The sentence "others refer to them as giant rivers of ice" is in the present tense.
The past tense would have used referred, the future tense would have used, will refer.
Verbs tell you if a sentence is past present or future.
There is no future tense verb in this sentence. The sentence is present simple (is).
present, current, after, future, following, subsequent
Present tense.
The italicized verb "examined" is in future perfect passive tense.
The two verbs are: will do = future watches = present simple
The expression "suppose to" isn't correct. It should be "supposed to"
The present is a moment in time discernible as intermediate between past and future
the will in your sentence is present tense, so it is present tense
This is a present simple sentence. The verb is pushes.Pushes is the third person singular form of push. The subject - the ice - is singular so the third person form of the verb is used.
present, current, after, future, following, subsequent
A sentence in future tense describes an action that will occur after the present moment. For example, "She will travel to Paris next summer." In this sentence, "will travel" indicates that the action is expected to take place in the future.