Why We Should All Know & Care About Antarctica
Neumayer Channel, Antarctic Peninsula. Photo by Warren Allmon.
“speak to the earth, and it shall teach thee” -Job 12:8
Antarctica is almost the definition of out-of-the-way, off-the-beaten-path, end-of-the-world places. Words like desolate, extreme, and of course frigid come immediately to mind. Antarctica is regarded by NASA as the closest you can get to visiting another planet without leaving Earth[1]. Antarctica is the only continent with no permanent human residents. It is distant from almost everywhere there are people: 4500 miles from Australia, 3700 miles from South Africa, 3100 miles from New Zealand, and “only” 600 miles from the southern tip of South America. It is the coldest, driest, highest, and windiest continent, and is 98% covered by ice and snow year-round. Although there are 70 permanent scientific bases in Antarctica representing 29 countries, there are no towns or cities or governments. The continent is administered internationally by the Antarctic Treaty, ratified in 1959, which says that it is to be used only for peaceful scientific purposes.[2] It is, for the moment, the place on Earth least modified by human activity (although see below), and an outstanding example of international cooperation.[3]
Map of Antarctica. Image credit: NASA (public domain).
Even a short visit to Antarctica, as I was recently fortunate enough to make as a faculty member accompanying a group traveling with Cornell’s Adult University (CAU), reinforces this extraordinary differentness. Most conspicuous, of course, is the ice. It is everything and everywhere in Antarctica. The ice amounts to 6.4 million cubic miles, with an average thickness of over one mile, holding over 60 percent of the world’s fresh water, equivalent (as author Stephen Pyne puts it in his mesmerizing book The Ice) “to sixty years of global precipitation or forty-six thousand years of flow by the Mississippi River”[4]. The extent and ubiquity of ice in Antarctica both numb and stimulate the eye and mind of a first-time visitor, as does the vocabulary used to describe its endless forms: bergy bits, growlers, pancakes, brash ice, white ice, blue ice, green ice, dirty ice, pack ice, frazil ice, grease ice, new ice, fast ice, and grounded ice, just to name a few. Its ceaselessly variable colors and textures ultimately transcend communication by words, or even photos.
The continent is also vast – as large as all 50 states of the US together – which is a shock if you know it only as the white strip across the bottom of a world map. And its climate is unbelievably harsh, with the Earth’s lowest recorded ground temperature (minus 135.8 °F) and highest recorded wind speed (199 miles per hour). Average temperature in the interior is minus 46.3 °F, with a relatively balmy average on the coast of 14 °F. It is by far the driest continent, with precipitation in the interior averaging less than two inches a year and an overall average precipitation of only 6.5 inches. (For comparison, the average annual temperature in Ithaca, New York is 46.3 °F and average precipitation is 38.29 inches.)[5]
Large tabular iceberg in Cierva Cove, Antarctic Peninsula. Photo by Warren Allmon.
The biology of Antarctica is also strikingly different from everywhere else on Earth. Among the understandably few land organisms, there are only two native species of vascular plants. The largest native land animal is a tiny wingless fly. Life in the seas around the continent is equally strange. As the noted biogeographer John Briggs wrote, Antarctica has ‘‘the world’s most distinctive marine biota’’[6]. The fish fauna, for example, is small in terms of species diversity, but 88% of the 322 known species exist nowhere else, an at least threefold higher level of unique species (endemism) than in faunas from other isolated marine localities. Among these are the notothenioids, a remarkable group of fishes that have diversified to meet the great adaptive challenges and opportunities of life in frigid Antarctic waters. The group is a classic but under-cited example of an “adaptive radiation”, in which numerous species have evolved to fit into a wide variety of ecological roles. Especially noteworthy is their absence of swim bladders, which they have compensated by a combination of skeletal and biochemical innovations, and presence of antifreeze proteins in many of these fishes, which keeps them from perishing in seawater that is below freezing.[7]
Antarctica’s oceans are also home to remarkably large numbers of species of sponges, sea spiders, brittle stars, and snails, although these almost all live in deeper waters than their relatives farther north to avoid being scoured away by ice. Brachiopods and crinoids, probably better known to paleontologists than modern beach combers because they were much more diverse and abundant in the Paleozoic Era (542-250 million years ago), are numerous in Antarctica. Conspicuously missing from most Antarctic marine ecosystems, however, are predators, especially crabs. This also gives a “Paleozoic” feel to these ecosystems. Ominously, such predators are showing up more often now that waters around Antarctica are warming, and this could threaten the native biota.[8]
And of course there are the penguins, six species of which live in and around Antarctica. More about them below.[9]
Yet, as unique and extreme and different as Antarctica is, it is also in important ways entirely representative and exemplary of what is happening to our planet. Antarctica is a place whose past has positioned it as a harbinger of our future.
