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08. Management Plans and Climate Change

How does one incorporate climate change into a protected area management plan?  Incorporating climate change components into protected area planning is a relatively new field and for some practitioners has not been considered in management planning or implementation. Below is an excerpt from the management plan for the Keālia National Wildlife Refuge, Hawai'i that addresses climate change.

Global Climate Changes and Projections

Global climate change is supported by a continuously growing body of unequivocal scientific evidence. The Intergovernmental Panel on Climate Change (IPCC) is a scientific intergovernmental body organized by the World Meteorological Organization and the United Nations Environment Programme in order to assess the causes, impacts, and response strategies to changes in climatic conditions. According to the Fourth Assessment Report by the IPCC, global temperatures on the Earth’s surface have increased by 1.33° F over the last 100 years. This warming trend has accelerated within the last 50 years, increasing by 0.23° F each decade. Global ocean temperatures to a depth of almost 2,300-feet have also increased, rising by 0.18° F 1961-2003 (Solomon et al. 2007).

Global forecasting models offer a variety of predictions based on different emission scenarios. The U.S. Government agency, Overseas Private Investment Corporation (OPIC), suggests that a further increase in greenhouse gas (GHG) emissions could double atmospheric concentrations of CO2 by 2060 and subsequently increase temperatures by as much as 2-6.5° F over the next century. Recent model experiments by the IPCC show that if GHG and other emissions remain at 2000 levels, a further global average temperature warming of about 0.18° F per decade is expected. Sea level rise (SLR) is expected to accelerate by two to five times the current rates due to both ocean thermal expansion and the melting of glaciers and polar ice caps. Recent modeling projects sea level to rise 0.59-1.93 feet by the end of the 21st century. These changes may lead to more severe weather, shifts in ocean circulation (currents, upwelling), as well as adverse impacts to economies and human health. The extent and ultimate impact these changes will have on Earth’s environment remains under considerable debate (OPIC 2000, Buddemeier et al. 2004, Solomon et al. 2007, IPCC 2007).

Climate Change in Hawai‘i

Climate change impacts expected for Hawai‘i are warmer temperatures (air and ocean), more severe droughts and floods, and a rise in sea levels. Giambelluca et al. (2008) reported that air temperatures in Hawai‘i have increased at a rate of 0.3° F/decade since 1975, which is comparable to the rate of increase in global temperatures. Temperature observations at the Mauna Loa Observatory 1977-2006 indicate a warming trend of 0.4° F/decade. Rainfall intensity has increased 12 percent in Hawai‘i between 1958-2006 but total rainfall has decreased about 15 percent over the last 20 years. These changes have and will continue to affect biologic and water resources on Maui and the other islands (Mimura et al. 2007, Oki 2004, Chu and Chen 2005, Turcotte and Malamud 2009, Fletcher 2010).

The Service is supporting the development of regional Landscape Conservation Cooperatives that will integrate local climate models with models of climate-change responses by species, habitats, and ecosystems. The local version of these Landscape Conservation Cooperatives is the Pacific Islands Climate Change Cooperative (PICCC), headquartered in Honolulu, but working across the Pacific. The PICCC was established in 2010 to assist those who manage native species, island ecosystems, and key cultural resources in adapting their management to climate change for the continuing benefit of the people of the Pacific Islands. The PICCC steering committee consists of more than 25 Federal, State, private, indigenous, and nongovernmental conservation organizations and academic institutions, forming a cooperative partnership that determines the overall organizational vision, mission, and goals.

Similar to the rest of the world, temperatures in Hawai‘i are rising. The EPA has estimated that the average surface temperature in Honolulu has increased by 4.4° F over the last century. In particular, nighttime temperatures are notably warmer, increasing by about 0.5° F per decade over the past 30 years. Recent studies have shown that this rising average night temperature is greater at high elevation sites than lower areas. Sea surface temperature near the islands has been increasing recently, showing a 0.72° F rise from 1957-1987. Sea level around the Hawaiian Islands is rising by 6-14 inches per century. Over the last 90 years, precipitation has also decreased approximately 20 percent (EPA 1998, Arakawa 2008, Giambelluca 2008).

Global and regional predictive climate simulations may not capture unique and important features of the Hawaiian climate. Existing large-scale models show large variability and uncertainty for the Hawaiian Islands; thus, applying these models to predict local conditions must be done with caution until more fine-scaled models are developed. Models from the IPCC and United Kingdom Hadley Centre’s climate model suggested that by 2100 annual temperatures in Hawai‘i could increase by 3° F, with a slightly higher increase in fall. Other estimates predict a 5-9° F rise by the end of the 21st century. Future changes in precipitation are uncertain, dependent largely on shifts in El Niño/La Niña events. Some predictions forecast an additional rise of 17-25 inches by 2100, while others suggested decreased precipitation. The trend in precipitation at the Refuge, shown in Figure 3.2, has been decreasing since 1950.  The temperatures, as shown in Figure 3.3, have been on a slight rise since 1950 (TenBruggencate 2007, Timm 2008).

