Climate Projections and Impacts

In line with the National Climate Change Policy for Climate and Disaster Resilient Low Emissions Development (2015), the Precautionary Principle applies and all GEF6 projects will take a "No Regrets" approach.

Source: Climate Change in Palau: Indicators and Considerations for Key Sectors - Pacific Islands Regional Climate Assessment (PIRCA 2020).

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Information on Climate Change projections came from the 2019 State of the Environment Report (2019 SOE)1 which compiled information from a wide variety of sources including the Coral Reef Research Foundation (CRRF), Palau International Coral Reef Center, PACCSAP (Pacific-Australia Climate Change Science and Adaptation Planning Program), the University of Hawaii Sea Level Center, and published studies. Information on expected impacts came from the PIRCA Climate Science Summary Update (2020)2 and published studies.

Air Temperature

Palau’s future climate projections indicate an increase of 0.7-1.7°F (0.4°C-1.0°C) of air temperature with increasing variability.

Human impacts:

Older persons, those with chronic diseases, and persons with disabilities may be more vulnerable to extreme heat days.
People who work outdoors (tour guides, farmers, construction workers, etc.) may be exposed to high heat days, both at a risk to their health and with potential loss of productivity.
Children in schools without air conditioning may suffer heat-related loss of learning.
Economic losses from crop losses may occur.
Economic costs and carbon emissions associated with cooling and air conditioning may increase.
Warming may increase the activity of disease vectors, such as dengue-carrying mosquitos.
Hotter days will increase water demand.

Environmental impacts:

Increasing temperature is associated with increased incidence of plant diseases and increased likelihood of pests, including in staple crops such as bananas.
Higher temperatures will increase evapotranspiration affecting the amount of water that crops require and the amount of water available in soil. This may enable crop expansion in some areas, but may also require more irrigation.
Seasonal planting and harvesting patterns may change as a result of changing temperatures, thus needing adjustment.
Higher temperatures combined with drier dry seasons increases the likelihood of fire.
Higher temperatures may be associated with increased spread of invasive species

Temperatures at multiple reef depths (shallow to deep) indicate an upward trend in water temperatures of about 0.03◦ per year (or 0.3°C per decade). Trends for deeper depths have greater variability. Projections for annual sea surface temperature are for a continued increase. By 2030, under a very high emissions scenario, this increase is projected to be 0.6-1.0°C (2019 SOE). Coral reef bleaching can occur when temperatures exceed 30 degrees for days to weeks. In mid-2019 there was no bleaching trend expected for Palau, but that is highly variable. By 2040 predictions suggest Palau will have widespread bleaching occurring annually. Declining coral reef health is associated with lower reef fishery productivity and may negatively impact Palau’s tourism industry. Combined with ocean acidification, declines of more than 50% are predicted under a business-as-usual scenario by 2100 for most of the islands in the central and western Pacific.

Ocean water acidity (declining pH) has been steadily increasing in Palau’s waters and is expected to continue to increase in the 21st century. Many areas in the Rock Islands are naturally more acidic, and coral reefs there are more acidification-resistent due to chronic exposure (but planning must account for these).

Human impacts:

Both nearshore and offshore fisheries have declined and are expected to decline more due to climate change, in all habitats. Reduced supply of fish and invertebrates will hurt income and food supplies.
Costs and carbon emissions associated with accessing fishing and gleaning areas will likely increase.
Combined with acidification, coral health is expected to decline, and Palau’s reefs and unique marine habitats (such as Jellyfish Lake) will not be able to support high numbers of tourists, with loss of income and negative impacts on Palau’s branding and value.

Environmental impacts:

- Coral reef health is expected to decline.
  - - Eastern reefs were heavily damaged by typhoons in 2012 and 2013 and were still in poor condition in 2016.
- The importance of coral refugia, such as resilient reefs in Ngermid, will increase.
- Nearshore and reef fishery availability and catches are expected to decline. Combined with the impact of ocean acidification and typhoons, reef fish abundance is predicted to decline by 23% by 2040, even under a best case scenario. Other scenarios predict a decline in reef fishery productivity by as much as 76%.
  - - Reef fisheries declined by approximately 18% in Ngerumekaol Channel (in Koror) between 1991 and 2014, despite its status as a protected area, likely due to the long-term effects of bleaching in 1998.
- Offshore fishery productivity – especially tuna – is expected to decline in Palau’s EEZ by 25% in the next few decades. Projected declines range by species, with declines 12-28%. Biomass north of Palau is expected to decrease by as much 43% (south of Palau it may increase by 15%).
- Increased sea surface temperature may increase the potential for aquatic animal diseases and harmful algal blooms.
  - - This may negatively impact tourist sites.
    - This is expected to decrease the productivity of aquaculture. Increased sea surface temperature may decrease the availability of wild seed.
- High water temperatures can negatively impact Palau’s unique marine lakes. Each marine lake has a unique assemblage of flora and fauna, including different species of jellyfish, many of which are endemic.
- Outside of the Rock Islands, coral skeletal bioerosion is expected to increase as waters become more acidic.
- Lower pH-tolerant coral reefs (refugia) will become more important.

