Overview of Main Climate Impacts on Marine Ecosystems

The two main impacts of climate change on marine ecosystems, as outlined by Hillebrand et al (2018), are shrinking biodiversity proportional to the degree of warming, and the decline of energy transfer up the food chain owing to primary production microorganisms becoming physically smaller.

Heneghan et al (2019) identified that climate change contributes to lower nutrient supply to phytoplankton, deoxygenation of ocean waters, less energy transferred across the food chain, and a diminished population of larger organisms.

Research by Peng et al (2018) highlighted increased upwelling and upper-ocean stratification in California, resulting in higher metabolism and grazing by zooplankton and therefore a fall in the biomass of phytoplankton.

In their 2013 study, Moore et al noted the curtailed export of organic matter from surface water by reason of stronger vertical stratification, which in turn impeded nutrient supply to the surface. This decreases phytoplankton biomass and chlorophyll, and negatively influences primary and export production (Moore et al 2013).

According to Doney et al (2012), climate impacts influences changes in behaviour and physiology of marine organisms, resulting in altered interaction among species and creation of new ecosystems; these impacts also contribute to poleward migration, drop in organism size and reproduction rates, and changes in their habitats and food web structures.

The Ocean Foundation considered the climate change impacts to include heat-driven migration, oxygen reduction or depletion, biodiversity loss, restructuring of ecosystems, and the disruption of ecological goods and services, while CNBC (2022) reported that warming endangers marine ecosystems and has catastrophic effects on fish populations.

What was most concerning to me upon review of those sources is not only their consensus on the effects of climate change on marine life, but also the very fundamental – microscopic - level at which the climate crisis is endangering all life on Earth.

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References:

1. Heneghan, R.F., Hatton, I.A., and Galbraith, E.D. (2019) ‘Climate change impacts on marine ecosystems through the lens of the size spectrum’. Emerging Topics in Life Sciences 3(2) 2019, pp.233–243.

2. Peng, X., Chai, F., Curchitser, E.N., Castruccio, F.S. (2018). ‘Future changes in coastal upwelling ecosystems with global warming: The case of the California Current System’. Scientific Reports volume 8, Article number: 2866 (2018) https://www.nature.com/articles/s41598-018-21247-7

3. Hillebrand, H., Brey, T., Gutt, J., Hagen, W., Metfies, K., Meyer, B., and Lewandowska A. (2018). ‘Climate change: Warming impacts on marine diversity’, in Salomon, M. and Markus, T. (eds) Handbook on Marine Environment Protection. (Cham: Springer, 2018).

4. Moore, J.K., Lindsay, K., Doney, S.C., Long, M.C., and Misumi, K. (2013). 'Marine Ecosystem Dynamics and Biogeochemical Cycling in the Community Earth System Model [CESM1(BGC)]: Comparison of the 1990s with the 2090s under the RCP4.5 and RCP8.5 Scenarios'. Journal of Climate. Volume 26: Issue 23. Pages 9291-9312. https://journals.ametsoc.org/configurable/content/journals$002fclim$002f26$002f23$002fjcli-d-12-00566.1.xml?t:ac=journals%24002fclim%24002f26%24002f23%24002fjcli-d-12-00566.1.xml

5. Doney, S.C., Ruckelshaus, M., Duffy, J.E., Barry, J.P., Chan, F., English, C.A., Galindo, H.M., Grebmeier, J.M., Hollowed, A.B., Knowlton, N., Polovina, J., Rabalais, N.N., Sydeman, W.J., and Talley, L.D. (2012). ‘Climate Change Impacts on Marine Ecosystems’. Annual Review of Marine Science. Vol. 4:11-37 https://www.annualreviews.org/doi/10.1146/annurev-marine-041911-111611

6. The Ocean Foundation (‘TOF’). ‘Ocean and Climate Change’. https://oceanfdn.org/ocean-and-climate-change/

7. CNBC. (2022). ‘Extreme heat driven by climate change is ‘new normal’ for oceans, study finds’. 2 February 2022. https://www.cnbc.com/2022/02/02/extreme-heat-driven-by-climate-change-is-new-normal-for-oceans.html