Sustained Antarctic Research: A 21st Century Imperative

Abstract

The view from the south is, more than ever, dominated by ominous signs of change. Antarctica and the Southern Ocean are intrinsic to the Earth system, and their evolution is intertwined with and influences the course of the Anthropocene. In turn, changes in the Antarctic affect and presage humanity's future. Growing understanding is countering popular beliefs that Antarctica is pristine, stable, isolated, and reliably frozen. An aspirational roadmap for Antarctic science has facilitated research since 2014. A renewed commitment to gathering further knowledge will quicken the pace of understanding of Earth systems and beyond. Progress is already evident, such as addressing uncertainties in the causes and pace of ice loss and global sea-level rise. However, much remains to be learned. As an iconic global “commons,” the rapidity of Antarctic change will provoke further political action. Antarctic research is more vital than ever to a sustainable future for this One Earth. The view from the south is, more than ever, dominated by ominous signs of change. Antarctica and the Southern Ocean are intrinsic to the Earth system, and their evolution is intertwined with and influences the course of the Anthropocene. In turn, changes in the Antarctic affect and presage humanity's future. Growing understanding is countering popular beliefs that Antarctica is pristine, stable, isolated, and reliably frozen. An aspirational roadmap for Antarctic science has facilitated research since 2014. A renewed commitment to gathering further knowledge will quicken the pace of understanding of Earth systems and beyond. Progress is already evident, such as addressing uncertainties in the causes and pace of ice loss and global sea-level rise. However, much remains to be learned. As an iconic global “commons,” the rapidity of Antarctic change will provoke further political action. Antarctic research is more vital than ever to a sustainable future for this One Earth. Antarctica and the Southern Ocean (“the Antarctic”) are intrinsic to the Earth system. Although remote, the Antarctic region is interconnected with the northern world by oceanic and atmospheric couplings, geopolitics, and international agreements. Climate variability and change are transmitted from low to high latitudes. In turn, change in the Antarctic has profound implications for the rest of the planet. The fate of Antarctic ice sheets determines, to a large degree, sea level, and the Southern Ocean plays a dominant role in global heat and greenhouse gas budgets. Therefore, scientific investigations of the Antarctic are critical to understanding the history and future trajectories of our planet.1Dutton A. Carlson A.E. Long A.J. Milne G.A. Clark P.U. DeConto R. Horton B.P. Rahmstorf S. Raymo M.E. 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Lett. 2018; 11: e12372Crossref Scopus (3) Google Scholar The global value of sustained scientific research in the Antarctic is best illustrated by policy responses to observations of ozone depletion over Antarctica. Long-term stratospheric ozone monitoring from the Antarctic continent led to the recognition of a developing ozone hole above Antarctica in the mid-1980s.14Farman J.C. Gardiner B.G. Shanklin J.D. Large losses of total ozone in Antarctica reveal seasonal ClOx/NOx interaction.Nature. 1985; 315: 207-210Crossref Scopus (0) Google Scholar Realization of the implications for life on Earth was swift and yielded an unprecedented rapid, globally agreed response to phase out the chlorofluorocarbons (CFCs) responsible for depletion. Discerning a causal link between the strengthening and poleward shift of the westerly winds over the Southern Ocean, along with their influence on Antarctic life, transformed the debate.15Bornman J.F. Barnes P.W. Robson T.M. Robinson S.A. Jansen M.A.K. Ballaré C.L. Flint S.D. Linkages between stratospheric ozone, UV radiation and climate change and their implications for terrestrial ecosystems.Photochem. Photobiol. Sci. 2019; 18: 681-716Crossref PubMed Google Scholar, 16Weimerskirch H. Louzao M. de Grissac S. Delord K. Changes in wind pattern alter albatross distribution and life-history traits.Science. 