Rapid climate change alters the environment and biological production of the Indian Ocean

• Published in: The Science of the total environment 2024-01, Vol.906, p.167342-167342, Article 167342
• Main Authors: Dalpadado, Padmini, Roxy, Mathew Koll, Arrigo, Kevin R., van Dijken, Gert L., Chierici, Melissa, Ostrowski, Marek, Skern-Mauritzen, Rasmus, Bakke, Gunnstein, Richardson, Anthony J., Sperfeld, Erik
• Format: Article
• Language: English
• Subjects: Biological time series; Climate change; Large marine ecosystem; Marine heat waves; Monsoonal productivity changes; Remote sensing
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2023.167342

We synthesize and review the impacts of climate change on the physical, chemical, and biological environments of the Indian Ocean and discuss mitigating actions and knowledge gaps. The most recent climate scenarios identify with high certainty that the Indian Ocean (IO) is experiencing one of the fastest surface warming among the world's oceans. The area of surface waters of >28 °C (IO Warm Pool) has significantly increased during 1982–2021 by expanding into the northern-central basins. A significant decrease in pH and aragonite (building blocks of calcified organisms) levels in the IO was observed from 1981–2020 due to an increase in atmospheric CO2 concentrations. There are also signals of decreasing trends in primary productivity in the north, likely related to enhanced stratification and nutrient depletion. Further, the rapid warming of the IO will manifest more extreme weather conditions along its adjacent continents and oceans, including marine heat waves that are likely to reshape biodiversity. However, the impact of climate change beyond the unprecedented warming, increase in marine heat waves, expansion of the IO Warm Pool, and decrease in pH, remains uncertain for many other key variables in the IO including changes in salinity, oxygen, and net primary production. Understanding the response of these physical, chemical, and biological variables to climate change is vital to project future changes in regional fisheries and identify mitigation actions. We accordingly conclude by identifying knowledge gaps and recommending directions for sustainable fisheries and climate impact studies. Figure. Overview of climate drivers of the Indian Ocean, their impacts and consequences. [Display omitted] •Indian Ocean experiences unprecedented warming with +1.7–3.8 °C century projections.•Significant decreases in pH and aragonite levels observed during last four decades.•Decreasing primary productivity in the north with varying model projections•Importance of establishing biological time series for fisheries management.•Importance of safeguarding biodiversity in marine protected and other vital areas.