Global warming is popularly viewed only as an atmospheric process. In fact, most heat uptake occurs in the ocean. How have subsurface ocean temperatures varied during past warm and cold intervals? How did scientists measure these climate changes? (National Geographic News)
- According to the Nat Geo News article, ocean researchers studied two sites in Indonesia, “because [the sites] are seen as representative of places where Pacific Ocean waters have mixed for millennia.” The sites are the Makassar Strait and Flores Sea. Look at our MapMaker Interactive, focused on these marine areas. What other bodies of water do you think contributed to the marine mixing? (You may want to zoom out to get “the big picture”!)
- The island nation of Indonesia is surrounded by seas and straits! According to the terrific Science article (read it!), the areas studied “serve as major conduits for exchange of water between the Pacific and Indian Oceans.” In particular, deep-ocean currents from the Celebes Sea, Molucca Sea, Banda Sea, Java Sea, Karamata Strait, even the South China Sea and Sulu Sea probably mixed in and around the Makassar Strait and Flores Sea.
- Using our MapMaker Interactive, turn on the “Sea Surface Temperature” layer. (Hint: It’s in the “Physical Systems – Water” panel.) Is this the ocean-temperature data researchers were studying?
- No! Our data layer is the sea surface temperature. Scientists in the article were studying subsurface temperature—water 920 meters (3,018 feet) beneath the surface.
- How did researchers determine what the subsurface ocean temperature was 10,000 years ago? (Our “media spotlight” photo gallery on “Armored Amoebas” might help!)
- They analyzed sediment cores from the ocean floor. These sediment cores included tiny creatures called foraminifera—forams for short. Forams are outstanding indicators of the state of the ocean. Their tests, or shells, record minute changes in the temperature, salinity, and chemical make-up of their marine environment. (In particular, the researchers studied the tests of this foram, Hyalinea balthica, and its ratio of magnesium to calcium, a method so reliable it has its own name: Mg/Ca paleothermometry. Use that to sound smart at your next party.)