Eddie Gonzales Jr. – MessageToEagle.com – Monash University’s research has revealed how regional climate drivers, including SAM (the Southern Annular Mode (SAM) and the El Niño-Southern Oscillation (El Niño), affect Antarctic ice.
Snow accumulation and surface melting are crucial for predicting Antarctica’s contribution to sea level rise.
This study addresses knowledge gaps in sea level rise prediction models, which impact coastal communities.
“The IPCC Sixth Assessment report states that there will likely be 40—77 centimeters of sea level rise by 2100, but more than 2 meters can’t be ruled out,” Professor Mackintosh said in a press release.
“Our lack of understanding of snowfall and surface melt processes on the Antarctic ice sheet affects our ability to predict ice sheet and sea level futures accurately.”‘
“Our new research has looked at two processes influencing this uncertainty: the SAM and El Niño.”
The SAM represents the north-south shift of westerly winds in the Southern Hemisphere. Its three phases—positive, neutral, and negative—impact rainfall, snowfall, and temperatures across Australia, Antarctica, and nearby regions.
A negative SAM – shifts winds northward and weakens them in Antarctica, increasing ice sheet surface melt.
A positive SAM – moves winds southward and strengthens them, reducing ice melt.
Research by SAEF Ph. D. candidate Dominic Saunderson examined East Antarctica’s summer surface ice melt over 40 years, identifying factors like temperature, snowfall, wind, and cloud cover as key contributors.
The research, published as two papers in Geophysical Research Letters, was led by Monash University scientists Jessica Macha, Dominic Saunderson and Professor Andrew Mackintosh from Securing Antarctica’s Environmental Future, an Australian Research Council research initiative.
The researchers state that determining the Antarctic Ice Sheet’s contribution to global sea level rise is a critical priority for Antarctic scientists.
Mr. Saunderson said that for example, in Wilkes Land, home to Australia’s Casey Station, a negative SAM correlates with warmer air temperatures, causing increased surface melting,”
In Dronning Maud Land, a negative SAM leads to reduced snowfall and darker surfaces. This increases sunlight absorption and melting, a process called snowmelt-albedo feedback.
SAEF Ph. D. candidate Jessica Macha studied how different El Niño types affect Antarctic snowfall. El Niño, the warming of central and eastern Pacific Ocean surface temperatures, alters weather patterns across the Pacific, impacting Australia and Antarctica.
Mrs. Macha and the team found that two types of El Niño –
- the Central Pacific and
- the Eastern Pacific El Niño
have distinct influences on snowfall patterns across Antarctica.
“During Central Pacific El Niño events, snow accumulation increases in the western Ross Sea region and decreases in the Amundsen Sea region. Meanwhile, during Eastern Pacific El Niño events, there are similar regional effects but to a lesser extent,” Mrs. Macha explained.
“In other parts of Antarctica, such as Dronning Maud Land and Wilkes Land, the type of El Niño influences snow accumulation in different ways.
With these findings , the researchers can better predict snowfall patterns across Antarctica in order to understand its current state of balance and future contribution to sea level rise.
Paper: J. M. A. Macha et al, Distinct Central and Eastern Pacific El Niño Influence on Antarctic Surface Mass Balance, Geophysical Research Letters (2024). DOI: 10.1029/2024GL109423
Written by Eddie Gonzales Jr. – MessageToEagle.com Staff Writer