OCEAN STATE REPORT (4) SUMMARY
MAJOR IMPACTS OF CLIMATE CHANGE OCEAN ACIDIFICATION: THE OCEAN IS BECOMING MORE ACIDIC
Atmospheric Carbon Dioxide
The ocean is a major sink of anthropogenic excess CO2. This absorption of carbon mitigates the effects of global warming, but it also results in a major threat to marine life — ocean acidification.
Absorbed by the ocean
The pH of contemporary surface ocean waters is already 0.1 pH units lower than in pre-industrial times. As pH is logarithmic, this 0.1 pH unit change is equivalent to a nearly 30% increase in ocean acidity since pre-industrial times.
Carbonic Acid Ocean Acidification
pH
Global Mean Sea Level Units: Centimetres/year
Trend from 1993-2018
8
TP-A drift corrected (Ablain), trend = 3.08 ± 0.39 mm yr-1
6 Global Mean Sea Level [cm]
SEA LEVEL RISE CONTINUES, BUT AT AN ACCELERATED PACE
Water
Ocean acidification threatens marine ecosystems and impacts many biological processes. Changing ocean chemistry is particularly dangerous to calcifying organisms like shellfish and coral.
Carbonate
TP-A drift corrected (Watson/Dieng), trend = 3.13 mm yr-1
4
2
TP-A drift corrected (Beckley), trend = 3.12 mm yr-1
0
-2 1992
1996
2000
2004
2008
2012
2016
no TP-A drift correction, trend = 3.35 mm yr-1
Sea level rise in centimetres (cm) for the period 1993-2018.The curves show different corrections for an instrument anomaly on the TOPEX-A altimeter (TP-A). The black, red and green curves show TP-A drift corrections applied based on work by Ablain, Watson/Dieng, and Beckley, respectively. The shaded red area shows a 90% confidence interval for each measurement, and the blue curve represents no TP-A correction. Source: Modified after WCRP Sea Level Budget Closure Group (2018), appears in the Copernicus Marine Ocean State Report 4. Warming Melting Atmosphere Continental Ice
Since 1993, global mean sea level has risen at a rate of 3.3 ± 0.4 mm per year. New calculations in the fourth Ocean State Report reveal that sea level rise is accelerating, with this rate increasing by 0.12 ± 0.073 mm/year each year. An instrument drift correction to the global mean sea level time series is also discussed in the fourth Ocean State Report. Knowledge of sea level rise is fundamental, as it allows us to better characterise the consequences of rising seas for coastal populations and low-lying areas.
6
Sea Level Rise
Ocean Thermal Expansion
Ocean Warming
