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Drought is a prominent feature of Hawaiʻi’s climate. However, it has been over 30 years since the last comprehensive meteorological drought analysis, and recent drying trends have emphasized the need to better understand drought dynamics and multi-sector effects in Hawaiʻi. Here, we provide a comprehensive synthesis of past drought effects in Hawaiʻi that we integrate with geospatial analysis of drought characteristics using a newly developed 100-year (1920–2019) gridded Standardized Precipitation Index (SPI) dataset. The synthesis examines past droughts classified into five categories: Meteorological, agricultural, hydrological, ecological, and socioeconomic drought. Results show that drought duration and magnitude have increased significantly, consistent with trends found in other Pacific Islands. We found that most droughts were associated with El Niño events, and the two worst droughts of the past century were multi-year events occurring in 1998–2002 and 2007–2014. The former event was most severe on the islands of O’ahu and Kaua’i while the latter event was most severe on Hawaiʻi Island. Within islands, we found different spatial patterns depending on leeward versus windward contrasts. Droughts have resulted in over $80 million in agricultural relief since 1996 and have increased wildfire risk, especially during El Niño years. In addition to providing the historical context needed to better understand future drought projections and to develop effective policies and management strategies to protect natural, cultural, hydrological, and agricultural resources, this work provides a framework for conducting drought analyses in other tropical island systems, especially those with a complex topography and strong climatic gradients.

Climate change is impacting public health in the Republic of the Marshall Islands (RMI). Meanwhile, migration within the RMI and abroad is driven, in part, by access to better healthcare, and migration is also expected to be accelerated by climate change. Based on a survey of 199 RMI households, this study used logistic regression and hierarchical clustering to analyze the relationships between climate stressors, climate-related health impacts, and migration outcomes and identify vulnerable segments of the population. Climate stressors were experienced by all respondents but no significant correlations were found between stressors, health impacts, and expectation to migrate. When grouped according to the climate stressors they faced, however, one group was characterized by low stressors, high wealth, and a low expectation to migrate, whereas another experienced very high climate stressors, low wealth, and a high expectation to migrate. Only the first exhibited a statistically significant relationship between climate-related health impacts and migration; however, for the second, climate stressors were significantly related to proximate determinants of health, and there was no association with migration. To create equitable adaptation outcomes across diverse society, policies should expand economic and education prospects and reduce vulnerability to the direct and indirect health impacts of climate change. Graphical Abstract Households that were surveyed in the Marshall Islands have experienced many climate stressors and direct impacts to health, as well as the determinants of health, in recent years.

Groundwater sustainability initiatives, including sustainable yield and watershed policy protection policies, are growing globally in response to increasing demand for groundwater, coupled with concerns about the effects of climate and land-cover change on groundwater supply. Improved understanding of the impacts of watershed management on groundwater yields and management costs—particularly in the broader context of climate and land-cover change—is critical to inform these initiatives and facilitate integrated land and water management. This study develops a novel, spatially explicit groundwater hydrologic ecosystem services framework, which combines stakeholder-defined land-cover scenarios, sustainable yield estimation using a groundwater simulation optimization approach, and economic valuation, and applies it in the most heavily utilized aquifer Hawai‘i (USA). Sustainable yield estimates and resulting differences in replacement costs are estimated for six land-cover scenarios (with varying levels of urban development and watershed management) crossed with two water demand scenarios in a context of a dry future climate (Representative Concentration Pathway [RCP] 8.5 mid-century). Land-cover change is found to be an important, though less significant drive of changes in groundwater recharge than climate change. The degree of watershed protection, through preventing the spread of high-water-use, invasive plant species, is projected to be a much stronger land-cover signal than urban development. Specifically, full forest protection increases sustainable yield by 7–11% (30–45 million liters per day) and substantially decreases treatment costs compared with no forest protection. Collectively, this study demonstrates the hydrologic and economic value of watershed protection in a context of a dry future climate, providing insights for integrated land and water policy and management in Hawai‘i and other regions, particularly where species invasions threaten source watersheds.

