Magnetic Field Reversal
Scientists now believe that the Earth's magnetic field is about to reverse.
科学家们现在相信，地球的磁场即将反转。
This is called magnetic field reversal.
这叫做磁场反转。
Every 200,000 to 300,000 years, the Earth's magnetic field reverses.
每20万到30万年，地球的磁场就会发生逆转。
In other words, the North and South magnetic poles switch places.
换句话说，北极和南极磁极互换位置。
This has happened many times in Earth's history, but it has been happening more lately.
这在地球历史上已经发生过很多次了，但是最近发生的更多。
What happens during a magnetic field reversal? -The Earth's magnetic poles switch places.
在磁场翻转过程中会发生什么?-地球的磁极互换位置。
What happens to magnetic field reversal? -The Earth's magnetic poles switch places.
磁场反转会发生什么?-地球磁极的位置变换。
Scientists now believe that the Earth's magnetic field is about to reverse.
科学家们现在相信，地球的磁场即将反转。
Recent research provides evidence that there have been five magnetic reversals during the past 500,000 years.
最近的研究提供了证据，表明在过去的50万年中，地球经历了5次磁极倒转。
The most recent event happened approximately 41,000 years ago.
最近一次发生在大约41000年前。
Recent studies have found that the Earth's magnetic field has weakened about 5% per decade.
最近的研究发现，地球磁场每十年减弱约5%。
At its current rate, the next reversal could happen within the next century.
按照目前的速度，下一个逆转可能在下个世纪发生。
How long is a decade? -10 years
十年有多长?-10年
According to the recent research, how long ago does the last reversal occur? -about 41,000 years ago
根据最近的研究，最近一次逆转发生在多久以前?-大约41000年前
Many scientists believe that the Earth's magnetic field is due to the Earth's rotation.
许多科学家认为地球的磁场是由地球的自转引起的。
Some people worry about the effects of a magnetic field reversal.
有些人担心磁场反转的影响。
They think there is a possibility that it could cause many problems.
他们认为这可能会引起很多问题。
For example, without a magnetic field, communications could be disrupted.
例如，如果没有磁场，通信就会中断。
Birds and other forms of life could become confused and get lost.
鸟类和其他形式的生命可能会迷失方向。
Another effect would be an increase in some forms of cancer, especially skin cancer.
另一个影响是某些癌症的增加，尤其是皮肤癌。
This would be because of an increase in the amount of radiation absorbed by our bodies.
这可能是因为我们身体吸收的辐射量增加了。
The possibility that a field reversal would be an extinction event is very low.
场反转成为灭绝事件的可能性非常低。
There is very little historical evidence to show that previous reversals have caused extinctions.
很少有历史证据表明以前的逆转导致了物种灭绝。
Humans have been on Earth for millions of years, during which there have been many reversals.
人类已经在地球上生活了数百万年，其间有过多次逆转。
Therefore, scientists believe that any changes would be temporary.
因此，科学家认为任何变化都是暂时的。
Another theory is that the Earth's outer layer could rotate around the liquid metal outer core that makes up most of the earth.
另一种理论是，地球的外层可以绕着构成地球大部分的液态金属外核旋转。
So in the next reversal continents could shift positions, from north to south.
所以在下一次的倒转中，大陆可能会改变位置，从北到南
Imagine, if that happened, Australia would be in the northern hemisphere.
想象一下，如果那样的话，澳大利亚会在北半球。
How likely is it that a field reversal would be an extinction event?- It's highly unlikely.
场反转是灭绝事件的可能性有多大?-不太可能。
The possibility that a field reversal would be an extinction event is very low. There is very little historical evidence to show that previous reversals have caused extinctions.
场反转成为灭绝事件的可能性非常低。很少有历史证据表明以前的逆转导致了物种灭绝。
With so many theories, how can we know what to believe?
有这么多的理论，我们怎么知道该相信什么呢?
This is important because some events require us to act well in advance.
这一点很重要，因为有些事件需要我们提前采取行动。
Otherwise it will be too late to prevent a catastrophe.
否则，要阻止一场灾难就太迟了。
This underlines the importance of getting reliable information, backed by strong evidence.
这强调了获得可靠信息的重要性，并有强有力的证据支持。
