Final answer:
Earth Scientists study seafloor spreading rates and global sea level changes to explain the dynamics of ocean basins. The Pacific Ocean is shrinking and deepening due to slower spreading rates, whereas the Atlantic Ocean is expanding and shallowing due to faster spreading at the mid-Atlantic Ridge.
Step-by-step explanation:
Earth Scientists use various methods to explain why the Pacific Ocean is getting smaller but deeper, and the Atlantic Ocean is getting wider and shallower. They compare the seafloor ages between the mid-Atlantic Ocean and off the coast of South America in the Pacific Ocean to determine spreading rates. The mid-Atlantic Ridge is spreading faster than the Pacific spreading ridges. This is determined by knowing that younger seafloors are typically closer to spreading centers; thus, the location where new material is added at a faster rate has more young seafloor near the ridge.
Illustrating the point, Europe and North America are moving apart by about 5 meters per century, a process that adds new ocean floor along the mid-Atlantic Rift, which is about 5000 km long. The total area of new ocean floor created in the Atlantic each century is calculated by multiplying this spreading distance (5 m/century) by the length of the rift, resulting in a vast expanse of new seabed.
Additionally, the gradual rise in global sea levels, both due to the melting of land ice and thermal expansion as the oceans warm, also affects ocean depths and areas. This global climatic change plays a role in the changing characteristics of our oceans. By studying and understanding these phenomena, Earth Scientists provide insights into the dynamic processes shaping our planet.