Ocean Acidification

The pCO₂ data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these mapped estimates.

Description of Time Series: Between 2016 and 2021 pCO2 showed a significant upward trend and was above the range of historical values. The estimated uncertainty of the pCO₂ values used to compute this regional average is ±19 μatm.

Description of Sea Surface pCO2:

Carbon dioxide (CO₂) released from fossil fuel burning and other human activities (also known as “anthropogenic CO₂”) not only accumulates in Earth’s atmosphere, but is also absorbed by seawater at the ocean surface. This process represents a double-edged sword for the planet: CO₂, which has negative consequences for climate change, is removed from the atmosphere but it also contributes to the acidification of ocean waters, which can harm sea life like corals and crabs. The partial pressure of CO₂ in seawater (pCO₂) represents the relative amount of CO₂ in the water. It is a critical metric for calculating the exchange of CO₂ across the air–sea interface and for tracking the effects of anthropogenic carbon on surface ocean chemistry.

Data Source:

Global observations of pCO₂ from automated shipboard systems that take in and analyze water while a vessel is moving are aggregated in the Surface Ocean CO₂ Atlas (SOCAT; Bakker et al., 2016). These shipboard observations have been combined with data from available observational, model-based, and satellite products (e.g., sea-surface temperature, salinity, and wind speed) to create estimates of surface ocean pCO₂ in U.S. Large Marine Ecosystems over multiple decades, using a technique known as machine learning (Sharp et al., 2024). The pCO₂ data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these mapped estimates. Uncertainty in pCO₂ is estimated from a data-based validation of the machine-learning algorithms for each Large Marine Ecosystem, scaled by the data coverage in a given month. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The pCO₂ data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these mapped estimates.

Description of Time Series: Between 2016 and 2021 pCO₂ showed no significant trend and was similar to historical values. The estimated uncertainty of the pCO₂ values used to compute this regional average is ±60 μatm.

Description of Sea Surface pCO2:

Carbon dioxide (CO₂) released from fossil fuel burning and other human activities (also known as “anthropogenic CO₂”) not only accumulates in Earth’s atmosphere, but is also absorbed by seawater at the ocean surface. This process represents a double-edged sword for the planet: CO₂, which has negative consequences for climate change, is removed from the atmosphere but it also contributes to the acidification of ocean waters, which can harm sea life like corals and crabs. The partial pressure of CO₂ in seawater (pCO₂) represents the relative amount of CO₂ in the water. It is a critical metric for calculating the exchange of CO₂ across the air–sea interface and for tracking the effects of anthropogenic carbon on surface ocean chemistry.

Data Source:

Global observations of pCO₂ from automated shipboard systems that take in and analyze water while a vessel is moving are aggregated in the Surface Ocean CO₂ Atlas (SOCAT; Bakker et al., 2016). These shipboard observations have been combined with data from available observational, model-based, and satellite products (e.g., sea-surface temperature, salinity, and wind speed) to create estimates of surface ocean pCO₂ in U.S. Large Marine Ecosystems over multiple decades, using a technique known as machine learning (Sharp et al., 2024). The pCO₂ data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these mapped estimates. Uncertainty in pCO₂ is estimated from a data-based validation of the machine-learning algorithms for each Large Marine Ecosystem, scaled by the data coverage in a given month. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The pCO₂ data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these mapped estimates.

Description of Time Series: Between 2016 and 2021 in pCO₂ showed a significant increasing trend and is at the upper range of historical values. The estimated uncertainty of the pCO₂ values used to compute this regional average is ±18 μatm.

Description of Sea Surface pCO2:

Carbon dioxide (CO₂) released from fossil fuel burning and other human activities (also known as “anthropogenic CO₂”) not only accumulates in Earth’s atmosphere, but is also absorbed by seawater at the ocean surface. This process represents a double-edged sword for the planet: CO₂, which has negative consequences for climate change, is removed from the atmosphere but it also contributes to the acidification of ocean waters, which can harm sea life like corals and crabs. The partial pressure of CO₂ in seawater (pCO₂) represents the relative amount of CO₂ in the water. It is a critical metric for calculating the exchange of CO₂ across the air–sea interface and for tracking the effects of anthropogenic carbon on surface ocean chemistry.

Data Source:

Global observations of pCO₂ from automated shipboard systems that take in and analyze water while a vessel is moving are aggregated in the Surface Ocean CO₂ Atlas (SOCAT; Bakker et al., 2016). These shipboard observations have been combined with data from available observational, model-based, and satellite products (e.g., sea-surface temperature, salinity, and wind speed) to create estimates of surface ocean pCO₂ in U.S. Large Marine Ecosystems over multiple decades, using a technique known as machine learning (Sharp et al., 2024). The pCO₂ data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these mapped estimates. Uncertainty in pCO₂ is estimated from a data-based validation of the machine-learning algorithms for each Large Marine Ecosystem, scaled by the data coverage in a given month. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The pCO₂ data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these mapped estimates.

Description of Time Series: Between 2016 and 2021 pCO₂ showed no trend but was mostly within the range of historical values. The estimated uncertainty of the pCO₂ values used to compute this regional average is ±3 μatm.

Description of Sea Surface pCO2:

Carbon dioxide (CO₂) released from fossil fuel burning and other human activities (also known as “anthropogenic CO₂”) not only accumulates in Earth’s atmosphere, but is also absorbed by seawater at the ocean surface. This process represents a double-edged sword for the planet: CO₂, which has negative consequences for climate change, is removed from the atmosphere but it also contributes to the acidification of ocean waters, which can harm sea life like corals and crabs. The partial pressure of CO₂ in seawater (pCO₂) represents the relative amount of CO₂ in the water. It is a critical metric for calculating the exchange of CO₂ across the air–sea interface and for tracking the effects of anthropogenic carbon on surface ocean chemistry.

