> 1) Whatever causes the higher overall rates in Utah (altitude and/or other variables) that interacts in a non-linear way with whatever is causing the national increase.
Any proponent of this hypothesis will face quite the uphill battle explaining why suicide rates are growing nowhere near as fast in Montana, Wyoming, Colorado, Idaho, New Mexico, Arizona, or Nevada.
> 2) Whatever factor that is driving the national increase is more influential in Utah for whatever reason. (e.g. maybe social networks are more harmful to more-judgmental Mormon communities)
Certainly possible. There are plenty of judgmental religious clusters in the US, but it's the state with all the Mormons that seems to be the outlier, which would need explanation.
> 3) There is some recent change in Mormon culture that has driven a change in teen suicide rates.
There certainly is a lot of recent changes in mormon culture as well as mormon teachings as of late, and ramping up quite dramatically for a good 20 years now. Before prop 8, there was almost no focus on homosexuality, now it is a regular topic. There have been some major policy changes, such as disallowing baptism of children of gay parents.
There has been a huge growth in focus on pornography and modesty over the last two decades. For example, you can find plenty of strapless and sleeveless dresses in the BYU homecoming archives, but none recently. You can read conference archives from 20 years ago and find few, if any, references to pornography or modesty...whereas every conference now will focus a large amount of time on the subjects.
> 4) Mormon culture has caused a change in suicide rates despite not changing.
It demonstrably has changed, so this one is out.
> Do you have any support that would make (3) or (4) sound more reasonable? Or do you have another hypothesis?
It's a combination of 2 and 3. For example, pornography is drastically more available now than 20 years ago, but that wouldn't be much of a problem if not coupled with the shame and judgment of mormon teachings combined with the drastic growth in focus on the subject. Same goes for everything related to sexuality: modesty and social media, homosexuality and the various legal/policy actions that the church has taken, etc. The combination of of social change, technological change, mormon shame/guilt/judgment, mormon obsession with perfection and social image, and recent mormon heel-digging behavior is precisely what I would think is the most plausible hypothesis.