Caitlin Keating-Bitonti and Eva Lipiec authored this CRS report (3 November 2022): 'Ocean Acidification: Frequently Asked Questions'.
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Summary
The ocean absorbs carbon dioxide (CO2) from the atmosphere. Chemical reactions between CO2 and water can change the pH of seawater (pH is a measure of water’s acidity or basicity). The current shift in the chemistry of seawater is toward a lower pH, commonly referred to as ocean acidification (OA). Scientific consensus is that rising CO2 concentrations in the atmosphere will continue to contribute to OA globally, primarily affecting the ocean’s surface waters.Some U.S. regions are experiencing impacts from OA (e.g., coastal waters of Oregon), and scientists expect that nearly all U.S. coastlines and open ocean waters will experience impacts of OA by 2100. OA also has negatively affected some marine organisms, such as reef-building corals and shellfish, and may affect others in the future. These impacts have had consequences for U.S. fisheries and aquaculture. Future OA’s economic impacts may include higher risks of storm damage to coastal communities and loss of tourism revenue from OA-caused degradation of coral reefs.
Congress has authorized federal agencies, such as the National Oceanic and Atmospheric Administration (NOAA) and the Environmental Protection Agency, to support activities that aim to adapt to and mitigate OA impacts. In 2009, Congress passed the Federal Ocean Acidification Research and Monitoring Act (FOARAM; 33 U.S.C. §§3701 et seq.), which, among other things, established the federal Interagency Working Group on Ocean Acidification (IWGOA) to coordinate OA activities across the federal government. IWGOA’s work includes studying OA’s potential impact on marine species and ecosystems as well as identifying adaptation and mitigation strategies.
Congress continues to show interest in OA. In 2022, Congress enacted the Coastal and Ocean Acidification Research and Innovation Act of 2021 (P.L. 117-167, Title VI, Subtitle E), which amended FOARAM. The amendments added acidification of coastal waters as a concern to be addressed; established an advisory board to the IWGOA; emphasized research on OA adaptation and mitigation strategies, the compounding effects of OA with other environmental stressors, and the socioeconomic impacts of OA; and authorized appropriations for NOAA and the National Science Foundation to conduct OA activities.
Also in 2022, Congress provided funding to NOAA for OA activities in the Consolidated Appropriations Act, 2022 (P.L. 117-103). During the 117th Congress, Members have introduced and considered other bills related to OA, some of which focused on examining and addressing the impacts of OA, among other activities. Proposed FY2023 appropriations bills would provide NOAA with increased funding compared with FY2022 levels and additional OA-related directives.
What Is Ocean Acidification?
Atmospheric gases, such as carbon dioxide (CO2), continuously diffuse into the surface of the ocean. Dissolved gases in the surface of the ocean are in near equilibrium with gases in the atmosphere. Thus, as more CO2 is emitted into the atmosphere, the surface of the ocean takes up more CO2. The increased uptake of atmospheric CO2 by the ocean alters the chemistry of seawater by decreasing its pH in a process referred to as ocean acidification, or OA (Figure 1).
OA alters seawater chemistry following a series of chemical reactions. When atmospheric CO2 dissolves into water (H2O), it forms carbonic acid (H2CO3). Some of the carbonic acid breaks up in ocean water, producing free hydrogen ions (H+). As the number of free hydrogen ions increases, the pH of the ocean decreases and the water becomes more acidic. The prevailing global average pH (a measure of hydrogen ion concentration) of water near the ocean surface is around 8.1, with regional variations.
How Might Ocean Acidification Change over the 21st Century?
Over the past two centuries, the average pH of water near the ocean surface has decreased by almost 0.1 unit. That change represents a 26% increase in the concentration of free hydrogen ions dissolved in seawater, because the pH scale is logarithmic (i.e., water with a pH of 8.0 is 10 times less acidic than water with a pH of 7.0 and 100 times less acidic than water with a pH of 6.0).Modeling studies project that OA will continue over the 21st century, but the rate of OA likely will depend on the rate of atmospheric CO2 emissions. Under the Intergovernmental Panel on Climate Change’s scenario involving a doubling of the concentration of atmospheric CO2 by 2050 with no additional climate change policies, models project that average surface ocean pH may decrease by 0.4 units by the year 2100 (Figure 2). However, using a scenario in which CO2 emissions reach net zero by 2050 or shortly thereafter, models project that average surface ocean pH may decrease by less than 0.1 unit by 2050 and may rise slightly in the second half of the 21st century (Figure 2). Figure 2 also shows the projected pathway of ocean surface pH for other CO2 emissions scenarios in modeling studies
Model projections of average global OA changes, such as the projections shown in Figure 2, are driven primarily by atmospheric CO2 simulations. In general, the global trend would reflect surface pH decline with increasing atmospheric CO2 concentrations. Regional seawater properties may influence the surface pH value, resulting in geographic variations in OA. See “What Factors Influence Ocean Acidification?” for a further discussion on the factors that may amplify regional variations in seawater pH.
Cutting to the chase...
What Are Recent Congressional Actions Addressing Ocean Acidification? }
In 2022, Congress enacted the Coastal and Ocean Acidification Research and Innovation Act of 2021 (P.L. 117-167, Title VI, Subtitle E), which amended FOARAM. The amendments included The addition of a coastal acidification definition and broadening of agency activities to consider coastal acidification:
The establishment of an advisory board to IWGOA '
A greater research focus on OA adaptation and mitigation strategies, on how OA may interact with other environmental stressors, and on the socioeconomic impacts of OA
Authorization of appropriations for FY2023 through FY2027
In FY2022, Congress appropriated $16 million to NOAA for the Integrated Ocean Acidification Program. Language accompanying the FY2022 appropriations act directed the program to prioritize efforts on “understanding, monitoring, and mitigating coastal ocean acidification, especially where it impacts fisheries and aquaculture”; to provide grants to nonfederal partners to operate “regional-scale research and education centers to address the impacts” of OA; and to establish a prize competition to “stimulate innovation” to advance understanding, research, or monitoring of OA and its impacts or to develop management or adaptation options for responding to OA.
Other bills regarding OA have been introduced in the 117th Congress. Some would direct the Secretary of Commerce or NOAA to work with the National Academies of Sciences, Engineering, and Medicine to examine the impact of OA and other environmental stressors on estuarine environments. Another bill would direct NOAA to support state and local OA vulnerability assessments and strategic research planning related to OA and its impacts on coastal communities, among other OA activities. Some bills would include OA and its impacts as part of broader climate change impacts or physical risks to be addressed in certain ways. In addition, proposed language to accompany House and Senate appropriations acts for FY2023 would increase funding for NOAA’s Integrated Ocean Acidification Program.The House committee report would support a prize competition to stimulate OA-related innovation, and the Senate draft explanatory statement would direct NOAA to work with nonfederal entities on research to complete FOARAM-mandated federal vulnerability assessments.
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