4 to 6 – February – 2013 Reducing Disaster Risk for a Healthy Pacific Honolulu, Hawaii Climate Change and Sea Level Rise in the Pacific Islands.

4 to 6 – February – 2013 Reducing Disaster Risk for a Healthy Pacific Honolulu, Hawai‘i

Climate Change and Sea Level Rise in the Pacific Islands

Sea Level Rise Impacts

Increased Flooding and Erosion Will Threaten both Natural and Built environments.

Critical public facilities and infrastructure will experience damage.

Freshwater resources will be at particular risk due to intrusion of salt water from the ocean; secondary effects include the fouling of sanitary systems.

Salinization will affect agricultural activity by decreasing the land area available for farming.

Foraging areas and nursery habitat for many coastal species, are expected to diminish.

Psychological effects of stress are likely to be gradual and cumulative.

Since the early 1990s, the rate of globally averaged sea-level rise has been estimated to be 3.4 ± 0.4 mm per year based on satellite altimeter measurements. This is twice the estimated rate for the 20th century as a whole based on tide gauge measurements.

Projections based on climate models and that do not include ice-sheet contributions are for an 18 to 59 cm rise in global sea level by 2100. Projections using "semi-empirical models“ yield higher estimates of global sea level rise, ranging from roughly 1 to 1.5 m by 2100.

Sea Level is Rising

Adapted from Church et al., 2008

Sea Level Rise through Time and Space.

Actionable Information?

Low signal to noise ratio, means at least over the next generation three is as much if not more change attributable to inundation events as sea level trends.

It is really about extremes, which generally occur when high tides combine with some non-tidal change in water level (e.g., tropical and extra-tropical storms, ocean mesoscale variability, and swell events from distant storms).

It is probably more about the next few months than it is the next few decades.

Sector-specific indicators/thresholds are required to make relevant connections between forcings and impacts.

The long term change in global mean sea level is not particularly meaningful.

Time-varying Extremes 1.0

‘Return level curves’ for different SLR scenarios can be used to support the siting and design of new facilities and infrastructure as well as identification of new habitat.

‘Threshold frequency curves’ for different SLR scenarios can be used to asses the risk to existing facilities and infrastructure, as well as species and ecosystem response.

…after Sweet, Merrifield, Marra

The ratio of mean non-tidal residual to mean extreme amplitude for annual maxima. Merrifield et al., 2012

Each location is unique

Extreme climatologies from tide gauges for each day of the year. Marra et al., 2012

Pago Pago Guam Honolulu

Time-varying Extremes 2.0

…after Menendez, Sweet, Merrifield, Marra

Midway Islands 50-year Return Level – storminess.

Honolulu 50-year Return Level – tide cycle.

Dr John J. Marra [email protected] Regional Climate Services Director, Pacific Region

For more on the PIRCA: http://www.eastwestcenter.org/PIRCA