2012; 335: 211-214Crossref PubMed Scopus (167) Google Scholar, 17Wang G. Hendon H.H. Arblaster J.M. Lim E.-P. Abhik S. van Rensch P. Compounding tropical and stratospheric forcing of the record low Antarctic sea-ice in 2016.Nat. Commun. 2019; 1013Crossref PubMed Scopus (6) Google Scholar Continued long-term assessment of these changes and system-wide effects will be critical if international goals are to be met. Some complexity remains, with indications that, despite the universal ratification of the Montreal Protocol18United Nations Development Program. Montreal Protocol. https://www.undp.org/content/undp/en/home/2030-agenda-for-sustainable-development/planet/environment-and-natural-capital/montreal-protocol.html.Google Scholar and its instruments, CFC-11 (trichlorofluoromethane) concentrations in the atmosphere are increasing.19Montzka S.A. Dutton G.S. Yu P. Ray E. Portmann R.W. Daniel J.S. Kuijpers L. Hall B.D. Mondeel D. Siso C. et al.An unexpected and persistent increase in global emissions of ozone-depleting CFC-11.Nature. 2018; 557: 413-417Crossref PubMed Scopus (74) Google Scholar This is an example of how Antarctic observations and research are critical to identifying global threats and assessing the efficacy of control measures. Today, Antarctic observations play a similar role regarding climate change and sea-level rise. Five years ago, a community-driven process identified the highest priorities and set an ambitious agenda for Antarctic research (Box 1).20Kennicutt M.C. Chown S.L. Cassano J.J. Liggett D. Massom R. Peck L.S. Rintoul S.R. Storey J.W.V. Vaughan D.G. Wilson T.J. et al.Polar research: six priorities for Antarctic science.Nat. News. 2014; 512: 23Crossref PubMed Scopus (0) Google Scholar, 21Kennicutt M.C. Chown S.L. Cassano J.J. Liggett D. Peck L.S. Massom R. Rintoul S.R. Storey J. Vaughan D.G. Wilson T.J. et al.A roadmap for Antarctic and Southern Ocean science for the next two decades and beyond.Antarct. Sci. 2015; 27: 3-18Crossref Scopus (70) Google Scholar Horizon Scanning—a systematic approach to retrieve, sort, organize, and prioritize information pertinent to the question posed—was used to identify the most important scientific questions from many.22Wintle, B.C., Kennicutt, and Sutherland, W.J. Scanning horizons in research, policy and practice. In Conservation Research, Policy and Practice. Sutherland, W.J., Brotherton, P., Davies, Z., Pettorelli, N., Vira, B., Vickery, J., eds. (Cambridge University). https://doi.org/10.1017/9781108638210.Google Scholar The first Antarctic Science Horizon Scan (“the Scan”) was followed by an assessment of the technology and infrastructure required to deliver the research. The Antarctic Roadmap Challenges (“the ARC”; Box 1) assessment included estimates of both cost and time to delivery.23Kennicutt M.C. Kim Y.D. Rogan-Finnemore M. Anandakrishnan S. Chown S.L. Colwell S. Cowan D. Escutia C. Frenot Y. Hall J. et al.Delivering 21st century Antarctic and Southern Ocean science.Antarct. Sci. 2016; 28: 407-423Crossref Scopus (14) Google Scholar It was recognized that identifying questions was a first step, but answers were the goal. The ARC provided a path to implementation.Box 1The First Antarctic and Southern Ocean Science Horizon Scan and the Antarctic Roadmap Challenges (ARC) Project: The ProcessThe first Antarctic and Southern Ocean Science Horizon Scan (the Scan)20Kennicutt M.C. Chown S.L. Cassano J.J. Liggett D. Massom R. Peck L.S. Rintoul S.R. Storey J.W.V. Vaughan D.G. Wilson T.J. et al.Polar research: six priorities for Antarctic science.Nat. News. 2014; 512: 23Crossref PubMed Scopus (0) Google Scholar was based on wide consultation