Data Source:

Global observations of pCO₂ from automated shipboard systems that take in and analyze water while a vessel is moving are aggregated in the Surface Ocean CO₂ Atlas (SOCAT; Bakker et al., 2016). These shipboard observations have been combined with data from available observational, model-based, and satellite products (e.g., sea-surface temperature, salinity, and wind speed) to create estimates of surface ocean pCO₂ in U.S. Large Marine Ecosystems over multiple decades, using a technique known as machine learning (Sharp et al., 2024). The pCO₂ data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these mapped estimates. Uncertainty in pCO₂ is estimated from a data-based validation of the machine-learning algorithms for each Large Marine Ecosystem, scaled by the data coverage in a given month. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The pCO₂ data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these mapped estimates.

Description of Time Series: Between 2016 and 2021 pCO₂ showed a significant increasing trend and was above historical values. The estimated uncertainty of the pCO₂ values used to compute this regional average is ±16 μatm.

Description of Sea Surface pCO2:

Carbon dioxide (CO₂) released from fossil fuel burning and other human activities (also known as “anthropogenic CO₂”) not only accumulates in Earth’s atmosphere, but is also absorbed by seawater at the ocean surface. This process represents a double-edged sword for the planet: CO₂, which has negative consequences for climate change, is removed from the atmosphere but it also contributes to the acidification of ocean waters, which can harm sea life like corals and crabs. The partial pressure of CO₂ in seawater (pCO₂) represents the relative amount of CO₂ in the water. It is a critical metric for calculating the exchange of CO₂ across the air–sea interface and for tracking the effects of anthropogenic carbon on surface ocean chemistry.

Data Source:

Global observations of pCO₂ from automated shipboard systems that take in and analyze water while a vessel is moving are aggregated in the Surface Ocean CO₂ Atlas (SOCAT; Bakker et al., 2016). These shipboard observations have been combined with data from available observational, model-based, and satellite products (e.g., sea-surface temperature, salinity, and wind speed) to create estimates of surface ocean pCO₂ in U.S. Large Marine Ecosystems over multiple decades, using a technique known as machine learning (Sharp et al., 2024). The pCO₂ data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these mapped estimates. Uncertainty in pCO₂ is estimated from a data-based validation of the machine-learning algorithms for each Large Marine Ecosystem, scaled by the data coverage in a given month. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The pCO₂ data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these mapped estimates.

Description of Time Series: Between 2016 and 2021 pCO₂ showed no significant trend and was above historical values. The estimated uncertainty of the pCO₂ values used to compute this regional average is ±23 μatm.

Description of Sea Surface pCO2:

Carbon dioxide (CO₂) released from fossil fuel burning and other human activities (also known as “anthropogenic CO₂”) not only accumulates in Earth’s atmosphere, but is also absorbed by seawater at the ocean surface. This process represents a double-edged sword for the planet: CO₂, which has negative consequences for climate change, is removed from the atmosphere but it also contributes to the acidification of ocean waters, which can harm sea life like corals and crabs. The partial pressure of CO₂ in seawater (pCO₂) represents the relative amount of CO₂ in the water. It is a critical metric for calculating the exchange of CO₂ across the air–sea interface and for tracking the effects of anthropogenic carbon on surface ocean chemistry.

Data Source:

Global observations of pCO₂ from automated shipboard systems that take in and analyze water while a vessel is moving are aggregated in the Surface Ocean CO₂ Atlas (SOCAT; Bakker et al., 2016). These shipboard observations have been combined with data from available observational, model-based, and satellite products (e.g., sea-surface temperature, salinity, and wind speed) to create estimates of surface ocean pCO₂ in U.S. Large Marine Ecosystems over multiple decades, using a technique known as machine learning (Sharp et al., 2024). The pCO₂ data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these mapped estimates. Uncertainty in pCO₂ is estimated from a data-based validation of the machine-learning algorithms for each Large Marine Ecosystem, scaled by the data coverage in a given month. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The pCO₂ data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these mapped estimates.

Description of Time Series: Between 2016 and 2021 pCO₂ showed a significant increasing trend and is at the upper range of historical values. The estimated uncertainty of the pCO₂ values used to compute this regional average is ±23 μatm.

Description of Sea Surface pCO2:

Carbon dioxide (CO₂) released from fossil fuel burning and other human activities (also known as “anthropogenic CO₂”) not only accumulates in Earth’s atmosphere, but is also absorbed by seawater at the ocean surface. This process represents a double-edged sword for the planet: CO₂, which has negative consequences for climate change, is removed from the atmosphere but it also contributes to the acidification of ocean waters, which can harm sea life like corals and crabs. The partial pressure of CO₂ in seawater (pCO₂) represents the relative amount of CO₂ in the water. It is a critical metric for calculating the exchange of CO₂ across the air–sea interface and for tracking the effects of anthropogenic carbon on surface ocean chemistry.

Data Source:

Global observations of pCO₂ from automated shipboard systems that take in and analyze water while a vessel is moving are aggregated in the Surface Ocean CO₂ Atlas (SOCAT; Bakker et al., 2016). These shipboard observations have been combined with data from available observational, model-based, and satellite products (e.g., sea-surface temperature, salinity, and wind speed) to create estimates of surface ocean pCO₂ in U.S. Large Marine Ecosystems over multiple decades, using a technique known as machine learning (Sharp et al., 2024). The pCO₂ data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these mapped estimates. Uncertainty in pCO₂ is estimated from a data-based validation of the machine-learning algorithms for each Large Marine Ecosystem, scaled by the data coverage in a given month. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The pCO₂ data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these mapped estimates.

Description of Time Series: Between 2016 and 2021 pCO₂ showed no significant trend and was above historical values. The estimated uncertainty of the pCO₂ values used to compute this regional average is ±60 μatm.

