Learn Danish: Ifølge professoren skal man interessere sig for klimaet. - According to the professor, one must take an interest in the climate.

Ifølge translates to according to and forms a prepositional phrase. Because the phrase Ifølge professoren takes up the first position in the sentence, the main verb skal must come right after it to follow the standard Danish V2 (verb-second) rule.

Why use the reflexive verb interessere sig for instead of just saying være interesseret i?

While both are grammatically correct, interessere sig for emphasizes the active choice of taking an interest in or engaging with the climate. Using this reflexive verb makes your Danish sound more dynamic and native-like compared to the static state of være interesseret i.

Why is the reflexive pronoun sig used when the subject is the indefinite man?

The indefinite pronoun man acts as a third-person singular subject. In Danish, any third-person subject requires the reflexive pronoun sig when the action reflects back onto the subject itself.

Does skal indicate the future tense here, or does it mean obligation?

Here, skal expresses obligation or necessity, translating to must or should. While skal often forms the future tense, the context of the professor's statement implies a strong recommendation or duty to care about the climate, rather than a mere prediction.