English hasn't always been the most common language in science and research. A little over 100 years ago, at the start of the 20th century, the dominant language for science was indeed German. And even before that, Latin.
Over the last few years, the use of the English language in scientific research papers has become more and more prevalent. According to Why English Matters, 98% of scientific articles published today are in English, and this alone is the key reason to why skilled English is so essential when building a career in Science.
Korean researcher Kumju Hwang has said "the reason that [non-native English-speaking scientitists] have to use English, at a cost of extra time and effort, is closely related to their continued efforts to be recognised as having internationally compatible quality and to gain the higest possible reputation"
And he is right, there are an estimated 1.5 billin of English speakers in the world today, out of the world's approximately 7.5 billion. But as English continues to spread and thrive worldwide, it is increasingly necessary to put an effort into learning English because it really does pay off.