Geology is Destiny
When I teach historical geology to college students, I frequently tell them that if they do not know the answer to a question – in class or on an exam – they stand a decent chance of being correct if they simply say “plate tectonics”. This is because almost everything about the Earth’s surficial geology can be explained by the theory that its crust is divided into rigid plates that grow at mid-ocean ridges and are destroyed at trenches.
Nowhere is this clearer than Antarctica. Antarctica is where and what it is because of the movement of the tectonic plates that comprise the Earth’s crust. About 250 million years ago, all of the continents were together in a giant supercontinent that geologists call Pangaea. This huge landmass started to break apart (a process that continues today) through the processes of seafloor spreading, with the “southern continents” (South America, Africa, Australia, Antarctica, and India) clinging together a bit longer, in a mass that geologists call Gondwana (or Gondwanaland). This smaller supercontinent moved over the South Pole and then began to come apart. Africa separated around 150 million years ago, and Australia around 85 million years ago. India separated around 130 million years and began its journey toward an eventual collision with southern Asia, which began around 50 million years ago.
These continental rearrangements would ultimately convert Antarctica’s climate from warm and equable to cold and extreme, a change testified to by the continent’s surprisingly rich fossil record. The abundant fossils from James Ross Island and Seymour Island, at the tip of the Antarctic Peninsula date from the Late Cretaceous Period through the end of the Eocene Epoch, roughly from around 70 million to around 35 million years ago. They tell a story of seas filled with mollusks and other marine invertebrates, sharks, birds, and early whales, and landscapes that were home to dinosaurs, forests, and land mammals.[10] (My own museum, the Paleontological Research Institution (PRI), houses one of the largest collections of fossils from Seymour Island in the world. It includes more than 7,000 specimens, most collected by William Zinsmeister, who was a professor at Purdue University from 1983 until his retirement in 2018. Syracuse University paleontologist and long-time PRI Board member Linda Ivany has also contributed specimens to the collection from her work on Seymour Island.)
The change came with the last separation in Gondwana, between South America and Antarctica. What is now the southern tip of South America, Tierra del Fuego, separated from the Antarctic Peninsula around 35 million years ago, at the end of the Eocene. Most geologists think that this split contributed to one of the most momentous events of Earth history in the past 65 million years. The separation formed the Drake Passage between South America and Antarctica, allowing ocean water to flow all the way around the Antarctic continent for the first time. This had the effect of insulating Antarctica from warm water coming from lower latitudes to the north, and refrigerated not only the South Pole but the entire globe.
Ocean current model showing the eddies in the Antarctic Circumpolar Current (ACC). Lighter colors indicate faster water speeds. Image Credit: Los Alamos National Laboratory (Flickr; Creative Commons Attribution-NonCommercial-NoDerivs-2.0 Generic license).
The current that formed around Antarctica when the Drake Passage opened – the Antarctic Circumpolar Current (ACC)[11] – is today the longest and strongest ocean current in the world. Isolated by it from the rest of the global ocean, the water around Antarctica (what we today call the Southern Ocean) became colder, and so did Antarctica. Glacial ice expanded dramatically on the continent and reached the coast (as represented by glacial dropstones – rocks picked up as the glaciers moved across the land – preserved in marine sediments). This cooled ocean water around the continent still further and increased its salinity (through formation of sea ice), causing it to sink and move northward as what oceanographers call Antarctic Bottom Water. This stirred the entire global ocean, bringing nutrients from the depths to the sunlight at the surface and stimulating biological productivity, resulting in, among other momentous events, such as the evolutionary diversification of whales and changes in the types of sediments accumulating on the ocean floors. Antarctic Bottom Water is a major component of Atlantic Meridional Overturning Circulation (AMOC), which is the “conveyor belt” that governs the distribution of temperature and chemistry in much of the world’s oceans (see below).
