The Sea Surface Temperature (SST) of the ocean is indicated by measurements taken at depths that range from 1 millimeter to 20 meters. Some measurements are made using shipboard instruments, but satellites now provide the majority of global SST data.
The primary cause of rising SST levels worldwide is climate warming due to excessive amounts of greenhouse gases being released into the atmosphere; heat from the warming atmosphere raises the temperature of the sea surface. Downwelling currents convey some of this heat to the ocean’s deeper layers, which are also warming, though lagging far behind the rise in SST.
Water expands as it warms and the increased volume causes sea level rise. Climate warming also melts glaciers and continental ice caps, adding water to the ocean and further increasing sea level rise. The rate of global sea level rise has accelerated over the past few decades.
According to the Intergovernmental Panel on Climate Change (IPCC), global sea surface temperatures are expected to rise by approximately 0.4 – 1.1°C by 2025.
Thermal expansion and the increased supply of meltwater from glaciers and continental ice caps could contribute a 1m-3m sea level rise by the end of this century (Dasgupta 2007).
How was this measured?
The sea surface temperature rise map was taken from Micheli et al.(2013), which uses detailed spatial analysis of rates of change in sea surface temperature, utilizing satellite remote sensing data for 1985-2006 from Nykjaer (2009).