with the community to develop a collective, international view of the most important future directions in Antarctic research.20Kennicutt M.C. Chown S.L. Cassano J.J. Liggett D. Massom R. Peck L.S. Rintoul S.R. Storey J.W.V. Vaughan D.G. Wilson T.J. et al.Polar research: six priorities for Antarctic science.Nat. News. 2014; 512: 23Crossref PubMed Scopus (0) Google Scholar, 21Kennicutt M.C. Chown S.L. Cassano J.J. Liggett D. Peck L.S. Massom R. Rintoul S.R. Storey J. Vaughan D.G. Wilson T.J. et al.A roadmap for Antarctic and Southern Ocean science for the next two decades and beyond.Antarct. Sci. 2015; 27: 3-18Crossref Scopus (70) Google Scholar A final list of 80 highest priority questions, distilled from nearly 1,000 questions submitted by the community, was agreed at a retreat attended by 75 representatives from 22 countries.24Scientific Committee on Antarctic Research. The Horizon Scan. https://www.scar.org/about-us/horizon-scan/process/.Google Scholar Attendees included researchers, national program directors or managers, and policy makers. Retreat participants were selected to ensure balance among disciplinary expertise, geographical origins, gender, stage of career, and representation of SCAR partner organizations and other stakeholders. The Scan outcomes were articulated as an “Antarctic Science Roadmap” (the Roadmap).21Kennicutt M.C. Chown S.L. Cassano J.J. Liggett D. Peck L.S. Massom R. Rintoul S.R. Storey J. Vaughan D.G. Wilson T.J. et al.A roadmap for Antarctic and Southern Ocean science for the next two decades and beyond.Antarct. Sci. 2015; 27: 3-18Crossref Scopus (70) Google Scholar A new team of 60 experts was assembled to conduct the Antarctic Roadmap Challenges (ARC) project.23Kennicutt M.C. Kim Y.D. Rogan-Finnemore M. Anandakrishnan S. Chown S.L. Colwell S. Cowan D. Escutia C. Frenot Y. Hall J. et al.Delivering 21st century Antarctic and Southern Ocean science.Antarct. Sci. 2016; 28: 407-423Crossref Scopus (14) Google Scholar, 25Council of Managers of National Antarctic Programs. Antarctic roadmap challenges. https://www.comnap.aq/Projects/SitePages/ARC.aspx.Google Scholar Participants included logisticians and operations experts, experienced Antarctic researchers, policy makers, select Scan contributors, and national Antarctic program personnel from 22 countries. A workshop was convened to consider a series of papers submitted by the Antarctic science community, survey results, summaries from the Scan, and other documents addressing future Antarctic research directions, essential technologies, and logistics requirements. The ARC project answered the question, “How will national Antarctic programs meet the challenges of delivery of Antarctic science over the next 20 years?” As entities that fund and support Antarctic science, national Antarctic programs face many practical and technical issues. ARC addressed four of seven challenges: availability of essential technologies, extraordinary logistics requirements (access), supporting infrastructure and international cooperation.23Kennicutt M.C. Kim Y.D. Rogan-Finnemore M. Anandakrishnan S. Chown S.L. Colwell S. Cowan D. Escutia C. Frenot Y. Hall J. et al.Delivering 21st century Antarctic and Southern Ocean science.Antarct. Sci. 2016; 28: 407-423Crossref Scopus (14) Google Scholar Challenges related to human resources, energy demands, and long-term sustainable funding were not considered. The first Antarctic and Southern Ocean Science Horizon Scan (the Scan)20Kennicutt M.C. Chown S.L. Cassano J.J. Liggett D. Massom R. Peck L.S. Rintoul S.R. Storey J.W.V. Vaughan D.G. Wilson T.J. et al.Polar research: six priorities for Antarctic science.Nat. News. 2014; 512: 23Crossref PubMed Scopus (0) Google Scholar was based on wide consultation with the community to develop a collective, international view of the most important future directions in Antarctic research.20Kennicutt M.C. Chown S.L. Cassano J.J. Liggett D. Massom R. Peck