Applying the ladder of abstraction

My grandfather claims that the fruits on his trees are ripening earlier and earlier in the year and that this must be due to global warming

1. Claim that fruits ripening earlier because of global warming. 

2. Concepts: empirical knowledge, evidence, memory, science, truth 

3. poor KQ: Do we need science to justify global warming? 

4 intermediate KQ: Can empirical knowledge justify the theory of global warming? 

5 good KQ: To what extent can we rely on empirical knowledge to achieve a scientific truth?