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.