Long-term trends in surface ocean pH in the North Atlantic
Presently available direct pH measurements do not have a sufficient data density in space or time in order to determine long-term trends across wider geographic regions, limiting our ability to assess the magnitude and impacts of ocean acidification. We overcome this limitation by using the much mor...
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ftunivbergen:oai:bora.uib.no:1956/17114 2023-05-15T17:29:23+02:00 Long-term trends in surface ocean pH in the North Atlantic Lauvset, Siv Kari Gruber, Nicolas 2017-12-02T14:03:54Z application/pdf https://hdl.handle.net/1956/17114 https://doi.org/10.1016/j.marchem.2014.03.009 eng eng Elsevier Norges forskningsråd: 214513 urn:issn:0304-4203 urn:issn:1872-7581 https://hdl.handle.net/1956/17114 https://doi.org/10.1016/j.marchem.2014.03.009 cristin:1150477 Attribution CC BY-NC-ND http://creativecommons.org/licenses/by-nc-nd/4.0/ Copyright 2014 Elsevier B.V. Marine Chemistry pH Ocean acidification Trend analysis Carbon cycle North Atlantic VDP::Matematikk og naturvitenskap: 400::Geofag: 450::Oseanografi: 452 VDP::Mathematics and natural scienses: 400::Geosciences: 450::Oceanography: 452 Peer reviewed Journal article 2017 ftunivbergen https://doi.org/10.1016/j.marchem.2014.03.009 2023-03-14T17:40:08Z Presently available direct pH measurements do not have a sufficient data density in space or time in order to determine long-term trends across wider geographic regions, limiting our ability to assess the magnitude and impacts of ocean acidification. We overcome this limitation by using the much more frequently measured fugacity of CO2 (fCO2), as synthesized in the SOCAT data product, from which we calculate pH using algorithms for alkalinity based on temperature and salinity. The estimated pH at 25 °C, i.e., pHsws25 °C has a calculation error of 0.0033 ± 0.0003, and evaluation using co-located pH observations yields a RMSE of 0.010 and a non-significant bias of 0.004. The estimated pHsws25 °C is rather sensitive to uncertainties and biases in fCO2, while uncertainties in alkalinity, temperature, and salinity matter much less. The high precision and low bias of the computed pH permit us to apply this method to data from the North Atlantic Subpolar Gyre, for which we find a statistically significant trend in surface ocean pHswsinsitu of − 0.0022 ± 0.0004 yr− 1 over the period 1981 to 2007. This long-term trend in pH is nearly entirely driven by the long-term trend in surface ocean fCO2, while the impact of temperature is negligible. This pH trend is very close to that expected based on the assumption of thermodynamic equilibrium of CO2 between the atmosphere and the surface ocean. publishedVersion Article in Journal/Newspaper North Atlantic Ocean acidification University of Bergen: Bergen Open Research Archive (BORA-UiB) Marine Chemistry 162 71 76 |
institution |
Open Polar |
collection |
University of Bergen: Bergen Open Research Archive (BORA-UiB) |
op_collection_id |
ftunivbergen |
language |
English |
topic |
pH Ocean acidification Trend analysis Carbon cycle North Atlantic VDP::Matematikk og naturvitenskap: 400::Geofag: 450::Oseanografi: 452 VDP::Mathematics and natural scienses: 400::Geosciences: 450::Oceanography: 452 |
spellingShingle |
pH Ocean acidification Trend analysis Carbon cycle North Atlantic VDP::Matematikk og naturvitenskap: 400::Geofag: 450::Oseanografi: 452 VDP::Mathematics and natural scienses: 400::Geosciences: 450::Oceanography: 452 Lauvset, Siv Kari Gruber, Nicolas Long-term trends in surface ocean pH in the North Atlantic |
topic_facet |
pH Ocean acidification Trend analysis Carbon cycle North Atlantic VDP::Matematikk og naturvitenskap: 400::Geofag: 450::Oseanografi: 452 VDP::Mathematics and natural scienses: 400::Geosciences: 450::Oceanography: 452 |
description |
Presently available direct pH measurements do not have a sufficient data density in space or time in order to determine long-term trends across wider geographic regions, limiting our ability to assess the magnitude and impacts of ocean acidification. We overcome this limitation by using the much more frequently measured fugacity of CO2 (fCO2), as synthesized in the SOCAT data product, from which we calculate pH using algorithms for alkalinity based on temperature and salinity. The estimated pH at 25 °C, i.e., pHsws25 °C has a calculation error of 0.0033 ± 0.0003, and evaluation using co-located pH observations yields a RMSE of 0.010 and a non-significant bias of 0.004. The estimated pHsws25 °C is rather sensitive to uncertainties and biases in fCO2, while uncertainties in alkalinity, temperature, and salinity matter much less. The high precision and low bias of the computed pH permit us to apply this method to data from the North Atlantic Subpolar Gyre, for which we find a statistically significant trend in surface ocean pHswsinsitu of − 0.0022 ± 0.0004 yr− 1 over the period 1981 to 2007. This long-term trend in pH is nearly entirely driven by the long-term trend in surface ocean fCO2, while the impact of temperature is negligible. This pH trend is very close to that expected based on the assumption of thermodynamic equilibrium of CO2 between the atmosphere and the surface ocean. publishedVersion |
format |
Article in Journal/Newspaper |
author |
Lauvset, Siv Kari Gruber, Nicolas |
author_facet |
Lauvset, Siv Kari Gruber, Nicolas |
author_sort |
Lauvset, Siv Kari |
title |
Long-term trends in surface ocean pH in the North Atlantic |
title_short |
Long-term trends in surface ocean pH in the North Atlantic |
title_full |
Long-term trends in surface ocean pH in the North Atlantic |
title_fullStr |
Long-term trends in surface ocean pH in the North Atlantic |
title_full_unstemmed |
Long-term trends in surface ocean pH in the North Atlantic |
title_sort |
long-term trends in surface ocean ph in the north atlantic |
publisher |
Elsevier |
publishDate |
2017 |
url |
https://hdl.handle.net/1956/17114 https://doi.org/10.1016/j.marchem.2014.03.009 |
genre |
North Atlantic Ocean acidification |
genre_facet |
North Atlantic Ocean acidification |
op_source |
Marine Chemistry |
op_relation |
Norges forskningsråd: 214513 urn:issn:0304-4203 urn:issn:1872-7581 https://hdl.handle.net/1956/17114 https://doi.org/10.1016/j.marchem.2014.03.009 cristin:1150477 |
op_rights |
Attribution CC BY-NC-ND http://creativecommons.org/licenses/by-nc-nd/4.0/ Copyright 2014 Elsevier B.V. |
op_doi |
https://doi.org/10.1016/j.marchem.2014.03.009 |
container_title |
Marine Chemistry |
container_volume |
162 |
container_start_page |
71 |
op_container_end_page |
76 |
_version_ |
1766123284721565696 |