Maths uses numbers to describe probabilities. Probabilities can be written as fractions, decimals or percentages. You can also use a probability scale, starting at (impossible) and ending at (certain).
Probabilities can be described in words. For example, the chance of an event happening could be 'certain', 'impossible' or 'likely'. In maths, probabilities are usually written as fractions or decimals between 0 and 1, or percentages between 0% and 100%.
It’s basically a 100% chance that the oceans will disappear in a few billion years, but according to some sources, most sealife (95%+) may be wiped out by the year 2100.