L.S. Rintoul S.R. Storey J.W.V. Vaughan D.G. Wilson T.J. et al.Polar research: six priorities for Antarctic science.Nat. News. 2014; 512: 23Crossref PubMed Scopus (0) Google Scholar, 21Kennicutt M.C. Chown S.L. Cassano J.J. Liggett D. Peck L.S. Massom R. Rintoul S.R. Storey J. Vaughan D.G. Wilson T.J. et al.A roadmap for Antarctic and Southern Ocean science for the next two decades and beyond.Antarct. Sci. 2015; 27: 3-18Crossref Scopus (70) Google Scholar A final list of 80 highest priority questions, distilled from nearly 1,000 questions submitted by the community, was agreed at a retreat attended by 75 representatives from 22 countries.24Scientific Committee on Antarctic Research. The Horizon Scan. https://www.scar.org/about-us/horizon-scan/process/.Google Scholar Attendees included researchers, national program directors or managers, and policy makers. Retreat participants were selected to ensure balance among disciplinary expertise, geographical origins, gender, stage of career, and representation of SCAR partner organizations and other stakeholders. The Scan outcomes were articulated as an “Antarctic Science Roadmap” (the Roadmap).21Kennicutt M.C. Chown S.L. Cassano J.J. Liggett D. Peck L.S. Massom R. Rintoul S.R. Storey J. Vaughan D.G. Wilson T.J. et al.A roadmap for Antarctic and Southern Ocean science for the next two decades and beyond.Antarct. Sci. 2015; 27: 3-18Crossref Scopus (70) Google Scholar A new team of 60 experts was assembled to conduct the Antarctic Roadmap Challenges (ARC) project.23Kennicutt M.C. Kim Y.D. Rogan-Finnemore M. Anandakrishnan S. Chown S.L. Colwell S. Cowan D. Escutia C. Frenot Y. Hall J. et al.Delivering 21st century Antarctic and Southern Ocean science.Antarct. Sci. 2016; 28: 407-423Crossref Scopus (14) Google Scholar, 25Council of Managers of National Antarctic Programs. Antarctic roadmap challenges. https://www.comnap.aq/Projects/SitePages/ARC.aspx.Google Scholar Participants included logisticians and operations experts, experienced Antarctic researchers, policy makers, select Scan contributors, and national Antarctic program personnel from 22 countries. A workshop was convened to consider a series of papers submitted by the Antarctic science community, survey results, summaries from the Scan, and other documents addressing future Antarctic research directions, essential technologies, and logistics requirements. The ARC project answered the question, “How will national Antarctic programs meet the challenges of delivery of Antarctic science over the next 20 years?” As entities that fund and support Antarctic science, national Antarctic programs face many practical and technical issues. ARC addressed four of seven challenges: availability of essential technologies, extraordinary logistics requirements (access), supporting infrastructure and international cooperation.23Kennicutt M.C. Kim Y.D. Rogan-Finnemore M. Anandakrishnan S. Chown S.L. Colwell S. Cowan D. Escutia C. Frenot Y. Hall J. et al.Delivering 21st century Antarctic and Southern Ocean science.Antarct. Sci. 2016; 28: 407-423Crossref Scopus (14) Google Scholar Challenges related to human resources, energy demands, and long-term sustainable funding were not considered. Since then, the imperatives for Antarctic research have grown. Climate change poses an existential threat to society and the future of the planet, with the urgent need “… to bring all nations into a common cause to undertake ambitious efforts to combat climate change and adapt to its effects ….”26United Nations Climate Change. The Paris Agreement. https://unfccc.int/process-and-meetings/the-paris-agreement/the-paris-agreement.Google Scholar Scientific understanding of the Antarctic is essential for this common cause. This is clearly articulated in the alternatives for the region presented from a 2070 vantage: one presenting an environmentally, as well as a politically, unrecognizable Antarctic region and world; and the other closer to that experienced throughout human history.9Rintoul S.R. Chown S.L. DeConto R.M. England M.H. Fricker H.A. Masson-Delmotte V. Naish T.R. Siegert M.J. Xavier J.C. Choosing the future of Antarctica.Nature. 