Description of Sea Surface pCO2:

Carbon dioxide (CO₂) released from fossil fuel burning and other human activities (also known as “anthropogenic CO₂”) not only accumulates in Earth’s atmosphere, but is also absorbed by seawater at the ocean surface. This process represents a double-edged sword for the planet: CO₂, which has negative consequences for climate change, is removed from the atmosphere but it also contributes to the acidification of ocean waters, which can harm sea life like corals and crabs. The partial pressure of CO₂ in seawater (pCO₂) represents the relative amount of CO₂ in the water. It is a critical metric for calculating the exchange of CO₂ across the air–sea interface and for tracking the effects of anthropogenic carbon on surface ocean chemistry.

Data Source:

Global observations of pCO₂ from automated shipboard systems that take in and analyze water while a vessel is moving are aggregated in the Surface Ocean CO₂ Atlas (SOCAT; Bakker et al., 2016). These shipboard observations have been combined with data from available observational, model-based, and satellite products (e.g., sea-surface temperature, salinity, and wind speed) to create estimates of surface ocean pCO₂ in U.S. Large Marine Ecosystems over multiple decades, using a technique known as machine learning (Sharp et al., 2024). The pCO₂ data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these mapped estimates. Uncertainty in pCO₂ is estimated from a data-based validation of the machine-learning algorithms for each Large Marine Ecosystem, scaled by the data coverage in a given month. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The pCO₂ data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these mapped estimates.

Description of Time Series: Between 2016 and 2021 pCO₂ showed no trend and was mostly above the range of historical values to historical values. The estimated uncertainty of the pCO₂ values used to compute this regional average is ±22 μatm.

Description of Sea Surface pCO2:

Carbon dioxide (CO₂) released from fossil fuel burning and other human activities (also known as “anthropogenic CO₂”) not only accumulates in Earth’s atmosphere, but is also absorbed by seawater at the ocean surface. This process represents a double-edged sword for the planet: CO₂, which has negative consequences for climate change, is removed from the atmosphere but it also contributes to the acidification of ocean waters, which can harm sea life like corals and crabs. The partial pressure of CO₂ in seawater (pCO₂) represents the relative amount of CO₂ in the water. It is a critical metric for calculating the exchange of CO₂ across the air–sea interface and for tracking the effects of anthropogenic carbon on surface ocean chemistry.

Data Source:

Global observations of pCO₂ from automated shipboard systems that take in and analyze water while a vessel is moving are aggregated in the Surface Ocean CO₂ Atlas (SOCAT; Bakker et al., 2016). These shipboard observations have been combined with data from available observational, model-based, and satellite products (e.g., sea-surface temperature, salinity, and wind speed) to create estimates of surface ocean pCO₂ in U.S. Large Marine Ecosystems over multiple decades, using a technique known as machine learning (Sharp et al., 2024). The pCO₂ data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these mapped estimates. Uncertainty in pCO₂ is estimated from a data-based validation of the machine-learning algorithms for each Large Marine Ecosystem, scaled by the data coverage in a given month. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The pCO₂ data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these mapped estimates.

Description of Time Series: Between 2016 and 2021 pCO₂ showed no upward trend and is at the top of the range of historical values.

Description of Sea Surface pCO2:

Carbon dioxide (CO₂) released from fossil fuel burning and other human activities (also known as “anthropogenic CO₂”) not only accumulates in Earth’s atmosphere, but is also absorbed by seawater at the ocean surface. This process represents a double-edged sword for the planet: CO₂, which has negative consequences for climate change, is removed from the atmosphere but it also contributes to the acidification of ocean waters, which can harm sea life like corals and crabs. The partial pressure of CO₂ in seawater (pCO₂) represents the relative amount of CO₂ in the water. It is a critical metric for calculating the exchange of CO₂ across the air–sea interface and for tracking the effects of anthropogenic carbon on surface ocean chemistry.

Data Source:

Global observations of pCO₂ from automated shipboard systems that take in and analyze water while a vessel is moving are aggregated in the Surface Ocean CO₂ Atlas (SOCAT; Bakker et al., 2016). These shipboard observations have been combined with data from available observational, model-based, and satellite products (e.g., sea-surface temperature, salinity, and wind speed) to create estimates of surface ocean pCO₂ in U.S. Large Marine Ecosystems over multiple decades, using a technique known as machine learning (Sharp et al., 2024). The pCO₂ data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these mapped estimates. Uncertainty in pCO₂ is estimated from a data-based validation of the machine-learning algorithms for each Large Marine Ecosystem, scaled by the data coverage in a given month. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The pCO₂ data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these mapped estimates.

Description of Time Series: Between 2016 and 2021 pCO₂ showed no significant trend but was near the top of the range of  historical values. The estimated uncertainty of the pCO₂ values used to compute this regional average is ±3 μatm.

Description of Sea Surface pCO2:

Carbon dioxide (CO₂) released from fossil fuel burning and other human activities (also known as “anthropogenic CO₂”) not only accumulates in Earth’s atmosphere, but is also absorbed by seawater at the ocean surface. This process represents a double-edged sword for the planet: CO₂, which has negative consequences for climate change, is removed from the atmosphere but it also contributes to the acidification of ocean waters, which can harm sea life like corals and crabs. The partial pressure of CO₂ in seawater (pCO₂) represents the relative amount of CO₂ in the water. It is a critical metric for calculating the exchange of CO₂ across the air–sea interface and for tracking the effects of anthropogenic carbon on surface ocean chemistry.

Data Source:

Global observations of pCO₂ from automated shipboard systems that take in and analyze water while a vessel is moving are aggregated in the Surface Ocean CO₂ Atlas (SOCAT; Bakker et al., 2016). These shipboard observations have been combined with data from available observational, model-based, and satellite products (e.g., sea-surface temperature, salinity, and wind speed) to create estimates of surface ocean pCO₂ in U.S. Large Marine Ecosystems over multiple decades, using a technique known as machine learning (Sharp et al., 2024). The pCO₂ data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these mapped estimates. Uncertainty in pCO₂ is estimated from a data-based validation of the machine-learning algorithms for each Large Marine Ecosystem, scaled by the data coverage in a given month. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The pH data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these estimates.

