How Climate Change And Security In The Indian Ocean Region May Impact On Australia

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HMAS Ballarat at sunrise in the Indian Ocean on the way to participate in Exercise Malabar. Photographer: LSIS Shane Cameron. © Department of Defence.

Key Points:

  • The Indian Ocean is being altered by a warming climate with profound influences on its marine anatomy and its links to weather, with those influences reaching far and wide into the African, greater Asian and Indo-Pacific regions.
  • The region’s geo-politics and security will come under increasing pressure as changing ocean and related weather phenomena make many Indian Ocean territories increasingly vulnerable to food insecurity and exposure to an array of extreme ocean and climate events.
  • There is a critical need to adequately monitor, understand and predict the relationships between the environmental, social, economic and geo-political elements of a changing Indian Ocean.
  • Being a major Indian Ocean marine hub, and in the context of the UN Decade of Ocean Science for Sustainable Development 2021-30, Perth can play an enhanced leadership role in this objective, including with support from the defence sector for the IIOE-2 (2015-25), as was previously the case for IIOE-1 (1959-65).


The Indian Ocean covers one fifth of the world’s surface area and abuts Australia, Asia, Africa and Antarctica giving it unique world-wide influence. Significantly, weather patterns in the ocean have long played a pivotal role in the historical development of countries across its littoral region. The seasonal monsoons, for example, typically associated with the Indian Ocean, greatly influenced early navigators and traders in their travels as well as those who invaded and conquered countries of the region.

Scope of the Challenge

As such, exploring the way the Indian Ocean influences climate and weather conditions is vitally important to the region, and therefore as a result to Australia’s security as well. Topics to consider are the potential consequences of climate change at environmental and related socio-economic levels, and the scientific research being undertaken to enhance the knowledge and understanding of those consequences for Australia and the region.

Around three billion people currently live  astride the Indian Ocean region. They rely on the ocean as a valuable food source and are impacted both positively and negatively by the monsoons and other weather patterns. Such patterns influence rains, winds, ocean currents, cyclones, floods and the security of regional maritime transport. In this context, an excellent summary of the Indian Ocean’s importance and of the emerging Indian Ocean Observing System (IndOOS) as a key element of the Global Ocean Observing System, is given by Beal et al 2019 in their seminal review report ‘IndOOS-2: A roadmap to sustained observations of the Indian Ocean for 2020-2030’.

The Indian Ocean also plays a significant role in mitigating the effects of global warming and associated climate change. Beal et al 2020 have provided a comprehensive summary of the importance of the Indian Ocean in global ocean heat budgets. The study  emphasises that due to its large heat capacity the global ocean absorbs more than 90% of the anthropogenically induced excess heat that enters into the overall Earth system (IPCC 2013). The Indian Ocean was referred to as having contributed to about one quarter of this global oceanic heat uptake, despite it representing about 13% of the global ocean surface (Cheng et al 2017).

Furthermore, Lee et al 2015 examined the relative importance of the Indian Ocean in receiving heat from the Pacific Ocean via the ‘Indonesian Throughflow’ between the two oceans during the warming ‘hiatus’ of the early 2000s. The authors drew conclusions from their analysis of data and computer modelling of the heat content of the important upper 700m of the oceans, which has been intensively monitored robotically by the global vertically profiling Argo network of salinity-temperature instruments. The study suggests that during the hiatus the Indian Ocean accounted for more than 70% of the global ocean heat gain in the upper 700m.

The Indian Ocean plays a disproportionately significant role in terms of its importance in the global heat picture.  However, unlike the Pacific Ocean, where long term research has been conducted, the Indian Ocean has been relatively under-analysed. In particular, the impact of this heat absorption on fish stocks and the ocean environment more generally requires further study.

In turn, understanding the significance of the Indian Ocean for climate and weather systems that impact Australia is critical. This is particularly the case for industries in Western Australia, especially the oil and gas industry with its extensive offshore infrastructure and drilling operations. Climate and weather also impact on numerous human activities particularly agriculture, defence and other related sectors such as those focussed on tourism, biodiversity conservation, maritime transport, and emergency response (relating to floods, droughts and fire). Of course, WA also has an abiding interest in the security and stability of the Indian Ocean region.

