Cryosphere - Tropical Glaciers
Worldwide, tropical glaciers are retreating. These glaciers are found in the high mountain environments of the Andes, East Africa, and Papua, Indonesia. Research efforts pertaining to the relationship between climate and glacier advance and retreat have intensified over the last few decades. This activity has increased because tropical glaciers help us understand how climate has changed within the tropics. This understanding is vital to discern global climate patterns over annual to decadal periods. Additionally, tropical glacier recession in the Andes of South America threatens an important water resource for many cities and agricultural areas. Scientists are also studying glacier-climate relationships in the tropics to refine current prediction models on how long glacial water supplies will last.
We currently have projects based in three tropical glacier areas: the Andes, East Africa, and Papua, Indonesia.
Over the past century, glaciers throughout the tropics have predominately retreated. These small glaciers, which respond quickly to climate changes, are increasingly important for understanding glacier-climate interactions. The glaciers on Mt. Jaya in Papua, Indonesia, are the last remaining tropical glaciers in the Western Pacific region. Rates of ice loss, calculated from area measurements for the Mt. Jaya glaciers in 1942, 1972, 1987, and 2005, indicate that these glaciers lost ice faster in each subsequent period. Preliminary modeling using 600 hPa atmospheric temperature, specific humidity, wind speeds, and surface precipitation and radiation fields, acquired from the NCEP Reanalysis dataset, indicates that the only climate variable having a statistically significant change with a magnitude great enough to strongly affect ice loss on these glaciers was an 0.24°C increase in atmospheric temperature between 1972 and 1987. However, accelerated ice loss occurred from 1988-2005 without large observed changes in climate, indicating that a more complex explanation may be required. Small, though statistically significant changes were found in regional precipitation with precipitation decreasing from 1972-1987 and increasing from 1988-2005. While these changes were not of sufficient magnitude to have greatly affected ice loss on these glaciers, increased precipitation along with a rising freezing level may have resulted in a greater proportion of the glacier surface being affected by rain. This may account for the increased recession rate observed in the latter period.
Current studies examine the changes of the glaciated area as well as the spatial patterns and distribution of specific glacier ranges in Bolivia. The spatial patterns include the location of glaciers as well as their area and the regional differences in the changes of two glacier ranges named the Cordillera Real and the Cordillera Apolobamba located in the Bolivian Andes Mountains.
These studies seek to answer the question of whether or not some glaciers in Bolivia are retreating faster than others and determine where they are located. They also examine the regional climate factors in order to better understand the correlation between these factors and the rate of glacier retreat. By studying the factors related to the area and mass changes of the tropical glaciers in the Andes Mountains, we will gain a better understanding of why and how quickly these glaciers are retreating.
Landsat satellite imagery will be used to determine the location and area of the glacier ranges. It will also be used to measure the atmospheric temperature, surface precipitation, specific humidity, wind speeds and radiation fields for this region of Bolivia. Measurements will cover over two decades of Landsat imagery and NCEP datasets to better assess the changes that have occurred in the Cordilleras Real and Apolobamba.