Description of Time Series: Between 2016 and 2021 pH showed a small downward trend and was below historical values.

Description of Sea Surface pH:

Man-made (or “anthropogenic”) CO₂ that is taken up by the ocean influences the chemistry of seawater, resulting in an increase in hydrogen ion concentration of the surface ocean (i.e. a decrease in surface ocean pH). pH can be viewed as a “master variable” in ocean chemistry, controlling acid-base balance in the sea. It is also a common way to quantify ocean acidification: average surface ocean pH has decreased by more than 0.1 units since the beginning of the industrial revolution (Jiang et al., 2023).

Data Source:

Mapped estimates of surface-ocean pCO₂ in U.S. Large Marine Ecosystems (LME’s) (Sharp et al., 2024), based on observations from the SOCAT database, have been paired with another key ocean-carbon variable called total alkalinity (TA), estimated from salinity, temperature, and spatial information using algorithms called ESPERs (Carter et al., 2021), to calculate surface ocean pH across the U.S. LME’s. The pH data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these estimates. Uncertainty in pH is determined by propagating pCO₂ and TA uncertainties through calculations, using reasonable estimates of uncertainty in required chemical constants and ancillary variables. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The pH data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these estimates.

Description of Time Series: Between 2016 and 2021 pH showed no significant trend and was similar to historical values.

Description of Sea Surface pH:

Man-made (or “anthropogenic”) CO₂ that is taken up by the ocean influences the chemistry of seawater, resulting in an increase in hydrogen ion concentration of the surface ocean (i.e. a decrease in surface ocean pH). pH can be viewed as a “master variable” in ocean chemistry, controlling acid-base balance in the sea. It is also a common way to quantify ocean acidification: average surface ocean pH has decreased by more than 0.1 units since the beginning of the industrial revolution (Jiang et al., 2023).

Data Source:

Mapped estimates of surface-ocean pCO₂ in U.S. Large Marine Ecosystems (LME’s) (Sharp et al., 2024), based on observations from the SOCAT database, have been paired with another key ocean-carbon variable called total alkalinity (TA), estimated from salinity, temperature, and spatial information using algorithms called ESPERs (Carter et al., 2021), to calculate surface ocean pH across the U.S. LME’s. The pH data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these estimates. Uncertainty in pH is determined by propagating pCO₂ and TA uncertainties through calculations, using reasonable estimates of uncertainty in required chemical constants and ancillary variables. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The pH data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these estimates.

Description of Time Series: Between 2016 and 2021 pH showed a significant decreasing trend and is at the lower end of the range of historical values.

Description of Sea Surface pH:

Man-made (or “anthropogenic”) CO₂ that is taken up by the ocean influences the chemistry of seawater, resulting in an increase in hydrogen ion concentration of the surface ocean (i.e. a decrease in surface ocean pH). pH can be viewed as a “master variable” in ocean chemistry, controlling acid-base balance in the sea. It is also a common way to quantify ocean acidification: average surface ocean pH has decreased by more than 0.1 units since the beginning of the industrial revolution (Jiang et al., 2023).

Data Source:

Mapped estimates of surface-ocean pCO₂ in U.S. Large Marine Ecosystems (LME’s) (Sharp et al., 2024), based on observations from the SOCAT database, have been paired with another key ocean-carbon variable called total alkalinity (TA), estimated from salinity, temperature, and spatial information using algorithms called ESPERs (Carter et al., 2021), to calculate surface ocean pH across the U.S. LME’s. The pH data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these estimates. Uncertainty in pH is determined by propagating pCO₂ and TA uncertainties through calculations, using reasonable estimates of uncertainty in required chemical constants and ancillary variables. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The pH data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these estimates.

Description of Time Series: Between 2016 and 2021 pH showed no significant trend and was similar to historical values.

Description of Sea Surface pH:

Man-made (or “anthropogenic”) CO₂ that is taken up by the ocean influences the chemistry of seawater, resulting in an increase in hydrogen ion concentration of the surface ocean (i.e. a decrease in surface ocean pH). pH can be viewed as a “master variable” in ocean chemistry, controlling acid-base balance in the sea. It is also a common way to quantify ocean acidification: average surface ocean pH has decreased by more than 0.1 units since the beginning of the industrial revolution (Jiang et al., 2023).

Data Source:

Mapped estimates of surface-ocean pCO₂ in U.S. Large Marine Ecosystems (LME’s) (Sharp et al., 2024), based on observations from the SOCAT database, have been paired with another key ocean-carbon variable called total alkalinity (TA), estimated from salinity, temperature, and spatial information using algorithms called ESPERs (Carter et al., 2021), to calculate surface ocean pH across the U.S. LME’s. The pH data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these estimates. Uncertainty in pH is determined by propagating pCO₂ and TA uncertainties through calculations, using reasonable estimates of uncertainty in required chemical constants and ancillary variables. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The pH data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these estimates.

Description of Time Series: Between 2016 and 2021 pH showed a significant decreasing trend and was below historical values.

Description of Sea Surface pH:

Man-made (or “anthropogenic”) CO₂ that is taken up by the ocean influences the chemistry of seawater, resulting in an increase in hydrogen ion concentration of the surface ocean (i.e. a decrease in surface ocean pH). pH can be viewed as a “master variable” in ocean chemistry, controlling acid-base balance in the sea. It is also a common way to quantify ocean acidification: average surface ocean pH has decreased by more than 0.1 units since the beginning of the industrial revolution (Jiang et al., 2023).

