Question Period Note: Climate Change Ocean: Acidification, Low Oxygen in the Oceans and Changes in Sea Ice

• Canadians know climate change is real; we are witnessing important impacts that are directly affecting Canadians and our coastal communities.
• Approximately 72,000 Canadians make their living directly from fishing and fishing-related activities. That is why we are working to secure the future of our fisheries through sustainable and responsible science-based fisheries management.
• Our department continues to research and study climate change related phenomena such as ocean acidification, low oxygen levels and changing sea ice, and their impacts on our fisheries and aquatic ecosystems.
• Understanding our ocean ecosystems in a changing world is now more important than ever for improving management and conservation measures.

• As a result of increasing CO2 in the atmosphere and a changing climate, we expect Canada’s oceans to become warmer, fresher due to melting sea ice, more acidic, and less oxygenated.
• Ocean acidification is the term used to describe the long-term change of ocean chemistry as CO2 is absorbed from the atmosphere. Since 1960, roughly one-third of all carbon dioxide emissions from the burning of fossil fuels have ended up in the ocean. To date, the only certain way to slow ocean acidification is by reducing global CO2 emissions.
• Atmospheric carbon dioxide, when absorbed by the ocean, alters ocean chemistry by forming carbonic acid, making the ocean more acidic and reducing the availability of calcium carbonate. This reduction in the availability of calcium carbonate can make it more difficult for several marine organisms to grow shells. When shell building organisms are at risk (including certain types of shelled phytoplankton that form the base of the marine food chain) the entire food web may also be at risk due to the lack of food availability, which can cause larger ecosystem changes.
• In the last decade, research into the effects of ocean acidification on plants and animals in the ocean has been extensive. Clear negative effects have been documented in species that form calcium carbonate for their shells or skeletal body parts.
• When shell-building organisms are at risk (including certain types of shelled phytoplankton that form the base of the marine food chain) the entire food web may also be at risk due to the lack of food availability, which can cause larger ecosystem changes. Human-driven rising nutrient loads and climate change are altering ocean biogeochemistry and increasing oxygen consumption, leaving some aquatic zones low or depleted in dissolved oxygen. In ocean and freshwater environments, the term "hypoxia" is used when the concentration of dissolved oxygen becomes too low to support most aquatic life in a water body. Oxygen concentrations have been declining in both open ocean and coastal waters for at least the past 50 years, largely because of human activities that have increased global temperatures and nutrient discharge to coastal waters.
• Hypoxia occurs naturally, but most often is a consequence of human-induced factors, especially nutrient pollution (also known as eutrophication) caused by agricultural runoff, fossil-fuel burning, and wastewater treatment effluent.
• Hypoxia and ocean acidification (OA) often occur at the same time due to warmer water temperatures and the addition of land-based nutrient sources. The effects of multiple stressors can further intensify the effects on aquatic organisms and ecosystems.
• Fisheries and Oceans Canada is undertaking activities to understand the state and extent of ocean acidification and low oxygen and the consequences of these changes on aquatic ecosystems and commercial fisheries through routine oceanographic monitoring, targeted research and delivery of the Aquatic Climate Change Adaptation Services Program (ACCASP). For example:
 DFO Scientists at the Maurice-Lamontagne Institute (Que) and Saint Andrews Biological Station (NB) are conducting research into the effects of ocean acidification on marine fauna and ecosystem processes in Atlantic Canada.
 DFO scientists are also exploring ecosystem impacts of hypoxia by studying the distribution of various groundfish species in relation to oxygen in the Northeast Pacific, Gulf of St. Lawrence and Scotian Shelf-Gulf of Maine.
• Natural climate patterns and climate change alter the atmosphere and the ocean. Both cause fluctuations and changes in sea-ice conditions. The effects in Arctic are that seasonal ice clears or melts earlier and forms later.
• According to the 2019 report Canada's Changing Climate Report (CCCR), perennial sea ice in the Canadian Arctic is being replaced by thinner seasonal sea ice. Summer sea ice area (particularly multi-year ice area) has declined across the Canadian Arctic at a rate of 5% per decade to 20% per decade since 1968 (depending on region); winter sea ice area decreased in eastern Canada by 8% per decade.
• In NOAA's ‘Arctic Report Card: Update for 2019’, scientists found that winter sea ice extent in 2019 narrowly missed surpassing the record low set in 2018, leading to record-breaking warm ocean temperatures in 2019 on the southern shelf. Bottom temperatures on the northern Bering shelf exceeded 4°C for the first time in November 2018.
• The report also showed that Bering and Barents Seas fisheries have experienced a northerly shift in the distribution of subarctic and Arctic fish species, linked to the loss of sea ice and changes in bottom water temperature.

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