Learn Turkish: İklim, Dünya'nın doğasını belirler. - The climate determines the Earth's nature.

The verb comes from belirlemek (to determine). The root is belirle-. Because the root ends in a vowel, making the aorist is simple: you just add the suffix -r to get belirler. Since the subject is "it" (İklim), it doesn't need any additional personal suffixes.

How do Dünya'nın and doğasını link together to mean "the Earth's nature"?

This forms a standard possessor-possessed relationship. The owner (Dünya, meaning Earth) takes the genitive suffix -nın (acting like "'s" in English). The owned item (doğa) takes the 3rd person possessive suffix -sı. The apostrophe is used because Dünya is a proper noun.

Why does doğasını have so many suffixes at the end?

Let's break it down! The root is doğa (nature). First, we add the possessive suffix -sı to mean "its nature". Next, because it is the specific direct object of the verb, it needs the accusative case suffix -ı. The -n- in the middle is a buffer letter always used when adding a case suffix to a 3rd-person possessive suffix: doğa + -sı + -n- + -ı.

Why is there a comma after İklim?

In Turkish, it is very common to put a comma right after the subject of the sentence. This clearly separates the subject from the rest of the sentence, helping you see exactly what is doing the action before reading the other details.