Sensitivity Of Glaciation In The Arid Subtropical Andes To Changes In Climate

Understanding the sensitivity of glaciers to changes in climate provides insight into the climatic drivers of past glaciations and helps us predict how glaciers and ice sheets may respond to future warming.

The South American Andes are ~7000 km long, and the full length of the range is glaciated, or has been glaciated as recently as the last Pleistocene (~20,000 years ago). This means that glaciers in the Andes exist, or have existed, in a broad range of climatic settings.

Between 18 and 27 Ā°S, in the subtropical Andes, there are rock and sediment deposits from past glaciers but no modern glaciers, even at altitudes over 6000 m. These glacial deposits have been used by scientists to identify when the glaciers that used to exist in the area were at their maximum extent. Those scientists found that maximum glaciation occurred at different times across three distinct sub-regions: the northern Altiplano, the hyper-arid western cordillera, and the more humid eastern cordillera.

While temperatures are similar across the three regions, the western cordillera is drier and receives more radiation than the other regions. The out-of-phase timing of glaciation across these three regions, likely due to those differences in climate, makes the subtropical Andes an especially interesting area to investigate the relationship between glaciers and climate.

We use a numerical glacier model to calculate the changes in climate, compared with today, that would have been required for glaciers to have previously existed in the subtropical Andes. The model calculates the changes in the modern climate, including temperature, precipitation, and radiation, required for glaciers to exist in each of the three regions.

Credit: Lauren Vargo

The eastern cordillera likely had glaciers ~23,000 years ago during the Last Glacial Maximum, when temperatures were ~6Ā°C colder than they are today. Our model shows that by simply decreasing temperatures by 6Ā°C in the eastern cordillera, the climate would support glaciers.

Maximum glaciations in the Altiplano and the hyper-arid western cordillera was likely closer to ~15,000 years ago, when temperatures were ~3.5Ā°C colder than they are today. Our model shows that in these regions, simply decreasing temperatures is not enough to support glaciers and that further increases in precipitation, decreases in incoming radiation, or a combination of both, is necessary.

In the Altiplano, increasing precipitation of 10 – 60%, in conjunction with lower incoming radiation of 7 – 12% and lower temperatures of 3.5 Ā°C would have supported glaciers in the area. In the western cordillera, for the same lower radiation and temperature, precipitation needs to be 90 – 160% higher than modern for the region to have supported glaciers.

We find that glaciation of the Altiplano and western cordillera is ~3 times more sensitive to changes in precipitation and ~2.5 times more sensitive to changes in shortwave radiation compared with the eastern cordillera. While all three regions are part of the arid subtropical Andes, the extremely high sensitivity of glaciation in the western cordillera is likely due to the especially low precipitation and high radiation in the area.

Credit: Lauren Vargo

These results suggest that future changes in precipitation and radiation can be as important as upcoming warming for future changes in subtropical glaciers.

These findings are described in the article entitledĀ Sensitivity ofĀ glaciation in the arid subtropical Andes to changes in temperature, precipitation, and solar radiation, recently published in the journalĀ Global and Planetary Change.Ā This work was conducted byĀ L.J.Ā Vargo from theĀ Victoria University of Wellington,Ā J.Ā Galewsky from theĀ University of New Mexico,Ā S.Ā Rupper from theĀ University of Utah, andĀ D.J.Ā Ward from theĀ University of Cincinnati.

About The Author

Lauren Vargo

Lauren Vargo currently works at the Antarctic Research Centre, Victoria University of Wellington. Lauren's research includes glaciology, climatology, and paleoclimatology.

Speak Your Mind!

READ THIS NEXT

How Does The Brain Relate To Working Memory In Young Children?

Have you ever repeated a phone number over and over in your mind in order to remember it, yet forgot it anyway while dialing? This common occurrence reflects a failure of working memory, a type of memory that can be thought of as a ā€œmental workspaceā€ or a temporary ā€œsticky noteā€ for information important for […]

3D Green Peanut Hull/Graphene Aerogels For Highly Efficient Oil-Water Separation

Graphene is a very amazing material for its unique gapless conical band structure, its efficient wide range of light absorption, its high mechanical strength, ļ¬‚exibility, thermal conductivity, and stability. [1-3] The study of graphene is a central interest across a diverse range of fields, such as photocatalysis, electrical conductivity, adsorption, and many other aspects. However, […]

The History Of Domestication Of Mandarins In China

The domestication of perennials is less well-known than the domestication of annual crops. Citrus is one of the most important fruit crops worldwide, growing in more than 114 countries. Citrus domestication is believed to have begun much more recently than the domestication of food crops, ca. 4000 years ago. Genetic evidence for mandarin domestication is […]

Homo Sapiens May Have Inherited Defenses Against RNA Viruses From Neanderthals

Though it was once thought that the evolution of the human species was a linear progression from ape-like ancestor to modern humans, recent findings have shown that extinct subspecies of early humans existed and that the line from our ancestors to us was substantially more complex. In fact, our Homo sapien ancestors are believed to […]

The Fastest Fish In The World

Some say the fastest fish in the world is the sailfish, but the real story is a bit more complicated. Ever wanted to know what the fastest fish in the world is? This turns out to be a difficult question to answer since it is relatively difficult to measure the top speed of a fish. […]

Producing New Flocculants Using Health-Friendly Ingredients In Water Treatment

Water purification is one of the inevitable problems affecting people throughout the world. Effluents resulting from industrial activities are the most problematic and challenging wastewaters and have become a concern, as scarcity and costs of water both become more evident. The development and implementation of solutions to enhance water treatment are crucial. Several traditional and […]

College Drinking Culture In Spain, Argentina, And The USA: An Examination Of Impulsivity, College Alcohol Beliefs, And Alcohol Outcomes

Across many countries and cultures, college students drink heavily. Students who drink heavily are at risk for a wide range of problems ranging from a hangover to unsafe and unplanned sex, and from poor academic performance to developing an alcohol-use disorder. Decades of research has found college student drinking culture to be a barrier towards […]