得回到更早的时间
Mike had to go back even further in time,
回到文明诞生之前
back before the beginning of civilisation.
若想了解
One of the best places to
太阳的漫长历史 最好的一个地方
get that long view of the history of the Sun
就是在冰里
is in ice.
他和其他科学家分♥析♥冰芯
He and his fellow scientists analysed ice cores
因为其上记录了
because they contain a signature
太阳数千年来的活动
of what's been happening to the Sun over thousands of years.
我们可以取出冰芯有效地追溯到过去
We can core into that effectively look back in time.
大致上 我们可以看到在九千年间
Roughly speaking, there are 20 to 30 grand maxima
有二三十个太阳活动极大和极小期
and grand minima in the 9,000 years that we can look at.
冰芯显示的结果
So what the ice showed
出乎人们意料
was something nobody could have predicted.
太阳有一个秘密的周期
The Sun had a secret rhythm.
在11年周期循环的同时
As well as an 11-year time frame,
它还有一个更长的周期
it also operated on a much longer timescale -
大太阳周期
the grand solar cycle,
平均大概三百年为一个周期
averaging every 300 years or so.
迈克·洛克伍德开创性的研究
And Mike Lockwood's ground-breaking research
帮助解释了17世纪发生的事
helped explain what was happening in the 17th century.
因为那时是大太阳周期的极小期
Because that was a time of a grand solar minimum,
紫外辐射降到最低
where UV light would be at its lowest.
不仅仅持续几年
Not just for years,
而且是几十年
but decades.
创造了条件
And that would create the conditions to allow the wind
让东风吹到英国
to blow from the east -
导致了霜冻嘉年华
leading to frost fairs
以及完美的小提琴被制♥作♥出来
and the production of beautiful violins.
这可以帮助解释最近的寒冬吗
Could that help explain the recent cold winters?
我们到了另一个大太阳周期的极小期吗
Have we reached another grand solar minimum?
答案是确定的
The answer was a convincing
不
No.
太阳活动的极大期刚刚结束
We seem to be coming out of a grand maximum of solar activity.
过去的经验告诉我们 将要进入太阳活动极小期
And we will, past experience tells us, go into a grand minimum.
多快进入是个问题
It's just a question of how soon.
少则四十年
It could be as little as 40 years time.
多达数百年
It could take a couple of hundred years.
但宇宙射线同位素的长♥期♥记录告诉我们
But the long-term record from cosmogenic isotopes tell us
太阳活动最终将会回到一个极小期
that it will, eventually, go back into a grand minimum again.
现在我们确切知道
We now know for sure that it wasn't
并不是大太阳周期
the grand solar cycle that was responsible for Britain
使英国经历了连续两年破纪录的寒冬
shivering through two record-breaking cold winters on the trot.
当然 正常11年周期的结束
Of course, the end of the regular 11-year cycle
以及其他自然天气因素
combined with other natural weather factors,
也在史无前例的寒冬中起了作用
played a part in these record-breaking winters.
但是一些专家认为这还不够
But some experts didn't think that was enough.
还少了点什么
Something was missing.
在过去的几年中
Over the last few years,
来自世界各地的气候学家
climate scientists from around the world
试图找出
have been trying to figure out
到底发生了什么
what might have been happening.
其中一位领军人物是亚当·斯凯夫博士
One of the leading lights of that group is Dr Adam Scaife.
他和他的团队一直在积累和分♥析♥
He and his team have been accumulating and analysing
海量的天气数据
mountains of weather data.
奇怪的是 他们认为这个问题的答案
Weirdly, they believe the answer to the problem
就在北极
lies in the Arctic.
更奇怪的是
Even weirder,
他们认为正是北极变暖
they think the warming of the Arctic
导致了全球怪象
may be holding the key.
但为何在北极变暖的同时
But how can it be getting warmer in the Arctic,
英国却变的更冷呢
yet colder in Britain?
