Read the excerpt from "Climate Change: An Overview.” By the early twentieth century, carbon emissions from fossil-fuel burning reached 1 billion tons a year. Automobiles, airplanes, and domestic and agricultural energy demands all contributed to the rising trend. In the 1950s, scientists used a new generation of equipment to confirm that carbon-dioxide concentrations were doubling and that this would have the effect of increased temperatures.

This excerpt primarily describes the

long-term effect of increasing carbon emissions.
long-term effect of decreasing temperatures.
short-term effect of decreasing the use of new technology.
short-term effect of increasing energy demands.