Final answer:
Without oceans, Earth would experience more extreme seasonal temperature changes due to the lack of water's moderating effect on climate. The usual concerns about ice cap melting would be irrelevant, but other greenhouse effects might still cause climate changes. The overall temperature could become cooler because of reduced heat retention.
Step-by-step explanation:
If Earth were entirely covered in dry land with no oceans, the seasonal temperature changes would be more extreme than they are now. Water has a high specific heat capacity, which means it absorbs a lot of heat before it gets very hot, and it releases a lot of heat before it gets very cold. This regulates the Earth's temperature, making the climate milder, especially in coastal regions. Without oceans, the land would heat up and cool down much faster, leading to harsher climates with hotter summers and colder winters.
Moreover, the global climate change effects, such as the melting of ice caps and the movement of climate gradients up mountains, would not occur in the same manner without oceans. For instance, the rate of melting of the polar ice caps would not be a concern, as the polar ice caps as we know them would not exist. However, the other aspects of climate change due to greenhouse gas emissions, such as atmospheric temperatures rising and shifts in climate patterns, could still affect a no-ocean Earth, although the dynamics would differ significantly.
Lastly, it is also crucial to understand that the greenhouse effect contributes to keeping Earth's climate in a range that supports life. With an increased land surface, the absorption and retention of heat would lessen, potentially leading to an overall cooler Earth, depending on the atmospheric composition.