In terms of temperature change - nuclear winter is estimated to be a ~3C global reduction in temperature for ~10-20 years.
And yes, you're right, photosynthesis would probably cease. We're going to see similar problems in the opposite direction, probably drought on a scale heretofore never experienced in human history in temperate areas. Imagine the climate of Los Angeles moving north to Vancouver BC, and similar cascading effects across the board.
And yes, you're right, photosynthesis would probably cease. We're going to see similar problems in the opposite direction, probably drought on a scale heretofore never experienced in human history in temperate areas. Imagine the climate of Los Angeles moving north to Vancouver BC, and similar cascading effects across the board.