Drought is a prominent feature of Hawaiʻi’s climate. However, it has been over 30 years since the last comprehensive meteorological drought analysis, and recent drying trends have emphasized the need to better understand drought dynamics and multi-sector effects in Hawaiʻi. Here, we provide a comprehensive synthesis of past drought effects in Hawaiʻi that we integrate with geospatial analysis of drought characteristics using a newly developed 100-year (1920–2019) gridded Standardized Precipitation Index (SPI) dataset. The synthesis examines past droughts classified into five categories: Meteorological, agricultural, hydrological, ecological, and socioeconomic drought. Results show that drought duration and magnitude have increased significantly, consistent with trends found in other Pacific Islands. We found that most droughts were associated with El Niño events, and the two worst droughts of the past century were multi-year events occurring in 1998–2002 and 2007–2014. The former event was most severe on the islands of O’ahu and Kaua’i while the latter event was most severe on Hawaiʻi Island. Within islands, we found different spatial patterns depending on leeward versus windward contrasts. Droughts have resulted in over $80 million in agricultural relief since 1996 and have increased wildfire risk, especially during El Niño years. In addition to providing the historical context needed to better understand future drought projections and to develop effective policies and management strategies to protect natural, cultural, hydrological, and agricultural resources, this work provides a framework for conducting drought analyses in other tropical island systems, especially those with a complex topography and strong climatic gradients.

Drought is a prominent feature of Hawaii's climate, however, the biological, ecological, cultural, and socioeconomic impacts of drought in Hawaii are not well understood. This paper provides a comp...

This chapter assessed the drivers of land use/land cover change and describes observed transitions in Hawaiʻi (USA), using the island of Maui as a case study. Over the last half-century, Maui has experienced periods of intensive agriculture, rapid urban development, population migration, and environmental change. To better understand landscape-level change on Maui, this chapter compared the available land cover products and quantified the spatial transitions between them. Between 1976 and the early 2000s, all products showed that agricultural land cover declined significantly (losses of 46–63%), built-up area expanded (gains of 105–273%), and grassland and bare land cover also increased (gains of 113–196%, and 46–137%, respectively). These transitions reflected documented shifts in Maui land management and environmental change over the past 40 years, but poor Kappa scores (from 0.47 to 0.62) highlighted the spatial disagreement between the different classifications. Furthermore, when each classification was examined individually, only the NOAA Coastal Change Analysis Program (C-CAP) product adequately reflected the more recent changes of the last 10–20 years. Based on this assessment, the NOAA C-CAP product is the recommended existing tool for analyzing spatial change in Hawaiʻi. It was designed with ecosystems management and change detection in mind and is the only high-resolution, internally-consistent product that is updated at regular intervals. Newer high-resolution imagery and ancillary spatial data on the drivers of change will provide opportunities to refine existing products and generate more recent information for tracking land cover change in Hawaiʻi.

Study region Oceania, South Pacific, Polynesia. Study Focus Changing climates have the potential to significantly impact global water resources availability. On many volcanic islands, groundwater is the primary drinking water source, thereby making it essential to manage this limited resource carefully. In this study, we developed high temporal and spatial resolution groundwater recharge estimates for the Island of Tutuila, American Samoa using the Soil Water-Balance-2 (SWB2) model. Additionally, we predicted future recharge by running the calibrated model with combinations of dynamically downscaled general circulation climate model (GCM) predictions, and future land-cover scenarios developed collectively with local stakeholder groups. New hydrological insights Present-day results indicate 57 % of Tutuila’s rainfall becomes groundwater recharge, 8 % evaporates from the canopy, 15 % evapotranspires, and 20 % discharges as stormflow-runoff. Future climate scenarios suggest recharge may increase by 8 % or 14 % depending on global emissions. Land-cover was a less significant driver of hydrologic change, although increases in impervious surfaces showed a negative impact on recharge. This work is maintained as an active open-source project on GitHub, the world’s leading software development platform, thereby enhancing transparency, reproducibility, and participation from stakeholders and managers in American Samoa. This study is the first of its kind from a location within the South Pacific Convergence Zone, and provides insights into how human activities on global and local levels affect the future sustainability of essential resources.