Above: Visual depiction of the formation of Antarctic Bottom Water. The cold water sinks and then moves northward, contributing to the broader thermohaline circulation of our ocean system. Graphic by “Fred the Oyster” (Wikimedia Commons; Creative Commons Attribution-ShareAlike 4.0 International license).
Left: Antarctica (center) and the ACC are an important part of the ocean circulation “conveyor belt.” Warm water (red) moves to Antarctica, cools, sinks, and thus turns into Antarctic Bottom water (blue) which moves northward as part of the Atlantic Meridional Overturning Circulation (AMOC). Graphic by “Avsa” (Wikimedia Commons; Creative Commons Attribution-ShareAlike 3.0 Unported license).
Antarctica and the ocean that surrounds it have thus been literally at the center of global climate change for millions of years. This appears to still be the case today.
The Present Foretells the Future
The isolation and seeming changelessness of Antarctica are misleading. The continent is changing, in some cases dramatically and rapidly, and the main cause of this change is almost certainly human activity, especially the increase in greenhouse gases in the atmosphere. The change is taking many forms and happening on many fronts, from biology to oceans to climate.
Emperor penguins on Snow Hill Island, Antarctica. Photo by Ian Duffy (Wikimedia Commons; Creative Commons Attribution 2.0 Generic license).
The biology of Antarctica is changing in numerous ways. New species are being introduced, both accidentally through human transportation and naturally as the climate warms and species from lower latitudes find they can survive in the polar region.[12] Disease is also changing. Avian influenza (“bird flu”), previously unknown in Antarctica, was reported for the first time in early 2024 in both seabirds and marine mammals[13]. Populations of some penguin species are declining, perhaps due to climate change and other factors.[14] Several species of albatrosses are threatened by ingesting fishing line and gear.[15] Krill – the tiny pink crustaceans near the base of Antarctic marine food chains – are declining in abundance, likely due to a combination of climate change, overfishing, and the recently rebounding populations of some species of whales in the Southern Ocean.[16]
The most conspicuous changes in the Antarctic are in climate. While the Arctic region has been showing signs of rapid climate change for some time, it had long been assumed that Antarctica was so cold that it would not show the signs of climate change for many decades. It is now clear, however, that this is not the case.
The patterns of climate change in the Antarctic are complex and still incompletely understood. This is for several reasons. First, research on Antarctic climate is still in its early phases; unlike much of the rest of the world, modern scientific work on the southern continent has really only been pursued intensively for the past 70 years or so. Second, Antarctica is a uniquely difficult place in which to do science. And finally, Antarctica’s climate system appears to be genuinely inherently complex.
