< Europe and Australia, collaborating to observe the global ocean
01.11.2016 02:16 Age: 177 days
Category: Home Slider, BlueWater, SRS, Argo, ANMN, SOOP

The oceans surrounding Australia have warmed, with the greatest surface warming to the west and south of the continent: State of the Climate 2016.

The CSIRO and Bureau of Meteorology have just released the 2016 State of the Climate report.


Cover of the report: State of the Climate 2016, Bureau of Meteorology & CSIRO

Time series of anomalies in sea surface temperature and temperature over land in the Australian region. Anomalies are the departures from the 1961–1990 average climatological period. Sea surface temperature values are provided for a boxed region around Australia (4–46 °S and 94–174 °E). © Bureau of Meteorology CLICK ON IMAGE TO ENLARGE

High-quality global sea-level measurements from satellite altimetry since 1993 (red line), in addition to longer-term records from tide gauges (blue line, with green shading providing an indication of the confidence range of the estimate). www.cmar.csiro.au/sealevel/. From 1993–2013 sea level has risen at a rate of about 2.6–2.9 mm per year with a confidence range of +/- 0.4 mm (Watson et al, 2015). © CSIRO CLICK ON IMAGE TO ENLARGE

This fourth, biennial State of the Climate report draws on the latest monitoring, science and projection information to describe variability and changes in Australia’s climate, and how it is likely to change in the future. Observations and climate modelling paint a consistent picture of ongoing, long-term climate change interacting with underlying natural variability.

Key points for the ocean are:

  • Ocean temperatures and ocean heat content have been steadily increasing globally.
  • The Argo global ocean observing system reveals that over the past decade ocean warming extends to a depth of at least 2000 m.
  • Globally-averaged sea level has risen over 20 cm since the late 19th century, with about one third of this rise due to ocean warming and the rest from melting land ice and changes in the amount of water stored on the land. The rise in mean sea level amplifies the effects of high tides and storm surges.
  • Oceans around Australia have become warmer and there is an increased level of acidity.

Ocean observations underpin this critical climate research and modelling, with IMOS data contributing to the report findings in four key sections:

Sea-surface temperature: remotely sensed sea surface temperature (SST) data are important inputs to climate models, and there is a need for high quality in-situ SST observations to improve validation of satellite SST and ocean models.  IMOS provides streams of high quality, near real-time (within 24 hours), SST observations from 14 vessels in previously un-validated regions around Australia such as coastal areas and the Southern Ocean.

Ocean heat content: ocean heat and salinity to a depth of 2,000 metres below the surface are observed by the global Argo float array. IMOS provides the cornerstone investment for Australia’s ongoing participation in the global Argo program, which has resulted in ~10% of the global array of 3,700 floats delivering a continuous data stream for the Australian region.

Sea level: satellites monitoring the height of the ocean (called altimeters) are the tool of choice for studying sea level rise.  Precise measurement from space pushes these satellite systems to their limits and some high quality measurements from within the ocean are required.  State-of-the-art GPS buoys maintained by IMOS provide the only altimeter calibration and validation sites in the Southern Hemisphere.

Ocean acidification: ocean acidity is measured in units of pH, and is monitored globally via a number of platforms including a network of repeat hydrographic surveys, time-series stations, floats and glider observations, and volunteer observing ships. IMOS maintains three acidification time-series stations around Australia (Kangaroo Island, Heron Island/Yongala and Maria Island) as well as measurements from volunteer observing ships, and data from these stations is contributing to the Global Ocean Acidification Observing Network (GOA-ON). 

The changes outlined in the report affect many Australians, particularly changes associated with increases in the frequency or intensity of heat events, fire weather and drought. Australia will need to plan for and adapt to some level of climate change. This report is a synthesis of the science informing our understanding of climate in Australia, and includes new information about Australia’s climate of the past, present and future. The science underpinning this report will help inform a range of economic, environmental and social decision-making and local vulnerability assessments, by government, industry and communities.

 

The State of the Climate 2016 report can be found on the Bureau of Meteorology or CSIRO websites.