The first or second conditional after "predict"?

Question

What's the difference in meaning?

1. Some scientists predict that if everyone in the world lived like an American, our fossil fuel supply would last for just fifteen more years.

Or:

2. Some scientists predict that if everyone in the world lives like an American, our fossil fuel supply will last for just fifteen more years.

Predict means to say something will happen, before it happens. Then, is there any room for a hypothetical situation as in Sentence 1?

Answer 1

The difference is in the degree of likelihood or plausibility the speaker is choosing to convey.

If everyone in the world lives ...

suggests that the speaker thinks this is something that could happen. Not necessarily that they think it likely, but that it is still a possibility.

If everyone in the world lived ...

suggests they think it unlikely to happen: not impossible, but less likely (more 'counter-factual') than the first case.