Experts consider which incident to be the least likely, but with the greatest potential impact on the environment and people?

The incident considered to be the least likely but with the greatest potential impact on the environment and people is nuclear. This assessment stems from the nature and consequences of a nuclear incident, such as a meltdown or a detonation of a nuclear weapon. The catastrophic effects of radiation release can lead to widespread contamination, long-term health effects like cancer, and severe ecological disruption.

The rarity of significant nuclear incidents enhances their perception as low probability events. However, when such incidents do occur, they can result in devastating consequences that affect vast areas, leave lasting legacies of pollution, and displace populations, thus underscoring their categorization as having the greatest potential impact on both the environment and human health. Other types of incidents, while also harmful, typically have more immediate or manageable consequences or are more frequently encountered in day-to-day scenarios, making the nuclear option stand out in terms of potential severity against the backdrop of likelihood.