What are some effects of even a small increase in temperatures?

Some effects include the introduction of new crops, the dying off of old crops, new weather patterns, and new animals species.

Explanation:

Crops may be able to survive in this slightly warmer climate more easily than they ever could before. The introduction of these new crops could eventually lead to a population increase which results in more communities and towns. New animals species can do one of two things. They can lead to an increase of population through hunting or they can disrupt the fragile ecosystem and lead to animal population decrease eventually resulting in an imbalanced ecosystem.

answer; taking up arms to defend the nation;

a drastic rise in oil prices ended decades of postwar.