Indicator: AAT-06 Average deep water salinity
Source: Department of the Environment and Heritage 2005, Southern Ocean studies reveal widespread changes, viewed 11 Jul 2006, http://www.aad.gov.au/Asset/magazine/2005autumn/03%20Southern%20Ocean%20studies%20reveal%20widespread%20changes.pdf.
In January 2005 a marine science and oceanography expedition found that ‘the deep waters of the Southern Ocean are cooler and less salty than they were 10 years ago’ (Department of the Environment and Heritage, Australian Antarctic Division, Autumn 2005, ‘Southern Ocean studies reveal widespread changes’, Australian Antarctic Magazine, p 4). While the changes are small in absolute terms (e.g. cooling of about 0.1 0C cooler and 0.015 parts per thousand less salty), they are large compared to variability in other regions (e.g. about 50 times larger than the changes in waters near Perth).
‘This change could affect the global pattern of ocean current movement, sometimes called the ‘ocean conveyor belt’. This conveyor belt influences climate by carrying heat around the globe, absorbing carbon dioxide and carrying oxygen to the deep ocean. One possible explanation (for the changes) is that more glacial ice is melting due to the impact of climate warming. But it could also be a natural climate cycle.’
More research is needed into the implications of these changes.
Australian Antarctic Territory — Environment - Atmosphere, climate and oceans
The sinking of dense water near Antarctica forms part of an ‘overturning’ or ‘conveyor belt’ pattern of oceans currents that influences global and regional climates. Any changes in these measurements can influence a large region of the ocean in just a few years. The conveyor belt influences climate by carrying heat around the globe, absorbing carbon dioxide and carrying oxygen to the deep ocean.
Other indicators for this issue:
- AAT-01 Monthly mean air temperature anomalies at Australian Antarctic stations
- AAT-04 Concentrations of greenhouse gases
- AAT-05 Average deep water temperatures
- A-01 Annual variation in the Southern Oscillation Index
- A-12 Trend in the area of the ozone hole