Given increasing technological capability, including satellites, robotics, and drones below the sea, as well as advanced computing, it is imperative that the coverage, accuracy and quality of ocean research and weather forecasting is better and more widely understood. This includes a deeper understanding of the way ocean currents and temperature changes can influence climate and weather conditions. Collating and understanding this knowledge will ensure that management-related adaptation and mitigation measures are conceived, designed, agreed on multilaterally, and implemented based on sound scientific evidence.

Impact of Oceanic & Related Weather Systems 

The Indian Ocean is a unique and globally critical ocean, with links to the Pacific, Atlantic and Southern Oceans. Water from the Pacific Ocean flows into the Indian Ocean through the Ombai, Lombok and Timor Sea gaps of the ‘Maritime Continent’ (this inflow is also known as the Indonesian Throughflow). This then propagates across the Indian Ocean connecting with the Atlantic and Southern Oceans and flows into many fundamentally important internal currents in the Indian Ocean. Some of these run adjacent to and along major coastal margins, including the WA coast, and all have significant effects on the biodiversity of the entire Indian Ocean.

The Indian Ocean is also the only ocean with a solid land mass just to the north of its tropical zone. This leads to the seasonally reversing monsoonal wind and weather systems which influence not only the countries on the Indian Ocean region and its island nations, but also countries across Africa, Asia as far north as Japan and China, and across Australia and into the Pacific. This influence on weather patterns experienced across Australia and beyond is a result of key processes operating in the Indian Ocean’s domain. Two of the most profoundly impacting processes are the Indian Ocean Dipole (IOD) and the Madden Julian Oscillation (MJO). 

The IOD is the name given to the difference between the sea surface temperatures of the respective tropical western and eastern sectors of the Indian Ocean. The IOD has three phases: neutral, positive and negative. When it is in a positive phase, sea surface temperatures around Indonesia are cooler than average, while those in the western Indian Ocean are warmer than average. There is an increase in the easterly winds across the Indian Ocean in association with this sea surface temperature pattern. This contributes to suppression of rainfall across Australia.

Conversely, during a negative phase, there are warmer than average sea surface temperatures near Indonesia and cooler than average temperatures in the western Indian Ocean, resulting in stronger westerly winds across the Indian Ocean, greater convection near Australia, contributing to enhanced rainfall across Australia. The IOD is therefore one of the key drivers of Australia’s climate, and can have a significant impact on southern Australian agriculture because its strongest impacts generally coincide with the winter crop-growing season. 

IOD events can also be related to El Niño–Southern Oscillation (ENSO) events. ENSO is an irregularly periodic variation in winds and sea surface temperatures over the tropical eastern Pacific Ocean, affecting the climate of much of the tropics and sub-tropics. The warming phase of the sea temperature is known as El Niño and the cooling phase as La Niña. When El Niño coincides with a positive IOD, the two phenomena can reinforce their dry effects. Likewise, when La Niña coincides with a negative IOD, the chance of above-average winter-spring rainfall typically increases. The IOD for early 2021 was assessed to be in a neutral phase, as per the Australian Bureau of Meteorology which provides regular updates on the IOD outlook.

The MJO is a global-scale feature of the tropical atmosphere that causes the major fluctuation in tropical weather on a weekly to monthly basis. It can be characterised as an eastward-moving pulse of cloud and rainfall near the equator. It is several thousand kilometres in scale, typically recurs every 30-60 days, and is associated with variations in wind, cloudiness and rainfall. 

The MJO effects are most evident over the Indian Ocean and western equatorial Pacific. They influence the timing, development and strength of the major global monsoon patterns, including the Indian and Australian monsoonsTropical cyclones are also more likely to develop in association with certain phases of a strong MJO event. The MJO has its greatest effect on the tropical areas of Australia during summer, although it can have some effect on parts of southern Australia. The MJO can affect the timing and intensity of active monsoon periods in northern Australia, and this can lead to enhanced rainfall – in terms of both intensity and duration.

