Trends and drivers in global surface ocean pH over the past 3 decades
We report global long-term trends in surface ocean pH using a new pH data set computed by combining <i>f</i>CO<sub>2</sub> observations from the Surface Ocean CO<sub>2</sub> Atlas (SOCAT) version 2 with surface alkalinity estimates based on temperature and salinit...
| Main Authors: | , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-03-01
|
| Series: | Biogeosciences |
| Online Access: | http://www.biogeosciences.net/12/1285/2015/bg-12-1285-2015.pdf |
| _version_ | 1818196533256912896 |
|---|---|
| author | S. K. Lauvset N. Gruber P. Landschützer A. Olsen J. Tjiputra |
| author_facet | S. K. Lauvset N. Gruber P. Landschützer A. Olsen J. Tjiputra |
| author_sort | S. K. Lauvset |
| collection | DOAJ |
| description | We report global long-term trends in surface ocean pH using a new pH data
set computed by combining <i>f</i>CO<sub>2</sub> observations from the Surface Ocean
CO<sub>2</sub> Atlas (SOCAT) version 2 with surface alkalinity estimates based on
temperature and salinity. Trends were determined over the periods 1981–2011
and 1991–2011 for a set of 17 biomes using a weighted linear least squares
method. We observe significant decreases in surface ocean pH in
~70% of all biomes and a mean rate of decrease of
0.0018 ± 0.0004 yr<sup>−1</sup> for 1991–2011. We are not able to calculate a
global trend for 1981–2011 because too few biomes have enough data for this.
In half the biomes, the rate of change is commensurate with the trends
expected based on the assumption that the surface ocean pH change is only
driven by the surface ocean CO<sub>2</sub> chemistry remaining in a transient
equilibrium with the increase in atmospheric CO<sub>2</sub>. In the remaining
biomes, deviations from such equilibrium may reflect that the trend of
surface ocean <i>f</i>CO<sub>2</sub> is not equal to that of the atmosphere, most notably
in the equatorial Pacific Ocean, or may reflect changes in the oceanic buffer (Revelle)
factor. We conclude that well-planned and long-term sustained observational
networks are key to reliably document the ongoing and future changes in
ocean carbon chemistry due to anthropogenic forcing. |
| first_indexed | 2024-12-12T01:35:35Z |
| format | Article |
| id | doaj.art-8905fe5bdaab4568b3e1a4c19bedf8cd |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-12-12T01:35:35Z |
| publishDate | 2015-03-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-8905fe5bdaab4568b3e1a4c19bedf8cd2022-12-22T00:42:51ZengCopernicus PublicationsBiogeosciences1726-41701726-41892015-03-011251285129810.5194/bg-12-1285-2015Trends and drivers in global surface ocean pH over the past 3 decadesS. K. Lauvset0N. Gruber1P. Landschützer2A. Olsen3J. Tjiputra4Geophysical Institute, University of Bergen, NorwayEnvironmental Physics, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Zurich, SwitzerlandEnvironmental Physics, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Zurich, SwitzerlandGeophysical Institute, University of Bergen, NorwayBjerknes Center for Climate Research, Bergen, NorwayWe report global long-term trends in surface ocean pH using a new pH data set computed by combining <i>f</i>CO<sub>2</sub> observations from the Surface Ocean CO<sub>2</sub> Atlas (SOCAT) version 2 with surface alkalinity estimates based on temperature and salinity. Trends were determined over the periods 1981–2011 and 1991–2011 for a set of 17 biomes using a weighted linear least squares method. We observe significant decreases in surface ocean pH in ~70% of all biomes and a mean rate of decrease of 0.0018 ± 0.0004 yr<sup>−1</sup> for 1991–2011. We are not able to calculate a global trend for 1981–2011 because too few biomes have enough data for this. In half the biomes, the rate of change is commensurate with the trends expected based on the assumption that the surface ocean pH change is only driven by the surface ocean CO<sub>2</sub> chemistry remaining in a transient equilibrium with the increase in atmospheric CO<sub>2</sub>. In the remaining biomes, deviations from such equilibrium may reflect that the trend of surface ocean <i>f</i>CO<sub>2</sub> is not equal to that of the atmosphere, most notably in the equatorial Pacific Ocean, or may reflect changes in the oceanic buffer (Revelle) factor. We conclude that well-planned and long-term sustained observational networks are key to reliably document the ongoing and future changes in ocean carbon chemistry due to anthropogenic forcing.http://www.biogeosciences.net/12/1285/2015/bg-12-1285-2015.pdf |
| spellingShingle | S. K. Lauvset N. Gruber P. Landschützer A. Olsen J. Tjiputra Trends and drivers in global surface ocean pH over the past 3 decades Biogeosciences |
| title | Trends and drivers in global surface ocean pH over the past 3 decades |
| title_full | Trends and drivers in global surface ocean pH over the past 3 decades |
| title_fullStr | Trends and drivers in global surface ocean pH over the past 3 decades |
| title_full_unstemmed | Trends and drivers in global surface ocean pH over the past 3 decades |
| title_short | Trends and drivers in global surface ocean pH over the past 3 decades |
| title_sort | trends and drivers in global surface ocean ph over the past 3 decades |
| url | http://www.biogeosciences.net/12/1285/2015/bg-12-1285-2015.pdf |
| work_keys_str_mv | AT sklauvset trendsanddriversinglobalsurfaceoceanphoverthepast3decades AT ngruber trendsanddriversinglobalsurfaceoceanphoverthepast3decades AT plandschutzer trendsanddriversinglobalsurfaceoceanphoverthepast3decades AT aolsen trendsanddriversinglobalsurfaceoceanphoverthepast3decades AT jtjiputra trendsanddriversinglobalsurfaceoceanphoverthepast3decades |