Title

Global Ocean acidification - mean sea water pH time series and trend from Multi-Observations Reprocessing

Alternate title

GLOBAL_OMI_HEALTH_carbon_ph_area_averaged

Date (Creation)

2018-02-12

Edition

3.4

Edition date

2023-11-30

Citation identifier

1c5fe986-1cd7-4c56-aeff-7bba0b4ff554

Abstract

'''DEFINITION'''

Ocean acidification is quantified by decreases in pH, which is a measure of acidity: a decrease in pH value means an increase in acidity, that is, acidification. The observed decrease in ocean pH resulting from increasing concentrations of CO2 is an important indicator of global change. The estimate of global mean pH builds on a reconstruction methodology,

* Obtain values for alkalinity based on the so called “locally interpolated alkalinity regression (LIAR)” method after Carter et al., 2016; 2018.

* Build on surface ocean partial pressure of carbon dioxide (CMEMS product: MULTIOBS_GLO_BIO_CARBON_SURFACE_REP_015_008) obtained from an ensemble of Feed-Forward Neural Networks (Chau et al. 2022) which exploit sampling data gathered in the Surface Ocean CO2 Atlas (SOCAT) (https://www.socat.info/)

* Derive a gridded field of ocean surface pH based on the van Heuven et al., (2011) CO2 system calculations using reconstructed pCO2 (MULTIOBS_GLO_BIO_CARBON_SURFACE_REP_015_008) and alkalinity.

The global mean average of pH at yearly time steps is then calculated from the gridded ocean surface pH field. It is expressed in pH unit on total hydrogen ion scale. In the figure, the amplitude of the uncertainty (1σ ) of yearly mean surface sea water pH varies at a range of (0.0023, 0.0029) pH unit (see Quality Information Document for more details). The trend and uncertainty estimates amount to -0.0017±0.0004e-1 pH units per year.

The indicator is derived from in situ observations of CO2 fugacity (SOCAT data base, www.socat.info, Bakker et al., 2016). These observations are still sparse in space and time. Monitoring pH at higher space and time resolutions, as well as in coastal regions will require a denser network of observations and preferably direct pH measurements.

A full discussion regarding this OMI can be found in section 2.10 of the Ocean State Report 4 (Gehlen et al., 2020).

'''CONTEXT'''

The decrease in surface ocean pH is a direct consequence of the uptake by the ocean of carbon dioxide. It is referred to as ocean acidification. The International Panel on Climate Change (IPCC) Workshop on Impacts of Ocean Acidification on Marine Biology and Ecosystems (2011) defined Ocean Acidification as “a reduction in the pH of the ocean over an extended period, typically decades or longer, which is caused primarily by uptake of carbon dioxide from the atmosphere, but can also be caused by other chemical additions or subtractions from the ocean”. The pH of contemporary surface ocean waters is already 0.1 lower than at pre-industrial times and an additional decrease by 0.33 pH units is projected over the 21st century in response to the high concentration pathway RCP8.5 (Bopp et al., 2013). Ocean acidification will put marine ecosystems at risk (e.g. Orr et al., 2005; Gehlen et al., 2011; Kroeker et al., 2013). The monitoring of surface ocean pH has become a focus of many international scientific initiatives (http://goa-on.org/) and constitutes one target for SDG14 (https://sustainabledevelopment.un.org/sdg14).

'''CMEMS KEY FINDINGS'''

Since the year 1985, global ocean surface pH is decreasing at a rate of -0.0017±0.0004e-1 per year.

'''DOI (product):'''

https://doi.org/10.48670/moi-00224

Credit

E.U. Copernicus Marine Service Information

Point of contact

Organisation name	Individual name	Electronic mail address	Role
MULTIOBS-LSCE-GIF-FR			Production Unit

Maintenance and update frequency

Annually

Other

P0M0D0H/P0M0D0H

Maintenance note

N/A

GEMET - INSPIRE themes, version 1.0

• Oceanographic geographical features

Discipline

• in-situ-observation

Climate and Forecast Standard Names

• sea_water_ph_reported_on_total_scale

Temporal scale

• multi-year

Area of benefit

• marine-resources
• marine-safety
• coastal-marine-environment
• weather-climate-and-seasonal-forecasting

Reference Geographical Areas

• global-ocean

Processing level

• N/A

Model assimilation

• Not Applicable

Use limitation

See Copernicus Marine Environment Monitoring Service Data commitments and licence at: http://marine.copernicus.eu/web/27-service-commitments-and-licence.php

Access constraints

Other restrictions

Use constraints

License

Other legal constraints

No limitations on public access

Aggregate Datasetindentifier

ceab89ee-9a9a-4e6c-9ff2-9bbf8b28d8b1

Association Type

Cross reference

Initiative Type

Document

Aggregate Datasetindentifier

9bc2bb3b-6a2a-471e-962f-2479145bec8e

Association Type

Cross reference

Initiative Type

Document

Aggregate Datasetindentifier

810388db-580e-4e78-a6c1-648cf88b02ad

Association Type

Cross reference

Initiative Type

Document

Title

Bakker, D. et al.: A multi-decade record of high-quality fCO2 data in version 3 of the Surface Ocean CO2 Atlas (SOCAT), Earth Syst. Sci. Data, 8, 383-413, https://doi.org/10.5194/essd-8-383-2016, 2016.

