Deep thinking on the world’s oceans

Changes in deep ocean conditions affect global climate, with deep warming contributing to sea-level rise and the deep ocean absorbing atmospheric carbon dioxide.

To assess change, researchers determine the amount of energy (in the form of heat), water and gases (including carbon dioxide), entering and exiting the ocean. They rely on valuable but infrequent deep ocean measurements from ships, incorporated into sophisticated computer models, to project the extent of future warming.

“It may seem far removed from rising temperatures or shifts in rainfall cycles but the deep ocean is a significant component of the Earth’s climate system,” says Deep Ocean workshop coordinator, Dr Bernadette Sloyan from the CSIRO Wealth from Oceans Flagship.

“The deep oceans play a crucial role in setting the rate and nature of global climate change and variability through their moderation of heat, freshwater, and carbon cycles.

“This workshop will help guide the next three to four years of internationally focused deep ocean research, generating a greater understanding of ocean dynamics for inclusion in the next report of the Intergovernmental Panel on Climate Change.”

Despite numerous technological advances over the last several decades, ship-based surveys remain the only method for obtaining high-quality observations of a suite of physical, chemical and biological parameters over the full water column, especially for the deep ocean below two kilometres (52 per cent of global ocean volume).

Predicting climate change and sea-level rise depends critically on knowledge of the changing balances of greenhouse gases, heat and water, and the processes governing them.