Published in June 2021, this briefing explores mitigation strategies and adaptation actions both for and by the ocean, as well as the importance of supporting better inclusion of the ocean in international climate change negotiations.
The ocean takes up heat and carbon, reducing the adverse effects of climate change. The ocean plays a central role in regulating climate and weather. The ocean has taken up more than 90% of the extra heat energy stored on the planet arising
from increased greenhouse gases and is taking up around 25% of the extra carbon emitted by human activities. The ocean also receives all the water from melting ice. Without such ocean uptake and storage of heat and carbon from the atmosphere, there would be much greater increases in air temperature and atmospheric CO2. However, those benefits also have costs: the ocean is warming, the rate of sea level rise is increasing, and the ocean is acidifying and losing oxygen vital to life. Furthermore, changes in ocean circulation and stratification as a consequence of climate change mean that the ocean may absorb heat and carbon at a reduced rate. In particular, climate model projections with anthropogenic forcing usually reveal a weakening in the Atlantic meridional overturning circulation over the next century, affecting how the ocean redistributes heat and carbon over the globe.