GREAT BARRlER REEF - Saint Ignatius' Moodle Community

Threats to the Great Barrier Reef:
Climate change
Climate change poses the biggest threat to the Great Barrier Reef. It is caused
by increased amounts of carbon dioxide and other greenhouse gases in the
air trapping the sun’s heat. Climate change affects the Great Barrier Reef in
many ways.
Warmer seas
As more of the Sun’s heat is trapped in the Earth’s
atmosphere, the sea becomes warmer. The average
annual water temperature in the Great Barrier Reef
is rising, leading to more cases of coral bleaching.
It could be one to three degrees Celsius warmer by
2100. Two severe bleaching events have already
occurred since 1998.
Impacts from climate change
have already been witnessed
and all parts of the [Great
Barrier Reef] ecosystem are
vulnerable to its increasing
effects, with coral reef habitats
the most vulnerable.
Great Barrier Reef Marine Park
Authority, 2009
Acidification
When there are high concentrations of carbon dioxide in the air, some enters seawater and
combines with it to make acid. This acidification slows or stops reef-building by corals by
stopping them from making their skeletons. Corals weaken and break. Water in the Great Barrier
Reef has already become measurably more acidic. Scientists predict that the process will speed
up in the future.
Rising sea level
Climate change causes the sea level to rise in two ways. As seawater warms, it expands and fills
more space. Also, as polar ice melts, it adds more water to the sea. In the Great Barrier Reef, the
sea level has risen around three millimetres each year since 1991. If this continues, sunlight will
stop reaching the reef, and corals will die.
More frequent and severe storms
Climate change is predicted to lead to more frequent and more severe storms. Storms break
coral reefs. Rapid climate change would devastate the Great Barrier Reef’s animals and plants.
They would not have time to adapt.
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The effects of climate change on the Great Barrier Reef include rising water
temperature, sea level and acidity, and predicted increased storm activity.
Storms can break off coral. This piece of Staghorn coral will die because
it has been broken from its base.
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Macmillan Digital Library: What’s the Issue? Set 2 © Michelle Atkins, Julie Murphy, Greg Reid, Geoff Thompson, Ashten Warfe/Macmillan Publishers Australia 2011 ISBN 978 1 4202 9209 1 Macmillan Digital Library: What’s the Issue? Set 2 © Michelle Atkins, Julie Murphy, Greg Reid, Geoff Thompson, Ashten Warfe/Macmillan Publishers Australia 2011 ISBN 978 1 4202 9209 1