A Century of Drought in Hawaiʻi: Geospatial Analysis and Synthesis across Hydrological, Ecological, and Socioeconomic Scales

Abstract

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-Induced Forest Mortality in the Tropical Pacific Islands: What Do We Really Know?

“…Widespread warming has had a subsequent impact on the availability of water. Frazier and Giambelluca (2017) showed that Hawaiian Islands became increasingly drier between 1920 and 2012, a trend that was already noted by Doty (1982) and has continued in the state (Madson et al 2023), particularly during ENSO events (Frazier et al 2022). A similar pattern was documented by McGree et al (2016) throughout the Pacific Islands and northeast Australia, where the frequency, magnitude, and duration of drought events were revealed to be increasing.…”

‘Ōhi‘a Lehua (Metrosideros polymorpha): A Most Resilient and Persistent Foundation Species in Hawaiian Forests

“…The current trend of increasing drought conditions across the state, driven by climte change, has also resulted in expanded encroachment of fires into mesic native forests that were previously less affected by fire events (Barton et al 2021, Frazier et al 2022). Predictive climate change models indicate a likely increase in the risk of fire affecting ‘ōhi‘a-dominated forests in the future (Trauernicht 2019).…”

Cap. 30. Hawái y las Islas del Pacífico Afiliadas a los Estados Unidos. En: La Quinta Evaluación Nacional del Clima

“…Las proyecciones para finales de siglo indican un aumento de las temperaturas de hasta 4.5 °F (2.5 °C) en las zonas elevadas (por encima de 9,800 pies) en un escenario intermedio (RCP4.5) y de hasta 9 °F (5 °C) en un escenario muy alto (RCP8.5) 47 . Las tendencias históricas de las precipitaciones son variables en toda la región y en algunas islas se observa aridez prolongada y aumento de la frecuencia, la severidad y la duración de las sequías (KM 4.1) 48,49,50 . La magnitud y la dirección de los cambios proyectados en las precipitaciones son actualmente muy inciertas (Figura 30.3); se proyecta que algunas zonas se sequen (p.…”

“…También es probable que se vean afectados los cultivos comerciales: el aumento de las temperaturas y de los patógenos de las plantas disminuirá el rendimiento del café, el aumento de las inundaciones reducirá el rendimiento del azúcar y el aumento de los vientos dañará las palmas de coco, las bananas y el árbol del pan 191 . En Hawái, las sequías se han hecho más largas y severas y son la principal causa de pérdida de cosechas 49 .…”

“…Se proyecta que el aumento de eventos de inundaciones costeras y la sequía impacten negativamente los ingresos agrícolas (KM 30.1). Por ejemplo, entre 2008 y 2016, Hawái perdió aproximadamente $53.5 millones (en dólares de 2022) en producción ganadera debido a la sequía más severa registrada, y los programas federales de seguros de cosechas pagaron $11.2 millones (en dólares de 2022) a los agricultores por las pérdidas causadas por la sequía durante 1996-2018, principalmente por las nueces de macadamia y el café 49 .…”