Sunday, January 5, 2014

Sea surface temperatures unusually warm around Australia in 2013

Sea surface temperatures around Australia in 2013 were unusually warm reported the Australian Bureau of Meteorology in it's annual climate statement. Record ocean temperatures were recorded for January and February, with November the second-highest on record. This continues a long term trend for increasing sea surface temperatures around Australia and globally.

Updates:


The BOM report stated:

Preliminary data, for the year to November, place SSTs for 2013 as the third-highest since 1910, 0.51 °C above the long-term average. Below-average annual SSTs have not been recorded for the Australian region since 1994; the region has seen a total rise in SSTs of approximately 1 °C since 1910, a similar value to that recorded for atmospheric warming over land.

SSTs were consistently very much above average off the western and southern coast of Australia from summer 2012-13 until May. Strong warm anomalies continued in waters to the south of the mainland throughout 2013. For the year to November, SSTs in the southern region were some 0.59 °C above average, surpassing the annual record (+0.56 °C in 1999) by 0.03 °C.

Professor Roger Jones, a Professorial Research Fellow at the Centre for Strategic Economic Studies at Victoria University and a Convening Lead Author (CLA) on the Intergovernmental Panel on Climate Change's Working Group II Fifth Assessment Report to be released later this year commented on sea surface temperatures:

"The consistently high sea surface temperatures around Australia mean that hotter conditions will continue. They will also contribute to a vigorous hydrological cycle, which can often manifest in greater extremes of rainfall, particularly in northern Australia. This vigour was reflected in a number of flooding events around the nation."

This sustained recent period of record high Sea surface temperatures extends from 2010, although you can see on the graph above the clear trend going back to the start of accurate records in 1910.

Update 7 January 2014: - Western Australian sea surface temperatures Roger Jones blogged specifically on the Western Australian sea surface temperatures. Here is some of what he had to say:

"The last two years are more than 0.2°C warmer than any previous years. This is a big increase for SST and suggests the Leeuwin current is going gangbusters down the WA coast. Interestingly, this part of the world was one of the first in Australia to warm, when in 1961, similar warming led to an increase in temperatures that affected coastal stations all the way to Cape Otway in Victoria. This is a big worry, and I wouldn’t be surprised if SWWA experiences unprecedented land temperatures over the next few years. SST in other parts of Australia was not exceptional through 2011-12, so it may be that SWWA is the climate canary, and not for the first time."


Update 9 January 2014 - Sharks and warming waters

There is some evidence that sharks are sensitive to sea surface temperatures and come closer to shore in warmer seas. A South African study published in August 2013 conducted over five years seems to indicate water temperature and climatic phenomena influence the abundance of white sharks.

From the study abstract - Environmental Influences on the Abundance and Sexual Composition of White Sharks Carcharodon carcharias in Gansbaai, South Africa (Full paper):

MEI, an index to quantify the strength of Southern Oscillation, differed in its effect on the recorded numbers of male and female white sharks, with highly significant interannual trends. This data suggests that water temperature and climatic phenomena influence the abundance of white sharks at this coastal site. In this study, more females were seen in Gansbaai overall in warmer water/positive MEI years. Conversely, the opposite trend was observed for males. In cool water years (2010 to 2011) sightings of male sharks were significantly higher than in previous years.

Christopher Hart, who built the website on Impacts of rising sea surface temperatures on white shark migration in October 2012, wrote:

Ocean temperature appears to have a large impact on white shark migratory patterns, and a shift towards warmer ocean temperature will likely alter the global distribution of white sharks.

It seems rising sea surface temperatures could also throw the migration of white sharks out of synchronisation with their main prey. Cape fur seals breeding cycle is primarily regulated by photoperiod - the length of the day - and as sea surface temperatures rise a trophic mismatch could result. Hart says that "If sharks can no longer time migrations to arrive in southern Africa in cadence with seal abundance, ramifications throughout the food chain will be observed."

Barnett State Government targets Great white for shark cull

In the meantime, under the Barnett state government more than $20 million has been allocated over the next four years to “address public safety and help mitigate the risk sharks pose to water users”. The shark cull program involves setting baited drum lines to catch large sharks along the shores of heavily-used beaches and hiring professional shark hunters to patrol these areas and kill large sharks.

Greens South Metro MLC Lynn MacLaren said in a December media release, "The WA Government has justified its unpopular new shark cull policy by citing experiences elsewhere yet an examination of the few places in the world where drum lines have been introduced shows that drum lines kill far more harmless species than they do tiger and great white sharks,” Ms MacLaren said.

“An examination of the annual reports of the KwaZulu-Natal Sharks Board in Natal, South Africa, shows that for the past two years, the number of tiger and great white sharks caught in drum lines and nets off Natal has been outnumbered by five times by the capture of smaller sharks, catfish, humpback whales and leatherback and green turtles." said Ms Mclaren.

Over 100 marine scientists wrote to the Premier opposing the shark cull and questioning it's effectiveness for reduction of shark attacks. (PDF) The Australian Marine Conservation Society has a petition to stop the cull, as well as a petition at change.org with over 50,000 supporters as at 9 January 2014.

The Great White Shark (Carcharodon carcharias) is listed as vulnerable under the Federal EPBC Act with an associated recovery plan. The species is also listed on Appendix II of the Convention on International Trade in Endangered Species of Fauna and Flora (CITES) and also on Appendices I and II of the Convention on Migratory Species (CMS). It is listed as vulnerable on the IUCN redlist.