Data Source:

Mapped estimates of surface-ocean pCO₂ in U.S. Large Marine Ecosystems (LME’s) (Sharp et al., 2024), based on observations from the SOCAT database, have been paired with another key ocean-carbon variable called total alkalinity (TA), estimated from salinity, temperature, and spatial information using algorithms called ESPERs (Carter et al., 2021), to calculate surface ocean pH across the U.S. LME’s. The pH data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these estimates. Uncertainty in pH is determined by propagating pCO₂ and TA uncertainties through calculations, using reasonable estimates of uncertainty in required chemical constants and ancillary variables. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The pH data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these estimates.

Description of Time Series: Between 2016 and 2021 pH showed no significant trend and was below historical values.

Description of Sea Surface pH:

Man-made (or “anthropogenic”) CO₂ that is taken up by the ocean influences the chemistry of seawater, resulting in an increase in hydrogen ion concentration of the surface ocean (i.e. a decrease in surface ocean pH). pH can be viewed as a “master variable” in ocean chemistry, controlling acid-base balance in the sea. It is also a common way to quantify ocean acidification: average surface ocean pH has decreased by more than 0.1 units since the beginning of the industrial revolution (Jiang et al., 2023).

Data Source:

Mapped estimates of surface-ocean pCO₂ in U.S. Large Marine Ecosystems (LME’s) (Sharp et al., 2024), based on observations from the SOCAT database, have been paired with another key ocean-carbon variable called total alkalinity (TA), estimated from salinity, temperature, and spatial information using algorithms called ESPERs (Carter et al., 2021), to calculate surface ocean pH across the U.S. LME’s. The pH data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these estimates. Uncertainty in pH is determined by propagating pCO₂ and TA uncertainties through calculations, using reasonable estimates of uncertainty in required chemical constants and ancillary variables. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The pH data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these estimates.

Description of Time Series: Between 2016 and 2021 pH showed a significant decreasing trend and is now at the low end of the range of historical values.

Description of Sea Surface pH:

Man-made (or “anthropogenic”) CO₂ that is taken up by the ocean influences the chemistry of seawater, resulting in an increase in hydrogen ion concentration of the surface ocean (i.e. a decrease in surface ocean pH). pH can be viewed as a “master variable” in ocean chemistry, controlling acid-base balance in the sea. It is also a common way to quantify ocean acidification: average surface ocean pH has decreased by more than 0.1 units since the beginning of the industrial revolution (Jiang et al., 2023).

Data Source:

Mapped estimates of surface-ocean pCO₂ in U.S. Large Marine Ecosystems (LME’s) (Sharp et al., 2024), based on observations from the SOCAT database, have been paired with another key ocean-carbon variable called total alkalinity (TA), estimated from salinity, temperature, and spatial information using algorithms called ESPERs (Carter et al., 2021), to calculate surface ocean pH across the U.S. LME’s. The pH data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these estimates. Uncertainty in pH is determined by propagating pCO₂ and TA uncertainties through calculations, using reasonable estimates of uncertainty in required chemical constants and ancillary variables. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The pH data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these estimates.

Description of Time Series: Between 2016 and 2021 pH showed no significant trend and was similar to historical values.

Description of Sea Surface pH:

Man-made (or “anthropogenic”) CO₂ that is taken up by the ocean influences the chemistry of seawater, resulting in an increase in hydrogen ion concentration of the surface ocean (i.e. a decrease in surface ocean pH). pH can be viewed as a “master variable” in ocean chemistry, controlling acid-base balance in the sea. It is also a common way to quantify ocean acidification: average surface ocean pH has decreased by more than 0.1 units since the beginning of the industrial revolution (Jiang et al., 2023).

Data Source:

Mapped estimates of surface-ocean pCO₂ in U.S. Large Marine Ecosystems (LME’s) (Sharp et al., 2024), based on observations from the SOCAT database, have been paired with another key ocean-carbon variable called total alkalinity (TA), estimated from salinity, temperature, and spatial information using algorithms called ESPERs (Carter et al., 2021), to calculate surface ocean pH across the U.S. LME’s. The pH data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these estimates. Uncertainty in pH is determined by propagating pCO₂ and TA uncertainties through calculations, using reasonable estimates of uncertainty in required chemical constants and ancillary variables. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The pH data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these estimates.

Description of Time Series: Between 2016 and 2021 pH showed no trend and was largely below the range of historical values.

Description of Sea Surface pH:

Man-made (or “anthropogenic”) CO₂ that is taken up by the ocean influences the chemistry of seawater, resulting in an increase in hydrogen ion concentration of the surface ocean (i.e. a decrease in surface ocean pH). pH can be viewed as a “master variable” in ocean chemistry, controlling acid-base balance in the sea. It is also a common way to quantify ocean acidification: average surface ocean pH has decreased by more than 0.1 units since the beginning of the industrial revolution (Jiang et al., 2023).

Data Source:

Mapped estimates of surface-ocean pCO₂ in U.S. Large Marine Ecosystems (LME’s) (Sharp et al., 2024), based on observations from the SOCAT database, have been paired with another key ocean-carbon variable called total alkalinity (TA), estimated from salinity, temperature, and spatial information using algorithms called ESPERs (Carter et al., 2021), to calculate surface ocean pH across the U.S. LME’s. The pH data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these estimates. Uncertainty in pH is determined by propagating pCO₂ and TA uncertainties through calculations, using reasonable estimates of uncertainty in required chemical constants and ancillary variables. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The pH data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these estimates.

Description of Time Series: Between 2016 and 2021 pH showed no significant trend but was at the low end of the range of historical values.

Description of Sea Surface pH:

Man-made (or “anthropogenic”) CO₂ that is taken up by the ocean influences the chemistry of seawater, resulting in an increase in hydrogen ion concentration of the surface ocean (i.e. a decrease in surface ocean pH). pH can be viewed as a “master variable” in ocean chemistry, controlling acid-base balance in the sea. It is also a common way to quantify ocean acidification: average surface ocean pH has decreased by more than 0.1 units since the beginning of the industrial revolution (Jiang et al., 2023).

