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March 31, 2020

Antarctica’s summer of extreme heat

Scientists record first reported heatwave at Antarctica’s Casey research station.

This summer, while drought, heatwaves and bushfires ravaged Australia, Antarctica was also experiencing a summer of extreme weather.

In East Antarctica, scientists recorded the first reported heatwave event at Casey research station in the Australian Antarctic Territory, with extreme maximum and minimum temperatures recorded over three consecutive days in January. Record high temperatures were also reported at bases on the Antarctic Peninsula.

In a research paper published today (31 March 2020) in Global Change Biology, scientists from the 榴莲视频app of 榴莲视频app (UOW), Australian Antarctic Division (AAD), 榴莲视频app of Tasmania and 榴莲视频app of Santiago, Chile, report on the heatwave and its impact on Antarctica鈥檚 plants, animals and ecosystems.

While the Antarctic Peninsula has experienced rapid warming over the past decades, until now East Antarctica has been mostly spared from warming associated with global climate change.

UOW climate change biologist Senior Professor , the paper鈥檚 lead author, said between 23 and 26 January this year, Casey recorded its highest ever minimum and maximum temperatures.

鈥淗eatwaves are classified as three consecutive days with both extreme maximum and minimum temperatures,鈥� Professor Robinson said.

鈥淚n those three days in January, Casey experienced minimum temperatures above zero and maximum temperatures above 7.5掳C, with its highest maximum temperature ever, 9.2掳C on 24 January, followed by its highest minimum of 2.5掳C the following morning.鈥�

鈥淚n the 31 year record for Casey, this maximum is 6.9掳C higher than the mean maximum temperature for the station, while the minimum is 0.2掳C higher.鈥�

 ^{Senior Professor Sharon Robinson in the lab. Picture: Paul Jones, UOW}

 

Elsewhere in Antarctica record temperatures were also reported in February.

On 6 February, the Argentine research base Esperanza on the northern tip of the Antarctic Peninsula recorded a maximum temperature of 18.4掳C. At the time it was the highest temperature recorded anywhere in Antarctica, almost 1掳C hotter than the previous record of 17.5掳C.

Three days later the new record was broken when Brazilian scientists reported a maximum temperature of 20.75掳C at Marambio Base, also on the Antarctic Peninsula.

The February average daily temperature exceeded the long-term means by 2掳C for Esperanza, and 2.4掳C for Marambio.

Antarctic ecologist Dr Dana Bergstrom, Principle Research Scientist at the AAD and Visiting Scholar at UOW, said the hot summer would most likely lead to long-term disruption to local populations, communities, and the broader ecosystem. This disruption could be both positive and negative.

鈥淢ost life exists in small ice-free oases in Antarctica, and largely depends on melting snow and ice for their water supply,鈥� Dr Bergstrom said.

鈥淢elt water flooding can provide additional water to these desert ecosystems, leading to increased growth and reproduction of mosses, lichens, microbes and invertebrates.

鈥淗owever excessive flooding can dislodge plants and alter the composition of communities of invertebrates and microbial mats.

鈥淚f the ice melts completely, early in the season, then ecosystems will suffer drought for the rest of the season.鈥�

Higher temperatures can also cause heat stress in plants and animals adapted to cold Antarctic conditions.

Dr Bergstrom said further studies were needed to understand the full impact of the heatwave.

鈥淓xtreme events often have impacts for years after the event. Long-term study of areas affected by the heatwave will allow us to track this impact,鈥� she said.

^{Antarctic ecologist Dr Dana Bergstrom in Antarctica.}

 

AAD atmospheric scientist Dr Andrew Klekociuk said the warmer temperatures were linked to above average temperatures across parts of Antarctica, and other meteorological patterns in the Southern Hemisphere that occurred during the spring and summer of 2019. 

These patterns were influenced in part by the early breakup of the ozone hole in late 2019, due to rapid warming in the stratosphere 鈥� the atmospheric region above 12 km altitude.

鈥淭he upper levels of the atmosphere at the edge of Antarctica were strongly disturbed in the spring of 2019, and effects of this likely further influenced the lower atmosphere over Antarctica during the summer,鈥� Dr Klekociuk said.

Professor Robinson said extreme events associated with global climate change are predicted to increase in frequency and impact, and Antarctica was not immune to them.

鈥淭he extreme weather experienced in Antarctica over its summer months illustrates how changing extremes are impacting even the most remote areas of the planet,鈥� she said.

ABOUT THE RESEARCH

鈥楾he 2019/2020 summer of Antarctic heatwaves鈥� by Sharon A. Robinson, Andrew R. Klekociuk, Diana H. King, Marisol Pizarro Rojas, Gustavo E. Z煤帽iga and Dana M. Bergstrom is published in the 31 March issue of Global Change Biology (DOI: 10.1111/GCB.15083).

Fieldwork in Antarctica was supported by the Australian Antarctic Division and the Instituto Ant谩rtico Chileno (INACH). The research received funding from the Australian Research Council, the Australian Antarctic Science Program, INACH and the 榴莲视频app of 榴莲视频app鈥檚 Global Challenges Program.