Climate and system variability

2016
Marine environment
Pressures
Marine Temperate East
Marine South West
Great Barrier Reef
Marine North West
Marine South East

Seasonal variability

Climatic variability associated with increased monsoonal activity during the summer months in the tropical north and seasonal cycles in the temperate south leads to variations in water temperature (e.g. Figure MAR4), rainfall patterns (affecting ocean salinity), surface winds, oceanic currents and tidal regimes, which can influence the degree of vertical mixing through the water column (Feng et al. 2003, Ridgway & Condie 2004, Ridgway 2007, Redondo-Rodriguez et al. 2012, Ceccarelli et al. 2013).

These seasonal cycles in ocean physical processes have been relatively stable on evolutionary timescales, and species within the marine environment have evolved in response. Ocean primary productivity demonstrates variation in response to seasonal cycles in ocean processes (Tilburg et al. 2002, Thompson et al. 2015b). This is reflected in secondary producers and higher-order marine organisms that have also evolved to synchronise biological processes such as breeding or migration with these cycles (e.g. Stevens & Lyle 1989, McPherson 1991, Heithaus 2001, Gill 2002, Patterson et al. 2008). Any change in the duration or intensity of seasonal cycles on timescales shorter than that in which organisms in the marine environment can adapt may lead to mismatches in biological processes, resulting in deleterious impacts on marine populations. Understanding how natural variability drives processes within the marine environment, and how extremes in this variability affect marine organisms and processes is therefore essential to both quantifying and understanding the impacts associated with anthropogenically driven climate change.

Current projections of climate suggest that changes to seasonal cycles are occurring and will continue to occur, but with considerable variability across Australia. Climate zones within the marine environment have moved polewards, resulting in shifts in associated seasonality (Lough 2008). Extremes associated with the summer months will become more prevalent (Reisinger et al. 2014), particularly when coupled with ENSO (see Interannual and subdecadal variability). Modelled simulations of the climate under the Intergovernmental Panel on Climate Change (IPCC) emissions scenarios identify that seasonal monsoon and cyclone systems are likely to intensify (Christensen et al. 2013). How these will affect seasonal cycles in marine ecosystems is not yet clear, but shifts in the onset of seasonal migrations and breeding have been observed elsewhere (e.g. Dufour et al. 2010, Asch 2015).

soe2016_mar_fig4_sea_surface_temperature_monthly_average-01.png
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Source: Data from the Australian Ocean Data Network

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Figure MAR4     Monthly averages of sea surface temperature in the South-east Marine Region, 2005–14

Climate and system variability

Interannual and subdecadal variability

Australia’s marine environment is also influenced by cycles in climate on interannual timescales associated with several natural climate phenomena, such as ENSO, the Indian Ocean Dipole (IOD) and the Southern Annular Mode (SAM), also known as the Antarctic Oscillation. Of the climate phenomena that occur in the Southern Hemisphere, ENSO and the IOD potentially have the most widespread influence on the Australian marine environment, habitats, communities and species groups, whereas the influence of the SAM is mostly across the central and southern parts of Australia. Variability in the phases of these climate phenomena change rainfall patterns, sea surface temperatures, surface winds and oceanic currents, which can influence the degree of vertical mixing through the water column and the relative location of cyclone events (McBride & Nicholls 1983, Lough 1994, Lau & Nath 2000, Feng et al. 2010). Changes in the timing and magnitude of seasonal variability caused by these climate phenomena (McBride & Nicholls 1983, Mitchell & Wallace 1996, Lau & Nath 2000, Feng et al. 2010) have flow-on impacts on the marine environment and, in particular, species that have adapted to take advantage of seasonal cycles for processes such as breeding or feeding.

Simultaneous fluctuations in the phases of these climatic phenomena, or particularly strong phases of each, can result in extreme changes in ocean processes, contributing to events such as the marine heatwave that occurred in the waters off Western Australia during the summer of 2010–11 (Pearce et al. 2011, Pearce & Feng 2013). This event, driven by the occurrence of a strong La Niña phase of ENSO, superimposed on long-term increasing water temperatures associated with climate change (see Climate change), resulted in widespread bleaching of corals across the North-west Marine Region. It was also associated with fish and invertebrate deaths, extensions and contractions in species distributions, variations in recruitment and growth rates, impacts on trophic relationships, and shifts in community structure, particularly in relation to kelp forests across the North-west and South-west marine regions (Wernberg et al. 2016). Variations in the catch rates of exploited species were also recorded after the event (Pearce et al. 2011, Pearce & Feng 2013).

