Encompassing approximately 70% of the Earth’s surface, oceans wield substantial influence over weather and climate patterns. As a global reservoir, oceans engage in a continuous exchange of heat, moisture, and carbon with the atmosphere, thereby driving weather dynamics and impacting the climate.
Their influence on climate is manifested through various mechanisms, such as the absorption of solar radiation, release of heat necessary for atmospheric circulation, emission of aerosols affecting cloud cover, contribution to rainfall over land, and absorption and storage of atmospheric carbon dioxide for extended periods, ranging from years to millions of years.
Interaction between oceans and atmosphere for the stabilization and regulation of climatic variations:
• Global circulation: Both the oceans and the atmosphere facilitate the transport of heat from the equatorial regions towards the polar regions, with approximately equal efficiency. The atmosphere accomplishes this through a complex global wind pattern that blows across the ocean’s surface, thereby propelling corresponding ocean currents. Although ocean currents move more slowly than winds, they possess a significantly higher heat storage capacity. As these winds drive ocean circulation, warm water is transported along the sea surface towards the poles, releasing heat into the atmosphere during the journey.
• Role of heat transport and ocean circulation: The vast heat content within the oceans plays a pivotal role in stabilizing the Earth’s temperature. Compared to the atmosphere and land, the ocean’s heat capacity is considerably greater. Consequently, the ocean gradually warms during summer, maintaining cooler air temperatures, and cools gradually during winter, ensuring warmer air. This characteristic results in coastal cities like San Francisco experiencing minimal temperature fluctuations throughout the year, while inland cities such as Fargo, ND encounter wider temperature ranges.
• Biological pump: Oceanic biological productivity serves as both a source and a sink for carbon dioxide, a greenhouse gas that influences climate. The biological pump is a process in the ocean where phytoplankton convert carbon dioxide and nutrients into carbohydrates, leading to the production of reduced carbon. A portion of this carbon sinks to the seafloor and becomes buried in sediments.
• Carbon dioxide exchange: Carbon dioxide is also exchanged at the air-sea interface. It dissolves in cold water at high latitudes, subsequently being subducted with the water. The carbon dioxide remains in the deeper ocean for extended periods, ranging from years to centuries, before resurfacing and being released back into the atmosphere as the warmed water ascends.
Hence, heat transport and ocean circulation serve as crucial factors connecting physical oceanography with climate variability. Additionally, biological oceanography impacts climate through the biological pump. Collectively, air-sea gas fluxes and the penetration of solar radiation represent feedback loops between physical and biological oceanographic processes that ultimately influence climate. Accordingly, the ocean is often regarded as the thermal memory of the climate system.