Sea temperature and ocean acidification have climbed during the last three decades to levels beyond what is expected due to natural variation alone, a new study led by Princeton researchers finds.
Meanwhile other impacts from climate change, such as changes in the activity of ocean microbes that regulate the Earth’s carbon and oxygen cycles, will take several more decades to a century to appear. The report was published Aug. 19 online in the journal Nature Climate Change.
The study looked at physical and chemical changes to the ocean that are associated with rising atmospheric carbon dioxide due to human activities. “We sought to address a key scientific question: When, why and how will important changes become detectable above the normal variations that we expect to see in the global ocean?” said Sarah Schlunegger, a postdoctoral research associate at Princeton University’s Program in Atmospheric and Oceanic Sciences (AOS).
The study confirms that outcomes tied directly to the escalation of atmospheric carbon dioxide have already emerged in the existing 30-year observational record. These include sea surface warming, acidification and increases in the rate at which the ocean removes carbon dioxide from the atmosphere.
In contrast, processes tied indirectly to the ramp up of atmospheric carbon dioxide through the gradual modification of climate and ocean circulation will take longer, from three decades to more than a century. These include changes in upper-ocean mixing, nutrient supply, and the cycling of carbon through marine plants and animals.
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