The strongest El Niño phase of ENSO since 1998 occurred in 2015–16. Similarly to the Western Australian heatwave, this was superimposed on an increasing baseline of ocean temperatures associated with climate change, and resulted in the highest sea surface temperatures across the Great Barrier Reef on record. These extreme temperatures caused extensive coral bleaching and die-off, particularly across northern regions of the Great Barrier Reef and parts of north-western Australia (see Quality of habitats and communities). A marine heatwave was also recorded off eastern Tasmania from December 2015 to May 2016 in association with the same conditions, although impacts of this heatwave on the marine environment are yet to be established.

The ability to predict climate variability in the marine environment beyond the presence of annual cycles is not well developed, and forecasts beyond 1–2 years are highly inaccurate (Kirtman et al. 2013, Evans et al. 2015). Even our current ability to predict the phase of ENSO varies. It is possible to predict the likelihood of an El Niño event, but it is not so easy to predict its timing or strength. The accuracy of prediction declines rapidly as the time to the event increases, because even small perturbations to the system (such as the random occurrence of a tropical cyclone) can lead to a very different ENSO phase later in the year (Jin et al. 2008).

Predictability of ENSO is further complicated by the diversity of ENSO behaviours. No 2 events are alike, and the onset and progression of each event are characterised by unique changes to sea surface temperatures, surface winds and the mixed layer (Singh et al. 2011). Long-term records of ENSO demonstrate high multidecadal variability, with some decades experiencing less variability in ENSO and others experiencing more (Harrison & Chiodi 2015). Although it is almost certain that climate phenomena such as ENSO will continue to occur and be the dominant mode of interannual variability, the influence that climate change might have on these phenomena is unclear (Brown et al. 2013, Christensen et al. 2013, Evans et al. 2015).

Interdecadal variability

Climate cycles also occur on longer timescales, with the Pacific Decadal Oscillation (PDO; Mantua & Hare 2002) the most important phenomenon influencing the Australian marine environment. The PDO has been described as a pattern of climate variability similar to ENSO, with positive phases having similar effects on the climate to El Niño and negative phases similar effects to La Niña, but operating on scales from 15 years to as long as 70 years (Mantua & Hare 2002). This results in initially abrupt transitions to conditions that are then stable across multiple decades (Hilborn et al. 2003). Interactions between phases of the PDO and ENSO can either modulate or strengthen the phases of ENSO (Cai & van Rensch 2012), with flow-on effects on ocean processes and the marine environment (see Interannual and subdecadal variability). Biological responses to the PDO include changes in primary productivity, which are transmitted through the food chain, resulting in changes in productivity of higher trophic levels (Hare & Mantua 2000, Hilborn et al. 2003). A recent negative phase of the PDO has been associated with increased rainfall and La Niña conditions in the Temperate East Marine Region (Cai & van Rensch 2012). However, how the PDO drives variability is less well understood for the Australian marine environment than for other regions of the Pacific Ocean. Climate variability on decadal scales associated with features such as the PDO is not currently predictable (Evans et al. 2015).

Feng M, Meyers G, Pearce A & Wijffels S (2003). Annual and interannual variations of the Leeuwin Current at 32°S. Journal of Geophysical Research: Oceans 108(C11):3355, doi:10.1029/2002JC001763.

Ridgway KR & Condie SA (2004). The 5500-km-long boundary flow off western and southern Australia. Journal of Geophysical Research: Oceans 109:C04017, doi:10.1029/2003JC001921.

Redondo-Rodriguez A, Weeks SJ, Berkelmans R, Hoegh-Guldberg O & Lough JM (2012). Climate variability of the Great Barrier Reef in relation to the tropical Pacific and El Niño–Southern Oscillation. Marine and Freshwater Research 63:34–47.

Ceccarelli DM, McKinnon AD, Andréfouët S, Allain V, Young J, Gledhill DC, Flynn A, Bax NJ, Beaman R, Borsa P, Brinkman R, Bustamante RH, Campbell R, Cappo M, Cravatte S, D’Agata S, Dichmont CM, Dunstan PK, Dupouy C, Edgar G, Farman R, Furnas M, Garrigue C, Hutton T, Kulbicki M, Letourneur Y, Lindsay D, Menkes C, Mouillot D, Parravicini V, Payri C, Pelletier B, Richer de Forges B, Ridgway K, Rodier M, Samadi S, Schoeman D, Skewes T, Swearer S, Vigliola L, Wantiez L, Williams A, Williams A & Richardson AJ (2013). The Coral Sea: physical environment, ecosystem status and biodiversity assets. In: Lesser M (ed.), Advances in marine biology, vol. 66, Academic Press, London, 213–290.