See my 2017 article on The Great White shark, climate change and ocean carbon cycles

Global sea surface temperature trends

NOAA reported record global sea surface temperatures in August. The November 2013 NOAA National Climatic Data center global analysis report stated:

"Globally, the average ocean temperature for September-November was the fourth highest on record for the period, at 0.58°C (1.04°F) above average. As indicated by the Land & Ocean Temperature Percentiles map, very few regions were below average, most notably the Southern Ocean off the tip of South America. Many areas were much warmer than average, with sections of the eastern Atlantic, parts of the south central and southeast Indian Ocean, and parts of the south central and western equatorial Pacific Ocean observing record warmth."

Elevated SST impacts: Stronger storms, migrating fisheries, coral bleaching

While elevated sea surface temperatures (SST) may not cause an increase in frequency of tropical cyclones as a number of factors need to come together for their formation, higher sea surface temperatures are known to add energy to storms increasing the intensity of tropical cyclones and typhoons.

Elevated SST contributed to Typhoon Usagi, Typhoon Haiyan that impacted the Philippines and Asia, and ex-cyclone Oswald that brought extreme torrential rain to the Queensland and northern NSW coasts causing extensive flooding and destruction in January 2013.

In October tropical cyclone Phailan formed in the warm waters of the Bay of Bengal, the strongest cyclone ever measured in the Indian Ocean according to US meteorologist Eric Holthaus. It's rapid intensification was aided by ocean surface temperatures in the Bay of Bengal that were warmer than 28 degrees Celsius (82.4 degrees Fahrenheit), which is "about as warm as ocean water can get," Holthaus said, according to a livescience report. Widespead warnings and evacuation of hundreds of thousands of people from coastal areas avoided large loss of life, though causing extensive flooding and damage to coastal areas.

Higher water temperatures are also driving fish species to greater depths or higher latitudes. Scientists have identified that fish are migrating to cooler waters. Elevated sea surface temperatures such as the 2010/2011 extreme marine heat wave of the coast of Western Australia have a large impact on marine ecosystems. These events also exacerbate the velocity of climate change for many marine species.

Marine scientists have warned repeatedly that Global Warming imperils coral reefs: 2 degrees warming is too hot. Higher sea surface temperatures will cause coral bleaching and a collapse of the sensitive coral ecosystem and marine diversity.

Coral reefs are already under pressure due to agricultural nutrient pollution, coastal development and destruction of coastal wetlands.

This next section is a partial repost from my January 2012 blog on the velocity of climate change that affects many marine species in southern Australia. Rising sea surface temperatures will literaly push many marine species to the edge of the southern continental shelf, then to extinction.

Australian Seaweed species being pushed to the brink

A study published in Current Biology on November 8, 2011 - Seaweed Communities in Retreat from Ocean Warming - examined the impact of warming ocean on seaweed communities in southern Australian waters.

According to research led by Assistant Professor Thomas Wernberg from The University of Western Australia's Ocean's Institute, modern seaweed communities to the south are becoming more similar to past communities in the north, with several temperate species moving poleward (south). The results predict that up to one quarter of species in southern Australian waters might retract towards extinction.

The researchers found changes in seaweed communities in both the Indian and Pacific Oceans, consistent with rapid warming over the past decades.

"We found that continued warming might drive potentially hundreds of species towards the edge of the Australian continent beyond which there is no refuge," Assistant Professor Wernberg said.

The researchers believe while some species may be able to make some adjustments to cope with natural cooling and warming cycles, the predicted rate and strength of warming in the coming decades is likely to force many retreating species further south and beyond the limits of available habitat.

"The potential for global extinctions is concerning because one quarter of all macroalgal species in the world are found off Australia and these marine habitats support equally unique fish and invertebrate communities," Assistant Professor Wernberg said.

The velocity of climate change points to Oceans at high risk of unprecedented Marine extinction as scientists warn with Coral Reefs and Ocean Biodiversity threatened by Climate Change.

Marine scientists have also consistently warned of another high profile marine chemistry problem: Ocean Acidification Accelerating; Severe Damages Imminent. You can watch 2 videos on ocean acidification: Acid Test and a presentation by marine chemist Andrew Dickson. Marine scientists also appealed to climate negotiators at Durban in December 2011 to act on reducing CO2 emissions to reduce Ocean Acidification.


Sources:

  • NOAA National Climatic Data Center, State of the Climate: Global Analysis for November 2013, published online December 2013, retrieved on January 4, 2014 from http://www.ncdc.noaa.gov/sotc/global/2013/11
  • Australian Bureau of Meteorology Annual climate statement 2013, issued 3 January 2014
  • Towner AV, Underhill LG, Jewell OJD, Smale MJ (2013) Environmental Influences on the Abundance and Sexual Composition of White Sharks Carcharodon carcharias in Gansbaai, South Africa. PLoS ONE 8(8): e71197. doi:10.1371/journal.pone.0071197 (Full Paper)
  • Christopher Hart, October 2012, Impacts of rising sea surface temperatures on white shark migration, Retrieved 9 January 2014.
  • Thomas Wernberg, Bayden D. Russell, Mads S. Thomsen, C. Frederico D. Gurgel, Corey J.A. Bradshaw, Elvira S. Poloczanska, Sean D. Connell, in Current Biology - 8 November 2011 (Vol. 21, Issue 21, pp. 1828-1832) - Seaweed Communities in Retreat from Ocean Warming (abstract)
  • University of Western Australia Media Release, October 28, 2011 - Ocean flora retreating to the brink