Climate change in Guam encompasses the effects of climate change, attributed to man-made increases in atmospheric carbon dioxide, in the U.S. territory of Guam.
The United States Environmental Protection Agency reports that "[i]n the coming decades, changes in the earth’s atmosphere are likely to alter several aspects of life in Guam. The air and ocean are warming, sea level is rising, and the ocean is becoming more acidic. These changes are likely to damage or destroy much of Guam's coral reef ecosystems, increase damages from flooding and typhoons, reduce the availability of fresh water during the dry season, and make air temperatures uncomfortably hot more often than they are today".
Coral loss
"Warming waters are likely to damage much of the coral around Guam. Average water temperatures around Guam have risen more than one degree over the last century, in addition to the year-to-year changes associated with the El Niño-Southern Oscillation ("El Niño"). Rising water temperatures harm the algae that live inside corals and provide food for them. The loss of algae weakens corals and can eventually kill them. This process is commonly known as "coral bleaching" because the loss of the algae also causes the corals to turn white. Coral bleaching is becoming more common around Guam, including record-breaking bleaching that has occurred throughout the western Pacific since 2013. Elevated water temperatures also cause outbreaks of diseases that can harm or kill corals. Increasing ocean acidity also damages corals. By changing the balance of minerals in sea water, higher acidity decreases the ability of corals to produce calcium carbonate, which is the primary component of their skeletons. The Pacific Ocean has become about 25 percent more acidic in the past three centuries, and acidity is likely to increase another 40 to 50 percent by 2100. Over the next 50 to 60 years, warming and acidification are likely to harm coral reefs around Guam and throughout the world, and widespread loss of coral is likely".
"Warming and acidification could result in widespread damage to marine ecosystems. Guam is home to a diverse array of fish species. Sharks, rays, grouper, snapper, and hundreds of other fish species rely on healthy coral reefs for habitat. Reefs also protect nearshore fish nurseries and feeding grounds. A significant fraction of reef-dwelling fish are likely to lose their habitats by 2100. Increasing acidity would also reduce populations of shellfish and other organisms that depend on minerals in the water to build their skeletons and shells".
Tropical cyclones
As the climate changes, typhoons may cause more damage. Guam lies in one of the world's most active regions for tropical cyclones. In 2002, Typhoon Pongsona caused $700 million in damages, destroyed 1,300 homes, and left the island without power. In just the last few years, neighboring islands have suffered from some of the strongest and most damaging tropical cyclones ever recorded, including Super Typhoons Haiyan (2013), Maysak (2015), and Soudelor (2015). Although warming oceans provide typhoons with more potential energy, scientists are not yet sure whether typhoons have become stronger or more frequent. Nevertheless, wind speeds and rainfall rates during typhoons are likely to increase as the climate continues to warm. Higher wind speeds and the resulting damages can make insurance for wind damage more expensive or difficult to obtain.
Rising sea level and coastal flooding
Sea level has risen by about four inches relative to Guam's shoreline since 1993. If the oceans and atmosphere continue to warm, sea level around Guam is likely to rise one to three feet in the next century. Sea level rise submerges low-lying areas, erodes beaches, and exacerbates coastal flooding from typhoons and tsunamis. Coastal homes and infrastructure will flood more often as sea level rises because storm surges will become higher as well. Homes, businesses, roads, and the Port of Guam are vulnerable to the impacts of storms and sea level rise. The loss of coral reefs compounds this problem because reefs help protect the shore from waves and storm damage. As reefs die, they lose their structural integrity and provide less protection to the shore. If larger waves strike the shore, beaches will erode more rapidly.