External forcing mechanisms controlling the North Atlantic coastal upwelling regime during the mid-Holocene

• Main Authors: Hernández, Armand, Cachão, Mário, Sousa, Pedro, Trigo, Ricardo M., Luterbacher, J., Vaquero, José Manuel, Freitas, Maria C.
• Other Authors: Fundação para a Ciência e a Tecnologia (Portugal), Junta de Extremadura, Ministerio de Economía y Competitividad (España), European Organisation for the Exploitation of Meteorological Satellites
• Format: Article in Journal/Newspaper
• Language: English
• Published: Geological Society of America 2021
• Subjects: Quaternary simulation; Southern Europe upwelling; orbital forcing; pressure; middle Holocene; ocean circulation; models; North Atlantic; mechanism; microfossils; Holocene; Iberian Peninsula; Europe; high pressure; dynamics; ecosystems; Climate forcing; Coastal environments; Cenozoic; Climate; Atlantic Ocean; Atmosphere
• Online Access: http://hdl.handle.net/10261/238734; https://doi.org/10.1130/G48112.1; https://doi.org/10.13039/501100001871; https://doi.org/10.13039/501100003329; https://doi.org/10.13039/501100010560; https://doi.org/10.13039/501100014181

Nearshore upwelling along the eastern North Atlantic margin regulates regional marine ecosystem productivity and thus impacts blue economies. While most global circulation models show an increase in the intensity and duration of seasonal upwelling at high latitudes under future human-induced warmer conditions, projections for the North Atlantic are still ambiguous. Due to the low temporal resolution of coastal upwelling records, little is known about the impact of natural forcing mechanisms on upwelling variability. Here, we present a microfossil-based proxy record and modeling simulations for the warmest period of the Holocene (ca. 9-5 ka) to estimate the contribution of the natural variability in North Atlantic upwelling via atmospheric and oceanic dynamics. We found that more frequent high-pressure conditions in the eastern North Atlantic associated with solar activity and orbital parameters triggered upwelling variations at multidecadal and millennial time scales, respectively. Our new findings offer insights into the role of external forcing mechanisms in upwelling changes before the Anthropocene, which must be considered when producing future projections of midlatitude upwelling activity. © 2021 The Authors. All Rights Reserved. This work was financed by projects PDCTM/PP-/MAR/15231/1999 and CANAL-POCTI/32724/PAL/2000 of the Fundação para a Ciência e a Tecnologia, Portugal. Project Holmodrive (PTDC/CTA-GEO/29029/2017) and FCT- UIDB/50019/2020 from the Fundação para a Ciência e a Tecnologia also supported this research. Hernández was supported by a BdP–Marie Curie Cofund fellowship (2016 BP 00023). Vaquero acknowledges financial support from the Economy and Infrastructure Counseling of the Junta of Extremadura (IB16127-GR18097) and from the Ministry of Economy and Competitiveness of the Spanish government (CGL2017–87917-P). Sousa was supported by project LSA SAF–DCOP-3 (European Organisation for the Exploitation of Meteorological Satellites). We thank three anonymous reviewers for their constructive ...