It appears to me that the complete deindustrialization of the imperial core is a historical arc that, since 1973, has been more or less unstoppable. The question is, if a socialist world revolution were to happen in the near future, and they basically established JDPON, how would it be possible to reindustrialize the former imperialist nations without relying on exploiting the former periphery countries? The actual productive capacity has been decimated.
Pure doomerism. We are headed for crop failures, but we currently massively overproduce food for the human population, and produce that food very inefficiently.
Even the worst case scenario for climate change predicts a peak production in 2040, at almost 50% higher than current, and then a decline of 25% over the next 50 years. If there's mass death, it will be because capitalism fucks over distribution and acclimation as it always does, but the scenario you are describing isn't supported by any climate/agricultural science.
There is enough space, there is enough water and there is enough agricultural land to accommodate two billion climate migrants in the north and south over the next eighty years, and it's something we can accomplish.