Antarctic rainfall could increase through 2100

Liquid precipitation (i.e., rain and drizzle) along the coast of Antarctica could increase in amount, frequency and intensity over the next 80 years, according to a study recently published in Geophysical Research Letters.

The study – carried out jointly by scientists at EPFL, the French National Centre for Scientific Research (CNRS) at Sorbonne University, and the University of Aveiro – found that if high levels of greenhouse gases continue to be released into the atmosphere, average rainfall across Antarctica could rise by 240% between now and 2100.

The more frequent showers could accelerate the melting of some of the continent’s large ice sheets and ice shelves, which would contribute to rising sea levels around the globe.

Higher rainfall could also have dramatic consequences for Emperor and Adélie penguin chicks. Since the chicks’ feathers aren’t yet waterproof, they can freeze when moisture in the air cools and winds pick up. The 2013–2014 breeding season of one of the biggest colonies of Adélie penguins, located around the Dumont d’Urville research station in southeast Antarctica, was a complete reproductive failure due in large part to heavy rainfall.

“We expect rain events to pick up not only in frequency, but also in intensity” says Etienne Vignon, a CNRS scientist at Sorbonne University and the study’s lead author.

Today most of the precipitation in Antarctica is snow. Rain is rare, and when it does occur, it’s usually on the continent’s coasts. The scientists estimate that rain falls up to four days per year on average on the coast of eastern Antarctica and more than 50 days on average on the northwestern Antarctic Peninsula.

Interview with Alexis Berne, the head of EPFL’s Environmental Remote Sensing Laboratory (LTE) and the study’s last author

What new insight does your study bring?
Most precipitation in Antarctica falls as snow, but our study is the first to take a systematic approach to analyzing rainfall on the continent. We also investigated the associated trends, both future and past, taking account of the entire continent and not just one particular region. Our research involved collecting and analyzing meteorological reports from 10 stations – including some reports dating back 50 years – to get an idea of rainfall occurrence over the past few decades. The only major trend we saw was on the Antarctic Peninsula, where the number of rainfall days increased until 1998 and then decreased between 1998 and 2015, in line with the region’s natural weather variability.

What do you predict for the coming decades?

The outlook is changing. Based on scenarios recently developed under the CMIP6 research project, the number of days and the intensity of Antarctic rainfall is expected to increase significantly, especially in coastal areas and on ice shelves. Our models show that this additional rainfall will be the main cause of higher total precipitation on the Antarctic Peninsula in the future. More frequent and more intense rainfall could be a threat to the birds living on the edges of the ice cap and could accelerate glacial melting – in particular on the Ronne and Ross ice shelves in western Antarctica.

How does this study fit in with the other research being performed at your lab?
At the LTE, we do a lot of research on Antarctic precipitation, both by analyzing data collected out in the field and by running simulations on our meteorological and climate models. From here in Switzerland the topic could seem remote, but Antarctic precipitation heavily influences the mass of the Antarctic ice cap, which directly influences the change in global sea levels. One of our goals is to better understand how microphysical processes interact with atmospheric circulation so that we can quantify Antarctic precipitation, improve our models and simulations, and ultimately generate more reliable precipitation forecasts.

Do you plan to make another expedition to Antarctica?

We’re currently working with a team of French scientists to plan another expedition for taking large-scale measurements, with the hope of collecting entirely new data over the next few years that can be used to characterize the formation of Antarctic precipitation and estimate both its volume and phase (rain or snow).

Note

Geophysical Research Letters is the American Geophysical Union’s journal for high-impact, short-format reports with immediate implications spanning all Earth and space sciences.