Marine Climate

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East Australian Current

Tasmania eac

Lead Author: 

Ken Ridgway 1

Co Authors: Katy Hill 2

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What is happening?

The intensification of flow and accelerated warming observed in the EAC is also seen in other Southern Hemisphere western boundary current systems, driven by the strengthening and contraction south of Southern Hemisphere westerlies (wind), although regional responses mean rates of warming differ among systems. A range of species, including plankton, fish and invertebrates, are now found further south because of enhanced transport of larvae and juveniles in the stronger EAC and the high rate of regional warming.

What is expected?

EAC flow will increase off southeast Australia with a compensating decrease off north-east Australia.

What we are doing about it?

New observations established as part of IMOS are beginning to provide an integrated view of the EAC. Long-term monitoring at Maria Island (Tas),and Port Hacking (NSW), are being sustained and enhanced as part of a network of National Reference Stations; a new station has also been established at North Stradbroke Island (Qld). IMOS is also supporting the Ships of Opportunity XBT network (provides temperature profiles every 25 km along ship tracks) in the Tasman Sea, which captures key limbs of the EAC system; and is delivering these data in real time.

Summary

The East Australian Current (EAC) is a complex and highly energetic western boundary system in the south-western Pacific off eastern Australia. The EAC forms part of the western boundary of the South Pacific Gyre and the linking element between the Pacific and Indian Ocean gyres.

The EAC is similar to other western boundary currents and is dominated by a series of mesoscale eddies which produce highly variable patterns of current strength and direction. Seasonal, interannual and particularly strong decadal changes are observed in the EAC which tend to mask the underlying long-term trends related to greenhouse gas (GHG) forcing.

Observations from a long-term coastal station off Tasmania show that the EAC has strengthened and extended further southward over the past 60 years. The south Tasman Sea region has become both warmer and saltier with mean trends of 2.28°C/century and... continued on the full report

Ocean acidification

Carbonic-acid-3d-vdw

Lead Author: 

William R. Howard 1

Co Authors: Merinda Nash 2, Ken Anthony 3, Katherine Schmutter 4, Helen Bostock 5, Donald Bromhead 6, Maria Byrne 7, Kim Currie 5, Guillermo Diaz-Pulido 8, Stephen Eggins 9, Michael Ellwood 9, Bradley Eyre 10, Ralf Haese 11, Gustaaf Hallegraeff 12, Katy Hill 13, Catriona Hurd 14, Cliff Law 5, Andrew Lenton 15, Richard Matear 15, Ben McNeil 16, Malcolm McCulloch 17, Marius N. Müller 12, Philip Munday 18, Bradley Opdyke 9, John M. Pandolfi 19, Russell Richards 20, Donna Roberts 21, Bayden D. Russell 22, Abigail M. Smith 23, Bronte Tilbrook 15, Anya Waite 17, Jane Williamson 24

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Dr Donna Roberts and Dr Will Howard


Author: Marine Climate Change 2012
Ocean Acidification - Carbon dioxide dissolving in the oceans has lowered pH by 0.1 units since 1750, representing a 30% increase in hydrogen ion (acid) concentration | Time: 12.42 min

What is happening?

Most conclusions about biological responses to ocean acidification in Australian waters come from laboratory manipulations rather than observations. However, reduced calcification observed in Southern Ocean zooplankton suggest ocean acidification is already impacting biological systems.

What is expected?

Great Barrier Reef corals and coralline algae will continue to experience reduced calcification rates. Benthic calcifiers, such as molluscs and deep-water corals in Antarctic and southern Australian waters, will show reduced calcification and/or increased dissolution.

What we are doing about it?

Research is underway to improve the methods and equipment used for high-precision carbonate chemistry measurements. Monitoring of carbon chemistry in the open ocean and some shallow coastal systems, including the Great Barrier Reef, has already commenced. Research is underway to investigate effects of ocean acidification on whole coral ecosystems in the Great Barrier Reef.

Summary

Increasing atmospheric CO2 concentration is causing increased absorption of CO2 by the world’s oceans, in turn driving a decline in seawater pH and changes in ocean carbonate chemistry that are collectively referred to as ocean acidification. Evidence is accumulating to suggest ocean acidification may directly or indirectly affect many marine organisms and ecosystems, some of which may also hold significant social and economic value to the Australian community.

This report aims to provide a brief overview of the current state of scientific knowledge regarding the process of ocean acidification; current and future projected levels of ocean acidification; and, observed and projected impacts of current and future predicted levels of ocean acidification on marine organisms and ecosystems in the region. This report also briefly discusses potential social and economic implications, policy... continued on the full report

Temperature

Temperature

Lead Author: 

Janice M. Lough 1

Co Authors: Alex Sen Gupta 2 and Alistair J. Hobday 3

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What is happening?

