Award: OCE-1434530

Intellectual Merit Climate variability substantially influences the structure, functioning, and productivity of coastal upwelling zones with implications for ecosystem services, biodiversity, and the health of coupled human-marine systems. In previous research in the California Current System (CCS) (NSF awards #1130125 and #0929017), we found that coastal upwelling occurs in two biologically important, unrelated seasonal modes: a winter/early spring mode dominated by interannual variability, and a summer mode dominated by decadal-scale variability. Over the past century, summer upwelling intensity (rate) has increased while variability in upwelling has increased during the winter, both of which have important implications for this ecosystem. We do not know, however, if these patterns in upwelling are related to anthropogenic (global) climate change, interdecadal climate variability, or if the coherent responses of higher-trophic-level populations observed in the CCS are present in coastal upwelling ecosystems worldwide. To address these issues, we have undertaken a broader-scale comparative analysis of climatic impacts between the central-northern California Current System and southern (South African) portion of the Benguela Current System (BCS). Our major findings are: (1) Unlike the CCS, there are no clear seasonal modes of variability in BCS upwelling. (2) There is, however, recent evidence of similar trends in "warm-season" upwelling across systems, especially in decadal timescales. In particular, the magnitude of warm season upwelling increased in both systems from the mid-1990s to mid-2010s, though the rate of change has been slower in the BCS than CCS. (3) Indicators of upper-trophic productivity in the BCS covary less strongly than those in the CCS, which may be due to the lack of a dominant, synchronizing climate signal in the south Atlantic. Moreover, many of these upper-trophic processes, such as seabird reproductive success, are non-linear functions of anchovy and sardine populations in the western BCS. The climate drivers of these small pelagic fishes must be determined to understand climate forcing of the upper levels of the ecosystem. (4) Approximately 86% of the variability in BCS anchovy recruitment can be explained by summer (January-March) upwelling, a relationship that became evident from our upwelling indicators and application of new time series analysis that involved autoregressive modeling and testing for threshold responses. These climate impacts then translate to patterns in seabird reproductive success. (5) In the CCS, we made the unexpected discovery that as winter climate variability has increased over the past century, so too has synchrony within and among physical and biological indicators of marine, terrestrial, and freshwater environments of western North America. Rising synchrony could reduce biological resilience and increase the risk of extirpation. (6) In the CCS, long-term patterns in winter variability are inversely related with anchovy biomass. Thus, the degree of climate variability, and not just mean climate state, may be an important indicator of biological functioning in this ecosystem. (7) Future upwelling regions are expected to be located poleward of their current locations. This response is associated with the long-term migration of major atmospheric pressure cells associated with anthropogenic global warming. (8) Past trends in upwelling cannot be attributed to anthropogenic climate change. Natural variability in these systems is large. Broader Impacts To date, the comparative analysis of the CCS and BCS has resulted in 9 publications, 4 publications in the final stages of preparation, more than a dozen presentations at national or international meetings, and training for 2 undergraduate students, 1 graduate student, and 2 post-doctoral fellows. We also published a project website titled the California-Benguela Joint Investigation (CalBenJI) (http://www.faralloninstitute.org/calbenji-about), non-technical project summaries (http://www.faralloninstitute.org/calbenji-publications), and a blog (https://calbenjiproject.wordpress.com/2016/05/26/calbenji-project/) prepared by 2 undergraduate summer interns at Farallon Institute. Data have been made publically available for future use by other researchers, and we have applied new techniques in time series analysis to link climate and biology with potentially broad relevance to other ecosystems. The publically shared data associated with this project are linked at https://www.bco-dmo.org/project/564665. Last Modified: 01/16/2018 Submitted by: Ryan Rykaczewski