Novel methods for combining physical and social science research programs can integrate traditional research methods, stakeholder engagement, and environmental management. This chapter applies a participatory remote sensing approach to evaluate stakeholder perceptions of the presence of invasive plant species on Isabela Island, in the Galapagos Islands of Ecuador. An exercise on classification and change detection was carried out with agricultural landowners and employees of the Galapagos National Park Service, using photographs of different types of land cover commonly observed in the highland agricultural zone and surrounding National Park. Photos corresponded to GPS-validated locations within the spatial footprint of high-resolution satellite images from 2004 to 2010. Stakeholder classifications of remotely sensed imagery reveal competing accounts of the makeup of the land, with a high level of disagreement between the two (kappa = 0.39). An analysis of “shared” guava coverage and other introduced vegetation highlights key regions of agreement and divergence in land cover, land change, and land use—especially along the boundary between the farmland and the National Park. Change detection of landowner classifications showed a 19% decrease in guava within the National Park between 2004 and 2010, while the National Park Service employees perceived a 62% increase in the same region. Stakeholder perceptions of the Isabela highlands also differ qualitatively, where current environmental management initiatives focused on the consequences, rather than the causes, of species invasion. The results of this study provide compelling arguments for using participatory research methods as a tool to directly engage stakeholders in the research process and reconcile visions of productivity or degradation in shared spaces for conservation and economic activities.

This project developed an integrated land cover/hydrological modeling framework using remote sensing and geographic information systems (GIS) data, stakeholder input, climate information and projections, and empirical data to estimate future groundwater recharge on the Island of Maui, Hawaiʻi, USA. End-of-century mean annual groundwater recharge was estimated under four future land cover scenarios: Future 1 (conservation-focused), Future 2 (status-quo), Future 3 (development-focused), and Future 4 (balanced conservation and development), and two downscaled climate projections: a coupled model intercomparison project (CMIP) phase 5 (CMIP5) representative concentration pathway (RCP) 8.5 “dry climate” future and a CMIP3 A1B “wet climate” future. Results were compared to recharge estimated using the 2017 baseline land cover to understand how changing land management and climate could influence groundwater recharge. Estimated recharge increased island-wide under all future land cover and climate combinations and was dominated by specific land cover transitions. For the dry future climate, recharge for land cover Futures 1 to 4 increased by 12%, 0.7%, 0.01%, and 11% relative to 2017 land cover conditions, respectively. Corresponding increases under the wet future climate were 10%, 0.9%, 0.6%, and 9.3%. Conversion from fallow/grassland to diversified agriculture increased irrigation, and therefore recharge. Above the cloud zone (610 m), conversion from grassland to native or alien forest led to increased fog interception, which increased recharge. The greatest changes to recharge occurred in Futures 1 and 4 in areas where irrigation increased, and where forest expanded within the cloud zone. Furthermore, new future urban expansion is currently slated for coastal areas that are already water-stressed and had low recharge projections. This study demonstrated that a spatially-explicit scenario planning process and modeling framework can communicate the possible consequences and tradeoffs of land cover change under a changing climate, and the outputs from this study serve as relevant tools for landscape-level management and interventions.

This article focuses on two innovative approaches to teaching human–environment interactions and international engagement in geography: (1) utilization of an agent-based model (ABM) at undergraduate levels to explicitly demonstrate complexity theories, and (2) implementation of a teaching experiment that connects students simultaneously enrolled in companion courses in North Carolina and in the Galapagos Islands through various multimedia and synthetic approaches to enrich a case study of conservation challenges to a World Heritage Site. Spatial simulation models are used to complement integrative geographic learning, to demand higher order skills of students and build critical thinking in college classes.

We conducted a time series analysis using the Moderate Resolution Imaging Spectroradiometer MODIS satellite data product over the Alcedo volcano region of Isabela Island in the Galapagos to determine vegetation changes before, during, and after a feral goat invasion and eradication project. Enhanced vegetation index EVI values for the Alcedo region of Isabela Island were analysed from 2000 to 2010 with respect to the presence of a large population of goats that was eradicated between 2004 and 2006. This study finds large-scale, seasonal vegetation pattern changes between 2000 and 2005, and 2005 and 2010. Statistically significant EVI decreases prior to and during eradication in zones where goats were present in high numbers and increases following eradication in zones with lower goat density are found. EVI appears to have changed little over the entire study period, though earlier imagery would likely reveal stronger positive post-eradication trends. Because EVI primarily reveals greenness and little about vegetation composition and structure, we find that long-term in situ vegetation monitoring is also needed to obtain a meaningful assessment of the effects of invasion and eradication at the species level.

