Comment No. Extreme heat will very likely be #1. (Score 1) 22
The natural cascades of man-made global warming have only kicked into overdrive in recent years. Basic common sense tells us that the rate is only going to increase in the foreseeable future. Meaning that regular heat itself will be the main problem. And way earlier than 2050.
Point in case: It's nearing the end of September and temperature and humidity was flat-out tropical this weekend in western Germany. The water table here has been nothing but dropping for the last decade or so with zero replenishment happening and it ain't looking like that's gonna change. Rains have mostly reduced to short warm drizzles or the occasional 3-hour long flash-flood with a years worth of water coming down in an hour in selected counties. And flowing away within 24 hours. The first farmers in Germany are starting to move towards dryland agriculture (in effing Germany!), the complete vanishing of alpine glaciers is due in 5 years or so, perhaps even earlier and the famous German forrest with their Beeches, Oaks, Sykamores and such are officially a thing of the past because the water-cycle can't support them anymore.
Tourists have been steering clear of the mediterranean in recent years because the water was too warm. Not the air (although that too), the effing _water_ was too warm.
So I'd say in 2050 smoke from forrest-fires is likely to be one of our lesser problems.