Territory of Guam
Guam’s climate is almost uniformly warm and humid throughout the year. The mean annual temperature is 81.9 °F (27.7°C) in 2007 [4]. Generally, the range is from the low 70s to the middle 80s. The coolest and least humid months, marked by prevailing westerly tradewinds, are in December through February. Although the warmest months are from March through August, the trade winds blow steadily from the east or northeast. There are two seasons, the dry and the rainy. The dry season typically begins in December and extends through June. The rainy season falls within the remaining months [5].
The annual rainfall totals 80-110 inches (2,032-2,794 mm) [5], with the total precipitation of 88 inches (2,235 mm) in 2007 [4]. Three-quarters of the rain falls between June and December, averaging about 85 inches (215 cm) a year on the lowland coast around Apra Harbor and 110 inches (280 cm) in the highest mountain locations of the southern half of the island [7]. During the rainy season there is a breakdown of the trades, and on some days the weather may be dominated by westerly moving storm systems that bring heavy showers, or steady and sometimes torrential rain [6]. Guam lies within the typhoon belt and is periodically struck by tropical storms and typhoons [7]. Guam has experienced numerous typhoons, which are most frequent from June through December. An average of three tropical storms and one typhoon pass within 180 nautical miles (330 km) of Guam each year. Since 1962, ten of thirteen major disaster declarations resulted from typhoons, and two of the other disasters were associated with climate [2]. The most intense typhoon to pass over Guam recently was Super Typhoon Pongsona, with sustained winds of 125 miles per hour on December 8, 2002, leaving massive destruction as the oil tanks in Apra Harbor caught fire [1, 2]. The loss of harbor operations made response to the disaster more difficult [2].
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Damage from Typhoon Pongsona. Source: Andrea Booher, FEMA News Photo. Dededo, Guam, December 16, 2002 -- Powerlines are damaged on the island of Guam caused by Supertyphoon Pongsona which struck Guam on December 8, 2002. |
As a higher island, Guam has greater freshwater resources, which means that there were fewer problems with water supply during the 1997-1998 ENSO event. Super Typhoon Paka hit Guam in December 2007, which was the last rainfall for the next few months and the island was recovering from the storm when the results of the strong ENSO came.
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Wildfire in Umatac, Guam: Source: C. Anderson, 2003. Annual dry seasons combined with carelessness and arson often result in wildfires in Umatac, Guam. During the 1997-1998 ENSO event, Guam recorded 1600 fires. As the fires destroy topsoil, they often result in increased sedimentation on coral reefs and stress on the marine environment. |
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Burning fuel tank during Typhoon Pongsona.
Source: Andrea Booher, FEMA News Photo. Apra Harbor, Guam, December 12, 2002 -- Firefighters extinguish fires from jet fuel tanks that were burning out of control due to Supertyphoon Pongsona. The fire blocked access to gasoline supplies for the island and has caused the shutdown of Apra Harbor, the primary supply and fuel delivery point for Guam. |
Typhoon Pongsona on Guam
On December 2, 2002 the Joint Typhoon Warning Center (JTWC) issued a Tropical Cyclone Formation Alert. The depression was upgraded by the Japan Meteorological Agency to Tropical Storm Pongsona on December 3. On December 5, both the JTWC and the JMA upgraded Pongsona to a typhoon while centered about 1150 km (715 miles) southeast of Guam. On December 7, JTWC assessed Pongsona as a 240 km/h (150 mph) supertyphoon. Early morning on December 8, the eyewall made landfall on Guam. Typhoon Pongsona produced strong wind gusts peaking at 278 km/h (173 mph), which left the entire island of Guam without power and destroyed about 1,300 houses. Damage on the island totaled over $700 million (2002 USD, $800 million 2007 USD) and was considered by the Federal Emergency Management Agency (FEMA) the costliest United States disaster in 2002 in a single state or territory [3, 8].
During the height of the typhoon at Cabras Island on Guam, a gasoline tank caught fire, believed to be from friction caused by extremely high winds running through its ventilation system. The tank exploded, sending its lid airborne and spreading the fire to other nearby tanks. The proximity of the tanks as well as low water pressure hampered firefighting efforts, and the fire was extinguished five days later; it resulted in three destroyed gasoline tanks with two more caught on fire. While the fire was burning, transportation of gasoline from the port to the rest of Guam was suspended resulting in a halt in gasoline sales for the general public [8].
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Water conservation measures were enacted to ensure water for drinking, household use, and agriculture, while also fighting wildfires. The worst problems during the drought were the severe wildfires, which contributed to loss of vegetation and destabilized hillsides and stream banks, resulting in erosion and sedimentation. The coral reefs, which provide habitat, food, and protection for the islands, as well as attraction for its main tourism industry, could experience increased pressure from extreme events that result in bleaching or sedimentation that covers and kills the reefs. During disasters throughout Micronesia, people from atoll islands historically migrate to Guam because it usually has more food and water resources available. With increased migration from the impacts of climate change, Guam's resources may exceed their carrying capacity. (See the Stakeholder Dialogue page, Territory of Guam, April 24-25, 2006.)
Sources
[1] Central Intelligence Agency, The World Factbook, https://www.cia.gov/library/publications/the-world-factbook/geos/gq.html, accessed June 26, 2008.
[2] Federal Emergency Management Agency, http://www.fema.gov/femaNews/disasterSearch.do, accessed June 21, 2008.
[3] Federal Emergency Management Agency. 2003. Super Typhoon Pongsona: The First 100 Days Over $300 Million In Disaster Relief And Assistance, http://www.fema.gov/news/newsrelease.fema?id=2240, accessed June 25, 2008.
[4] National Climatic Data Center (NCDC), National Oceanic and Atmospheric Administration.
[5] National Weather Service Forecast Office, Tiyan, Guam, http://ns.gov.gu/climate.html.
[6] Shea, E., G. Dolcemascolo, C.L. Anderson, A. Barnston, C.P. Guard, M.P. Hamnett, S.T. Kubota, N. Lewis J. Loschnigg, & G. Meehl. 2001. Preparing for a Changing Climate: The Consequences of Climate Variability and Change for Pacific Islands. Honolulu: East-West Center, http://research.eastwestcenter.org/climate/assessment/report.htm, accessed June 18, 2008.
[7] U.S. Department of Interior. 2006. United States of American Insular Energy Assessment Report 2006. Suva, Fiji: Pacific Power Association, http://www.doi.gov/oia/reports/iaea2006report.doc, accessed June 23, 2008.
[8] Wikipedia, Typhoon Pongsona, http://en.wikipedia.org/wiki/Super_Typhoon_Pongsona#cite_note-femlast-0, accessed June 25, 2008.
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