A cross-disciplinary collaboration
This project is a collaboration between Rosie Alegado (Oceanography/Sea Grant), Axel Timmermann (Oceanography/Interactional Pacific Research Center) and Puakea Nogelmeier (Kawaihuelani Center for Hawaiian Language). As Hawai’i population grows, so too does the demand for freshwater. Understanding the forces that shape natural variability in rainfall from year to year can be vital for long-range water resources planning and management. Our long-term goal is to use indigenous-based historical records to reconstruct Hawaiian regional climate beyond the instrumental records.
Hawaiian language newspapers are a rich repository of historical data
Focusing on Hawaiian language newspapers presents an unparalleled opportunity to query an archive of indigenous knowledge for climate data and related topics. Spanning from 1834 – 1949, Native Hawaiian intellectuals, political and religious leaders, historians, cultural specialists and everyday kānaka (people) filled the pages of nearly one hundred different newspapers with over 125,000 pages of testimony about their lives, their lands, their lāhui (nation) and their environment. These contributors to the historical record were often making a distinct and purposeful documentation of their lives and beliefs, and the lives and beliefs of their kūpuna (ancestors), for the benefit of their mo‘opuna (descendants). As disease epidemics decimated the indigenous population, traditional knowledge concerning fishing, navigation, canoe carving and other skills, as well as epics of renowned warriors and legendary chiefs were shared in order to provide an intergenerational link to this information. Thus, these primary source materials have the potential to relay not only data about the state of the environment and indigenous resource management of that period, but function as repositories of much more ancient deep ancestral knowledge that may reach back over multiple centuries. Hawaiian language newspapers likely represent the richest holding of indigenous knowledge in the United States.
El Nino Southern Oscillation: a case study of long term climate patterns in the Hawaiian historical record
What is the El Nino Southern Oscillation?
One long-term climate pattern that can have significant impacts on inter-annual rainfall is the El Niño Southern Oscillation (ENSO). ENSO is a global climate mode characterized by variations in sea surface temperatures in the Eastern Tropical Pacific that modulates the magnitude of our local seasonal weather patterns (1) and changes large-scale ocean currents and atmospheric circulation patterns (2). For Hawai’i, El Niño events typically displace the subtropical jet stream, leading to decreased precipitation (3,4) in boreal winter (Fig. 1) and slightly enhanced rainfall in summer. In addition to causing changes in rainfall, ENSO may alter the frequency of extreme events such as flooding and tropical cyclone/hurricane activity (5,6) but these linkages are statistically less robust than for rainfall (4).
We assert that having a detailed understanding of the relationship between the dominant Pacific climate modes, such as ENSO and its flavors, the Pacific Decadal Oscillation (7) and the North Pacific Gyre Oscillation (8) and Hawai’i’s weather/climate and surrounding environment will have utility not only for water management, but also can inform policies on hazard resilience.
Assessing the impacts of ENSO and its potential secular changes on Hawai’i is hampered by the fact that periods of high and low ENSO activity are inherently unpredictable in the Pacific (9). Our current inability to determine changes in ENSO frequency, magnitude and duration derive from limitations in the reliability of our instrumental records, which extend back less than 150 years (10). The global observational record can be extended by reconstructing multi-century paleo-climates derived from annual tree rings, ice cores, lake sediments and coral records (11). Collectively, these proxies from diverse geographical locales reduce any biases or weakness in any individual proxy (10). Here we propose 2 complementary strategies to develop a deeper understanding of how climate modes, such as ENSO, affected regional climates in Hawai’i: introducing additional historical observations through Hawaiian language newspapers and developing climate indicators specific to Hawai’i using introduced and native tree species.
Our hypothesis: Native Hawaiians characterized regional weather and climate patterns, and that the underlying data can be analyzed to infer the behavior of large-scale Pacific climate modes such as ENSO.