2018; 558: 233-241Crossref PubMed Scopus (17) Google Scholar Here, we review progress against the priorities set out by the Scan and ARC, recognizing across each theme where progress has been made, where it is lagging, and what new challenges have arisen. In doing so, we recognize that the delivery of evidence does not guarantee a change in policy and that opinions vary on what policies should be adopted among the diverse stakeholders, states, and constituencies that are the 21st century world. The progress assessment is ordered according to the seven clusters of questions identified by the Scan: (1) Antarctic atmosphere and global connections, (2) Southern Ocean and sea ice in a warming world, (3) ice sheets and sea level, (4) the dynamic Earth: probing beneath Antarctic ice, (5) life on the precipice, (6) near-Earth space and beyond, and (7) human presence in Antarctica.21Kennicutt M.C. Chown S.L. Cassano J.J. Liggett D. Peck L.S. Massom R. Rintoul S.R. Storey J. Vaughan D.G. Wilson T.J. et al.A roadmap for Antarctic and Southern Ocean science for the next two decades and beyond.Antarct. Sci. 2015; 27: 3-18Crossref Scopus (70) Google Scholar An eighth topic, regarding effective engagement of diverse audiences, assesses the impact, delivery, and uptake of the Scan and ARC outputs with a goal of discerning lessons learned for effective communication that influences societal actions. Experts assessed progress by reviewing the scientific literature published in the last 5 years (Tables S1–S15). A transdisciplinary and critical perspective on progress was assured by including stakeholder representatives and others not involved in the Scan or ARC projects. Indications of progress do not infer that the Scan was the cause, as much research was already underway and other non-scientific factors were at play. The notation Q.## refers to specific Scan questions (Tables S1–S14).20Kennicutt M.C. Chown S.L. Cassano J.J. Liggett D. Massom R. Peck L.S. Rintoul S.R. Storey J.W.V. Vaughan D.G. Wilson T.J. et al.Polar research: six priorities for Antarctic science.Nat. News. 2014; 512: 23Crossref PubMed Scopus (0) Google Scholar, 21Kennicutt M.C. Chown S.L. Cassano J.J. Liggett D. Peck L.S. Massom R. Rintoul S.R. Storey J. Vaughan D.G. Wilson T.J. et al.A roadmap for Antarctic and Southern Ocean science for the next two decades and beyond.Antarct. Sci. 2015; 27: 3-18Crossref Scopus (70) Google Scholar Tropical oceans influence Antarctic climate on a variety of time scales via atmospheric teleconnections (Figure 1 and Tables S1 and S2).27Yuan X. Kaplan M.R. Cane M.A. The interconnected global climate system - a review of tropical - polar teleconnections.J. Clim. 2018; 31: 5765-5792Crossref Scopus (6) Google Scholar These tropical impacts are most apparent today in West Antarctica and are primarily linked to the tropical and subtropical Pacific Ocean. El Niño-Southern Oscillation (ENSO) variability on interannual timescales is the most prominent influence. These tropical forces modulate the impacts from the ozone hole in the stratosphere above Antarctica that propagate into the weather-active troposphere. These tropical and polar forces govern the behavior of the westerly winds around Antarctica affecting Southern Ocean circulation, sea-ice extent, heat and carbon sequestration, and oceanic biogeochemistry. The north/south pressure gradient over the Antarctic is expressed as the Southern Annular Mode, and understanding of its variation and change, and the causes and consequences thereof, are improving (Q.1, Q.3, Q.4, and Q.11). There is a growing understanding of the global atmospheric-oceanic coupled system (aka “oceanic-atmospheric bridge”) from model simulations and correlations of observations and how