1. Explain the difference between C3 and C4 plants and describe how changing the climate could impact the geographical spread of these plants.

The C3 plants uses the C3 pathway or the Calvin Cycle for the dark reaction of photosynthesis where as the C4 plants use the Hatch and slack pathway or the C4 pathway for the dark reaction of photosynthesis. There is a difference between C3 and C4 plants. C3 plants survives in cool and wet areas where as C4 plants survives in warm and dry areas. The C3 plants are found more around the world while the C4 plants are found more in very dry an arid places. 

2.  with the potential change in temperature during the springs and autumn months, what long term socio-economic problems do you think countries in the mid-to-upper latitudes might face?

With the potential change in temperature there is a chance that the temperatures in the spring and fall will start getting warmer faster and stay warm longer. Some problems included in countries in the mid-to-upper latitudes are the population in the cities can experince warmer temperatures for longer. And as we discussed about the urban heat island effect there will be more people who will pass away due to the increased heat. The crops in the middle latitudes will have trouble with adapting and will have to be moved farther north. Homes in the middle latitudes are not equipped for the increased temperatures. The animals also in these ranges will have to adapt or move to cooler temperatures if they can.