This project draws upon the unequaled excellence of Native Hawaiians to kilo honua (observe processes related to the Earth), to characterize regional climate variability and its connection to large-scale drivers, a reasonable notion given that other indigenous cultures in the Pacific have incorporated ENSO-related phenomena into their cultural systems. For example, in Samoa, extended ENSO conditions are associated with “taimasa” a distinct odor emanating from reefs that have been exposed for long periods of time. Indeed, indigenous Peruvian fisherman coined the warm ocean current that always appeared around Christmas “El Niño” and it wasn’t until the 1960s that climatologists realized this was a global phenomenon.
Integrating the information preserved in Hawaiian language newspapers into our analyses simultaneously broadens and perpetuates these often overlooked source materials as part of the canon of Hawaiian resources (14) while validating the legitimacy of indigenous scientific knowledge and as a crucial component of contemporary scientific discourse. Though initial forays into the archives will focus on the period for which we have overlapping dendrological data, future studies will attempt to delve farther back in Hawaiian history through the interpretation of ʻōlelo noʻeau (proverbs), ʻoli (chants) and moʻokuauhau (epic genealogies), and moʻolelo kaʻao (legendary traditions).
This project brings together individuals with expertise in climate science and Hawaiian language to detail with high geographic spatial resolution indices across the Hawaiian Islands that correlate with ENSO and the other modes of North Pacific climate variability.
Dendrology can complement historical observations
We will also use dendrochronology to independently build a robust spatially-stratified climate archive of rainfall and primary productivity across Hawai’i. Trees native to tropical regions usually do no produce tree rings, however introduced conifers (e.g. Cook Island and Norfolk pines), which are broadly distributed across the state have easily visible and annual rings, can provide evidence for floods, droughts, insect attacks, lightening strikes that occurred during the lifespan of the tree. In addition to introduced trees, we will explore tree ring analysis in the following endemic trees in collaboration with Patrick Hart (UH Hilo): mamane (Sophora chrysophylla), naio (Myoporum sandwicense), akoko (Chamaesyce olowaluana) (12,13) which will enable even further climate reconstruction (Fig. 2).
We will integrate information from historic records and dendrochronology to reconstruct regional climate anomalies and identify links to large-scale patterns of climate variability.
Phase I: Develop a “fingerprint” of climatological parameters that correlate highly with large-scale climate modes, such as ENSO.
To enable targeted and efficient searches of the Hawaiian language newspaper archive, we will identify ~15 weather stations across the Hawaiian Islands. For each station, seasonally stratified precipitation and temperatures anomalies will be correlated with large-scale anomalies of Pacific sea surface temperature, rainfall, sea level pressure, winds and wind speed, and ocean currents using the KNMI Climate Explorer database (http://climexp.knmi.nl/), which accesses existing observational and atmosphere and ocean reanalysis datasets. We will also map the frequency of extreme events such as storms/hurricanes, flooding, drought, snowfall to these stations.
Phase II: Perform targeted queries of the Hawaiian language newspaper database.
Using data from Phase I, we will conduct keyword searches (e.g. Hilo/rainfall/winter or Honolulu/temperature/summer) of scanned Hawaiian language newspapers. This work will be supervised by co-PI Nogelmeier. Our objective here is two-fold. First, we will develop a lexicon of Hawaiian language terms/phrases describing ENSO and other climate phenomena. We hypothesize the following non-climate events may be associated anomalous climate situations: fish kills, recruitment of fish species, disease as indigenous Hawaiian knowledge of long-term climate patterns informed resource management. Finally, we will use Hawaiian language newspapers to refine our knowledge of historical ENSO events prior to 1850.
Phase III: Develop novel methods to analyze tree rings.
We have developed a simple Matlab program to extrapolate annual precipitation data from digital images of tree ring cores and slabs. This method facilitates rapid processing of samples. Moreover, because climate reconstructions may be possible with cores rather than whole tree slabs, the protocol is much less invasive and can be performed on living trees with multiple paired replicates. PIs Alegado and Timmermann will oversee field-sampling trips to neighbor islands to obtain core samples. Every effort will be made to identify the oldest known introduced conifers and endemic trees on each of the major Hawaiian Islands. Proper collection permits will be obtained as necessary. Hawaiian tree ring data will be compiled and synthesized with data from Hawaiian language newspapers in a holistic database of climatologic observations.
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