Brazilian scientists have recorded the highest-ever Antarctic temperature. At midday on 9 February, air temperature at the Marambio research base hit 20.75ᵒC. This is the first time that a temperature exceeding 20ᵒC has been recorded anywhere within the Antarctic climate zone – the area further than 60 degrees south of the equator.
Marambio is located on Seymour Island, which lies around 70km from the mainland Antarctic Peninsula. Scientists were logging the temperature as part of a 20-year study of ground conditions in the area. The previous temperature record was 19.8ᵒC, recorded at the nearby Signy Island in January 1982.
Speaking to the French news agency AFP, Brazilian soil scientist Carlos Schaefer was keen to emphasise that this was a single point-measurement, and could not be used to predict future temperatures on the continent. Despite this, he did acknowledge the exceptional nature of this measurement. “We’d never seen a temperature this high in Antarctica”, he said.
A record-breaking week
The Seymour Island temperature is exceptional, and coincides with new temperature records elsewhere. Three days earlier, on 6 February, mainland Antarctica also experienced its highest recorded temperature. The Argentine Esperanza research base, at the northern tip of the Antarctic Peninsula, logged a value of 18.3ᵒC, exceeding the previous record of 17.5ᵒC.
A little-known phenomenon called the foehn effect probably links both of these new records. Foehn is an event where the rapid sinking of air causes one side of a mountainous area to become substantially hotter than the other. This effect may have pushed a high baseline temperature into the unprecedented levels seen in early February.
At the same time as these records, the World Meteorological Organisation reported that 2020 saw the hottest January on record, not just for Antarctica, but also the rest of the world. Over the past 50 years, average global temperatures have risen by 0.5ᵒC, but warming has disproportionately affected Antarctica – with an increase of around 3ᵒC. Decades of scientific research has uncovered much about the history of the continent, including the fact that Antarctica has witnessed such warming before, deep in its ancient past.
Past and future warmth
More than a century ago, Ernest Shackleton led an epic, and ultimately failed expedition attempting to cross Antarctica. Though the continent remains inhospitable today, decades of observations and discoveries mean we now have a much greater understanding of how the ice sheets form, grow, and ultimately calve into the sea.
More than 40 countries now operate bases, and during the summer months more than 4000 people live here. Continuous monitoring has allowed scientists to build up a picture of a continent undergoing significant change. As well as taking measurements of modern Antarctica, scientists can make use of the ancient records preserved in rocks and ice to understand how the continent has evolved over geological timescales.
Ice sheets have existed continuously in Antarctica for more than 30 million years, and that is not likely to change any time soon. However, the size of the ice sheets has varied a lot over this time. During warm periods, Antarctica has actually been much more hospitable to life than it is today. The frozen continent was once home to lush forests of cold-adapted trees, an array of invertebrate animals, and even small mammals. This ecosystem seems alien to us today, but it is possible that as Antarctica warms, more ice will melt, and more environments will open up to be colonised by life. The Antarctica of the future may look very different to the continent Shackleton explored all those years ago.
Sinking cities and flooded islands
More freshwater is stored in the Antarctic ice sheets than in all of the Earth’s rivers combined. If all the water contained in ice and snow in Antarctica were to melt, global sea levels would rise by around 60m. A rise of this scale would engulf most of London and turn central Oxford into a shallow sea.
Such a situation is highly unlikely, but UN scientists estimate that melting ice could contribute to more than a metre of global sea level rise by 2100. That would be enough to threaten many low-lying coastal communities worldwide, particularly in deltaic areas such as Bangladesh, and low-lying island nations such as the Maldives. To predict future sea level with greater accuracy, it is important that scientists gain a better understanding of how the Antarctic ice sheets will respond to warming.
The recent Antarctic temperature records came from the volatile West Antarctic. Evidence from the rock record shows that the last time the Earth underwent significant warming, around 120 thousand years ago, the West Antarctic Ice Sheet almost totally collapsed, rapidly contributing 3m of sea level rise over the course of a few centuries. Alarmingly, the mean global temperature of the Earth at this time was only slightly higher than today. If humans continue to emit greenhouse gases at current rates, climate scientists predict that the average temperature in 2100 will be greater than it was the last time the West Antarctic Ice Sheet collapsed.
The frontline of climate change
The recent arctic temperature record may be alarming. Yet, how much can we read into a single data point? Dr Schaefer rightly warns, “We can’t use this to anticipate climatic changes in the future.” However, the timing of this measurement will resonate with many people. The past few months have seen unprecedented wildfires in Australia, a record January global temperature, and widespread flooding across the UK. After more than a century of temperature measurements, the fact that once-rare events are happening so frequently is surely poignant. Climate change has never been a more prominent issue than in 2020, and these events remind us of the powerful changes our planet is experiencing.
Sources & Further Reading
British Geological Survey overview of sea level: https://www.bgs.ac.uk/discoveringGeology/climateChange/general/coastal.html
Web tool showing projected average of global sea level rise by 2100 under ‘business as usual’ CO2 emissions scenario: https://www.climsystems.com/slr-app/
Nicholls, R.J., Marinova, N., Lowe, J.A., Brown, S., Vellinga, P., De Gusmao, D., Hinkel, J. and Tol, R.S., 2011. Sea-level rise and its possible impacts given a ‘beyond 4 C world’in the twenty-first century. Philosophical transactions of the Royal Society A: mathematical, physical and engineering sciences, 369(1934), pp.161-181.
Sutter, J., Gierz, P., Grosfeld, K., Thoma, M. and Lohmann, G., 2016. Ocean temperature thresholds for Last Interglacial West Antarctic Ice Sheet collapse. Geophysical Research Letters, 43(6), pp.2675-2682.