如果北极冰川融化
If you melt the Arctic ice,
你可能会简单地认为其他地方也会变暖
you might naively think that would give warmer conditions further afield.
譬如 整个欧洲
For example, over Europe.
确确实实 当冰川体积减小时
It is, indeed, true that when you reduce the ice
海洋中会释放很多能量 因此在北极
that lets lots of heat out of the ocean, so in the Arctic,
在大气层底部
you see several degrees of warming
温度确实上升了几度
in the lower part of the atmosphere.
毫无疑问
And there's little doubt
北极确实正在变暖
that it's been getting warmer in the Arctic.
过去的十年里
In the last ten years,
海冰的总体积已经下降至极低点
the sea ice has reached record low levels.
从英国气象局所建立的
According to the Met Office's
极为复杂的计算机模型中可以看到
highly sophisticated computer models,
北极变暖并不意味着英国也会变暖
a hotter Arctic doesn't equal a warmer Britain.
北极变暖的同时
That warming that's happening
欧洲并没有随着一起变暖
over the Arctic is not seen over Europe.
导致这个现象的原因是
The reason for that is because
大气环流的变化 风的变化
the circulation changes, the wind changes.
当冰川体积减小时
It turns out when you remove the Arctic ice,
风向会变的更偏东
and the winds become more easterly.
因此北极的风向转为围绕着北极由东向西
So the winds start to circulate from east to west around the Arctic
并且开始影响北极以南
and south of the Arctic,
这个风向则是决定欧洲气温变化的原因
and that dominates the response over Europe.
因此 在北极海冰减小的同时
So instead of warming in the winter
欧洲的冬季并不会变的更温暖
over Europe when the ice is depleted
欧洲会变得更冷
we get cooling because we're
因为西伯利亚的冷风被气流带到了北欧
dragging the air from Siberia over northern Europe.
科学家还在试图解释
They're still trying to understand
这个现象出现的机制和原因
the mechanism that produces this effect,
但当我们把这个因素加入到众变量中去
but when you add this new factor to variables
例如太阳活动周期
like the Sun's solar cycle,
我们开始理解冬季变化的原因了
what happened to our winters starts to make sense.
整件事情中更奇怪的是
And perhaps what's even weirder
尽管全球都在变暖
is that as the world gets warmer,
有些地方却变得更冷
some bits of it can get colder.
当然 欧洲和英国只是地球的一部分
Of course, Europe and the UK is only one region of the globe.
还有其他地方 若是算出平均气温
There are many other regions, and when you average those up
全球是在变暖的
you still see warming.
欧洲更加寒冷
So the fact that Europe is cold
与此同时 美国也更冷
and the US is cold at the same time,
但与此同时
is balanced by the fact that
加拿大和地中海地区的冬季会更温暖
Canada and the Mediterranean tend to be milder in those winters.
所以当把风向的变化考虑在内
So when you integrate up this change in the winds,
那些偏东的风
the extra easterly winds,
在全球范围内看的时候
when you average it over the whole globe,
效果被互相抵消了
it cancels out.
因此 全球气温会继续变暖
So global warming can continue unaffected,
但局部地区的气温 例如英国和欧洲
but the regional temperatures over, say, UK and Europe,
可能会下降 至少几年之内温度会下降
can go down, at least for a few years,
而全球其他地方在变暖
as the globe warms up.
但是到最后 全球变暖会胜出
Even though, in the end, global warming will, of course, win,
如果气候继续朝这个方向发展
if we continue on that trend.
这也就是为什么 全球不断变暖
This is why, as the world gets warmer,
各种极端天气频现
it makes sense to talk about the weather getting weirder.
这个现象以不同方式影响着全球许多地方
It affects different parts of the planet in different ways.
但每一次的极端天气
But every extreme weather event
并不一定是全球怪象造成的
isn't an example of global weirding.
可怕的天气还是会出现