Atmosphere

Acidification

Developed as a research topic in past decade

• Increasing atmospheric carbon dioxide emissions
• Coastal nutrient enrichment, methane hydrates and acid gases from industrial emissions may also contribute locally, increasing variability

• Unprecedented rapid change to ocean carbonate chemistry
• Much of the ocean will become corrosive to shelled animals and corals, with effects starting in the Arctic by 2020

• Reduced calcification, growth and reproduction rates in many species
• Changes to the carbon and nitrogen composition of organic material
• Dissolution of unprotected calcium carbonate
  structures in some regions

• Impeded shell or skeletal growth and physiological stress in many species, including juvenile stages
• Change to biodiversity and ecosystems, and the goods and services they provide
• Cold and upwelling waters currently supporting key fisheries and aquaculture likely to be especially vulnerable

Warming

A relatively mature study area in terms of physical changes and physiology but poorly studied at ecosvstem and biogeochemical levels

• Increasing greenhouse gas emissions to the atmosphere

• Temperature increase,
  particularly in near-surface waters
• Less ocean mixing due to increased stratification
• Increased run-off and and sea-ice melt will also contribute to stratification in Arctic waters
• Increased in marine heat waves

• Decreased carbon dioxide solubility
• Increased speed of chemical and biological processes
• Reduced natural nutrient re-supply in more stratified waters

• Stress to organism physiology, including coral bleaching
• Extensive migration of species
• More rapid turnover of organic
  matter
• Nutrient stress for
  phytoplankton, particularly in warm waters
• Changes to biodiversity, food webs and productivity, with potential consequences for fisheries, coastal protection and tourism

Deoxygenation

Emerging issue, poorly studied

• Reduced oxygen solubility due to warming
• Decreased oxygen supply to the ocean interior due to less mixing
• Nutrient rich land run-off stimulating oxygen removal locally

• Less oxygen available for respiration especially in productive regions, and in the ocean interior
• Extended areas of low and very low oxygen (dead zones)

• Reduced growth and activity of zooplankton, fish and other oxygen-using organisms
• Endocrine disruption

• Stress to oxygen-using organisms
• Risk of species loss in low oxygen areas
• Impacts on reproductive success
• Shift to low oxygen-tolerant organisms, especially microorganisms and loss of ecosystem services in these areas

Sea Level Rise

A mature research area and a long-term issue

• Climate warming due to increased greenhouse gas emissions to the atmosphere

• Melting of glaciers and ice sheets
• Thermal expansion of seawater

• Increase in the volume of water in the ocean
• Rise in the level of seas

• Flooding of coastal and island habitats
• Erosion of shorelines , Loss of infrastructure
• Greater risk of impacts from storms and surges