Climate Change & Regional Security

The effects of climate change on the Indian Ocean will in turn likely have a significant impact on the security of the entire region. The environmental security issues faced by the region were articulated in the 2019 report ‘Environmental security in the eastern Indian Ocean, Antarctica and the Southern Ocean’. Many of these are closely related to climate change effects on the ocean.

For example, under a changing climate, wide-scale human displacement is considered inevitable, because of rising sea levels, floods, and other extreme weather events. This raises several questions: (a) Where will these displaced people go?  (b) How many will be internally displaced, and how many will seek to migrate overseas? (c) How will migratory attractive and targeted countries manage the resulting geo-political pressures, including border control and bio-security arrangements?

Climate change will also likely have a significant adverse effect on marine food security, which may include major declines in fish stocks. This in turn could have a substantial effect on coastal communities across the region that rely on fish as their main source of protein and/or income. For some countries, the potential disappearance of traditional fishing industries could lead to major economic dislocations, food insecurity, financial crises and  political instability. At the same time, growing competition for fish resources among countries inside and outside the region could lead to more disputes and even clashes between rival fishing groups and relevant state agencies.

Climate change is also be expected to influence the intensity, as well as other characteristics, of severe weather events such as cyclones and storm surges. While there could be short term impacts on lives and property, these severe weather events could severely affect the long-term prosperity and resilience of fragile communities or even entire nations. 

Importantly, in many cases these and other effects of climate change could interact, with cumulative and cascading consequences. A series of severe weather events could, for example, significantly reduce the economic and social resilience of some communities, leaving them more vulnerable to sea level rise or heightened food insecurity. This could further exacerbate the risk of large-scale human displacements and political stability exemplified by countries such as Bangladesh and Maldives.    

What may appear to be just an environmental issue could have unexpected security consequences. For example, Somali-based piracy over the past 15 years is a case in point that demonstrates the inter-relationship of these issues. The collapse of the Somali state in the 1990s led to the disappearance of law enforcement authorities, followed by the destruction of Somali fishing grounds by illegal fishers, mostly from outside the region. Impoverished Somali fishing-folk then turned to piracy, threatening the vital shipping lanes across the western Indian Ocean. This prompted a major international military response, including the deployment of naval vessels from many countries inside and outside the region. 

Further Study of the Indian Ocean

It is important that the anatomy and dynamics of the Indian Ocean are more widely understood for Australia. This is well recognised in many circles. However, while the Indian Ocean has been the subject of intensive study in the recent past, more research is sorely needed. 

Perth is an important centre in ongoing research aimed at better understanding the Indian Ocean and its impact on weather and climate. In this context and in respect to the United Nations Educational, Scientific and Cultural Organization (UNESCO’s) global mandate, its Intergovernmental Oceanographic Commission Perth Programme Office (PPO) was established in 1998. It is co-located with the Secretariat of the Intergovernmental Coordination Group of the Indian Ocean Tsunami Warning and Mitigation System which was established in response to the tragic 2004 Boxing Day tsunami. They are both located within the Perth office of the Bureau of Meteorology. This joint facility is the only one of its kind in the southern hemisphere under the UNESCO Intergovernmental Oceanographic Commission (IOC) framework. It operates under the trilateral support of the WA state government, the Australian Government and UNESCO, and works with, and through, Australian and international stakeholders deriving from many ocean and climate related academic and governmental institutional entities. 

The PPO’s role is to facilitate and support governments and scientific institutions in ocean/climate research and applications within, and relevant to, areas such as ocean/climate hazards and forecasting, marine and fisheries management, conservation and the blue economy. Its role covers the oceanic regions around Australia with a focus on the Indian and Southwest Pacific oceans. In fulfilling this role, the PPO has developed and maintains links between WA and Australian organisations and the Global Ocean Observing System and other global oceanographic research organisations and alliances. 

