Groundbreaking research sheds light on atmospheric changes behind accelerated melting, with implications for global sea-level rise
A recent study published in Communications Earth & Environment reveals significant findings regarding the rapid increase in surface melting across West Antarctic ice shelves over the last two decades. Led by Prof. Pranab Deb, Centre for Ocean, River, Atmosphere and Land Sciences (CORAL) at IIT Kharagpur and co-authored by leading atmospheric scientists including David Bromwich from the Byrd Center’s Polar Meteorology Group, the study offers fresh insights into the atmospheric drivers behind these dramatic shifts in Antarctic ice behavior.
a. Pacific Ocean sector of the Southern hemisphere. The red and blue boxes show the geographical extent of the South Pacific Convergence Zone (SPCZ) and West Antarctica (WA), respectively, as used in this study. b. West Antarctic domain, including key ice shelves and geographic locations referenced in the study. The black rectangle shows the geographical extent of the MacAyeal Ice Stream region used in the stacked anomaly calculation
Key Insights: A Climate Shift Driving Melting Ice
Utilizing satellite data and regional climate model outputs, the study compares two distinct periods – 1979–1998 and 1999–2018 – to understand the underlying causes of this transformation. While the earlier period was marked by a decrease in melt trends, the later period witnessed a significant reversal, with accelerated melting observed across major ice shelves in the Ross-Amundsen Sea sector.
The study identifies a crucial climatic event at the heart of this shift: the transition of the Interdecadal Pacific Oscillation (IPO) to its negative phase in the late 1990s. This shift resulted in a rise in sea surface temperatures and intensified convective activity in the South Pacific Convergence Zone (SPCZ). The resulting atmospheric changes set off a series of teleconnections – large-scale atmospheric interactions that influence distant regions.
One of the most profound effects of this teleconnection was the intensified high-pressure blocking over the Amundsen-Bellingshausen Sea region, directing warm marine air toward the Antarctic ice shelves. This warm air was a key driver of surface melting, with temperatures frequently exceeding the critical melting threshold.
Tropical Forces Unleash Warmth in the Polar Regions
The study highlights how changes in atmospheric circulation, particularly the behavior of Rossby waves – large atmospheric waves generated by Earth’s rotation – play a pivotal role in this process. These waves propagate through the atmosphere, influencing the movement of air masses and altering pressure patterns. The study shows that these waves, amplified by the SPCZ, strengthen high-pressure systems that bring warm air to the ice shelves, driving the surface melt. This warming cycle has become more frequent and intense since 1999.
In addition to these long-term atmospheric changes, the research also underscores the importance of interannual climate events, such as El Niño and the Southern Annular Mode, which can amplify or modulate the effects of the SPCZ teleconnection in the short term. The SPCZ, a region of intense tropical storm activity, acts as a powerful engine for atmospheric teleconnections – large-scale atmospheric interactions that can influence distant regions. As the SPCZ strengthens, it creates a chain reaction, sending warm marine air over the West Antarctic ice shelves, where it melts the ice from below.
Implications for Ice Shelf Stability and Global Sea-Level Rise
The findings have significant implications for understanding the future of West Antarctica’s ice shelves and the broader impacts on global sea levels. The enhanced frequency of blocking events and the prolonged warm air transport could lead to further destabilization of the ice shelves, which are crucial in regulating the flow of ice from the continent into the ocean. As these ice shelves weaken and disintegrate, they could contribute to rising sea levels, potentially affecting coastal communities worldwide.
David Bromwich, Principal Investigator at the Byrd Center’s Polar Meteorology Group, emphasized the importance of these findings: “Understanding the complex interactions between tropical convection, atmospheric circulation, and ice shelf stability is vital for accurately predicting the future of Antarctica’s ice sheets and their contribution to sea-level rise. This research highlights how even distant tropical influences can significantly impact polar regions.”
Advancing Climate Modeling
“This research also highlights the critical need to improve climate models by incorporating remote tropical influences, particularly those stemming from the South Pacific Convergence Zone, to better predict cryospheric changes. More accurate models could help policymakers and scientists prepare for the long-term effects of Antarctic ice loss on global sea levels,” said Prof. Pranab Deb, Centre for Ocean, River, Atmosphere and Land Sciences (CORAL) at IIT Kharagpur
By detailing the atmospheric mechanisms driving the recent increase in surface melting over West Antarctica, this study contributes to a deeper understanding of Antarctic climate variability and its future trajectory.
About the Study
The study was led by Pranab Deb, with contributions from David Bromwich (Byrd Center for Polar and Climate Research), Andrew Orr, Arnab Sen, and Kyle R. Clem. Using satellite data, climate model simulations, and observational analysis, the researchers were able to trace the role of tropical atmospheric influences in recent ice shelf melt trends.
The study is published in the prestigious journal Communications Earth & Environment, read more here: https://byrd.osu.edu/news/recent-rise-west-antarctic-ice-shelf-melting-linked-interdecadal-pacific-oscillation.
Media Coverage:
Times of India Malayala Manorama
Deccan Herald New Indian Express
Inputs from: Prof. Pranab Deb, Centre for Ocean, River, Atmosphere and Land Sciences (CORAL), IIT Kharagpur
Email: pranab@coral.iitkgp.ac.in
Edited By : Poulami Mondal, Digital & Creative Media Executive (Creative Writer)
Email: poulami.mondal@iitkgp.ac.in, media@iitkgp.ac.in, Ph. No.: +91-3222-282007
Follow us on: Facebook – IIT Kharagpur; Twitter – @IITKgp; Instagram – @iit.kgp; LinkedIn – Indian Institute of Technology
For news visit: https://kgpchronicle.iitkgp.ac.in/
