would as uncertainty?

[keannu]

Is this "would" for uncertainty or presumption or imaginary result of a conditional? When I can find implied conditional phrases in a sentence, I can guess it's the imagianry result, but things like this are vague.
I may be wrong, but my thinking is "would" as presumption denotes uncertainty, a low possibility, but "would" as imaginary result denotes certainty if some condition is met, so the translation of the two can become wholly different.

ex)There are still some people who choose to ignore the threat of global warming. However, the facts many weather experts are finding are quite worrying. The melting polar ice caps could produce a large amount of cold fresh water. This water could then flow south and disrupt the Gulf Stream, which is needed to keep Europe and parts of North America warm. As a result, what happened centuries ago could happen again - a change in global weather patterns, which would lead to harsher winters, droughts and possible crop failures. The worst scenario would be the start of a new ice age, which could occur in as little as two or three years.

[Tdol]

That's not uncertainty IMO.

[keannu]

That's not uncertainty IMO.

I guess that according to your opinion, "the worst scenario" can be a conditional phrase, so the whole sentence could be "If there were the worst scenario, it would be..." So is uncertainty(presumption) something without any conditional phrase implied?
How can you tell uncertainty and conditional? I'm always confused about what the criteria is and if the two have significant differences.

[5jj]

How can you tell uncertainty and conditional? I'm always confused about what the criteria is and if the two have significant differences.

I have stopped contributing to your threads, because it seems to me that you create much of the confusion yourself. As I have pointed out, tediously, words such as 'presumption' and the many other words that have cropped up in the hundreds of posts on this subject are merely labels.

It may be useful, in general terms, to group 'conditional sentences' (there's another label!) into groups or classes, but trying to fit every sentence containing 'would' into one or other of these classes is doomed to failure. They are not scientifically designed, mutually exclusive categories.

As you know from previous threads, 'would' can be used to signify a number of different ideas, so it is not at all surprising that, when used in (for example) five different utterances, each 'would' may have to be translated into another language in a different way from the others.

If you heard someone produce an utterance and, immediately afterwards, asked them precisely what they had in mind, I doubt very much if many people could tell you. And, even if they could, that does not mean that the listener would have interpreted it in exactly the same way.