Photo caption: PhD candidate Eva Nielsen created a new dataset of Antarctica’s temperatures. Photo credit: Gabrielle Koerich.
Te Whare Wānanga o Waitaha | ҕl (ҕl) PhD candidate Eva Nielsen created a new dataset of Antarctica’s temperature over the past 20 years analysing its trends and temperature extremes as part of her research.
Nielsen, who moved from Denmark to New Zealand to study Antarctic Studies at ҕl’s School of Earth and Environment, says Antarctica will experience significant changes due to global warming.
“Changes in the local climate can lead to an increase in melt, affecting ice-shelf stability and biodiversity, in the region but to study these effects, scientists need detailed temperature data,” Nielsen says
Her dataset is crucial for understanding local temperature extremes and variations that aren’t well captured by existing models.
“One of the big issues we have with understanding temperatures and their trends across Antarctica is that we don't have a lot of data. Antarctica is such a big continent and getting any data is difficult due to its remoteness and harsh environment,” says Nielsen.
“Weather stations are useful, but the problem is they don't give us the spatial information we need.” She says temperatures can vary a lot with factors like elevation. “If you walk five kilometers from a weather station you can get different temperatures.”
Nielsen created a unique dataset called AntAir ICE, covering detailed information from 2003 to 2021 on temperatures of Antarctica and its surrounding ice shelves using satellite imagery. Using this tool, Nielsen and her team analysed temperature trends and extremes over that period.
“Most importantly, we found that the Ross Sea region is warming a lot, and it's a significant warming, both in the summer mean and the annual mean and we’re the first to find that. We also found the Antarctic Peninsula is cooling, which agrees with a lot of the other research and that parts of Eastern Antarctica were cooling at a significant trend.”
“We also identified extreme temperatures and mapped these with the circulation patterns associated with these temperature extremes,” she says.
Nielsen says this is crucial because, while researchers may not have precise knowledge of daily weather changes in the future, they can better understand how large-scale weather patterns are shifting.
“By linking specific weather patterns to extreme events, we can anticipate if these events will become more frequent in a changing climate. Understanding these variations is crucial for studying ice shelf stability and local ecosystems.”
Nielsen is currently analysing Antarctica’s largest heatwave which occurred in March 2022, focussing on the McMurdo Dry Valley Area. It’s significant for New Zealand due to its proximity to Scott Base and research conducted there. This region also has a fragile ecosystem, with moss and lichens that are highly sensitive to freeze-thaw processes and the availability of meltwater.
She says during this time of the year, temperatures usually stay below zero degrees Celsius, but more than half of their weather stations measured above freezing temperatures and even one station as high as eight degrees Celsius. “The record-breaking March temperatures were recorded by seven stations, some measuring for as long as 27 years.
“These warm weather events are called atmospheric rivers, which involve a large influx of warm, moist air from the tropics reaching the Antarctic.”
Nielsen says these events are crucial for understanding how extreme temperatures affect the environment. “Although the March heatwave had a limited impact due to its short duration of above freezing temperatures, it's important to understand these processes because an event like this occurring in summer could have catastrophic effects, including flooding in the McMurdo Dry Valleys causing significant erosion of biomass.”
funded Nielsen’s PhD.
