One way to monitor global warming is to gauge the average temperature of the ocean. Researchers are doing this by measuring the time it takes sound pulses to travel underwater over large distances. At a depth of 1000 m, where ocean temperatures hold steady near 4C, the average sound speed is 1480m/s. It's identified from laboratory measurements that the sound speed increases 4.0m/s for every 1.0C increase in temperature. In one experiment, where sounds generated near California are detected in the South Pacific, the sound waves travel 8400km
If the smallest time change that can be dependably detected is 1.0 s, what is the smallest change in average temperature that can be gauged?