You've no doubt read that climate models predict a 4°C rise in global temperature by the end of the century. "Incompatible with organized society" is usually how this threshold is described. Nobody can picture that clearly, it's so vague. But you do have clear images for the direction in which we're moving.
California wildfires and their smoke are this transition. Fire is part of any deciduous forest-to shrub-to grassland- to desert ecological transition.
There are two big picture components.
1. Short term, jet stream changes due to Arctic warming create ridging which dries out the Western US.
... the amount of sea-ice found in the Arctic during the winter months is a driving force behind summertime weather conditions that control wildfire activity in the western United States during the summer.
In the case of western wildfires, the connection may be through a phenomenon called the “Arctic Amplification,” whereby temperatures in the highest latitudes of the northern hemisphere are increasing at much faster rates than the global average.
The process then works through what climatologists call a “teleconnection,” whereby what happens in one part of the world impacts the weather in other parts of the world. Atmospheric teleconnections are well-known, with one of the best examples being a reduction in Atlantic hurricane activity during strong El Nino years because El Nino is associated with increased high altitude winds over the Atlantic that tend to rip apart developing thunderstorms.
For wildfires, the connection is through the jet stream. Knapp and Soulé’s research presents evidence showing that increased undulations in the summertime jet stream over the western United States create warmer and drier conditions that are conducive for wildfire activity. The specific term they use is “ridging,” which means that the jet stream over the western United States bends northward. Under this northward bend extended periods of sinking air develop, which bring exceedingly warm and dry conditions.
They note there has been a 65 percent increase in the meridionality, or waviness, of the jet stream since the early 2000s, and this waviness causes the warmer and drier conditions. In turn, western wildfire activity has skyrocketed since 1980, ...
2. Long term (i.e. in about 85 years), we are moving toward a 4°C rise world where most of the US has become desert.
What the World Will Look Like 4°C Warmer Take a good look at their map.
Here's our piece of what the world will look like at 4°C rise.
The green area in Canada has arable conditions. Orange means desert. Red is underwater. Brown areas have been abandoned as uninhabitable. Where I'm typing this second, in Eastern Pennsylvania, will be abandoned in about 85 years. Here's the key.
The good news is that lots of that desert could be used for solar energy, if there were a civilization left capable of building it.
Since climate destabilization is nonlinear, we'll likely see staggered periods of slow change followed by very rapid degradation after tipping points. <sigh>