Increasing temperatures, carbon levels, and ocean acidity have negative impacts on marine systems.
In addition climate change, the buildup of carbon dioxide in the atmosphere has also been linked to changes in the chemistry of the oceans.
Measurements made over the last few decades have demonstrated that ocean carbon dioxide levels have risen in response to increased carbon dioxide in the atmosphere, leading to an increase in acidity (that is, a decrease in pH).
Ocean acidification is the result of an increase in carbon dioxide absorption by ocean water and the corresponding decrease in pH. As seawater becomes less alkaline – or more acidic – less calcium carbonate is available for corals, shellfish, and other sea life to build their shells and skeletons. Threats to ecosystems and species due to ocean acidification will be wide-ranging across the marine food web and associated coastal communities, but include significant changes in the chemical composition of coastal ecosystems. NOAA reports that increased absorption of carbon dioxide into the ocean has already begun to reduce calcification rates in reef-building and reef-associated organisms.
Ocean acidification has been linked to the disturbance of food webs and changing species distributions. Together with other biogeochemical changes, increasing ocean acidification may compromise the health of marine ecosystems as well as negatively impact many ocean goods and services and the communities that rely on them. These changes especially threaten marine organisms that build their structures calcium carbonate – such as corals, clams, oysters, and crustaceans – because more energy is required to build their shells, making less energy available for important biological processes such as growing, reproducing, and responding to stress. Researchers from the Woods Hole Oceanographic Institute found that some shelled-species faired better than others to increasing carbonic acid, however, overall impacts to ecosystems such as coral or oyster reefs appear to be negative, as research shows these systems are becoming increasingly threatened.
As coral and oyster reefs are degraded, the health of these systems and the plants and animals that depend on them becomes increasingly vulnerable. Additionally, these reef systems play important roles reducing the risk of coastal communities from natural hazards such as storms, flooding, and erosion. The USGS summarizes recent research that finds:
These findings make a strong case for the value of conservation of intact reef systems. The fact that over 7 million people live near reef systems in the United States provides additional basis for restoring degraded reef systems in order to enhance their wave attenuation potential, which can substantial reduce the vulnerability of coastal ecosystems and the communities in coastal areas.
Land trusts are responding to on-the-ground impacts of ocean acidification in various ways. Some groups are engaging in coral reef restoration work, and many more are undertaking advocacy and education to help raise awareness to this growing management challenge. In addition to employing strategic conservation planning to reduce risks and enhance resilience, some land trusts are also supporting efforts to mitigate greenhouse gas emissions to reduce the extent of future climate change.
Land trusts must determine the right planning approach for their organization, however, more and more, conservation organizations are working with their communities to identify opportunities to reduce vulnerabilities and prepare for changing temperatures. Agencies are making similar strides to implement projects that reduce risks and plan for resilience by incorporating adaptation, mitigation, and engagement into their strategic goals and objectives. For example, the U.S. Fish and Wildlife Service’s Strategic Plan for Responding to Accelerating Climate Change identifies seven planning and development goals to support sustainable landscapes. Conservation groups are increasingly partnering with agencies as well as other nonprofits and for-profit organizations to respond to this global challenge at local levels.
Resilience describes the ability of a system to persist through extreme change. By working to identify and reduce potential threats land managers can build resilience and achieve multiple management objectives. Assessing vulnerabilities is a critical step in the strategic conservation planning process that helps land trusts identify key threats to resources. Adaptive management planning enables conservation practitioners to implement interventions to reduce vulnerabilities and to monitor and revise strategies as new information becomes available. There is no one-size-fits-all solution to addressing management challenges associated with warming average temperatures, however, planning that acknowledges vulnerabilities can help land trusts better achieve their conservation objectives.
A pH unit is a measure of acidity ranging from 0-14. The lower the value, the more acidic the environment. Becoming more acidic is a relative shift in pH to a lower value. As carbon inputs to our oceans increase, pH decreases. NOAA reports that since the beginning of the Industrial Revolution, the pH of surface ocean waters has fallen by 0.1 pH units. Since the pH scale, like the Richter scale, is logarithmic, this change represents approximately a 30 percent increase in acidity.
Ocean acidification is occurring because the world’s oceans are absorbing increasing amounts of atmospheric carbon dioxide, leading to lower pH and greater acidity. These changes are threatening the fundamental chemical balance of ocean and coastal waters from pole to pole. Read more from NOAA's Ocean Acidification Program.
Oceans are an important element of the "long carbon" cycle. By absorbing CO2 from the air at the sea surface, carbon is combined with calcium by shell bearing marine organisms. When these organisms die their shells sink to the ocean floor. Over time the calcium compressed in the sea floor sediment returns to the land as limestone and dolomite rock. As CO2 becomes more available, however, the pH of the ocean declines, and this increase in acidity has been observed to negatively impact shell development in many species. The long-term impacts of these changes are uncertain. Learn more about Carbon Cycle Science.
Did you know land trusts are working to mitigate climate change? Learn more.