Data Source:

Mapped estimates of surface-ocean pCO₂ in U.S. Large Marine Ecosystems (LME’s) (Sharp et al., 2024), based on observations from the SOCAT database, have been paired with another key ocean-carbon variable called total alkalinity (TA), estimated from salinity, temperature, and spatial information using algorithms called ESPERs (Carter et al., 2021), to calculate surface ocean pH across the U.S. LME’s. The pH data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these estimates. Uncertainty in pH is determined by propagating pCO₂ and TA uncertainties through calculations, using reasonable estimates of uncertainty in required chemical constants and ancillary variables. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The pH data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these estimates.

Description of Time Series: Between 2016 and 2021 pH showed no significant trend and was below historical values.

Description of Sea Surface pH:

Man-made (or “anthropogenic”) CO₂ that is taken up by the ocean influences the chemistry of seawater, resulting in an increase in hydrogen ion concentration of the surface ocean (i.e. a decrease in surface ocean pH). pH can be viewed as a “master variable” in ocean chemistry, controlling acid-base balance in the sea. It is also a common way to quantify ocean acidification: average surface ocean pH has decreased by more than 0.1 units since the beginning of the industrial revolution (Jiang et al., 2023).

Data Source:

Mapped estimates of surface-ocean pCO₂ in U.S. Large Marine Ecosystems (LME’s) (Sharp et al., 2024), based on observations from the SOCAT database, have been paired with another key ocean-carbon variable called total alkalinity (TA), estimated from salinity, temperature, and spatial information using algorithms called ESPERs (Carter et al., 2021), to calculate surface ocean pH across the U.S. LME’s. The pH data shown here as an ecosystem indicator of ocean acidification represent regional annual averages of these estimates. Uncertainty in pH is determined by propagating pCO₂ and TA uncertainties through calculations, using reasonable estimates of uncertainty in required chemical constants and ancillary variables. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The Ω_ar data shown here as an ecosystem indicator of ocean acidification represent regional averages of these estimates.

Description of Time Series: Between 2016 and 2021 Sea Surface Ωar showed a significant decreasing trend and was lower than historical values.

Description of Sea Surface Ωar:

Many marine animals and plants build shells or other hard parts from the minerals aragonite and calcite, which are forms of the chemical compound calcium carbonate. The chemical building blocks of these minerals are calcium and carbonate ions, which are common constituents of seawater. However, one effect of ocean acidification is to reduce the carbonate ion concentration in seawater, making it more difficult for these minerals to form. The chemical expression that describes the tendency of these minerals to form at equilibrium is called the saturation state of that mineral: higher values support mineral formation, while lower values inhibit mineral formation, or even promote the dissolution of these minerals. We present here saturation-state estimates for the mineral aragonite (Ω_ar), which is used by many marine organisms including corals, mollusks, and some zooplankton to create hard parts. At 20°C, saturation state of the mineral calcite is about 50% higher than aragonite (Mucci, 1983)

Data Source:

Mapped estimates of surface-ocean pCO₂ in U.S. Large Marine Ecosystems (LME’s) (Sharp et al., 2024), based on observations from the SOCAT database, have been paired with another key ocean-carbon variable called total alkalinity (TA), estimated from salinity, temperature, and spatial information using algorithms called ESPERs (Carter et al., 2021), to calculate surface-ocean Ω_ar across the U.S. LME’s. The Ω_ar data shown here as an ecosystem indicator of ocean acidification represent regional averages of these estimates. Uncertainty in Ω_ar is determined by propagating pCO₂ and TA uncertainties through calculations, using reasonable estimates of uncertainty in required chemical constants and ancillary variables. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The Ω_ar data shown here as an ecosystem indicator of ocean acidification represent regional averages of these estimates.

Description of Time Series: Between 2016 and 2021 Sea Surface Ωar showed no significant trend and was similar to historical values.

Description of Sea Surface Ωar:

Many marine animals and plants build shells or other hard parts from the minerals aragonite and calcite, which are forms of the chemical compound calcium carbonate. The chemical building blocks of these minerals are calcium and carbonate ions, which are common constituents of seawater. However, one effect of ocean acidification is to reduce the carbonate ion concentration in seawater, making it more difficult for these minerals to form. The chemical expression that describes the tendency of these minerals to form at equilibrium is called the saturation state of that mineral: higher values support mineral formation, while lower values inhibit mineral formation, or even promote the dissolution of these minerals. We present here saturation-state estimates for the mineral aragonite (Ω_ar), which is used by many marine organisms including corals, mollusks, and some zooplankton to create hard parts. At 20°C, saturation state of the mineral calcite is about 50% higher than aragonite (Mucci, 1983)

Data Source:

Mapped estimates of surface-ocean pCO₂ in U.S. Large Marine Ecosystems (LME’s) (Sharp et al., 2024), based on observations from the SOCAT database, have been paired with another key ocean-carbon variable called total alkalinity (TA), estimated from salinity, temperature, and spatial information using algorithms called ESPERs (Carter et al., 2021), to calculate surface-ocean Ω_ar across the U.S. LME’s. The Ω_ar data shown here as an ecosystem indicator of ocean acidification represent regional averages of these estimates. Uncertainty in Ω_ar is determined by propagating pCO₂ and TA uncertainties through calculations, using reasonable estimates of uncertainty in required chemical constants and ancillary variables. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The Ω_ar data shown here as an ecosystem indicator of ocean acidification represent regional averages of these estimates.

Description of Time Series: Between 2016 and 2021 Sea Surface Ωar showed a downward trend but was mostly within the range of historical values.

