U.S. and global benchmark oil prices have seen their share of big moves since Israel launched attacks on Iran late last week, but there’s one indicator that helps investors put into perspective just how serious the situation is — and can become.

Oil prices have resumed their upward climb and U.S. futures are lower after Israel's military issued an evacuation warning to 330,000 people in Iran's capital Tehran.

Oil prices climbed on Tuesday as the Iran-Israel conflict raged with no end in sight, though major oil and gas infrastructure and flows have so far been spared from substantial impact.