Ocean temperatures around Australia have warmed by 0.68oC since 1910-1929, with south-west and south-eastern waters warming fastest. The rate of temperature rise in Australian waters has accelerated since the mid-20th century; from 0.08oC/decade in 1910-2011 to 0.11oC/decade from 1950-2011.

What is expected?

New results based on a relatively high scenario for greenhouse gas emissions (RCP8.5) indicate greatest warming in south-east (>3oC) and north-west waters (~2.5oC) by the end of this century.

What we are doing about it?

Investing in regional monitoring as part of the Integrated Marine Ocean Observing System (IMOS) to measure changes in ocean temperatures. Developing ocean models to project changes in coming decades. Ongoing development of seasonal forecasting models and applications to support timely adaptation responses by marine users.

Summary

Sea surface temperature (SST) surrounding Australia has undergone significant warming since the early 20th century. Average SST for the most recent 20-year period (1992-2011) was 0.68oC warmer than the period 1910-1929. This significant change in regionally-averaged SST is of similar magnitude to the warming of Australian air temperature (+0.74oC) and to globally-averaged land and sea temperatures (+0.71oC) between the same two periods. Australian region SST for every decade from 1921-1930 through 2001-2010 has been warmer than the preceding decade. The rate of globally-averaged temperature rise has accelerated since the mid-20th century; similarly, for Australian waters the rate of warming was 0.08oC/decade from 1910-2011 and 0.11oC/decade from 1950-2011. Since the first Report Card in 2009, the then warmest year (1998) for Australian region SST has been superseded by that in 2010. 15... continued on the full report

Sea level

Coast

Lead Author: 

John A. Church 1

Co Authors: Neil J. White 1, John R. Hunter 2 and Kathleen L. McInnes 1

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What is sea level rise?


Author: GreenCrossAustralia
John Church, CSIRO Fellow Centre for Australian Weather and Climate Change explains sea level rise. | Time: 4.15 min

What is happening?

Sea levels are rising around Australia, with fastest rates currently in northern Australia. New analyses of sedimentary records from the east coast of Tasmania confirm slow sea-level change over 1000s of years until the early 20th century, when there was a significant acceleration in the rate of sea-level rise. High sea-level events on annual to decadal timescales have increased by a factor of three during the 20th century.

What is expected?

Sea level will continue to rise during the 21st century and beyond, and result in inundation of low-lying coastal regions and coastal recession.

What we are doing about it?

Satellite altimeters and the Australian Baseline Sea Level Monitoring Array have provided a comprehensive picture of sea level around the Australian coastline since the early 1990s. Adaptation planning will be informed by national and regional assessments of coastal inundation and recession due to future changes in sea level and wave climate.

Summary

Many Australians live near the coast but coastal regions and their valuable ecosystems are threatened by rising sea levels. Globally, sea level is now rising after several centuries of relatively stable values. The rate of rise increased from the 19th to the 20th century and during the 20th century. The average of global-averaged sea-level rise during the 20th century was about 1.7 mm yr-1. The current rate (1993 to present) is about 3.1 ± 0.4 mm yr-1. Sea levels are rising around Australia and the frequency of extreme high sea-level events that occur on annual to decadal timescales has increased by a factor of about three during the 20th century. Sea-level rise is a result of expansion of the oceans as they warm and the addition of mass to the ocean from glaciers and ice caps, and the ice sheets of Greenland and Antarctica. Sea level will continue to rise during the 21st century and... continued on the full report

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Marine Environment

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Pelagic Fish

Pelagic fish1

Lead Author: 

Alistair J Hobday 1

Co Authors: Tim Ward2, Shane Griffiths3

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Alistair Hobday - Pelagic Fish


Author: Marine Climate Change 2012
Dr Alistair Hobday is a Principal Research Scientist at CSIRO Marine and Atmospheric Research. His research spans a range of topics, including spatial management and migration of large pelagic species, environmental influences on marine species, and | Time: 6.13 min

What is happening?

Increased reporting of tropical species from southern waters indicates distributions may be expanding south.

What is expected?

Increased occurrence and persistence of tropical species in southern waters as waters warm.

What we are doing about it?

There is increased modelling of distribution and abundance to refine understanding of impacts for tropical species, coastal small pelagic species, and large offshore species, and thus incorporate impacts of climate change into fisheries management.

Summary

Pelagic fishes and sharks occupy surface waters from the coast to the open ocean. There are ~260 pelagic species around Australia. While some of the most well known are the large offshore apex predators such as tunas, billfish and sharks, the mid-trophic level small pelagic species, such as sardines, anchovies, and squids, are critical to ecosystem function. In Australia, both small and large pelagic species have high ecological, economic and social value. Observed impacts of climate change are restricted to changes in local abundance and distribution, particularly southward range extensions. Little is known regarding changes in phenology, physiology or community structure. In future, general ocean warming around Australia and in particular on the east coast, in combination with predicted strengthening of the East Australian Current, is likely to see the distribution of a range of... continued on the full report

Microbes

Microbes

Lead Author: 

Nicole S. Webster 1

Co Authors: David G Bourne 1

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What is happening?

