Scientists now believe that the Earth's magnetic field is about to reverse.
This is called magnetic field reversal.
Every 200,000 to 300,000 years, the Earth's magnetic field reverses.
In other words, the North and South magnetic poles switch places.
This has happened many times in Earth's history, but it has been happening more lately.
译文：科学家们现在相信地球磁场即将转向，这就是所谓的磁场逆转。每20万到30万年，地球磁场就会发生逆转。也就是说，南北磁极会互换位置。地球史上这种情况发生过很多次，但最近发生得更多。
Exercises:
1.— What happens to magnetic field reversal?
— The Earth's magnetic poles switch places.
2. Scientists now believe that the Earth's magnetic field is about to reverse.
Recent research provides evidence that there have been five magnetic reversals during the past 500,000 years.
The most recent event happened approximately 41,000 years ago.
Recent studies have found that the Earth'smagnetic field has weakened about 5% per decade.
At its current rate, the next reversal could happen within the next century.
译文：最近的研究提供的证据表明，在过去50万年里有过5次磁逆现象。最近的一次发生在大约4.1万年前。最近的研究发现，地球磁场每十年减弱约5%。以目前的速度，下一次逆转可能在下个世纪内发生。
Exercises:
1.— How long is a decade?
— 10 years
2.— According to the recent research, how long ago does the last reversal occur?
— 41,000 years ago
3. Many scientists believe that the Earth's magnetic field is due to the Earth's rotation.
Repeat & Read Sentences:
1. Every 200,000 to 300,000 years, the Earth's magnetic field reverses.
2. The most recent event happened approximately 41,000 years ago.
3. Scientists now believe that the Earth's magnetic field is about to reverse.
4. Recent research provides evidence that there have been five magnetic reversals during the past 500,000 years.
Some people worry about the effects of a magnetic field reversal.
They think there is a possibility that it could cause many problems.
For example, without a magnetic field, communications could be disrupted.
Birds and other forms of life could become confused and get lost.
Another effect would be an increase in some forms of cancer, especially skin cancer.
This would be because of an increase in the amount of radiation absorbed by our bodies.
译文：有些人担心磁场逆转的影响，他们认为这可能会引发许多问题。例如，没有磁场，通讯就会中断。鸟类和其他形式的生命可能会搞混且迷路。另一个影响是一些癌症的增加，尤其是皮肤癌。这是因为我们身体吸收的辐射量增加了。
Exercises:
1. Some people worry about the effects of a magnetic field reversal.
2.— Why are some people worried about magnetic field reversal?
— They think it could cause many problems.
Put the sentences below in order:
(1) For example, without a magnetic field, communications could be disrupted.
(2) Birds and other forms of life could become confused and get lost.
(3) They think there is a possibility that it could cause many problems.
(4) Some people worry about the effects of a magnetic field reversal.
Correct Oder:(4) (3) (1) (2)
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.
Humans have been on Earth for millions of years, during which there have been many reversals.
Therefore, scientists believe that any changes would be temporary.
译文：磁场反转成为绝灭事件的可能性非常低。几乎没有历史证据表明之前的逆转导致了物种灭绝。人类已经在地球上生活了数百万年，在这期间发生了许多逆转。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.
So in the next reversal, continents could shift positions, from north to south.
Imagine, if that happened, Australia would be in the northern hemisphere.
译文：另一种理论认为，地球的外层可以围绕构成地球大部分的液态金属外核旋转。所以在下一次逆转中，大陆的位置可能会从北移到南。想象一下，如果这发生了，澳大利亚会在北半球。
Exercises:
1.— How likely is it that a field reversal would be an extinction event?
— It's highly unlikely.
2. 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.
With so many theories, how can we know what to believe?
This is important because some events require us to act well in advance.
Otherwise, it will be too late to prevent a catastrophe.
This underlines the importance of getting reliable information, backed by strong evidence.
译文：有这么多的理论，我们如何知道该相信什么呢?这一点很重要，因为有些事情需要我们提前采取行动。否则，阻止灾难的发生就太晚了。这强调了在有力证据的支持下获得可靠信息的重要性。
Exercise:
Some events require us to act well in advance to prevent them.
Repeat & Read Sentences:
1. Some people worry about the effects of a magnetic field reversal.
2. An increase in radiation causes some forms of cancer.
3. With so many theories, how can we know what to believe?