Climate change will lead to a ripple effect of chemical changes in ocean systems that will affect all habitats, organisms and humans by 2100. The conclusion reached by researchers from the University of Hawaii at Manoa after analyzing other aspects of marine ecosystems, such as the depletion of oxygen, states “that no corner of the world ocean will be untouched by climate change by 2100.”
While other models focus on well-known effects of climate change like ocean warming and ocean acidification, there are still other aspects of marine ecosystems that will be affected, according to the research, which was published in the journal PLOS Biology. Scientists from UH Manoa worked with an international group of oceanographers to develop this model of marine ecosystems. Some of the data used by the researchers came from the most recent report by the Intergovernmental Panel on Climate Change.
Changes in temperature, pH and oxygen were factored into the new models and run through two scenarios, a “business-as-usual” one that saw atmospheric carbon dioxide levels reaching 900 parts per million, and another that saw, through an immediate and concentrated effort to reduce CO2 emissions, CO2 levels rising to 550 ppm. The current CO2 level is at 393.31 ppm.
Based on the two scenarios, the researchers discovered that nearly all of the global ocean will be affected by climate change, save for small sections near the polar caps. According to the study, different levels of ocean warming, acidification, oxygen depletion and productivity shortfall, or lack of phytoplankton and other microorganisms necessary for photosynthesis, will affect the global ocean all at once. Specifically, researchers saw an increase in surface temperature ranging from 1.2 degrees Celsius to 2.6 degrees Celsius, a 2 to 4 percent decrease in dissolved oxygen, a decrease in phytoplankton production by 4 to 10 percent of current values, and a pH decrease of 0.15 to 0.31, notes the university.
Deep-sea habitats will be less affected than other habitats, such as coral reefs. A previous study from the researchers concluded climate change will affect the tropics first, followed by the polar regions.
In the polar regions, there may be some increase in oxygen and productivity, but invasive species already migrating to these waters will cancel out any potential benefits for humans in the future.
Lead author Camilo Mora, from UH Manoa, said in a statement, “The consequences of these co-occurring changes are massive — everything from species survival, to abundance, to range size, to body size, to species richness, to ecosystem functioning are affected by changes in ocean biogeochemistry.”
The researchers note the global nature of the study as it analyzed 32 marine habitats while factoring in economic and societal impact as a result of the changing oceans.
As oceans change so too will human activity, such as tourism and fishing, which could affect local economies and up to 870 million people. The university notes, “470 to 870 million of the world’s poorest people rely on the ocean for food, jobs and revenues, and live in countries where ocean goods and services could be compromised by multiple ocean biogeochemical changes.”