RAPIDLY RETREATING TROPICAL GLACIERS: PRESENT AND FUTURE SOCIETAL IMPACTS (Invited Presentation)

Tropical glaciers are highly sensitive indicators and recorders of climate change. Unfortunately, most are currently in retreat, primarily due to recent anthropogenic atmospheric warming although in some regions strong ENSO events augment melting by increasing air temperature and decreasing precipitation. The accelerating loss of low latitude glaciers is consistent with model predictions of vertical amplification of temperature in the Tropics. Long-term climate records from a collection of high-altitude tropical ice cores provide the context essential for determining the magnitude and rate of current climate changes that are significant in driving retreat. Here we assess the recent, rapid decline of glaciers in the Himalaya, the Peruvian Andes, Kilimanjaro in East Africa, and the ice fields in Papua Indonesia by quantifying the reduction in ice coverage and thickness. The melting of glaciers near populated areas is already affecting people whose livelihoods depend on the meltwater for crops and livestock and whose lives are endangered when glaciers collapse and/or glacial lake dams are breached. On regional to global scales the greatest near term impacts will be economic, especially in countries that rely on glacial streams for agriculture, hydroelectricity, municipal water supplies, ecosystem support, tourism, and recreation. The loss of glaciers from the world’s mountain ranges will contribute to near-term global sea level rise which threatens highly populated coasts. The loss of these mountain glaciers can also lead to growing geopolitical problems. For example, melting glaciers supply 40% of the economically essential dry season discharge from the Indus River which flows through the territories of 3 nuclear powers (China, Pakistan, and India). The current glacier retreat throughout the Peruvian Andes, which contains 70% of the world’s tropical glaciers, is contributing to emerging water resource crises and environmental hazards for both urban and rural populations. Understanding the impacts of this accelerating ice loss on future water resources requires information about past changes in high elevation glacier mass balance. Such data are urgently needed by policymakers, governmental agencies, and public resource administrators to help guide mitigation and adaptation strategies.