Description of Sea Surface Ωar:

Many marine animals and plants build shells or other hard parts from the minerals aragonite and calcite, which are forms of the chemical compound calcium carbonate. The chemical building blocks of these minerals are calcium and carbonate ions, which are common constituents of seawater. However, one effect of ocean acidification is to reduce the carbonate ion concentration in seawater, making it more difficult for these minerals to form. The chemical expression that describes the tendency of these minerals to form at equilibrium is called the saturation state of that mineral: higher values support mineral formation, while lower values inhibit mineral formation, or even promote the dissolution of these minerals. We present here saturation-state estimates for the mineral aragonite (Ω_ar), which is used by many marine organisms including corals, mollusks, and some zooplankton to create hard parts. At 20°C, saturation state of the mineral calcite is about 50% higher than aragonite (Mucci, 1983)

Data Source:

Mapped estimates of surface-ocean pCO₂ in U.S. Large Marine Ecosystems (LME’s) (Sharp et al., 2024), based on observations from the SOCAT database, have been paired with another key ocean-carbon variable called total alkalinity (TA), estimated from salinity, temperature, and spatial information using algorithms called ESPERs (Carter et al., 2021), to calculate surface-ocean Ω_ar across the U.S. LME’s. The Ω_ar data shown here as an ecosystem indicator of ocean acidification represent regional averages of these estimates. Uncertainty in Ω_ar is determined by propagating pCO₂ and TA uncertainties through calculations, using reasonable estimates of uncertainty in required chemical constants and ancillary variables. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The Ω_ar data shown here as an ecosystem indicator of ocean acidification represent regional averages of these estimates.

Description of Time Series: Between 2016 and 2021 Sea Surface Ωar showed a significant decreasing trend but was mostly within the range of historical values.

Description of Sea Surface Ωar:

Many marine animals and plants build shells or other hard parts from the minerals aragonite and calcite, which are forms of the chemical compound calcium carbonate. The chemical building blocks of these minerals are calcium and carbonate ions, which are common constituents of seawater. However, one effect of ocean acidification is to reduce the carbonate ion concentration in seawater, making it more difficult for these minerals to form. The chemical expression that describes the tendency of these minerals to form at equilibrium is called the saturation state of that mineral: higher values support mineral formation, while lower values inhibit mineral formation, or even promote the dissolution of these minerals. We present here saturation-state estimates for the mineral aragonite (Ω_ar), which is used by many marine organisms including corals, mollusks, and some zooplankton to create hard parts. At 20°C, saturation state of the mineral calcite is about 50% higher than aragonite (Mucci, 1983)

Data Source:

Mapped estimates of surface-ocean pCO₂ in U.S. Large Marine Ecosystems (LME’s) (Sharp et al., 2024), based on observations from the SOCAT database, have been paired with another key ocean-carbon variable called total alkalinity (TA), estimated from salinity, temperature, and spatial information using algorithms called ESPERs (Carter et al., 2021), to calculate surface-ocean Ω_ar across the U.S. LME’s. The Ω_ar data shown here as an ecosystem indicator of ocean acidification represent regional averages of these estimates. Uncertainty in Ω_ar is determined by propagating pCO₂ and TA uncertainties through calculations, using reasonable estimates of uncertainty in required chemical constants and ancillary variables. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The Ω_ar data shown here as an ecosystem indicator of ocean acidification represent regional averages of these estimates.

Description of Time Series: Between 2016 and 2021 Sea Surface Ωar showed no significant trend and was similar to historical values.

Description of Sea Surface Ωar:

Many marine animals and plants build shells or other hard parts from the minerals aragonite and calcite, which are forms of the chemical compound calcium carbonate. The chemical building blocks of these minerals are calcium and carbonate ions, which are common constituents of seawater. However, one effect of ocean acidification is to reduce the carbonate ion concentration in seawater, making it more difficult for these minerals to form. The chemical expression that describes the tendency of these minerals to form at equilibrium is called the saturation state of that mineral: higher values support mineral formation, while lower values inhibit mineral formation, or even promote the dissolution of these minerals. We present here saturation-state estimates for the mineral aragonite (Ω_ar), which is used by many marine organisms including corals, mollusks, and some zooplankton to create hard parts. At 20°C, saturation state of the mineral calcite is about 50% higher than aragonite (Mucci, 1983)

Data Source:

Mapped estimates of surface-ocean pCO₂ in U.S. Large Marine Ecosystems (LME’s) (Sharp et al., 2024), based on observations from the SOCAT database, have been paired with another key ocean-carbon variable called total alkalinity (TA), estimated from salinity, temperature, and spatial information using algorithms called ESPERs (Carter et al., 2021), to calculate surface-ocean Ω_ar across the U.S. LME’s. The Ω_ar data shown here as an ecosystem indicator of ocean acidification represent regional averages of these estimates. Uncertainty in Ω_ar is determined by propagating pCO₂ and TA uncertainties through calculations, using reasonable estimates of uncertainty in required chemical constants and ancillary variables. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The Ω_ar data shown here as an ecosystem indicator of ocean acidification represent regional averages of these estimates.

Description of Time Series: Between 2016 and 2021 Sea Surface Ωar showed a significant downward trend and was similar to historical values.

Description of Sea Surface Ωar:

Many marine animals and plants build shells or other hard parts from the minerals aragonite and calcite, which are forms of the chemical compound calcium carbonate. The chemical building blocks of these minerals are calcium and carbonate ions, which are common constituents of seawater. However, one effect of ocean acidification is to reduce the carbonate ion concentration in seawater, making it more difficult for these minerals to form. The chemical expression that describes the tendency of these minerals to form at equilibrium is called the saturation state of that mineral: higher values support mineral formation, while lower values inhibit mineral formation, or even promote the dissolution of these minerals. We present here saturation-state estimates for the mineral aragonite (Ω_ar), which is used by many marine organisms including corals, mollusks, and some zooplankton to create hard parts. At 20°C, saturation state of the mineral calcite is about 50% higher than aragonite (Mucci, 1983)

Data Source:

Mapped estimates of surface-ocean pCO₂ in U.S. Large Marine Ecosystems (LME’s) (Sharp et al., 2024), based on observations from the SOCAT database, have been paired with another key ocean-carbon variable called total alkalinity (TA), estimated from salinity, temperature, and spatial information using algorithms called ESPERs (Carter et al., 2021), to calculate surface-ocean Ω_ar across the U.S. LME’s. The Ω_ar data shown here as an ecosystem indicator of ocean acidification represent regional averages of these estimates. Uncertainty in Ω_ar is determined by propagating pCO₂ and TA uncertainties through calculations, using reasonable estimates of uncertainty in required chemical constants and ancillary variables. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The Ω_ar data shown here as an ecosystem indicator of ocean acidification represent regional averages of these estimates.