Tilburg CE, Subrahmanyam B & O’Brien JJ (2002). Ocean color variability in the Tasman Sea. Geophysical Research Letters29(10):1487, doi:10.1029/2001GL014071.

Thompson PA, O’Brien TD, Paerl HW, Peierls BL, Harrison PJ & Robb M (2015b). Precipitation as a driver of phytoplankton ecology in coastal waters: a climatic perspective. Estuarine, Coastal and Shelf Science 162:119–129.

McPherson GR (1991). A possible mechanism for the aggregation of yellowfin and bigeye tuna in the north-western Coral Sea, Information Series QI91013, Queensland Department of Primary Industries, Brisbane.

Heithaus MR (2001). The biology of tiger sharks, Galeocerdo cuvier, in Shark Bay, Western Australia: sex ratio, size distribution, diet, and seasonal changes in catch rates. Environmental Biology of Fishes 61:25–36.

Gill PC (2002). A blue whale (Balaenoptera musculus) feeding ground in a southern Australian coastal upwelling zone. Journal of Cetacean Research and Management 4(2):179–184.

Patterson TP, Evans K, Carter TI & Gunn JS (2008). Movement and behaviour of large southern bluefin tuna (Thunnus maccoyii) in the Australian region determined using pop-up satellite archival tags. Fisheries Oceanography 17:352–267.

Lough JM (1994). Climate variation and El Niño–Southern Oscillation events on the Great Barrier Reef: 1958 to 1987. Coral Reefs 13:181–185.

Christensen JH, Krishna Kumar K, Aldrian E, An S-I, Cavalcanti IFA, de Castro M, Dong W, Goswami P, Hall A, Kanyanga JK, Kitoh A, Kossin J, Lau N-C, Renwick J, Stephenson DB, Xie S-P & Zhou T (2013). Climate phenomena and their relevance for future regional climate change. In: Stocker TF, Qin D, Plattner G-K, Tignor M, Allen SK, Boschung J, Nauels A, Xia Y, Bex V & Midgley PM (eds), Climate change 2013: the physical science basis, contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, United Kingdom, & New York, USA, 1217–1308.

McBride JL & Nicholls N (1983). Seasonal relationships between Australian rainfall and the Southern Oscillation. Monthly Weather Review 111:1998–2004.

Lau N-C & Nath MJ (2000). Impact of the ENSO on the variability of the Asian–Australian monsoons as simulated in GCM experiments. Journal of Climate 13:4287–4309.

Feng M, McPhaden MJ & Lee T (2010). Decadal variability of the Pacific subtropical cells and their influence on the southeast Indian Ocean. Geophysical Research Letters 37:L09606, doi:10.1029/2010GL042796.

Mitchell TP & Wallace JM (1996). ENSO seasonality: 1950–78 versus 1979–92. Journal of Climate 9:3149–3161.

Pearce A, Lenanton R, Jackson G, Moore J, Feng M & Gaughan D (2011). The ‘marine heat wave’ off Western Australia during the summer of 2010/11, Fisheries Research Report 222, Western Australian Department of Fisheries, Perth.

Pearce AF & Feng M (2013). The rise and fall of the ‘marine heat wave’ off Western Australia during the summer of 2010/2011.Journal of Marine Systems 111–112:139–156.

Wernberg T, Bennett S, Babcock RC, de Bettignies T, Cure K, Depezynski M, Dufois F, Fromont J, Fulton CJ, Hovey RK, Harvey ES, Holmes TH, Kendrick GA, Bradford B, Santana-Garcon J, Saunders BJ, Smale DA, Thomsen MS, Tuckett CA, Tuya F, Vanderklift MA & Wilson S (2016). Climate-driven regime shift of a temperate marine ecosystem. Science 353:169–172.

