News: Reporting on our oceans
At school you receive report cards to keep track of how you’re going and to
identify strengths and weaknesses. Report cards are good for students – what
about our oceans?
The 2012 Marine Climate Change in Australia Report Card was released last week. It includes
information on factors such as ocean temperatures, sea levels, ocean currents and the El Niño
Southern Oscillation. It also includes the impacts these may have on marine plants, animals and
microbes.
The report card isn’t the work of a few researchers – over 80 Australian marine scientists from 34
research institutions, including the CSIRO, contributed research to the report card. Why so many
people? The reason is that scientists tend to specialise. For instance, a marine scientist may be an
expert on ocean currents, but know very little about fish. The report card covers such a wide range of
scientific disciplines that many experts were needed.
The report card is also different from many other scientific announcements in that it is not the result of a
single experiment or group of experiments. Instead, it brings together the observations, results and
conclusions from hundreds of scientists. This is useful as it means that the information closely reflects
the current opinions of the scientific community.
The report card doesn’t just include observations, it also includes predictions. These both have a
confidence rating from low to high. Science is not always clear-cut. Ideally, scientists will clearly
communicate how confident they are in their results and conclusions. Some of the observations and
predictions in the report card have a high level of confidence, while others only have a low level. By
increasing the data from experiment and observation scientists can increase the confidence in their
conclusions.
The previous report card was published in 2009. The 2012 report card confirmed that climate change is
already affecting our oceans, which is in turn affecting marine life in different ways. It also included
some ways that people are already adapting to the effects that climate change is having on our oceans
and marine life. Report cards such as these are useful for drawing together results from a large number
of studies into one place and for keeping track of how our oceans are changing. Hopefully in years to
come, our oceans’ grades will start improving.
More information
Read about all the findings of the 2012 Marine Climate Change in Australia Report Card
CSIRO: Report card shows Australia’s oceans are changing
Careers link
Marine careers
The 2012 report card confirmed that climate change is already affecting our oceans.
Image: CSIRO
Try this: Heavy water
You will need
• Measuring jug
• Salt
• Sand
• Kitchen scales
• Water
• Spoon
What to do
1. Half fill the jug with water. Take note of the
volume of water.
2. Add a spoonful of sand to the jug. What
happens to the volume? Add another few
spoonfuls and check again.
3. Empty the jug and rinse it out. Half fill it with
You will need these materials.
water again. Take note of the volume of water.
4. Weigh the jug on the scales.
5. Leaving the jug on the scales, add a spoonful
of salt to the water and stir to dissolve. What
happens to the mass?
6. Keep adding salt and stirring until no more
will dissolve. What is the final mass? What
about the volume?
What’s happening?
Half fill the jug with water. Add
some sand. What happens to the
volume?
Adding sand to the water changed its volume.
But why didn’t the volume change when salt
was added?
Table salt is also known as sodium chloride.
Salt crystals are made of sodium and chloride
ions. The ions have different charges, so they
attract each other. While the crystals might look
solid and continuous, the ions don’t actually
touch – there is space between them. This
space is so small that our eyes can’t detect it so
we just see a salt crystal. The same thing goes
for water: the water molecules don’t touch and
there is space between them.
When salt and water are mixed, the sodium and
chloride ions are more strongly attracted to the
water molecules and the crystals dissolve to
form a solution. The ions are small enough to fit
into the empty spaces between the molecules.
This means that while the mass of the solution
increases, there is no increase in volume.
The fact that the volume stays the same while
the mass increases means that solutions are
denser than pure water. The saltier the solution,
the denser it is. Once no more salt can
dissolve, the solution is said to be saturated.
Adding more salt will increase the volume as
there are no more spaces between the water
molecules.
Applications
The difference in density between solutions is
important in the ocean. In the polar regions
surface water freezes, creating a layer of water
Repeat, but this time weigh the jug
on some scales and add salt. After
the salt has dissolved, what
happens to the mass and the
volume?
under the ice that is saltier and thus denser
than normal sea water.
The denser, saltier water sinks to the bottom
and more surface water flows in to fill the gap
under the ice. Some of this water freezes, again
creating denser, saltier water which sinks.
This process creates a large volume of
descending water. As it sinks to the bottom of
the ocean, it pushes the water already there
out, eventually pushing it towards the equator.
When it gets closer to the equator it warms up
and rises and begins flowing back towards the
poles.
This current is known as the thermohaline
circulation and is involved in a number of the
Earth’s ocean and climate processes.
Try another salty Science by Email activity
More information
Solutions and mixtures
The thermohaline circulation – the great ocean
conveyor belt
New South Wales: Deep Oceans exhibition
The deepest parts of the ocean are some of the toughest places to live. The Deep Oceans
exhibition at the Australian Museum takes you on a journey to meet some of the bizarre
creatures that call these murky marine depths home.
The exhibition runs until 14 October. For more information and tickets, go to the Australian
Museum website.
Quiz questions
1. What colour is the pigment lycopene?
2. What animal product is usually pasteurised before human consumption?
3. What went extinct first: dinosaurs or trilobites?
4. What type of animal is the main carrier of Hendra virus?
5. What is thought to have started with the Big Bang?
Websites
Read it!
Science meets poetry at Science Rhymes. Read some of the poems here.
See it!
Check out the shortlist for the 2012 New Scientist Eureka Prize for Science Photography.
Did you know?
New research from Australian and American researchers has shown that
speech can be used to measure the severity of depression, as well as
response to treatment.
Quiz answers
1. Lycopene is red – it’s the pigment that gives tomatoes their colour.
2. Milk is usually pasteurised before human consumption.
3. Trilobites went extinct before dinosaurs.
4. Bats are the main carriers of Hendra virus.
5. The Universe is thought to have started with the Big Bang. Theoretical physicists from
Victoria have proposed a new model for the formation of the Universe.
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Written by Patrick Mahony • Edited by Mike McRae • Email sciencemail@csiro.au
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