Impacts of Emerging Climate Issues
Climate change will result in a wide variety of impacts, including rising sea level, reduced ice cover and thawing of permafrost, loss of marine habitat, shifting distribution ranges for marine organisms and an imbalance between growth and recruitment within ecosystems.
Two emerging impacts of concern among the scientific community are currently being investigated by DFO ocean climate scientists; ocean acidification and hypoxia.
Ocean Acidification: The earth's oceans are vast carbon sinks. In the 200 years since the industrial revolution began, the oceans have absorbed about 30% of the carbon dioxide (CO2) released by the burning of fossil fuels. But this climactic benefit has come at a cost. Carbon dioxide dissolves in the surface water and forms carbonic acid, lowering the pH of ocean waters. The more CO2 the ocean absorbs, the more acidic they will become. There are serious concerns about the ability of marine ecosystems to adapt to acidification. Organisms that form calcium carbonate skeletons and shells, such as coccolithophores and pteropods (food source for salmon), will be greatly limited in their ability to form their outer protective shells since a decline in pH decreases the saturation state of CaCO3. Commercial species such as lobster and shellfish are also vulnerable to this impact.
Hypoxia: Low oxygen (hypoxia) has dramatic impacts on aquatic ecosystems, and the tolerance of marine fish and invertebrates to this condition is highly species dependent. At oxygen levels below 30 percent saturation, cod and other species that are intolerant of hypoxia either migrate to other geographic regions or die. Deoxygenation is now recognized as one of the likely consequences of climate change. The long term observations analyzed by DFO scientists have provided insight into climate change over the decades and the growing knowledge and awareness of hypoxia (dead zones) in Canadian waters.
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