Sea level rise

Sea level projections vary widely, ranging from 1.6 to 7 inches (4 to 18 cm) by 2030. Palau’s sea level is rising at the global rate when yearly rates are considered (SOE 2019). However, sea level rise is variable, with some years seeing drops in sea level associated with El Nino. Since 1993, sea level in Palau has increased by approximately 9 mm/year. Using Palau’s yearly rate, sea level rise by 2030 is expected to be around 90 mm (9 cm; 3.5 inches).

Human impacts:

Homes near the coast are vulnerable to damage and loss from sea level rise, coastal erosion, or from flooding during storms.
Many cultural and historical sites are in low-lying areas and risk being damaged or lost due to sea level rise.

Environmental impacts:

Salt water intrusion into low lying taro patches, farms, and water sources is a growing problem, with loss of crops. An estimated 6% of taro crops are lost annually due to salt water intrusion.
Coral reefs are not expected to be highly impacted by sea level rise, as shallow reef flats are able to grow at pace with sea level rise. Drops in sea level can lead to mortality of some corals.
- - The importance of resilient coral refugia will increase.
Mangroves generally have low vulnerability to sea level rise, as they are able to grow at pace with the rising seas.

Stronger Typhoons and Storms

20 typhoon strength storms passed through Palau’s EEZ between 1945 and 2013, averaging 1 typhoon every 3 years. Kayangel was the most often the closest point to the typhoon. Predictions are not clear on the expected future frequency of typhoons, although some models predict a decrease in the number of typhoons. However, those that will occur are expected to be of higher intensity, with an increase in wind speed of 2-11% and increase in rainfall intensity of 20%.

Human impacts:

Storms can cause power outages and require evacuation for safety. Older adults and persons with disabilities, foreigners without support networks, and children are particularly vulnerable to storm impacts.
Economic impacts from storms also disproportionately impact poor and vulnerable populations through lost income and recovery costs.
Mental health impacts are associated with strong storms, especially in coastal populations.
Storms can disrupt communications, transportation networks, food supply, housing, and infrastructure (including water, electricity, and sewer) which carry health and safety risks.
With a high reliance on imported foods, typhoons can disrupt food security. There was a 3-week delay in resuming imports after typhoons in 2012 and 2013.
Coastal flooding is expected to negative impact coastal properties and infrastructure.

Environmental impacts:

Storms can cause significant damage to coral reefs and marine environments. Some shallow coral reefs lost nearly all live coral cover after typhoons.
- - Recovery of many damaged reefs takes over a decade.
  - Deeper reefs (30-150 meters deep) have also declined due to the effects of storms sending sediment and rubble downslope. This will likely continue.
  - Algal blooms on reefs in Palau have been documented after typhoons.
Seagrass cover declined by 20-30% from 2011 levels after typhoons in 2012 and 2013, both inside and outside protected areas.
- - Seagrass extent is expected to further decrease by 5-20% by 2035.
  - Fish biomass in seagrass declined significantly between 2011 and 2015 (to near zero grams/square meter) and invertebrate biomass has been historically low.
Shorelines are susceptible to erosion and landward movement due to storms. Shorelines in Palau have generally stabilized due to new vegetation, but in some places, a steady loss of beach has been seen. Mangroves protect shorelines.
Where land has a slope of 12% or higher, that land is at high or medium risk of slope failure following intense rainfall events.

Increasing rainfall, Rainfall variability, and Extreme weather

Total annual rainfall appears to have increased by 7.6 cm (~3 inches) between 1948 and 2011. It is difficult to project exactly how rainfall will change, except that rainfall variability is expected to increase. Rainfall in the wet season is projected to increase by 2% by 2030 and up to 8% by 2090. Projections show extreme rainfall days are likely to occur more often and be more intense, with rainfall lasting longer days (wetter wet seasons and drier dry seasons). However, the number of months with high rainfall shows a decreasing trend, suggesting increasing frequency of possible drought.

Human impacts:

Droughts are associated with water shortages and water rationing. This disrupts the local economy as well as food security.
Intense rainfall after a drought is associated with higher sediment and pollution loads in water supplies, increasing the likelihood of water-borne disease and ill health. This also stresses the public utility.
Warming may increase the activity of disease vectors, such as dengue-carrying mosquitos

Environmental impacts:

- Increased rainfall and increased intensity of storms and typhoons is associated with higher rates of erosion and sedimentation.
- Accelerated erosion from forests may result in loss of topsoil, organic matter, and nutrients.
- Some trees in Palau’s forests are not well adapted to dry seasons, and may be stressed by more frequent droughts.
- The risk of fire significantly increases during the dry season.
- Prolonged rainfall (wetter wet seasons) are associated with loss flowers and less fruiting in forest trees.
- Areas that are highly dependent on agriculture must consider water sources during dry seasons. For instance, 18% of Airai's farms are irrigated.

National Environmental Protection Council (NEPC), Government of Palau. 2019 State of the Environment Report, Republic of Palau. 100 pages. 2019.
Wendy Miles, Zena Grecni, Erbai Xavier Matsutaro, and Victoria Keener. Climate Change in the Republic of Palau: Indicators and Considerations for Key Sectors. PIRCA Climate Science Summary Update, Palau. Second Order Draft – Apr 10, 2020.