El drenaje masivo del lago glacial en la remota Patagonia fue capturado por satélite.

Solo los satélites estaban presentes cuando el cuarto lago glacial más grande del mundo se secó repentinamente en 2020. Investigadores de Universidad de Hokkaido El evento reveló y examinó recientemente su fuente, el colapso de un afloramiento de sedimentos cerca de la salida del lago.

Los lagos glaciares se crean cuando el agua derretida de un glaciar en retirada se mantiene en su lugar por el hielo o la morrena que deja el mismo u otro glaciar. Un clima más cálido contribuye al aumento global reciente en el número y tamaño de estos lagos, y también contribuye a un derretimiento más rápido de los glaciares.

Sin embargo, estos lagos pueden drenarse repentinamente si los diques que los mantienen en su lugar fallan por varias razones diferentes. Un evento catastrófico como este no solo pone en peligro directamente la seguridad humana, sino que también tiene un impacto en los ecosistemas río abajo debido a la repentina afluencia de tanta agua dulce. Por lo tanto, es necesario observar los lagos glaciares e investigar cómo interactúan con su entorno. Desafortunadamente, dada su ubicación a menudo remota, esto presenta un desafío.

El área del lago (arriba) y el nivel del lago (abajo) cayeron drásticamente durante un período de 4 meses en 2020. Credit: Shuntaro Hata, Shin Sugiyama, Kosuke Heki, Comunicaciones de la Tierra y el Medio Ambiente26 de agosto de 2022.

Mientras investigaba las fluctuaciones de los glaciares en la Patagonia chilena usando imágenes satelitales, Shin Sugiyama[{” attribute=””>Hokkaido University and doctoral student Shuntaro Hata discovered that the proglacial lake Lago Greve had significantly shrunk between April and July of 2020.

In their publication of these findings in the journal Communications Earth & Environment, they add further analysis of the available data confirming that the lake’s water level dropped by 18 meters, which translates to a loss of 3.7 cubic kilometers (or, giga-tonnes) of water—the largest such event observed by a satellite to date. This massive loss of water even impacted the Earth’s gravitational field, as recorded by GRACE satellites, although the quantitative data from these satellites is inconsistent with the actual volume of water drained.

Finally, careful analysis of the satellite imagery and topographic data from before and after the event enabled them to deduce that the cause of the release probably was the collapse of a sediment bump close to the outlet of the lake.

Shuntaro Hata (left) and Shin Sugiyama (right), authors of the study, with Matthias Scheiter (center left) and Rodrigo Traub (center right). Credit: Shin Sugiyama.

This study opens up many interesting aspects. For one, it points the way for future research on glacial dynamics. Sugiyama explains: “These results provide detailed information on large-scale glacial lake outburst floods, which occur very rarely, and are important for understanding disasters caused by glacial lake failures.” It also highlights the possibility and the current limitations of using GRACE satellite data for observing such events.

The researchers suggest: “The importance of GRACE measurements in studying such events would be increased if the calculation of the gravity field readings is adapted for localized events.” And finally, the study provides concrete data that can be used to better understand the dynamics of the interactions between glaciers and the lakes they form, as “the observed changes in the water level of glacial lakes can be used to predict changes in the glacier inflow into the lakes.”

Reference: “Abrupt drainage of Lago Greve, a large proglacial lake in Chilean Patagonia, observed by satellite in 2020” by Shuntaro Hata, Shin Sugiyama, and Kosuke Heki, 26 August 2022, Communications Earth & Environment.
DOI: 10.1038/s43247-022-00531-5