The DOI matches its Crossref record; 62 of the 64 references it cites were found in a registry or an index; 2 of the 11 sources its claims cite were checked for support.
Canary current upwelling: More or less?
Open accessAbstract
It has been hypothesized that coastal upwelling in the four major eastern boundary current systems might be intensified as global warming could result in a greater land-sea temperature gradient and hence strengthen alongshore winds. Recent research has suggested a substantial increase of upwelling intensity off Northwest Africa. Evidence there is based on the derivation of a proxy for upper ocean temperatures from the alkenone unsaturation index (U37K') derived from two sediment cores recovered off Cape Ghir, Morocco. An accelerating decrease of over 1. °C during the last century was concluded for near surface temperature near the Cape. Support for this conclusion was found in an increase in Bakun's upwelling index for the same area. The evidence for a general intensification of upwelling within the whole Canary current upwelling system is examined here. Using available estimates of wind from PFEL, NCAR/NCEP, ECMWF, ICOADS and WASWind plus measured wind data from coastal meteorological stations, no evidence of a coherent intensification in winds at the regional scale off Northwest Africa is found. Moreover, sea surface temperature records from ships-of-opportunity (ICOADS data set) and also from the Pathfinder satellite AVHRR data set show a significant and correlated increase at all latitudes in the region, including in the area around Cape Ghir. It is concluded that there is no evidence for a general increase in upwelling intensity off Northwest Africa or Iberia. The apparent lowering of SST off Cape Ghir indicated by the alkenone unsaturation index can be explained by coccolithophorids (phytoplankton from which the U37K' signal is derived) living deeper in the water column. The distribution of most phytoplankton (including coccolithophorids) will deepen and have less overlap with mixed layer temperatures as the ocean warms, resulting in a near surface temperature estimate that is increasingly biased by subsurface temperatures and lower than the actual SST. © 2013 Elsevier Ltd.
Overview
AI snapshot
Written from the paper’s full text.
TL;DR
The paper tests the hypothesis that coastal upwelling in the Canary Current system has intensified, and finds no evidence of a coherent regional increase in upwelling-favourable winds off Northwest Africa or Iberia. It argues that the apparent alkenone-derived SST cooling off Cape Ghir is an artefact of coccolithophorids living deeper in the water column as the ocean warms.
Key findings
- Using wind estimates from PFEL, NCAR/NCEP, ECMWF, ICOADS and WASWind plus measured wind data from coastal meteorological stations, "no evidence of a coherent intensification in winds at the regional scale off Northwest Africa is found."
- Sea surface temperature records from ships-of-opportunity (ICOADS) and the Pathfinder satellite AVHRR data set "show a significant and correlated increase at all latitudes in the region, including in the area around Cape Ghir."
- The authors conclude "there is no evidence for a general increase in upwelling intensity off Northwest Africa or Iberia," in direct contrast to earlier studies (e.g. McGregor et al. 2007, who reported a 1.2 °C SST reduction off Cape Ghir over the last century, and Narayan et al. 2010).
- The apparent lowering of SST off Cape Ghir from the alkenone unsaturation index (U^K′_37) is explained by coccolithophorids living deeper in the water column; as the ocean warms, their distribution deepens and overlaps less with mixed-layer temperatures, biasing the near-surface temperature estimate low relative to actual SST.
Methods
- Design: re-examination of the evidence for general intensification of upwelling across the whole Canary Current upwelling system, using publicly available wind and SST data sets for the North Atlantic upwelling region between Dakar, Senegal (15°N) and Galicia, Spain (43°N).
- Data: wind from PFEL, NCAR/NCEP, ECMWF, ICOADS and WASWind, plus measured wind from coastal meteorological stations; SST from ICOADS ships-of-opportunity and Pathfinder AVHRR satellite data; sediment-core alkenone (U^K′_37) proxy records from two cores off Cape Ghir, Morocco (from McGregor et al.).
- Analysis: documentation of temporal trends in atmospheric forcing and oceanic response, consideration of factors affecting reliability of the different wind and SST time series, and exploration of the SST–alkenone proxy temperature relationship.
Limitations
- The paper states that "the evidence that wind velocity is increasing and SST decreasing in the NW African upwelling region as a whole has many uncertainties," and notes that different analyses give conflicting results (e.g. Pardo et al. found weakening, Narayan et al. found increasing upwelling intensity).
- Evident from the supplied text: only the abstract, introduction and the start of the Data section (pages 1–3 of 42) are available, so the paper's detailed results, statistical tests and its own stated limitations section are not present in the provided fragment.
Model-written summary. Check it against the paper before relying on it.
