Quick Facts About Guam

Climate change projections developed by the Pacific Islands Climate Adaptation Science Center show that warming by 3-6 degrees F by the end of this Century is virtually certain for Guam, similar to global projections. In terms of precipitation, there will be an overall reduction in rainfall by 10-15% under the worst case scenario (RCP 8.5), which has implications for groundwater recharge.  Under this scenario, wet season rainfall is expected to decrease and dry season rainfall is expected to increase, both by 10-20% relative to current observations.  These projections also indicate that the total number of storms impacting Guam will decrease, but that year-to-year variability will continue.  For farmers and households, increasing unpredictability of rainfall events increases the risk of flooding and crop disease, while drought conditions in the dry season can increase crop stress, irrigation costs, and wildfire risk.   Storm events, especially typhoons, can be extremely destructive both to crops and local infrastructure required to transport food to market.

For Guam and other Pacific Islands, climate change may resemble weather extremes already familiar to many Islanders.  For example, El Niño years are typically associated with drought and cooler ocean temperatures on Guam. During La Niña events, which often immediately follow El Niño, stronger trade winds push warmer waters to the Western Pacific, increasing ocean temperature, sea level and rainfall.  Experience with weather extremes like these may help Pacific Islanders prepare for and anticipate future conditions.  Other aspects of climate change, however, will likely push conditions beyond what has been experienced in the past.  

Climate Change in Guam

rising temperature graph

Rising Temperatures

Rising temperatures will increase the frequency of hot days and warm nights in Guam. Hot days can be unhealthy and even dangerous, especially for children and the elderly. High air temperatures can cause heat stroke and dehydration and affect people’s cardiovascular and nervous systems.

cracked dry soil


Most of Guam’s fresh water comes from the northern part of the island, which has a “lens” of fresh groundwater floating on top of the heavier, saltier water. During droughts, rising sea level could make fresh water less available, in particular groundwater, which provides 80 percent of Guam’s water supply.

bleached coral reef

Coral Reef Bleaching

According to research from the University of Guam, rising sea temperatures killed 34% of Guam’s coral reefs between 2013 and 2017 and the island only narrowly avoided a mass coral bleaching event.

Additional environmental issues of major concern

Deforestation for agriculture

Limited freshwater resources

Limited food resources