Ding, off goes my backlink alarm.
Interesting discussion. The sad truth is that we don't know. Neither BC nor the rest of Canada gather the kind of statistics that would let us analyse what is causing an uptick in rescues - a very disappointing situation to be in. I have hopes that this might be fixed soon, but even if we install a system that gathers the right kind of data it will be at least 3 years before we could take a stab at an analysis.
Of course this lets us speculate to our hearts content.
The biggest issue is that SAR looks a lot different in other parts of the province than in the lower mainland so most of us in the South West of the province, or those of us who only watch TV will have a very skewed picture. Most of the SAR that makes the evening news is heavily dominated by incident proximity to Vancouver.
My personal feeling is that the current trend is being driven by population increase, and social media.
More people in the backcountry means more risk, and more rescues. More people can be driven by the popularity of backcountry sports, or just more people in general (and the percentage of people taking part in those sports remaining relatively constant).
The other factor, labelled as "social media" I believe has a more complex and nuanced cause. People are gathering information via the internet - whether it's social media or a trail web site. This information might contain where the trailhead is, how long it takes, relative efforts, and pictures and ratings by other hikers. However this "information" doesn't translate into knowledge.
So people feel empowered by the internet - the barrier to entry into the sport of hiking is very low. You don't need to join a club or meet someone to be your mentor, you can just head out. The issue is that the things you don't know will kill you. This is why I was not surprised last year when we long lined a young, solo hiker wearing the equivalent of comfortable mall clothing while sitting on a ledge between a cliff above and a cliff below.
Of course, this is just speculation with no real evidence to back it up.