Date (Creation)

2019-05-08

Association Type

Cross reference

Initiative Type

Reference

Title

Bopp, L. et al.: Multiple stressors of ocean ecosystems in the 21st century: projections with CMIP5 models, Biogeosciences, 10, 6225–6245, doi: 10.5194/bg-10-6225-2013, 2013.

Date (Creation)

2019-05-08

Association Type

Cross reference

Initiative Type

Reference

Title

Carter, B.R., et al.: Updated methods for global locally interpolated estimation of alkalinity, pH, and nitrate, Limnol. Oceanogr.: Methods 16, 119–131, 2018.

Date (Creation)

2019-05-08

Association Type

Cross reference

Initiative Type

Reference

Title

Carter, B. R., et al.: Locally interpolated alkalinity regression for global alkalinity estimation. Limnol. Oceanogr.: Methods 14: 268–277. doi:10.1002/lom3.10087, 2016.

Date (Creation)

2019-05-08

Association Type

Cross reference

Initiative Type

Reference

Title

Chau, T. T. T., Gehlen, M., and Chevallier, F.: A seamless ensemble-based reconstruction of surface ocean pCO2 and air–sea CO2 fluxes over the global coastal and open oceans, Biogeosciences, 19, 1087–1109, https://doi.org/10.5194/bg-19-1087-2022, 2022. Gehlen, M. et al.: Biogeochemical consequences of ocean acidification and feedback to the Earth system. p. 230, in: Gattuso J.-P. & Hansson L. (Eds.), Ocean acidification. Oxford: Oxford University Press., 2011.

Date (Creation)

2019-05-08

Association Type

Cross reference

Initiative Type

Reference

Title

Gehlen M., Thi Tuyet Trang Chau, Anna Conchon, Anna Denvil-Sommer, Frédéric Chevallier, Mathieu Vrac, Carlos Mejia (2020). Ocean acidification. In: Copernicus Marine Service Ocean State Report, Issue 4, Journal of Operational Oceanography, 13:sup1, s88–s91; DOI: 10.1080/1755876X.2020.1785097

Date (Creation)

2019-05-08

Association Type

Cross reference

Initiative Type

Reference

Title

IPCC, 2011: Workshop Report of the Intergovernmental Panel on Climate Change Workshop on Impacts of Ocean Acidification on Marine Biology and Ecosystems. [Field, C.B., V. Barros, T.F. Stocker, D. Qin, K.J. Mach, G.-K. Plattner, M.D. Mastrandrea, M. Tignor and K.L. Ebi (eds.)]. IPCC Working Group II Technical Support Unit, Carnegie Institution, Stanford, California, United States of America, pp.164.

Date (Creation)

2019-05-08

Association Type

Cross reference

Initiative Type

Reference

Title

Kroeker, K. J. et al.: Meta- analysis reveals negative yet variable effects of ocean acidifica- tion on marine organisms, Ecol. Lett., 13, 1419–1434, 2010.

Date (Creation)

2019-05-08

Association Type

Cross reference

Initiative Type

Reference

Title

Orr, J. C. et al.: Anthropogenic ocean acidification over the twenty-first century and its impact on cal- cifying organisms, Nature, 437, 681–686, 2005.

Date (Creation)

2019-05-08

Association Type

Cross reference

Initiative Type

Reference

Title

van Heuven, S., et al.: MATLAB program developed for CO2 system calculations, ORNL/CDIAC-105b, Carbon Dioxide Inf. Anal. Cent., Oak Ridge Natl. Lab., US DOE, Oak Ridge, Tenn., 2011.

Date (Creation)

2019-05-08

Association Type

Cross reference

Initiative Type

Reference

Language

eng

Topic category

• Oceans

Description

bounding box

Begin date

1985-01-01

Supplemental Information

display priority: 99999

Codespace

EPSG

Number of dimensions

2

Dimension name

Row

Dimension name

Column

Cell geometry

Area

Transformation parameter availability

Distribution format

Name	Version
NetCDF-4

OnLine resource

Protocol	Linkage	Name
WWW:STAC	https://stac.marine.copernicus.eu/metadata/GLOBAL_OMI_HEALTH_carbon_ph_area_averaged/global_omi_health_carbon_ph_area_averaged_202303/dataset.stac.json	global_omi_health_carbon_ph_area_averaged

Hierarchy level

Series

Statement

The myOcean products depends on other products for production or validation. The detailed list of dependencies is given in ISO19115's aggregationInfo (ISO19139 Xpath = "gmd:MD_Metadata/gmd:identificationInfo/gmd:aggregationInfo[./gmd:MD_AggregateInformation/gmd:initiativeType/gmd:DS_InitiativeTypeCode/@codeListValue='upstream-validation' or 'upstream-production']")

Attribute description

observation

Content type

Physical measurement

Descriptor

temporal resolution: annual mean

Descriptor

vertical level number: 0

Included with dataset

Feature types

Point series

Metadata

File identifier

1c5fe986-1cd7-4c56-aeff-7bba0b4ff554

Metadata language

English

Character set

UTF8

Hierarchy level

Series

Hierarchy level name

Copernicus Marine Service product specification

Date stamp

2025-04-22T09:21:57.800168Z

Metadata standard name

ISO 19139, MyOcean profile

Metadata standard version

0.2

Metadata author

Organisation name	Individual name	Electronic mail address	Role
CMEMS		servicedesk.cmems@mercator-ocean.eu	Local service desk