Integrity signals
Registry
Cites
Statistics
Verification
Claims the paper makes
4 No full text of the sources · 3 Own interpretation · 2 Own result · 1 Supported · 1 Supported so far · 1 Not checked yet
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Moreover, sea surface temperature records from ships-of-opportunity (ICOADS data set) and also from the Pathfinder satellite AVHRR data set show a significant and correlated increase at all latitudes in the region, including in the area around Cape Ghir.”
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A result the paper reports from its own data — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“Using available estimates of wind from PFEL, NCAR/NCEP, ECMWF, ICOADS and WASWind plus measured wind data from coastal meteorological stations, no evidence of a coherent intensification in winds at the regional scale off Northwest Africa is found.”
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
In the paper
“More recently, McGregor et al. (2007) found strong support for the hypothesis through evidence of a dramatic lowering of inferred SSTs in the northwest African upwelling region over the last century.”
What the sources say
- Not checked — no full text of the sourcecites McGregor et al., 2007 source
boostedcorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“It is concluded that there is no evidence for a general increase in upwelling intensity off Northwest Africa or Iberia.”
- Also stated in: § 1. Introduction · boosted
“Our results clearly indicate that there is no evidence for increasing intensity of upwelling along this seaboard, in direct contrast to earlier studies.”
boosted- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- Also stated in: § 1. Introduction · boosted
None of the sources cited for this claim have been checked yet.
In the paper
“For example, the reported northward encroachment of more sub-tropical and tropical species of fish (Quéro et al., 1998; Brander et al., 2003; Graham & Harrod, 2009) is incongruent with decreasing temperatures in this coastal zone.”
What the sources say
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: unclear — It is unclear whether the paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The apparent lowering of SST off Cape Ghir indicated by the alkenone unsaturation index can be explained by coccolithophorids (phytoplankton from which the View the MathML sourceU37K′ signal is derived) living deeper in the water column.”
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
- Rests on an assumption: The UK’37 alkenone unsaturation index signal is derived from coccolithophorids.
- Probably not a substantial claim. 4
- It may state two separate claims as one. 2
Every source the paper cites for this claim was checked and supports it.
In the paper
“Pardo et al. found “weakening of the upwelling intensity in the Iberian/Canary and NW African regions”.”
What the sources say
- Supportedcites Pardo et al., 2011 source
The Summary and Conclusions state that upwelling intensity generally weakened in the Iberian/Canary region and that this pattern extended southward into the NW African region. The Interannual Variability section also reports weakening in both regions, while noting local and period-specific exceptions. (LLM, conf=0.94)
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
- Supported
The sources with a verdict support this claim; the rest weren’t checked yet, have no full text we could read, or their verdicts aren’t rated yet.
In the paper
“Other more detailed studies like Narayan et al. (2010) and Pardo et al. (2011) have examined long term variation in the Canaries and other upwelling zones with varied results.”
What the sources say
- Not checked — no full text of the sourcecites Narayan et al., 2010 source
- Supportedcites Pardo et al., 2011 source
The Introduction says the study examines long-term changes in the Iberian/Canary region and extends the analysis to other major upwelling systems. Section 3.2 reports differing trends across those regions, supporting the description of varied results. No page numbers are provided in the supplied passages. (LLM, conf=0.93)
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
In the paper
“Their alkenone unsaturation index indicates a reduction of sea surface temperature (SST) in the Cape Ghir upwelling of 1.2oC over the last century, coincident with the observed increase in atmospheric CO2 levels.”
What the sources say
- Not checked — no full text of the sourcecites McGregor et al., 2007 source
hedgedcorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
In the paper
“Bakun (1990) presented evidence of a tendency for stronger upwelling in the Californian, Iberian, Moroccan and Peruvian areas during the period from 1945 to 1985.”
What the sources say
- Not checked — no full text of the sourcecites Bakun, 1990 source
plaincorrelational- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
A conclusion the paper draws from its own results — it cites no other source for it, so there is none to check. The quote shows it is in the paper.
In the paper
“The distribution of most phytoplankton (including coccolithophorids) will deepen and have less overlap with mixed layer temperatures as the ocean warms, resulting in a near surface temperature estimate that is increasingly biased by subsurface temperatures and lower than the actual SST.”
plaindirect- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: passes — The paper’s conclusions depend on it.
- Based: passes — The paper gives a reason why it holds.
It may state two separate claims as one.
A claim is checked only against the cited paper’s full text, never its abstract, and none is available for its sources.
In the paper
“In global studies of trends in Large Marine Ecosystems, including the Canary Current LME (Belkin, 2009; Sherman et al., 2009), it was concluded that the “most striking result is the consistent warming” by amounts exceeding 0.6oC over 25 years in mid to low latitudes.”
What the sources say
plain- Asserted: passes — The authors put it forward as true.
- Checkable: passes — It can be checked against evidence.
- Load-bearing: fails — The paper’s conclusions may not depend on it.
- Based: passes — The paper gives a reason why it holds.
