Although the flows are vastly more complex than I make out — the vast area of warmer surface water warms the atmosphere. (watertechbyrie.com)
The ability for CO2 to warm the surface of a planet through the absorption of infrared radiation is well known. (skepticalscience.com)
In global average, increases in greenhouse gas concentrations or in solar radiation bring warmer surface temperatures since they add energy to the climate system. (gcrio.org)