Oceans will likely experience a decrease in marine productivity, an increase in ocean acidification, and an increase in the number of oxygen dead zones.
Decreased Sea Ice Habitat
The average thickness of Arctic sea ice has declined markedly over the past few decades. It is estimated that the thickness will further decrease by approximately 15% for every 1.8°F (1°C) of global warming. Arctic sea ice is vital for seals, polar bears, and walruses to hunt and rest.
It is uncertain whether animals that are dependent on sea ice habitats could adapt to a significant loss of sea ice.
Increased Dead Zones
As ocean water warms, ocean oxygen levels are likely to decline, exacerbating low-oxygen zones in coastal areas and deeper waters. These dead zones degrade habitat and can lead to extensive fish and invertebrate mortality.
Implement early warning and notification systems for events of coastal oxygen deprivation.
Brazil, India, Gulf Coast, Western Europe, China
Decreased Catch Potential of Fisheries
With global average warming of 3.6°F (2°C), catch potential could decrease by up to 40% in the tropics, as commercial species shift away from the warming waters there. Many of the complexities of marine ecosystems that affect fisheries are not well understood.
Put practices into place to sustain fisheries in a changing climate. Use adaptive management principles in natural resource management plans to reduce ecosystem vulnerabilities. Encourage alternative vocations in traditional fishing communities.
Increased Catch Potential of Fisheries
With global average warming of 3.6°F (2°C), catch potential could increase by 30–70% in high latitudes as commercial species shift away from the tropics due to ocean warming. Many of the complexities of marine ecosystems that affect fisheries are not well understood.
Put practices into place to sustain fisheries in a changing climate. Incorporate adaptive management principles in natural resource management plans to take advantage of fishery changes, while reducing ecosystem vulnerabilities.
Coral Reef Decline
Rising CO2 concentrations and ocean acidification reduce shell and skeleton growth in marine species such as corals and mollusks. Coral reefs will tend to erode rather than grow, harming the diverse forms of life that are reef-dependent.
Implement systems to evaluate and manage ecosystem impacts.
Affected Polar Marine Species
Due to invasion of warm water species and high local extinction rates, marine species in the Arctic and Southern Ocean will continue to shift geographic ranges and many will die off.
Marine species are generally adapting by migrating down to deeper, cooler waters.
Arctic and Southern Oceans
Decreased Ocean Productivity
Warming of the ocean surface is projected to decrease production of organic compounds in the oceans of the tropics and subtropics. This decreased production will reduce nutrient availability in surface waters.
Conduct evaluations and put systems into place to manage ecosystem impacts.
Western Atlantic Ocean off the coast of Great Britain, Black Sea