The world’s oceans have taken up 93% of the heat from human global warming to date and about 30% of the carbon dioxide. This has slowed the rate of the warming of Earth’s surface to only 1.2 C since 1850. If Earth had no oceans the atmosphere would be 36 C warmer by now! However, a consequence of all that heat going into the ocean is that water expands when heated and sea-level is rising. One third of the observed global sea-level rise since 1880 is from ocean thermal expansion.
The warming of the ocean has wider impacts, including marine heatwaves and can contribute to polar ice melt, especially the Antarctic ice sheet where one third of its ice sits on bedrock below sea level and is already melting at an accelerating rate due to ocean warming.
To find out more about the ocean and thermal expansion:
- NASA explains thermal expansion
- The Ocean as a carbon sink from the Ocean & Climate Platform
- Global changes to ocean heat are monitored by NASA
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Vertical land movements
Vertical land movement has a direct impact on local sea level along coastlines.
Polar ice melt
An urgent priority for scientists is estimating the rate at which the Antarctic ice sheet will melt over the coming decades and centuries.
Shared socioeconomic pathways
These comprise different socio-economic assumptions that drive future greenhouse gas emissions.