Kirtman B, Power SB, Adedoyin JA, Boer GJ, Bojariu R, Camilloni I, Doblas-Reyes FJ, Fiore AM, Kimoto M, Meehl GA, Prather M, Sarr A, Schär C, Sutton R, van Oldenborgh GJ, Vecchi G & Wang HJ (2013). Near-term climate change: projections and predictability. In: Stocker TF, Qin D, Plattner G-K, Tignor M, Allen SK, Boschung J, Nauels A, Xia Y, Bex V & Midgley PM (eds),Climate change 2013: the physical science basis, contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, United Kingdom, & New York, United States, 953–1028.

Evans K, Brown JN, Sen Gupta A, Nicol SJ, Hoyle S, Matear R & Arrizabalaga H (2015). When 1 + 1 can be > 2: uncertainties compound when simulating climate, fisheries and marine ecosystems. Deep-Sea Research II: Topical Studies in Oceanography 113:312–322.

Jin EK, Iii JLK, Wang B, Park C-K, Kang I-S, Kirtman BP, Kug J-S, Kumar A, Luo J-J, Schemm J, Shukla J & Yamagata T (2008). Current status of ENSO prediction skill in coupled ocean–atmosphere models. Climate Dynamics 31:647–664.

Singh A, Delcroix T & Cravatte S (2011). Contrasting the flavors of El Niño–Southern Oscillation using sea surface salinity observations. Journal of Geophysical Research: Oceans 116:C06016, doi:10.1029/2010JC006862.

Harrison DE & Chiodi AM (2015). Multi-decadal variability and trends in El Niño–Southern Oscillation and tropical Pacific fisheries implications. Deep-Sea Research II: Topical Studies in Oceanography 113:9–21.

Brown J, Sen Gupta A, Brown J, Muir L, Risbey J, Whetton P, Zhang X, Ganachaud A, Murphy B & Wijffels S (2013). Implications of CMIP3 model biases and uncertainties for climate projections in the western tropical Pacific. Climatic Change119:147–161.

Mantua NJ & Hare SR (2002). The Pacific Decadal Oscillation. Journal of Oceanography 58:35–44.

Cai W & van Rensch P (2012). The 2011 southeast Queensland extreme summer rainfall: a confirmation of a negative Pacific Decadal Oscillation phase? Geophysical Research Letters 39:L08702, doi:10.1029/2011GL050820.

Ridgway KR & Condie SA (2004). The 5500-km-long boundary flow off western and southern Australia. Journal of Geophysical Research: Oceans 109:C04017, doi:10.1029/2003JC001921.

Stevens JD & Lyle JM (1989). Biology of three hammerhead sharks (Eusphyra blochii, Sphyrna mokarran and S. lewini) from northern Australia. Australian Journal of Marine and Freshwater Research 40:129–146.

Reisinger A, Kitching RL, Chiew F, Hughes L, Newton PCD, Schuster SS, Tait A & Whetton P (2014). Australasia. In: Barros VR, Field CB, Dokken DJ, Mastrandrea MD, Mach KJ, Bilir TE, Chatterjee M, Ebi KL, Estrada YO, Genova RC, Girma B, Kissel ES, Levy AN, MacCracken S, Mastrandrea PR & White LL (eds), Climate change 2014: impacts, adaptation, and vulnerability, part B, Regional aspects, contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, United Kingdom, & New York, United States, 1371–1438.

Dufour F, Arrizabalaga H, Irigoien X & Santiago J (2010). Climate impacts on albacore and bluefin tunas migrations phenology and spatial distribution. Progress in Oceanography 86:283–290.

Asch RG (2015). Climate change and decadal shifts in the phenology of larval fishes in the California Current ecosystem.Proceedings of the National Academy of Sciences of the United States of America 112:E4065–E4074, doi:10.1073/pnas.1421946112.

Lau N-C & Nath MJ (2000). Impact of the ENSO on the variability of the Asian–Australian monsoons as simulated in GCM experiments. Journal of Climate 13:4287–4309.

Hilborn R, Quinn TP, Schindler DE & Rogers DE (2003). Biocomplexity and fisheries sustainability. Proceedings of the National Academy of Science of the United States of America 100:6564–6568.

Hare SR & Mantua NJ (2000). Empirical evidence for north Pacific regime shift in 1977 and 1989. Progress in Oceanography47:103–145.

Evans K, Bax NJ, Smith DC (2016). Marine environment: Climate and system variability. In: Australia state of the environment 2016, Australian Government Department of the Environment and Energy, Canberra, https://soe.environment.gov.au/theme/marine-environment/topic/2016/climate-and-system-variability, DOI 10.4226/94/58b657ea7c296