Description
- Abstract:
- Understanding the characteristics and drivers of climate variations is imperative to advancing our knowledge about the evolution and changes of the Earth system. The Holocene is an ideal period to study climate variations on decadal to millennial timescales because of the relatively similar climate mean state compared to the present and the relatively well constrained boundary conditions compared to earlier periods. Although analyses on proxy records and climate models have shed new insights about Holocene climate change, there remain challenges in interpreting proxy records, supplementing regions with sparse proxy records, and synthesizing proxy records to understand the empirical spatiotemporal change of Holocene climate. In addition, we lack sufficient understanding of how proxy records and climate models inform current anthropogenic warming differently. By analyzing satellite observations of wind, sea surface temperature (SST), and chlorophyll in Baja California, we find that Ekman upwelling, the most common interpretation invoked in explaining SST variability in upwelling regions, is not the most important mechanism and that its importance depends on timescale. This underscores the importance of timescale in proxy interpretation. We then reconstructed past surface ocean conditions in the Northeast Pacific using marine sediment cores. We find that the SST in the Northeast Pacific varies over space and time and that its evolution does not correspond to changes in productivity and latitudinally averaged temperature. To expand on implications of SST patterns, we synthesized Pacific SST and western North America (wNA) hydroclimate proxy records and compared the patterns with climate models. Our results highlight the connection between Pacific SST and wNA and emphasize the role of precession and carbon dioxide in driving climate change in this region. Lastly, we compared the time of emergence of warming between a paleoclimate reanalysis product with a climate model. We find that proxy records suggest that the influence from anthropogenically driven warming might be happening later than what climate models suggest because climate models have a stronger signal and a weaker noise. All these results together advance our understanding on proxy records and climate models and improve our knowledge about Holocene climate change.
- Notes:
- Thesis (Ph. D.)--Brown University, 2023
Citation
Cheung, Anson Hill-yu,
"Global and Pacific Temperature, Productivity, and Western North America Hydroclimate Change during the Holocene"
(2023).
Earth, Environmental and Planetary Sciences Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://repository.library.brown.edu/studio/item/bdr:2qprp6s9/
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Earth, Environmental and Planetary Sciences Theses and Dissertations
Theses and Dissertations for the Earth, Environmental and Planetary Sciences department....