I'm aware you said its still a ways off but "green bridges"[1] as well as other persistent pests could become a big issue especially in a broadacre monoculture operation (which is what agriculture generally is if we're talking staple crops). Also from experience with dealing with perennial pastures removing them should the disease get out of control would be a nightmare when the root systems are established. Victory Gardens definitley sound like a good idea though. Just my 2c
increased evaporation - water vapor is a potent green house gas
increased co2 > increased diffusion into seawater - isnt acidity of the ocean increasing, making it more difficult for the shelled sea life to even develop?
1: https://www.agric.wa.gov.au/grains/control-green-bridge-pest...