To summarize: Antarctica is still colder than the Arctic, but it is – overall – warming just as quickly and losing ice. Ice mass loss from the Antarctic Ice Sheet has accelerated over the last four decades, from about 40 billion tons/year in 1979–1990 to about 252 billion tons/year in 2009–2017.[17]
Air temperatures in Antarctica as a whole rose rapidly in the late twentieth century, but different areas saw different patterns. In East Antarctica, temperatures rose slightly between 1958 and 2012, but the trend is not statistically significant.[18] At the South Pole (which is in East Antarctica), temperatures have cooled in recent decades (perhaps due to fewer warm ocean air masses reaching the continent’s interior).[19] In West Antarctica, multiple recent studies report warming (e.g., temperature increase of between 2 and 6 °F between 1958 and 2010).[20]
There was a slight overall increase in Antarctic sea-ice extent from 1979 to 2014. After this, sea-ice declined steeply and has since exhibited large year-to-year fluctuations, but around a lower average extent. In 2022 low sea ice contributed to a “catastrophic breeding failure” of emperor penguins, in which 80% of chicks on sea ice in the Bellingshausen Sea, an area along the west side of the Antarctic Peninsula, drowned.[21] Sea ice was at a historic low in 2023, when researchers concluded that a "regime shift" may be taking place “in which previously important relationships no longer dominate sea ice variability”.[22]An analysis of the variability of summer sea ice around Antarctica just published in April 2024 similarly finds that patterns “are consistent with theoretical indicators of a critical transition, or regime shift” in the continent’s sea ice system.[23]
These are not the only examples of scientists warning, in wording unusual for peer-reviewed research papers, that what have come to be known as “tipping points” – critical points in a situation, process, or system beyond which significant and often unstoppable changes take place – may be happening in Antarctic climate. Change in the West Antarctic Ice Sheet (WAIS) (particularly the Pine Island and Thwaites glaciers) is especially concerning, and may be past its tipping point and in danger of imminent collapse.[24] An innovative recent study used analysis of the genetics of an octopus species living around West Antarctica to infer that during the Last Interglacial Period, 125,000 years ago (the last time the Earth was as warm as it is today), the WAIS was mostly or completely absent, allowing the octopuses to traverse the Antarctic Peninsula, much of which is below sea level.[25] This suggests that the modern WAIS may indeed be on borrowed time. The melting of the entire WAIS would raise global sea level by as much as 15 feet.[26]
Still more evidence of the central place of Antarctica in the global ocean comes from a study just published this month (April 19, 2024) suggesting that warming of waters around Antarctica is slowing the AMOC, reducing the northward movement of cooler water and thereby causing higher sea level in the North Atlantic as the warmer waters expand.[27] The lead author of the study notes: "Although these regions are tens of thousands of miles away from each other and abyssal areas are a few miles below the ocean surface, our results reinforce the notion that even the most remote areas of the world's oceans are not untouched by human activity".[28]
The Meaning of Antarctica
“Meaning” is a human construct. Places have no inherent meaning, only what we give, or take from them, what they stimulate in us. But such feelings nevertheless have enormous significance for what inspires and motivates us, and gets us out of bed in the morning. It is in this context that the words of Argentinian Antarctic experts Izaguirre Irina and Gabriela Mataloni resonate. In a recent book, they wrote:
“…it must be taken into account how full of meaning Antarctica is for the whole of mankind, as the only continent which has been preserved for the ages in a pristine state and the one where all countries have agreed on permanent peace. Antarctica is devoted to science and peace, and so it should remain forever.”[29]
Antarctica has been at the literal center of global oceans and climate for 100 million years, and it still is. Antarctica’s unique geological history informs us about its future, but that future is also representative of the rest of the Earth. The white continent is thus both different and entirely typical. And it is telling us something. Antarctica is the least human-influenced continent, a place we thought would be the last to change and change the least. But Antarctica is clearly changing now, faster and sooner than we thought it would. Antarctica is the only “international continent”, dedicated to peace and science, but that could change too as nations struggle for power, influence, and increasingly scarce resources. In so many ways, Antarctica is the continent of the twenty-first century, and we should all know and care about that.
Brash and pancake ice in Cierva Cove, Antarctic Peninsula. Photo by Warren Allmon.
Acknowledgements
Thanks to Alex Allmon, Tom Cronin, Linda Ivany, and Jennifer Tegan for comments on previous drafts.
Notes
[2] Secretariat of the Antarctic Treaty: https://www.ats.aq/index_e.html
[3] An excellent introduction to the people and nations who do science in Antarctica is given in Walker (2013).
[4] Pyne (1986: 10).
[6] Briggs (2003), quoted in Eastman (2005).
[7] Excellent introductions to the biota and environments of Antarctica can be found in books by Moss (1988), Shirihai (2007), and Fox (2019).
[8] Aronson et al. (2015), and references therein.
[10] For descriptions of the geology and paleontology of James Ross and Seymour Islands, see Stilwell and Long (2011), and Witts et al. (2016).