Long-term climate change may be increasing temperature and reducing precipitation, groundwater recharge, and streamflow in Hawai‘i for extended periods. Oki (2004) looked at long-term trends in streamflow from 1913-2004 for seven streams in Hawai‘i, including three on Maui, that 1) had data available, 2) were free of upstream regulation or diversion, and 3) represented a variety of physical and climatological characteristics. He reported statistically significant declines in baseflow in all seven streams but a statistically significant decline in total annual flow in only one of the streams. These baseflow declines are consistent with a long-term downward trend in rainfall observed over much of the State during that same period and may reflect a decrease in groundwater storage and recharge. However, the author states that detection of the trends was dependent on the period of record considered. He says that the downward trends may just reflect higher than average baseflows from 1913 to the 1940s, followed by a period with little or no trend in baseflows.

 

Sea Level Rise

According to the IPCC, the oceans are now absorbing more than 80 percent of the heat added to the Earth’s climate system. Since 1961, this absorption has caused average global ocean temperatures to increase and seawater to expand. Thermal expansion of the sea is the primary cause of global sea level changes. Melting ice-sheets, ice caps, and alpine glaciers also influence ocean levels. Worldwide, sea level changes have historically occurred on a small scale; however, scientific evidence suggests that the current, accelerated rate of global change began between the mid-1800s and 1900s. Similarly, sea levels in the Pacific have regularly changed over the centuries due to variations in solar radiation. Since 1800, sea levels in the Pacific region have been rising. During the last century, these levels have risen about 6 inches and this is likely to rapidly increase in the next century (Noye and Grzechnik 2001, GAO 2007).

Due to localized geographic and oceanographic variations, it is not possible to discuss SLR on a global scale. Near Pacific Island ecosystems, SLR is influenced by the rate and extent of global sea level rise, as well as changes in episodic events, such as the El Niño Southern Oscillation (ENSO) and storm-related conditions. Topography and exposure to normal and storm swell produce localized differences. Furthermore, it is important to note that shoreline sea levels are historically and currently influenced by isostatic tectonic changes as the islands move with the Pacific Plate, which are not due to global changes in sea level. Thus, sea level change in the Pacific is highly variable due to geologic uplift (Michener et al. 1997, Carter et al 2001).

Sea level rise is expected to exacerbate inundation, storm surge, erosion, and other coastal hazards. Currently, ocean waters only occasionally reach Main Pond during high tides with large waves. The frequency of these events will likely increase due to SLR. It is also likely that Mā‘alaea Beach may be more prone to erosion which may threaten habitat and infrastructure in the area.

In an effort to address the potential effects of sea level changes on national wildlife refuges, the Service contracted the application of the Sea Level Affects Marshes Model (SLAMM) 6 for several Pacific Region Refuges. This analysis is designed to assist in development of long-term management plans. The SLAMM model predictions for Keālia Pond NWR suggest that inland inundation within this Refuge will occur given SLR scenarios below 3 feet (eustatic). It is in the 3-feet scenario that rising waters begin to have an impact on the main part of the Refuge. The dry land (and beaches) between the Main Pond and the ocean, which acts as a natural impoundment against inundation, becomes heavily eroded in higher scenarios.

There is little or no tidal influence within the Refuge, however, after 3 feet of SLR salt water is predicted to move beyond the road barrier. Within this SLAMM application, a connectivity algorithm was used to determine when floodwaters are predicted to penetrate beyond the road resulting in more frequent flooding and salinity changes within the Refuge. Under the highest SLR scenarios, N. Kīhei Rd. is predicted to be regularly flooded and convert to ocean beach or open water if left as is without human intervention.

There is always uncertainty about how regularly flooded wetlands will respond to SLR. The most important effects of SLR at Main Pond and Māalaea Flats are the gradual inundation and flooding of historic wetlands and dryland areas, as well as increases in the salinity of wetlands. Salinity alterations have the potential to shift aquatic plants and animal communities that do not tolerate high salinity. Higher sea levels may inundate these low-lying land areas, potentially helping Refuge personnel to reclaim/restore former wetland areas for endangered waterbirds.

 

Ecological Responses to Climate Change

Evidence suggests that recent climatic changes have affected a broad range of individual species and populations in both the marine and terrestrial environment. Organisms have responded by changes in phenology (timing of seasonal activities) and physiology; range and distribution; community composition and interaction; and ecosystem structure and dynamics. The reproductive physiology and population dynamics of amphibians and reptiles are highly influenced by environmental conditions such as temperature and humidity. For example, sea turtle sex is determined by the temperature of the nest environment; thus, higher temperatures could result in a higher female to male ratio. In addition, increases in atmospheric temperatures during seabird nesting seasons will also have an effect on seabirds and waterbirds (Duffy 1993, Walther et al. 2002, Baker et al. 2006).