Probably not a substantial claim. The paper’s conclusions may not depend on it.
The paper relies on this without support.
The UK’37 alkenone unsaturation index signal is derived from coccolithophorids.
“coccolithophorids (phytoplankton from which the View the MathML sourceU37K′ signal is derived)”
Claims other papers make about this one
Each is checked against this paper’s own text: does it say what the citing paper says it does?
The source backs part of the claim, not all of it — or backs it for a different population, condition or comparison.
In the citing paper
“They therefore conclude no intensification in winds off Northwest Africa.”
From Recent Trends in SST, Chl‐a, Productivity and Wind Stress in Upwelling and Open Ocean Areas in the Upper Eastern North Atlantic Subtropical Gyre (2021) · cites this paper as Barton et al. (2013)
Experimental — accuracy not yet measuredThe source backs part of the claim, not all of it — or backs it for a different population, condition or comparison.
In the citing paper
“This idea was originally supported by emerging interregional patterns of observed sea-surface wind stress, and has been periodically tested against time series of observed data in all four regional EBUS [12,13].”
From Anticipated Effects of Climate Change on Coastal Upwelling Ecosystems (2015) · cites this paper as [12]
Experimental — accuracy not yet measuredThe cited source says what the claim attributes to it.
In the citing paper
“Barton et al. (2013) support this discussion by underlining the variations in different data sets and locations (even positive and negative trends for the same location).”
From Recent Trends in SST, Chl‐a, Productivity and Wind Stress in Upwelling and Open Ocean Areas in the Upper Eastern North Atlantic Subtropical Gyre (2021) · cites this paper as Barton et al. (2013)
Citations
Cites
Estimates of the Regression Coefficient Based on Kendall's Tau
Sen, P. K. (1968) · Journal of the American Statistical Association · doi:10.1080/01621459.1968.10480934 · Cited by 15,277
Uppala, S. M., Kållberg, P. W., Simmons, A. J., Andrae, U., Bechtold, V. D. C., Fiorino, M., Gibson, J. K., Haseler, J., Hernandez, A., Kelly, G. A., et al. (2005) · Quarterly Journal of the Royal Meteorological Society · doi:10.1256/qj.04.176 · Cited by 7,010
Data Analysis Methods in Physical Oceanography
(2014) · Elsevier eBooks · doi:10.1016/c2010-0-66362-0 · Cited by 1,597
Ryther, J. H. (1969) · Science · doi:10.1126/science.166.3901.72 · Cited by 1,503
Global Climate Change and Intensification of Coastal Ocean Upwelling
Bakun, A. (1990) · Science · doi:10.1126/science.247.4939.198 · Cited by 1,288
Müller, P., Kirst, G., Ruhland, G., von Storch, I., & Rosell‐Melé, A. (1998) · Geochimica et Cosmochimica Acta · doi:10.1016/s0016-7037(98)00097-0 · Cited by 1,100
Rapid warming of large marine ecosystems
Belkin, I. M. (2009) · Progress in Oceanography · doi:10.1016/j.pocean.2009.04.011 · Cited by 1,017
Further evaluation of long-chain alkenones as indicators of paleoceanographic conditions
Prahl, F. G., Muehlhausen, L. A., & Zahnle, D. L. (1988) · Geochimica et Cosmochimica Acta · doi:10.1016/0016-7037(88)90132-9 · Cited by 860
Organic geochemistry: principles and applications
(1994) · Choice Reviews Online · doi:10.5860/choice.31-4371 · Cited by 733
Santer, B. D., Wigley, T. M. L., Boyle, J. S., Gaffen, D. J., Hnilo, J. J., Nychka, D. W., Parker, D. E., & Taylor, K. E. (2000) · Journal of Geophysical Research Atmospheres · doi:10.1029/1999jd901105 · Cited by 695
Research works printed but not linked: 3
- Isemer, H.-J., 1995. Trends in marine surface winds speed: ocean weather stations versus voluntary observing ships. In: Proceedings of the International COADS Workshop, Kiel, Germany, NOAA Environmental Research Laboratories and Institut fur Meereskunde, pp. 68–84.
- Prahl, 2007, Biogeochemical assessment of alkenone export depth in the summertime euphotic zone of the Gulf of California, Extended Abstracts Presented at the ACS National Meeting, 47, 483
- Smith, 1968, Upwelling, Oceanography and Marine Biology, Annual Review, 6, 11
Cited by
Sorted by citations
Anticipated Effects of Climate Change on Coastal Upwelling Ecosystems
Bakun, A., Black, B. A., Bograd, S. J., García-Reyes, M., Miller, A. J., Rykaczewski, R. R., & Sydeman, W. J. (2015) · Current Climate Change Reports · doi:10.1007/s40641-015-0008-4 · Cited by 470
“This idea was originally supported by emerging interregional patterns of observed sea-surface wind stress, and has been periodically tested against time series of observed data in all four regional EBUS [12, 13].”