[11] This date for the formation of the ACC has long been the consensus opinion of most geologists, but a recent study (Evangelinos et al., 2024) argues that the ACC actually formed much later, in the Late Miocene, about 14 million years ago. There is also strong evidence that a decline in concentration of carbon dioxide in the atmosphere contributed to the cooling (see, e.g., Pagani et al., 2011; CenCO2PIP Consortium, 2023). This CO2 decline, in turn, may have been triggered by a combination of slowing of seafloor spreading and its associated volcanism and uplift of the Himalayas, which increased weathering of rocks which absorbs CO2. So plate tectonics is the ultimate cause in any case!
[18] Nicolas and Bromwich (2014).
[19] Turner et al. (2014).
[20] Bromwich et al. (2013).
[21] Fretwell et al. (2023).
[22] Purich and Doddridge (2023). See also https://earthobservatory.nasa.gov/images/151692/exceptionally-low-antarctic-sea-ice
[23] Hobbs et al. (2024).
[24] Schmidt et al. (2023); Naughten et al. (2023). See also https://www.ipcc.ch/report/ar6/wg1/downloads/factsheets/IPCC_AR6_WGI_Regional_Fact_Sheet_Polar_regions.pdf; and https://www.bas.ac.uk/data/our-data/publication/antarctic-tipping-points/
[25] Lau et al. (2023).
[27] Biló et al. (2024).
[29] Izaguirre and Mataloni (2000); translated by Ines Hujvat.
References and Further Reading
Aronson, R.B., M. Frederich, R. Price, and S. Thatje, 2015. Prospects for the return of shell-crushing crabs to Antarctica. Journal of Biogeography, 42: 1–7. doi: 10.1111/jbi.12414
Biló, T.C., R.C. Perez, S. Dong, W. Johns, and T. Kanzow, 2024. Weakening of the Atlantic Meridional Overturning Circulation abyssal limb in the North Atlantic. Nature Geoscience. doi: 10.1038/s41561-024-01422-4
Briggs, J.C., 2003. Marine centres of origin as evolutionary engines. Journal of Biogeography, 30:1–18. doi: 10.1046/j.1365-2699.2003.00810.x
Bromwich, D.H., J.P. Nicolas, A.J. Monaghan, M.A. Lazzara, L.M. Keller, G.A. Weidner, and A.B. Wilson, 2013. Central West Antarctica among the most rapidly warming regions on Earth. Nature Geoscience, 6(2): 139-145. doi: 10.1038/ngeo1671
CenCO2PIP Consortium, 2023. Toward a Cenozoic history of atmospheric CO2. Science, 382(6675). doi: 10.1126/science.adi5177
Eastman, J.T., 2005. The nature of the diversity of Antarctic fishes. Polar Biology, 28: 93–107. doi: 10.1007/s00300-004-0667-4
Evangelinos, D., J. Etourneau, T. van de Flierdt, X. Crosta, C. Jeandel, J.A. Flores, D.M. Harwood, L. Valero, E. Ducassou, I. Sauermilch, and A. Klocker, 2024. Late Miocene onset of the modern Antarctic Circumpolar Current. Nature Geoscience, pp.1-6. doi: 10.1038/s41561-023-01356-3
Fox, A., ed., 2019. The Antarctic Peninsula. A visitor’s guide. The Natural History Museum and British Antarctic Survey, London, 144 p.
Fretwell, P.T., A. Boutet, and N. Ratcliffe, 2023. Record low 2022 Antarctic sea ice led to catastrophic breeding failure of emperor penguins. Communications Earth & Environment, 4(1): 273. doi: 10.1038/s43247-023-00927-x
Hobbs, W., P. Spence, A. Meyer, S. Schroeter, A.D. Fraser, P. Reid, T.R. Tian, Z. Wang, G. Liniger, E.W. Doddridge, and P.W. Boyd, 2024. Observational evidence for a regime shift in summer Antarctic sea ice. Journal of Climate, 37(7): 2263-2275. doi: 10.1175/JCLI-D-23-0479.1
Izaguirre, I., and G. Mataloni, 2000. Antártida. Descubriendo el continente blanco. Nuevo Extremo, Buenos Aires, Argentina, 187 p.
