Question: what are the two most abundant greenhouse gases in the earth’s atmosphere
[{'answer': 'water vapor , carbon dioxide', 'provenance': [{'wikipedia_id': '21350772', 'title': 'Greenhouse gas', 'start_paragraph_id': 1, 'start_character': 228, 'end_paragraph_id': 1, 'end_character': 256, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '21350772', 'title': 'Greenhouse gas', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 467, 'bleu_score': 0.5505544575158461, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 9639642508986507485}, 'section': 'Section::::Abstract.'}]}]