Description of Time Series: Between 2016 and 2021 Sea Surface Ωar showed a significant downward trend but was below the range of historical values.

Description of Sea Surface Ωar:

Many marine animals and plants build shells or other hard parts from the minerals aragonite and calcite, which are forms of the chemical compound calcium carbonate. The chemical building blocks of these minerals are calcium and carbonate ions, which are common constituents of seawater. However, one effect of ocean acidification is to reduce the carbonate ion concentration in seawater, making it more difficult for these minerals to form. The chemical expression that describes the tendency of these minerals to form at equilibrium is called the saturation state of that mineral: higher values support mineral formation, while lower values inhibit mineral formation, or even promote the dissolution of these minerals. We present here saturation-state estimates for the mineral aragonite (Ω_ar), which is used by many marine organisms including corals, mollusks, and some zooplankton to create hard parts. At 20°C, saturation state of the mineral calcite is about 50% higher than aragonite (Mucci, 1983)

Data Source:

Mapped estimates of surface-ocean pCO₂ in U.S. Large Marine Ecosystems (LME’s) (Sharp et al., 2024), based on observations from the SOCAT database, have been paired with another key ocean-carbon variable called total alkalinity (TA), estimated from salinity, temperature, and spatial information using algorithms called ESPERs (Carter et al., 2021), to calculate surface-ocean Ω_ar across the U.S. LME’s. The Ω_ar data shown here as an ecosystem indicator of ocean acidification represent regional averages of these estimates. Uncertainty in Ω_ar is determined by propagating pCO₂ and TA uncertainties through calculations, using reasonable estimates of uncertainty in required chemical constants and ancillary variables. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The Ω_ar data shown here as an ecosystem indicator of ocean acidification represent regional averages of these estimates.

Description of Time Series: Between 2016 and 2021 Sea Surface Ωar showed a significant downward trend and was similar to historical values.

Description of Sea Surface Ωar:

Many marine animals and plants build shells or other hard parts from the minerals aragonite and calcite, which are forms of the chemical compound calcium carbonate. The chemical building blocks of these minerals are calcium and carbonate ions, which are common constituents of seawater. However, one effect of ocean acidification is to reduce the carbonate ion concentration in seawater, making it more difficult for these minerals to form. The chemical expression that describes the tendency of these minerals to form at equilibrium is called the saturation state of that mineral: higher values support mineral formation, while lower values inhibit mineral formation, or even promote the dissolution of these minerals. We present here saturation-state estimates for the mineral aragonite (Ω_ar), which is used by many marine organisms including corals, mollusks, and some zooplankton to create hard parts. At 20°C, saturation state of the mineral calcite is about 50% higher than aragonite (Mucci, 1983)

Data Source:

Mapped estimates of surface-ocean pCO₂ in U.S. Large Marine Ecosystems (LME’s) (Sharp et al., 2024), based on observations from the SOCAT database, have been paired with another key ocean-carbon variable called total alkalinity (TA), estimated from salinity, temperature, and spatial information using algorithms called ESPERs (Carter et al., 2021), to calculate surface-ocean Ω_ar across the U.S. LME’s. The Ω_ar data shown here as an ecosystem indicator of ocean acidification represent regional averages of these estimates. Uncertainty in Ω_ar is determined by propagating pCO₂ and TA uncertainties through calculations, using reasonable estimates of uncertainty in required chemical constants and ancillary variables. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.

The Ω_ar data shown here as an ecosystem indicator of ocean acidification represent regional averages of these estimates.

Description of Time Series: Between 2016 and 2021 Sea Surface Ωar showed no significant trend and was similar to historical values.

Description of Sea Surface Ωar:

Many marine animals and plants build shells or other hard parts from the minerals aragonite and calcite, which are forms of the chemical compound calcium carbonate. The chemical building blocks of these minerals are calcium and carbonate ions, which are common constituents of seawater. However, one effect of ocean acidification is to reduce the carbonate ion concentration in seawater, making it more difficult for these minerals to form. The chemical expression that describes the tendency of these minerals to form at equilibrium is called the saturation state of that mineral: higher values support mineral formation, while lower values inhibit mineral formation, or even promote the dissolution of these minerals. We present here saturation-state estimates for the mineral aragonite (Ω_ar), which is used by many marine organisms including corals, mollusks, and some zooplankton to create hard parts. At 20°C, saturation state of the mineral calcite is about 50% higher than aragonite (Mucci, 1983)

Data Source:

Mapped estimates of surface-ocean pCO₂ in U.S. Large Marine Ecosystems (LME’s) (Sharp et al., 2024), based on observations from the SOCAT database, have been paired with another key ocean-carbon variable called total alkalinity (TA), estimated from salinity, temperature, and spatial information using algorithms called ESPERs (Carter et al., 2021), to calculate surface-ocean Ω_ar across the U.S. LME’s. The Ω_ar data shown here as an ecosystem indicator of ocean acidification represent regional averages of these estimates. Uncertainty in Ω_ar is determined by propagating pCO₂ and TA uncertainties through calculations, using reasonable estimates of uncertainty in required chemical constants and ancillary variables. The complete dataset is available at https://www.ncei.noaa.gov/data/oceans/ncei/ocads/metadata/0287551.html.