Jones, J.M., S.T. Gille, H. Goosse, N.J. Abram, P.O. Canziani, D.J. Charman, K.R. Clem, X. Crosta, C. De Lavergne, I. Eisenman, and M.H. England, 2016. Assessing recent trends in high-latitude Southern Hemisphere surface climate. Nature Climate Change, 6(10): 917-926. doi: 10.1038/nclimate3103
Lau, S.C., N.G. Wilson, N.R. Golledge, T.R. Naish, P.C. Watts, C.N. Silva, I.R. Cooke, A.L. Allcock, F.C. Mark, K. Linse, and J.M. Strugnell, 2023. Genomic evidence for West Antarctic Ice Sheet collapse during the Last Interglacial. Science, 382: 1384-1389. doi: 10.1126/science.ade0664
Moss, S., 1988. Natural history of the Antarctic peninsula. Columbia University Press, New York, 208 p.
Naughten, K.A., P.R. Holland, and J. De Rydt, 2023. Unavoidable future increase in West Antarctic ice-shelf melting over the twenty-first century. Nature Climate Change, 13(11): 1222-1228. doi: 10.1038/s41558-023-01818-x
Nicolas, J.P., and D.H. Bromwich, 2014. New reconstruction of Antarctic near-surface temperatures: Multidecadal trends and reliability of global reanalyses. Journal of Climate, 27(21): 8070-8093. doi: 10.1175/JCLI-D-13-00733.1
Pagani, M., M. Huber, Z. Liu, S.M. Bohaty, J. Henderiks, W. Sijp, S. Krishnan, and R.M. DeConto, 2011, The role of carbon dioxide during the onset of Antarctic glaciation. Science, 334: 1261-1264. doi: 10.1126/science.1203909
Purich, A., and E.W. Doddridge, 2023. Record low Antarctic sea ice coverage indicates a new sea ice state. Communications Earth & Environment. 4: 314. doi: 10.1038/s43247-023-00961-9
Pyne, S.J., 1986. The ice. A journey to Antarctica. University of Iowa Press, Iowa City, 428 p.
Schmidt, B.E., P. Washam, P.E. Davis, K.W. Nicholls, D.M. Holland, J.D. Lawrence, K.L. Riverman, J.A. Smith, A. Spears, D.J.G. Dichek, and A.D. Mullen, 2023. Heterogeneous melting near the Thwaites Glacier grounding line. Nature, 614: 471-478. doi: 10.1038/s41586-022-05691-0
Shirihai, H., 2007. A complete guide to Antarctic wildlife. The birds and marine mammals of the Antarctic continent and the Southern Ocean. 2nd ed. Bloomsbury Publishing, London, 544 p.
Stilwell, J.D., and J.A. Long, 2011. Frozen in time. Prehistoric life in Antarctica. CSIRO Publishing, Collingwood, Victoria, Australia, 237 p.
Turner, J., N.E. Barrand, T.J. Bracegirdle, P. Convey, D.A. Hodgson, M. Jarvis, A. Jenkins, G. Marshall, M.P. Meredith, H. Roscoe, and J. Shanklin, 2014. Antarctic climate change and the environment: an update. Polar Record, 50(3): 237-259. doi: 10.1017/s0032247413000296
Turner, J., H. Lu, I. White, J.C. King, T. Phillips, J.S. Hosking, T.J. Bracegirdle, G.J. Marshall, R. Mulvaney, and P. Deb, 2016, Absence of 21st century warming on Antarctic Peninsula consistent with natural variability. Nature, 535(7612), pp.411-415. doi: 10.1038/nature18645
Walker, G., 2013. Antarctica. An intimate portrait of a mysterious continent. Harper, New York, 416 p.
Witts, J.D., R.J. Whittle, P.B. Wignall, J.A. Crame, J.E. Francis, R.J. Newton, and V.C. Bowman, 2016. Macrofossil evidence for a rapid and severe Cretaceous–Paleogene mass extinction in Antarctica. Nature Communications, 7(1): 11738. doi: 10.1038/ncomms11738