Ecology
Overview
 The Importance of the Global OceansThe importance of Earth’s oceans to life on our planet can be summed up in a few vital statistics…
Covering 71% of the Earth’s surface, the oceans comprise 97% of the planet’s total stock of water. They provide habitats for biodiversity, playing host to almost 50% of known species, and supporting the life of an estimated 80% of all sea-, sky- and land-dwelling creatures.
They provide one-fifth of the animal protein in human diets, over one in three people of the entire planet’s population live in coastal areas and they contribute to the livelihood of hundreds of millions of people.
There are also billions of tiny single-celled plants floating around in our seas that contribute around 50% of the total oxygen in our biosphere, which, together with our rainforests on land, act as the lungs of our planet.
The oceans also play a vital role in regulating how heat from the sun is redistributed around the planet, which in turn drives the weather patterns and the climate in many areas.
Any seemingly small-scale disturbance in the delicate balance of our global oceans could have large-scale effects across the complicated and interconnected Earth System that governs processes and life on the planet.
 The Impact of Increasing Atmospheric CO2When CO2 dissolves in seawater, it forms carbonic acid, thereby acidifying the ocean. Although this reaction is independent of climate change, as more CO2 enters the atmosphere, so more is likely to be absorbed by the oceans. The potential impacts of this ocean acidification are only just starting to be understood, but it could have many repercussions for life both in, and beyond, the seas. In addition, with reduced sea ice cover continuing to amplify warming in the Arctic, and with further sea ice loss predicted over the coming decades, the effects could be both diverse and far-reaching. Explore this section to find out more about the potential impacts of this ocean change on the ecology of our planet. For more information on the science behind ocean acidification and sea ice loss, click on the links at the top of this page.
Potential Impacts of Ocean Acidification
 There are two main lines of research looking into the potential impacts of ocean acidification on marine organisms. Firstly, many marine organisms form calcium carbonate shells, which may be susceptible to corrosion in a more acidic ocean.
Secondly, all organisms have a specific balance of internal body processes, which can be affected by a change in acidity levels. Many marine organisms have a pH level inside their cells which is the same as the surrounding seawater, and so if seawater pH changes then this could affect some of the important biological processes that regulate an organism's energy supply, behavior, growth and reproduction.
On Shellfish
Increased acidity in the oceans is likely to reduce the availability of a mineral called carbonate. This is used to form the shells and skeletons of many marine organisms, by a process known as calcification.
Reduction in calcification has an effect similar to osteoporosis in humans, slowing growth and making shells and skeletons weaker in many organisms exposed to these conditions. This could have an impact on species including lobsters, crabs, mussels, oysters and sea urchins.
Increase in seawater acidity may also lead to changes in the overall form and structure, metabolism, levels of physical activity, behaviour patterns and ability to reproduce in these shellfish.
 On Small Marine Organisms
Also likely to be affected by a reduction in calcification are tiny organisms such as pteropods (a type of mollusc) and phytoplankton (tiny single-cell plant organisms) that float around in plankton.
Whilst most people have never heard of these two species, they form a vital part of the food web. Any negative impact on them will also be felt on the larger creatures that rely on them for food.
The health and resistance of phytoplankton is also of vital importance to planetary health: the sea is teeming with them, and together they convert huge quantities of inorganic CO2 into living matter. This is the interface where life is created in the oceans, and the process releases a major percentage of the world's oxygen into the atmosphere, making phytoplankton vital for life outside of the oceans too.
Research to date shows a variety of responses to acidification by different types of phytoplankton. As such, we don’t yet know how their ability to help to regulate the planet's overall climate or to sustain life will be affected.
 On Coral ReefsBecause they require very high levels of carbonate to build their skeletons, delicate corals may face an even greater risk than shellfish.
Coral reefs serve as habitat for a quarter of all fish species during at least part of their lifetime. If the commercial fish stocks living in the cold-water corals found in deep waters are reduced, this may have an impact on the food supply of people in many areas throughout the world.
Scientists have also recently found that the reefs not only harbour an incredible array of biodiversity, but also appear to have been actively involved in the generation of new life forms. Losing this source of new species could have a profound effect on the future of life in our oceans.
The loss of coral reefs would also reduce the protection that they offer coastal communities against storm surges, hurricanes and tsunamis. Thousands of miles of shorelines will become more prone to erosion, flooding, property damage and, in extreme cases, loss of life.
Given the role that coral reefs play in tourism, we can reasonably expect any losses to also affect this billion-dollar industry.
On Marine Food Webs The effects of ocean acidification could be felt throughout the food web, upsetting the delicate balance of many marine ecosystems and decreasing biodiversity.
If this happens, it not only threatens marine organisms themselves, but also the protein supply and food security of millions of the world’s poorest people.
 On Ocean Noise LevelsThe absorption of sound in seawater changes with the chemical make-up of the water itself. Although the process is not entirely understood, we do know that increasing levels of ocean acidification means low-frequency sounds will travel further underwater, thus making the oceans more ‘noisy’.
As yet it is unclear how this could affect marine animals that use low-frequency acoustics to find their way around or locate food and mates. It may mean they can now communicate over longer distances, but it may also mean that the increase in background noise acts as a distraction or covers sounds important for their natural behaviour patterns.
