The ocean is a major influence on weather and climate. It shapes how the Earth's energy, water and carbon systems function:

• The ocean absorbs much of the sun's energy, or solar radiation, that reaches the Earth. When the ocean loses heat by evaporation, this heat loss drives atmospheric circulation and weather patterns. Water vapor in the atmosphere condenses to form rain (and, in turn, sleet and snow). Water condensation over warm ocean provides the energy for hurricanes and cyclones.
  

The El Niño Southern Oscillation (ENSO) causes important changes in global weather patterns because it changes the way heat is released in the atmosphere in the Pacific Basin.

• The ocean dominates the Earth's water cycle. The five great ocean basins - the Atlantic, Pacific, Indian, Arctic and Southern - contain 97% of the water found on Earth. The water vapor they release into the atmosphere returns as rain, sleet and snow supplying the planet with fresh water. Most rain that falls on land originally evaporated from the tropical ocean.
  

• The ocean is also a major influence on the carbon cycle. The ocean absorbs roughly half of all carbon dioxide from the atmosphere. Half of the photosynthesis (or primary productivity) on Earth takes place within microbes that live in the sunlit layers of the ocean. 
  

The ocean has, and will continue to have, a significant effect on climate change by absorbing, storing, and moving heat, carbon and water. The ocean, in turn, is also affected by climate change due to increasing concentrations of greenhouse gases, including carbon dioxide. The impacts of climate change include:

• Sea level rise due to direct warming and expansion of oceans as well as melting of glaciers.
• Ocean acidification due to increased uptake of carbon dioxide and changes in ocean chemistry
  
• Human health impacts from changes in the seasonality and geographic scope of infectious diseases of humans, animals, and plants
  
• More extreme weather events due to increased ocean surface temperature and changes in ocean circulation patterns

Additional Resources:
NOAA: http://www.education.noaa.gov/Climate/