Some data suggest that the average global
temperature will increase by 1°C–2°C by the
year 2050. If this occurs, a major concern for
humans would most likely be that
(1) sea levels might rise enough to flood some
coastal areas
(2) long-term stability of the climate will benefit
ecosystems
(3) the availability of salt water for agricultural
use will increase
(4) the threat of extinction of land organisms will
decrease