12. A new research has shown that some 40 to 50 million years ago, climate of Antarctica ... (BE) similar to the coasts of California of today.

The correct answer is 'is'. **Explanation:** The task is to transform the word in brackets so that it fits grammatically and contextually into the sentence. 'BE' needs to be changed to the correct form of the verb 'to be' in the present simple tense. Since 'climate' is singular, the correct form is 'is'.