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John J. Marra

Abstract (from AGU100): The state of Hawaiʻi and city of Honolulu experienced an unprecedented number of minor flooding episodes during 2017 due to the combination of seasonal high tides and record‐high mean sea levels. To quantify the impact of sea level rise on the tendency for flooding events to cluster in future years, we developed a hierarchical statistical model describing the number of days per year for which sea level exceeds a prescribed threshold in Honolulu as a function of annual mean sea level and the amplitude of the highest tides. Based on this model, we generate probabilistic projections of exceedance days per year for the 21st century, which show pronounced inflections in the frequency of exceedance...
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Projecting the Frequency and Impact of Future Coastal Flooding and Inundation Events in the Pacific Islands
Increasing numbers of hazardous inundation events due to climate change is a serious threat to the culture, habitat, and infrastructure of the Hawaiian and U.S.-Affiliated Pacific Islands. The information currently available to stakeholders, however, is primarily confined to maximum or mean water level and does not include how often incursions are likely to occur. We propose to quantify the effect of local factors and Pacific climate variability on the frequency of inundation events in centers of population and infrastructure in Pacific island communities. We will produce seasonal outlooks that project the number of incursions above a given level at a particular site in 3-6 month windows. We choose seasonal outlooks,...
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Supporting a Collaborative Regional Assessment of Future Climate Impacts on Natural Resources in the Pacific Islands
In order to better document, manage, and adapt to the impacts of future climate variability and change on diverse natural resources in Hawaiʻi and the US Affiliated Pacific Islands (USAPI), several regional climate research programs including the Pacific RISA, the PICCC, the NOAA RCSD, and the East-West Center came together in 2011-2012 to collaboratively produce the Pacific Islands Regional Climate Assessment (PIRCA) (Keener, 2012) for the 2014 U.S. National Climate Assessment (NCA). Natural resource managers in sectors such as freshwater, coastal inundation and hazard response, and marine and terrestrial ecosystems need frequently updated summaries of regional and local climate trends, projections, and impacts...
Drought is a signifcant climate feature in Hawai‘i and the U.S.-Affliated Pacifc Islands (USAPI), at times causing severe impacts across multiple sectors. Below-average precipitation anomalies are often accompanied by higher-than-average temperatures and reduced cloud cover. The resulting higher insolation and evapotranspiration can exacerbate the effects of reduced rainfall. These altered meteorological conditions lead to less soil moisture. Depending on the persistence and severity of the conditions, drier soil can cause plant stress, affecting both agricultural and natural systems. Hydrological effects of drought include reductions in streamfow, groundwater recharge, and groundwater discharge to springs, streams,...
Abstract (from http://journals.ametsoc.org/doi/abs/10.1175/JAMC-D-16-0284.1): Sea level anomaly extremes impact tropical Pacific Ocean islands, often with too little warning to mitigate risks. With El Niño, such as the strong 2015/16 event, comes weaker trade winds and mean sea level drops exceeding 30 cm in the western Pacific that expose shallow-water ecosystems at low tides. Nearly opposite climate conditions accompany La Niña events, which cause sea level high stands (10–20 cm) and result in more frequent tide- and storm-related inundations that threaten coastlines. In the past, these effects have been exacerbated by decadal sea level variability, as well as continuing global sea level rise. Climate models,...
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