How do you quantify truth?

I believe you mean “qualify” truth, as quantify suggests counting. The “truth” is something consistent with an actual occurring in the natural world. The problem with people and truth, people really want validation or a “cheat code” at life, not truths. Empirical evidence is one way to count it.

Also if you mean your friend is a “financier” then DONT! It is a bad habit to attempt to persuade someone of anything they are not open to, unless you have no concern for the relationship’s prospects.

Ideas are a funny thing, some take them as seriously as their own identity, more seriously than “truth” even.

This intention you have for being convincing reminds me of the schools of rhetoric in ancient times. Convincing and right are separate endeavors.

After all of that, try speaking towards your subject’s best interests.

Are property investments at risk from rising water levels?

Are industries poised to be made or broken on the most accurate ten year forecast on climate change?

I might recommend taking a meaningful interest in persuasive arguments in general if you want to “up your game.”

Otherwise, it is worth noting how awkward and unrewarding taking responsibility for the thoughts, beliefs and ideas of others usually turns out.

Go talk to a farmer whose livelihood depends on the weather and you will find few who don’t believe the weather is screwy today and it is hard to make a living. Over the course of 20-30 years watching in one place you do see a difference in the timing of the seasons, plant community, patterns of rainfall in such.

Now if you spend all your time in air conditioning you might not notice and that is part of why your friend can sustain his belief system.

well there are ice ages. can't have them without some sort of climate change. your friend should believe in ice ages.