This study investigates the community of Puerto Villamil, located on Isabela Island in the western portion of the Galapagos archipelago. Urban development and humanenvironment interactions are examined through a geographic information science perspective by (1) constructing a time-series of aerial photographs and satellite images, (2) mapping the current water and sewage infrastructure in the community using GPS and digitized analog maps, (3) assessment of the current urban setting within the context of community growth, with special reference to water quality measures at locations within and adjacent to the community, interviews and focus group discussions with health officials and local residents about water-borne disease and human health, and an analysis of the proximity of the community and its water and sewage infrastructure to the surrounding environment.

Analysis of marine and coastal systems is of fundamental importance to environmental scientists, engineers, and managers. Since the 1960s, remote sensing has played an important role in characterizing the marine environment, with particular emphasis on sea surface features, temperature, and salinity; mapping of shorelines, wetlands, and coral reefs; local fisheries and species movements; tracking hurricanes, earthquakes, and coastal flooding; and changes in coastal upwelling and marine productivity. This chapter reviews marine applications of remote sensing worldwide, exploring contemporary satellite systems, research themes, and analytical methods. In the Galapagos Islands of Ecuador, marine remote sensing has been limited to the use of large-scale daily image-gathering systems, such as CZCS, MODIS, SeaWiFS, and AVHRR, due to persistent cloud cover and constrained research budgets. Recent advances in satellite technology and availability, however, offer new opportunities for remote sensing in the Galapagos archipelago and beyond. Moderate-resolution sensors like SPOT and Landsat continue to be relevant for regional-scale evaluations of marine and coastal environments, identifying hotspots or focal areas for the use of more fine-grained imagery like QuickBird, WorldView-2, and aerial photographs. Radar systems like Aquarius and SAR show promise in new lines of oceanographic research, including sea surface salinity and the differentiation of mangrove subspecies. The use of ancillary or in situ data for calibration and validation of remotely-sensed image analysis can overcome the limitations of sensors used in bathymetric applications, while advances in cellular and GPS technology facilitate real-time reporting from citizen scientists for integrated monitoring of environmental and social change.

This chapter examines the social sustainability of the tourism industry in Galapagos critically, from its inception in the 1960s, dominated by live-aboard cruises, to the present day as island-based touring has gained momentum over the “floating hotel” cruise ship model. While the economic and environmental implications of this shift have been described, the industry’s social and cultural effects have rarely been considered. In particular, how today’s residents of the archipelago are engaged in the tourism industry, and who controls and benefits from those engagements, are at the heart of this inquiry. Based on research conducted in the islands between 2007 and 2010, this chapter uses cluster analysis of a large survey of Galapagos residents to identify social and demographic characteristics that are conducive to supporting particular types of development and conservation. Responses to economic restrictions or perceived lack of opportunities are investigated through cases of illicit environmental behavior. Finally, the benefits and costs of the current tourism model are considered in the context of long-term management and social sustainability. In the absence of meaningful regulations, the industry’s unprecedented growth in recent years has exacerbated social stratification within the resident population, leading to individual acts of resistance against regulations which, along with a lack of regulation, increases the potential for irreversible environmental impacts.

The climate science community of professionals in Hawai’i and the U.S.-Affiliated Pacific Islands is a vast interdisciplinary and international group, with the potential for spatial and sectoral barriers to communication and collaboration. This study sought to (1) assess the structural nature and expanse of climate-based communication between professionals across sectors in the Pacific Islands region; (2) identify key regional hubs and isolated groups both sectorally and spatially; and, (3) create a set of place-based tools that would increase and facilitate the connectedness of climate change resources (human, research, and adaptation). Social network analysis was chosen as a versatile method to assess the network and create free tools to facilitate future collaborations among stakeholders across spatial and disciplinary boundaries. Given the complexities of the large network, an innovative approach was used for data collection, blending a nominalist (researcher-created list of names) and realist (participant-created list in open fields) survey construction. Participants indicated frequency of communication to capture both active coworkers and periodic collaborators, consistent with the realities of the network. Survey participation was not confidential and was used to create region-wide and sub-regional maps that can be used by stakeholders to increase connectedness, in line with use-inspired science. Study results reveal a simultaneously diffuse and strongly connected network, with no isolated spatial or sectoral groups. The most central network members are those with a strong networking component to their professions. Gaps in communication were also revealed. Future research should evaluate the use and long term benefits of the created networking tools, and the specific nature of local and international communications within each sub-network.