MethodIntensification and spatial homogenization of coastal upwelling under climate change
Wang, D., Gouhier, T. C., Menge, B. A., & Ganguly, A. R. (2015) · Nature · doi:10.1038/nature14235 · Cited by 447
Under Pressure: Climate Change, Upwelling, and Eastern Boundary Upwelling Ecosystems
García-Reyes, M., Sydeman, W. J., Schoeman, D. S., Rykaczewski, R. R., Black, B. A., Smit, A. J., & Bograd, S. J. (2015) · Frontiers in Marine Science · doi:10.3389/fmars.2015.00109 · Cited by 272
“In part, this is a result of the substantial spatial heterogeneity in physical characteristics within EBUS, which emphasizes the role of local processes and resultant local biotic effects (Nelson and Hutchings, 1983; Dorman and Winant, 1995; Barton et al., 2013; Bakun et al., 2015).”
BackgroundInfluentialClimate Change Impacts on Eastern Boundary Upwelling Systems
Bograd, S. J., Jacox, M. G., Hazen, E. L., Lovecchio, E., Montès, I., Buil, M. P., Shannon, L. J., Sydeman, W. J., & Rykaczewski, R. R. (2022) · Annual Review of Marine Science · doi:10.1146/annurev-marine-032122-021945 · Cited by 200
“…intensity off the Iberian Peninsula (Lemos & Pires 2004, Barton et al. 2013, Bode et al. 2019) and off northwest Africa (Gómez-Gesteira et al. 2008, Barton et al. 2013), while others have reported an upwelling intensification trend off northwest Africa (Cropper et al. 2014,Benazzouz et al. 2015).”
BackgroundHas upwelling strengthened along worldwide coasts over 1982-2010?
Varela, R., Alvarez, I., Santos, F., deCastro, M., & Gómez-Gesteira, M. (2015) · Scientific Reports · doi:10.1038/srep10016 · Cited by 175
“…WSp PFEL (15.5-41.5°N) 1967-2007 (Annual) − Barton et al. (2013) WSp NCEP/NCAR (15-42.5°N) 1967-2007 (Annual) − Barton et al. (2013) WSp ECMWF (15-40°N) 1967-2007 (Annual) + Barton et al. (2013) WSp ICOADS (15-41°N) 1967-2007 (Annual) + Barton et al. (2013) WSp WASWind (16-44°N) 1967-2007…”
Influential
Metadata
- Authors
- Barton, E. D., Field, D. B., & Roy, C.
- Affiliations
- Instituto de Investigacións Mariñas (ES)
- Hawaii Pacific University (US)
- Centre National de la Recherche Scientifique (FR)
- Corresponding author
- Barton, E.D.
- Venue
- Progress in Oceanography
- Publisher
- Elsevier BV
- Published
- 2013-09
- Volume
- 116
- Pages
- 167-178
- ISSN
- 0079-6611 (ISSN-L)
- OpenAlex
- W2004932320
- Cited by
- 134
- References
- 64
- Citations by year
- 2026: 7 · 2025: 5 · 2024: 13 · 2023: 10 · 2022: 19 · 2021: 11 · 2020: 14 · 2019: 10 · 2018: 11 · 2017: 8 · 2016: 8 · 2015: 11 · 2014: 4 · 2013: 3
- FWCI
- 6.10
- Type
- journal article
- Language
- en
- Open access
- green
- hdl.handle.net
- Licence
- Locations
- Progress In Oceanography (publishedVersion)
- HAL (Le Centre pour la Communication Scientifique Directe) (submittedVersion)
- DIGITAL.CSIC (Spanish National Research Council (CSIC)) (submittedVersion, other-oa)
- Topics
- Physical Sciences › Earth and Planetary Sciences › Oceanography › Oceanographic and Atmospheric Processes
- Physical Sciences › Environmental Science › Global and Planetary Change › Climate variability and models
- Physical Sciences › Earth and Planetary Sciences › Oceanography › Marine Plankton and Biogeochemistry
- Keywords
- global warming, alkenone unsaturation index, sea surface temperature, coccolithophores, mixed layer temperature, alongshore winds, Maghreb, Iberia, eastern boundary currents
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
A language model drew the claims from the paper on 2026-10-16, under version 3 of the claim definition (model deepseek-v4.1-flash, prompt extract-v3).
A second model labelled each claim on 2026-10-16 (model jev-1.13-20260917, definition revision gold-guideline-v0.2).
Cited sources are checked with a language model’s help (gpt-6-sol).
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
What counts as a claim ›How we measure confidence ›How we check this ›
Are you an author, or do you see a problem with this page? Request a review
