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CSIRO recently release a new report on marine climate change impacts in Australia.  It can be viewed or downloaded here.  The summary is below.

What is happening?

Ocean temperatures around Australia have warmed 0.7°C since 1910-1929, with south-west and south-eastern waters warming fastest (HIGH confidence)

Carbon dioxide dissolving in the oceans has lowered pH by 0.1 units since 1750, representing a 30% increase in hydrogen ion (acid) concentration (HIGH confidence)

Global sea levels have risen by 20 cm over 1870-2004 (HIGH confidence)

Little evidence of change in wave heights due to climate  change (LOW-MEDIUM confidence); Strong interannual wave directional variability associated with ENSO on eastern coast (MEDIUM-HIGH confidence)

Southward flow has strengthened so warmer, saltier water is now found 350 km further south compared to 60 years ago (HIGH confidence)

Little evidence of change in ENSO variability due to global warming (LOW-MEDIUM confidence)

Southward flow has slightly weakened since the 1970s (MEDIUM confidence)

Expansion of mangroves into salt marsh habitat in south-east Australia and into freshwater wetlands in northern Australia driven by sea-level rise and soil subsidence associated with reduced rainfall (MEDIUM confidence)

A southern range extension of 300 km into Moreton Bay, Qld, of the tropical seagrass Halophila minor consistent with a warming and a strengthening East Australian Current (LOW confidence)

Loss of algal habitat off eastern Tasmania associated with a southward range expansion of a sea urchin assisted by the strengthening of the East Australian Current and warmer temperatures (HIGH confidence)

Expansion of sub-tropical species, including harmful species, into south-eastern waters is driven by warming and a strengthening of the East Australian Current (MEDIUM confidence)

Although there are no long-term data in Australia, species elsewhere are shifting distributions polewards (LOW confidence)

Sea surface warming has led to extensive coral bleaching events and declines in coral condition on the Great Barrier Reef and on north-western reefs (HIGH confidence). Ocean acidification and increased thermal stress are the likely causes of a >10% reduction in the growth rates of massive Porites corals on the Great Barrier Reef (MEDIUM confidence)

Numbers of tropical species at sub-tropical and temperate latitudes are increasing as temperatures warm indicating that some species are shifting their ranges southward (LOW confidence)

Southward range expansions in south-eastern waters are linked to warming temperatures and a strengthening of the East Australian Current; estuarine fish abundances are linked to annual fluctuations in freshwater discharge (rainfall), which is declining (MEDIUM confidence)

Replacement of small cool-temperate species in southern waters by sub-tropical and tropical species driven by warmer temperatures (LOW confidence)

Warmer sand temperatures, from increased air temperature, has increased mortality of sea turtle eggs and hatchlings at the Mon Repos rookery in south-east Qld (HIGH confidence)

Little penguins are altering their breeding time in response to warmer temperatures, and chick growth of tropical and sub-tropical seabirds has slowed in response to less food availability as temperatures warm (LOW confidence)

What is likely to happen in this century?

Australian ocean temperatures will be 1°C warmer by 2030 and 2.5°C warmer by 2100 (HIGH confidence), with the greatest warming in south-eastern waters (HIGH confidence)

Ocean pH will decrease by a further 0.2-0.3 units by 2100 (MEDIUM confidence)

Global sea levels will continue to rise 5-15 cm by 2030 and 18-82 cm by 2100 (MEDIUM confidence)

No significant change in surface waves along Australia’s eastern coast (LOW confidence); Increasing storm wave frequency, and increasing southerly wave direction, along Australia’s southern and western coasts (LOW confidence)

Likely to strengthen by a further 20% by 2100 (MEDIUM confidence)

A background “El Niño-like” pattern is projected this century (MEDIUM confidence), with no change in ENSO event amplitude or frequency (LOW confidence)

Weakening will continue over the coming century (LOW confidence)

Mangrove areas are likely to expand further landward, driven by sea-level rise and soil subsidence due to reduced rainfall (MEDIUM confidence)

Declines in seagrass abundance and extent due to sea-level rise, increased storminess and warmer temperatures (MEDIUM confidence)

Range shifts and local extinctions of cool-temperate species will occur along Australia’s temperate coastline (MEDIUM confidence)

Increased episodes of harmful algal blooms in south-eastern waters in response to extreme rainfall events and warming temperatures (LOW confidence)

Changes in community structure resulting from modified productivity regimes, as well as range extensions with warming, such as the potential for venomous jellyfish to extend southward, particularly on the east coast (LOW confidence)

Frequency and severity of mass coral-bleaching events will increase as temperatures warm, leading to declines in coral reef health (HIGH confidence). Ocean acidification will reduce coral growth rates making reefs more susceptible to erosion and disturbance from storms (HIGH confidence)

Loss of diversity and widespread changes in the composition of coral reef fish communities following degradation of coral reefs (HIGH confidence)

Breeding populations of tropical species establish in southern waters; reduction in the abundance of estuarine species as rainfall, therefore riverflow, is reduced (MEDIUM confidence)

Increased occurrence of tropical species in southern waters (MEDIUM confidence)

Declines of reef-associated sea snakes as temperatures warm and coral reefs degrade (LOW confidence); some tropical sea turtle nesting beaches will produce 100% females (MEDIUM confidence)

Warmer temperatures and an El Niño-like future climate are expected to reduce food availability for breeding seabirds leading to a reduction in breeding success (MEDIUM confidence)

 

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