Changes in ocean temperature, circulation, and storm surge due to climate change will impact seabird breeding and foraging. The ENSO has been shown to cause seabirds to abandon habitats, nest sites, and foraging areas for colder/warmer waters. Studies have found that nesting success is reduced for some species during this climatic event. Oceanographic changes associated with ENSO may also increase or decrease food supply for seabirds and subsequently impact populations that forage offshore. Shifts in marine temperature, salinity, turbidity, currents, depth, and nutrients will have an impact on seabird and waterbird prey composition and availability. Although these potential changes may impact seabirds throughout the Hawaiian Islands, contrary evidence suggests that seabirds may have coped with and evolved around climatic changes in the past (Duffy 1993).

Warming has also caused species to shift toward the poles or higher altitudes and changes in climatic conditions can alter community composition. For example, increases in nitrogen (N) availability can favor those plant species that respond to N rises. Similarly, increases in CO2 levels can impact plant photosynthetic rates, decrease nutrient levels, and lower herbivore weights. Although there is uncertainty regarding these trajectories, it is probable that there will be ecological consequences (Vitousek 1994, Walther et al. 2002, Ehleringer et al. 2002).

Climate change has the potential to influence two important ecological issues in the State of Hawai‘i: endangered species and pest species. The majority of U.S. endangered species are found in the State of Hawai‘i. Species declines have resulted from habitat loss, introduced diseases, and impacts from pest species. Changes in climate will add an additional threat to the survival of these species. For example, warmer night temperatures can increase the rate of respiration for native vegetation, resulting in greater competition from pest plants. Furthermore, climate change may enhance existing pest species issues because alterations in the environment may increase the dispersal ability of flora or fauna. Species response to climate change will depend on the life history, distribution, dispersal ability, and reproduction requirements of the species (DBEDT and DOH 1998, Middleton 2006, Giambelluca 2008).

Climate Change at Keālia Pond NWR

Most of the anticipated climate change impacts at Keālia Pond NWR involve water supply and water quality. Tributary streams that flow into Main Pond originate in the West Maui Mountains, which is one of the wettest places in the world. Hydrologic conditions at Main Pond are largely dependent on streamflow inputs, which can be highly variable from year to year and are affected by climatic conditions and upstream regulation. Both short-term interannual climate variability and long-term decadal variability affect streamflows on Maui and the other islands. Many of the droughts in Hawai‘i are related to El Niño events, which are associated with drier than normal winters. The PDO also influences Hawaiian climate. The pattern of ocean-atmosphere variability associated with ENSO phenomenon occurs on a relatively short time scale of 1 to several years while the PDO is a longer term phenomenon occurring over 1 to several decades. Rainfall and streamflow tends to be low in winter during El Niño periods and high during La Niňa periods, especially during positive (warm) phases of the PDO. Temperature may be affected by PDO phases too. A number of studies suggest that climate change could be a major factor in accentuating the current climate regimes and the changes from normal that come with ENSO events (Mimura et al. 2007, Oki 2004).

It is difficult to assess the relative threat of long-term changes in rainfall and runoff to the Main Pond. Certainly declines in rainfall and runoff, including baseflow, would affect the water supply for the Pond. Warmer air temperatures may mean warmer water temperatures, decreased dissolved oxygen (DO), and greater evaporation. Nuisance issues of blowing dust and fish kills may also be expected to be more common. Presently, the water level record at Main Pond is not long enough to assess whether or not the frequency of dry conditions has already increased in response to warmer temperatures, increasing evaporation, and decreasing precipitation. However, any gradual, long-term changes in rainfall and stream inflow may be overshadowed by more immediate and direct changes in upstream regulation and diversion and land management practices. As will be discussed below, such changes have the potential to greatly modify Pond hydrology and ecology.

More severe flooding would also affect the Main Pond in a number of ways. They may increase the frequency or severity of disturbance in the Pond and may also increase sediment loads reaching the Pond, which could affect water quality and Pond bathymetry. More severe flooding would also underscore the hydrologic function of the Main Pond with respect to ameliorating flooding and runoff to the ocean. The Main Pond is valuable for retaining storm water and reducing the velocity of flood waters. This wetland minimizes flooding of N. Kihei Rd., protecting the road as well as allowing through-traffic during most rain storms.

The Pond and surrounding area act as a buffer, capturing flood waters and holding them before they move into the ocean (either as surface flow or subsurface seepage). The wetland also protects the adjacent beach and offshore coral reef ecosystem from deleterious effects of erosion, sedimentation, and eutrophication associated with flood waters.

Most of the islands of the northwestern end of the Hawaiian archipelago are low sand and coral islands. A foot of SLR could inundate much of the dry land of the NWHI and high islets such as Molokini will have high value for seabirds in search of new protected nesting areas above water.

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