The effects of global warming and melting polar ice have already had an impact in terms of extended droughts, more extreme hurricanes and tornadoes, floods and forest fires. Resultant changes in ocean temperatures may affect ocean currents, pushing storms in northern latitudes northward. These changes many push humanity and agriculture northward, populating previously remote regions of Canada, Russia, and elsewhere.
The rapid acceleration of polar ice melt, and extreme weather events experienced by the world as of late, may demonstrate that global warming is here to stay and perhaps beyond intervention and blame to some degree. The general runaway effect involves loss of polar ice, loss of solar reflectivity, ocean warming (and possible diminishing of ocean currents) which will push precipitation towards the poles. Together with a predicted 8–10 degree increase in temperatures, look for desert areas to expand and agriculture to also move towards the poles. Since there is much greater land mass in the Northern Hemisphere, look for previously chilly Canada and Russia to become larger ag and population centers by 2100.
The Reasons for Changes in Weather Patterns and Warming
The reasons for higher temperatures by 2100 are relatively simple. Increases in CO2 and Methane are trapping solar heat in our atmosphere, while melting polar ice is reflecting less, and trapping more sunlight. If the situation is not reversed (via some miraculously rapid CO2/Methane reduction or Geoengineering marvel), we may all have to live with this warmer climate, with extended droughts and extreme weather. Actually, what we may be seeing is an continuation of a process that began 10,000 years ago, when polar ice extended into Europe and the Great Lake States (and the Middle East was actually green and fertile, not the desert we see today). When the polar ice recedes, the tropical climate gets hotter and wetter, the mid latitudes drier, and the northern latitudes warmer and wetter (much of Canada and Russia have previously been colder and drier). Due to resultant lower temperature differentials between the poles and the equator, we are likely to see a decline in ocean currents (which are driven by this temperature differential). A lack of ocean currents has the effect of both a) further warming the planet, due to a diminishing of CO2 eating phytoplankton, and b) Pushing atmospheric pressure zones northward, keeping storms from reaching the mid latitudes. We may already be seeing this effect at work, judging from the increased droughts and forest fires in California, Europe, and Australia. Scientists are careful to say there are other factors complicating the relationship between melting ice and rainfall patterns (including the Pacific Decadal Oscillation, The boyand possibly orbital effects such as Milankovich Cycles). In fact, scientists concede that weather models are almost impossibly hard to predict with high accuracy (given many overlapping and complicating factors). What follows will be my prediction, based upon generally known phenomenon. (scied.ucar.edu, 2019),(greentumble.com,2018),(Kahn,2017),(Kintic,2017)

The World 100 Million Years Ago
This is not exactly comforting, but animal life actually thrived during the last great warming period, the Cretaceous Period (roughy 144 to 65 million years ago), when the dinosaurs dominated. There was no polar ice, the equator was blistering hot (averaging in the high 90s F), while even the most northern and southern latitudes were largely frost-free and averaging about 40 degrees F. CO2 in the atmosphere was much higher than it is today (about 2,000 ppm, compared to about 415 ppm), which may give us some hope for survival. Ocean levels were anywhere from 330 to 800 feet higher than today (!) The increase in CO2 was due to a massive decay in vegetative matter, combined with several volcanic events. Though the earth was busy creating the balance of conifers and tropical vegetation that we see today, there were not enough plants to offset this CO2 increase. Nevertheless, animals and plants apparently thrived, although in a much hotter and more humid environment. (How, 2022),(Wang,Gao,Ibarra,Wu,Wang,2021),(Britannica.com,nd.)
What if Cretaceous Conditions Began Happening Again
The year 2100 will likely be a far cry from Cretaceous conditions, but it may be a pretty good hint of things to come. For starters, ocean levels may rise about four feet, which may have the effect of major flooding in coastal cities. Temperatures may rise by 4 degrees F, which may make deserts hotter and northern climates (again, think Russia and Canada, also Alaska, Greenland, Scandinavia) more hospitable and farmable. Tropical areas will continue to be tropical, only even hotter and wetter (good for some ag, not so good for other ag). (nca2014.globalchange.gov,2014)

How Will We Adapt:
For this discussion, I will talk primarily about the Northern Hemisphere, since the Southern Hemisphere has so much less farmable/livable land mass (suffice it to say that Australia and Argentina may suffer the same fates as California). Given normal technological growth, we may see both a gradual migration of humanity northward, but also an ability to adapt to these conditions. Agriculture is already moving towards fruits and vegetables, which actually like desert conditions (hotter, drier) and need less water. The “grain belts” currently in places like the Midwest and Ukraine, will surely shift northward into Russia, Canada and elsewhere. Grain may actually become less important to our diet, as our population may shift away from meat and dairy (and the 40% of grain that feeds that industry). Forests will very likely shift northward, and shrink substantially. If energy can be produced cheaply and cleanly (think solar, wind, nuclear here), dry areas may continue to be cheap energy producers and thus livable using artificial climate controls, perhaps in some sort of biodome oases.