Potential Impacts of Sea Ice Loss
 On WildlifeMany species are dependent on the sea ice to survive. Polar bears hunt on it, using it to travel from one region to another to get enough food to maintain healthy fat reserves. Certain seals use the ice as a resting place, for giving birth, raising pups and for feeding. Walrus rely on sea ice for easier access to food, using it as a diving platform to feed on clams on the sea floor of continental shelves. If the ice edge retreats, they'll only have access to deep waters, where this food source won’t be found.
The undersurface of the sea ice is a growth site for algae and invertebrates that sustain the fish that narwhals, beluga whales and seals predominantly feed on. Its loss could have a disruptive effect on this vital marine food chain.
Above the ice, species such as caribou and muskox may no longer be able to use the ice as a migratory route between islands and mainland areas.
Bird species may also be affected. For example, ivory gulls nest on rocky coastal cliffs and fly out to the sea ice to fish through cracks and scavenge on its surface. Retreating sea ice could have serious consequences on their ability to reach food with which to feed their young.
Large sections of the Arctic Archipelago will open up to shipping, and structures will be erected to enable the exploitation of the oil and gas reserves that become accessible. The increased noise, traffic, pollution and potential cargo spillages, including oil, will lead to further disturbances in the delicate balance of the marine ecosystems. On Ocean Acidification It is commonly expected that, as the sea ice melts and more water is exposed to increased levels of atmospheric CO2, the Arctic Ocean will increasingly acidify. However, this is complicated by the processes that go on during sea ice formation and melting, so research is being undertaken to work out how these processes will contribute to ocean acidification. This has a host of potential repercussions that can be explored in the acidification section.  On Indigenous CommunitiesIndigenous communities based around the Arctic Ocean, such as the Aleuts, Indians, Inuits, Chukchi and Métis, may face enormous changes in terms of both culture and how they meet their people’s basic needs of food, shelter, and clothing.
In the past, these people were able to predict the weather using traditional indicators such as clouds, winds and currents, but climate change means this is increasingly difficult. The changing migratory patterns of Arctic wildlife have made it more difficult to hunt food, and unexpected storms have left hunting parties stranded.
Absence of sea ice along Arctic coastlines, or thinning of sea ice on previously traditional travel routes, also has safety implications; coastal areas become increasingly prone to landslides and floods, potentially uprooting entire villages. On Geo-Political ConsiderationsThe Arctic’s profile in the foreign policies of its surrounding countries has been raised in light of its melting sea ice. As this happens, it becomes possible to access the oil, gas and mineral deposits and other natural resources previously unreachable underneath.
Since up to 25% of the Earth’s estimated remaining oil and gas reserves lie under the Arctic Ocean’s seabed, an international legal process is already underway to determine ownership rights.
The melting sea ice has also meant that the Northwest Passage, the most direct shipping route from Europe to Asia, may soon become ice-free and open to the shipment of goods during the summer. Discussions continue whether the passage is an international strait or internal Canadian waters, the outcome of which will decide how such increased traffic would be regulated. On Sea Levels Whilst melting sea ice doesn’t directly contribute to increasing sea levels, the melting of glaciers, ice caps and land-based ice sheets does. In addition, as the increasingly large area of open water absorbs more heat, its volume expands. In combination, these two factors contribute to global rising sea levels.
Such increases threaten low-lying areas around the globe with beach erosion, coastal flooding, and contamination of freshwater supplies with seawater.
Current predictions suggest that global sea levels may well rise by between 30-100cm by 2100, leaving potentially 300 million people in danger of flooding.
At particular risk are countries such as Bangladesh where millions of people live on low-lying land. Even major cities like London, Shanghai, Bangkok and New York could end up below sea level if adequate flood protection solutions are not developed.  On Global Weather Patterns Global weather is driven by the differences in air temperature between tropical regions and the Poles, so any significant warming in the Arctic has an impact on atmospheric conditions in the Northern Hemisphere. This can lead to destabilization of weather patterns across the globe, creating more unpredictable and extreme weather.
Warmer water in the oceans pumps more energy into tropical storms, meaning that hurricanes could be stronger and potentially more destructive to homes and property across the world.
Warmer temperatures also increase the probability of drought. Greater evaporation, particularly during summer and autumn, could worsen these drought conditions and increase the risk of wildfires in areas of heavy forestation. Agriculture and water supplies can also expect to be affected.
An increase of heat energy in the climatic system could also lead to heavier rainfall in some areas, increasing the risk of domestic flooding.
As surface waters in the Arctic Ocean warm, global ocean circulation may also be affected. Since different ocean currents transport waters with different characteristics, supporting different ecosystems, changes in ocean circulation could affect fisheries and other marine resources.On Methane Production & Release Rapid regional warming in the Arctic risks bringing about the release of vast quantities of methane stored in the Arctic seabed or from the breakdown of rotten vegetative matter in the now-melting tundra soils (also called permafrost).
The release of this potent greenhouse gas could set in motion powerful climate feedbacks which will have an impact far beyond the Arctic itself, amplifying and accelerating the consequences of global warming.
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