Multi-decadal Ocean Change

Monthly sampling of CO2 levels in the atmosphere from sites in Hawaii and north Queensland (source: World Data Centre for Greenhouse Gases http://ds.data.jma.go.jp/gmd/wdcgg/)
Monthly sampling of CO2 levels in the atmosphere from sites in Hawaii and north Queensland

Evidence is growing to suggest that the South Equatorial Current (SEC) flowing into the Coral Sea will experience long-term change reflecting a strengthened South Pacific Gyre caused by stronger southeast trade winds.

The increase in the southern branch of the SEC is at the expense of the seasonal South Equatorial Counter Current (SECC) and will reinforce the flow of the EAC into the Tasman Sea; an area that is already experiencing some of the fastest rates of ocean warming in the world’s oceans.

Long-term changes in temperature associated with global warming are also considered the greatest threat to the survival of coral reefs in the next 100 years. In addition the rising partial pressure of CO2 dissolved in seawater is making the oceans less basic and slightly more acidic and could have a profound consequence for all marine organisms building calcareous body structures (e.g. shells, skeletons, fish otoliths).  

The following high-level science questions will guide the Queensland IMOS observing strategy in this area:

Ocean Heat Content

  • Are changes in ocean temperatures in the Coral Sea similar at all depths?
  • Do changes in ocean temperatures in the Coral Sea change the depth of the mixed layer?
  • Do Coral Sea temperature variations drive changes in temperature on the continental shelf?

Global carbon budget

  • Do changes in pCO2/pH on the GBR shelf mirror trends observed at deep ocean reference sites?