The reporting frequency of microbialmediated disease outbreaks affecting marine organisms is increasing and could contain a climate change signal. Disease events (or breakdown in microbial symbioses) in corals, sponges and some other species have already been linked with warmer seawater temperatures.

What is expected?

With warmer temperatures in the future, microbial-mediated disease outbreaks or disruptions to symbiosis are likely to become more frequent and wide-spread.

What we are doing about it?

Initiatives are underway for monitoring long-term changes in microbial biodiversity through genomic analysis of water samples. Investigations of environmental stress thresholds for microbial symbioses of key marine species are also in progress. Construction of national infrastructure including the SEASim aquarium at AIMS and state-of-the-art facilities at SIMS will increase capacity to investigate changes in community structure and function of marine microorganisms under climate scenarios.

Summary

Microorganisms are critical to all biogeochemical cycles and affect all living organisms via their symbiotic and pathogenic partnerships. A fundamental question for climate change scientists and marine microbiologists is what effects human induced changes will have on the services marine microbes perform for the planet. Whilst recent developments in technology have revolutionized our ability to characterize and define microbial communities and greatly enhanced our understanding of their functional roles and thresholds, we are still unable to measure complex microbial processes in a way that allows scientists to incorporate microbes in global climate models. In addition, Australia has a complete lack of long term data sets on marine microbial community dynamics, making it impossible to infer the potential impacts of climate change. Research on marine microbiology must therefore rapidly... continued on the full report

Marine Mammals

022

Lead Author: 

Nicole Schumann 1

Co Authors: John. P. Y. Arnould 1, Nick Gales 2 and Robert Harcourt 3

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What is happening?

Substantial evidence that sea surface temperature influences foraging locations and reproductive success of marine mammals. However, studies on long-term effects of warming are rare, with only one study providing evidence that dugongs extend their range in warm years.

What is expected?

Warmer water temperatures are likely to have a profound influence on the distribution of marine mammals; the ranges of species currently associated with tropical and temperate waters are likely to expand southwards.

What we are doing about it?

The Australian Animal Tracking and Monitoring System (AATAMS) is using acoustic technology, satellite tags and biologgers to monitor coastal and oceanic movements of marine mammals. This will elucidate links between climate change in Australia’s coastal seas and the Southern Ocean, and responses of marine mammals.

Summary

Australian waters are home to 52 recognised marine mammal species. Of these, at least seven are listed as threatened, though insufficient information exists on a further 25 to determine conservation status. Foraging locations, foraging behaviour, distribution and reproductive success of several marine mammal species have been linked to climatic factors. Similarly, cetacean and dugong strandings, drowning of seal pups, habitat loss and exposure of coastal species to altered water conditions and disease have followed storms, floods and cyclones.

There is currently a very low to low level of confidence in the predicted effects of climate change on Australian marine mammals. This is due to a distinct lack of information on most species, with almost nothing known of the distributions, population sizes or ecologies of many species, particularly cetaceans. Therefore, the adaptive capacity... continued on the full report

Coral Reefs

Coral

Lead Author: 

Kenneth R N Anthony¹

Co Authors: Paul Marshall 2

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What is happening?

During the past three decades, coral reefs have been impacted by a growing number of thermal bleaching events although their occurrence and severity have varied substantially in space and time. Numerous experimental and observational studies have established a causative link between thermal anomalies (stress) and coral bleaching

What is expected?

Projected increases in the frequency and severity of thermal stress events will increase the risk of mass coral bleaching events , leading to chronic degradation of most coral reefs by the middle to late parts of the century. Ocean acidification will reduce reef calcification driving a shift from net reef accretion to net erosion of reef structure..

What we are doing about it?

Formal adaptation plans are being implemented to help communities and industries that depend on Australia’s coral reefs to deal with the serious impacts of climate change. The Great Barrier Reef Climate Change Adaptation Strategy and Action Plan outlines strategies and measures to support ecosystem resilience, support adaptation by reef-dependent communities and industries, and raise awareness of the importance of urgent action to mitigate climate change if we are to improve the outlook for coral reefs.

Summary

Coral reefs worldwide are sensitive to climate change and ocean acidification. Australia has some of the World’s most spectacular coral reef ecosystems: the Great Barrier Reef (GBR) in the east and Ningaloo Reef in the west. Coral reefs also occur south of the GBR (extending to Lord Howe Island) and across northern Australia, including north Western Australia. The threat from climate change to the healthy functioning of these systems represents a significant risk to Australia’s natural heritage. Australian coral reefs support billions of dollars of economic activity per year, notably through tourism but also through commercial fishing and recreational activities. Climate change and ocean acidification will compromise the ability of coral reefs to sustain the ecosystem goods and services upon which society has come to depend.

The projected increase in the frequency and intensity... continued on the full report


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