By acting as a facilitator, the PPO aims to ensure the valuable knowledge and data generated by the Global Ocean Observing System takes into account the needs of a wide range of WA and Australian stakeholders and the broader community who might use and benefit from the information. Those beneficiaries deriving for example from marine research (academia, state and federal research organisations), marine natural resource industries and maritime transport constituents provide a critical link between the scientific research and applications occurring at ocean basin scales to research and its application at local Australian and  WA scales. 

The PPO has been actively promoting and facilitating scientific alliances and related programs such as the Second International Indian Ocean Expedition 2015-25 (IIOE-2), as well as educational initiatives to better understand and transfer knowledge on the Indian Ocean’s oceanic and related climatic properties. These alliances focus on physical oceanography, biogeochemistry, knowledge transfer via capacity building initiatives, multinational and multidisciplinary collaborative programs, and most recently linking future activities under its mandate with the forthcoming UN Decade of Ocean Science for Sustainable Development (2021-30) . 

The IIOE-2 is a major effort relating to these initiatives, and which the PPO has helped spawn and now co-manages, (along with the Hyderabad-based Indian National Centre for Ocean Information Services of the Indian Ministry of Earth Sciences). It has brought together a wide international multi-disciplinary alliance at the highest scientific and institutional levels responding to a comprehensive scientific plan and an associated implementation strategy.

The IIOE-2 was motivated by the need to advance understanding of oceanic, atmospheric and geologic processes and their interactions in the Indian Ocean, and to determine how these dynamics affect climate, marine biogeochemical cycles, ecosystems, and fisheries, both within the region and globally. This understanding is needed to predict the impacts of climate change, pollution, and increased fish harvesting on the Indian Ocean as well as the influence of the Indian Ocean on weather patterns across Australia. 

Outstanding Questions

There are still several globally important questions requiring further examination to understand better the impact of global warming on the Indian Ocean and its surrounds, including Australia. Some policy related questions to guide future research include:

  • What is the carbon anatomy of the Indian Ocean and its association with ocean acidification and the global atmospheric carbon budget? 
  • How is Indian Ocean warming linked to bleaching of critical marine ecosystems, such as coral reefs and other calcium-based organisms and animals in the ocean?
  • How does the Indian Ocean’s warming and changing current and weather systems impact on the more recently understood phenomena of marine heat waves, such as those that affected the entire west coast of Australia in 2011 and 2019? 
  • How does the Indian Ocean’s changing character impact on the fundamentally important coupled ocean-weather phenomena such as the Indian Ocean Dipole, the Madden Julian Oscillation, and the genesis, strength, temporal and spatial characteristics of extreme events (such as cyclones, waves, coastal water level changes, rainfall, drought and fire).
  • How is the changing Indian Ocean affecting broadscale food security in fisheries, such as the ocean-wide tuna dynamics?

This new understanding of the Indian Ocean is also fundamental to policymakers for the development of management strategies. The IIOE-2 will continue to produce multinational collaborations examining fundamentally important scientific questions in the Indian Ocean via major oceanic field campaigns, engaging some of the region’s and the world’s major ocean and climate science institutions. The improved understanding that the IIOE-2 of unlocking also has strong relevance to the ecologies and human societies of island and Indian Ocean region communities. 

The scientific, commercial and defence communities in WA can have an important role in supporting ocean and coupled climate research in the Indian Ocean. Indeed, the defence community’s support of ground-breaking research in ocean science is well placed in history. For example, Defence played a critical world-leading role in the First International Indian Ocean Expedition (IIOE-1; Behrman 1981) during 1959-65 through the deployment of HMAS Gascoyne and HMAS Diamantina.

The support of the defence community in the IIOE-2 would be welcomed, as new frontiers in ocean and climate science are explored to benefit the countries of the Indian Ocean region, Australia included.

About Multiple Authors

Dr Nick D’Adamo, Dr David Brewster, Dr Paul McLeod, John Roberts and John Loney

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