polar modes are relayed through northern and southern mid to low latitudes possibly influencing, and predicting, distant global weather phenomena (e.g., monsoon rainfall patterns).28Liu T. Li J. Li Y. Zhao S. Zheng F. Zheng J. Yao Z. Influence of the may Southern annular mode on The South China Sea summer monsoon.Clim. Dyn. 2018; 51: 4095-4107Crossref Scopus (6) Google Scholar, 29Prabhu A. Kripalani R. Oh J. Preethi B. Can the Southern annular mode influence the Korean summer monsoon rainfall?.Asia Pac. J. Atmos. Sci. 2017; 53: 217-228Crossref Scopus (1) Google Scholar While descriptions of climate variability and change in Antarctica are improving, direct continent-wide observations of atmospheric variables, such as temperature and pressure, only date to the 1950s. Indirect measures of temperatures from ice core records augment observations as far back as 2000 years before present, and the number of ice cores is growing.30Stenni B. Curran M.A.J. Abram N.J. Orsi A. Goursaud S. Masson-Delmotte V. Neukom R. Goosse H. Divine D. van Ommen T. et al.Antarctic climate variability on regional and continental scales over the last 2000 years.Clim. Past. 2017; 13: 1609-1634Crossref Scopus (22) Google Scholar In these records, broad-scale cooling was apparent until 1900 followed by warming in the Antarctic western hemisphere. Spatial extrapolations of surface air temperature measurements demonstrated that warming extends from the Antarctic Peninsula into central West Antarctica, but there has been little or no recent change in East Antarctica.31Nicolas J.P. Bromwich D.H. New reconstruction of Antarctic near-surface temperatures: multidecadal trends and reliability of global reanalyses.J. Clim. 2014; 27: 8070-8093Crossref Scopus (89) Google Scholar Trends in the Southern Annular Mode and tropical influences are suggested as causal factors. Antarctic precipitation for the last 200 years is also derived from reconstructions of ice core records and here too, both record availability and understanding of the underlying variation and its mechanisms is advancing.32Medley B. McConnell J.R. Neumann T.A. Reijmer C.H. Chellman N. Sigl M. Kipfstuhl S. Temperature and snowfall in Western Queen Maud Land increasing faster than climate model projections.Geophys. Res. Lett. 2018; 45: 1472-1480Crossref Scopus (9) Google Scholar Large but opposing trends are found across West Antarctica, especially for recent decades, while precipitation changes are muted in East Antarctica. After considering the influence of the Southern Annular Mode, a steady spatially variable increase in precipitation remains, likely caused by global warming (Q.6 and Q.8).31Nicolas J.P. Bromwich D.H. New reconstruction of Antarctic near-surface temperatures: multidecadal trends and reliability of global reanalyses.J. Clim. 2014; 27: 8070-8093Crossref Scopus (89) Google Scholar The role of extreme atmospheric events in the surface air mass balance above Antarctica is being explored. The impact of the top 10% of daily precipitation events across Antarctica has been evaluated using a regional atmospheric model simulation.33Turner J. Phillips T. Thamban M. Rahaman W. Marshall G.J. Wille J.D. Favier V. Winton V.H.L. Thomas E. Wang Z. et al.The dominant role of extreme precipitation events in Antarctic snowfall variability.Geophys. Res. Lett. 2019; 46: 3502-3511Crossref Scopus (2) Google Scholar A key attribute of precipitation events is the penetration of warm, moist air masses over the ice sheet. Extreme precipitation events dominated the annual total being primarily responsible for interannual variations in snowfall. These results complicate interpretation of ice core records based on annual samples, pointing to the need for finer-scale records. The importance of surface melting for the future evolution of the Antarctic ice sheet was emphasized by the “ice-cliff instability” hypothesis, discussed below and the realization that widespread melting on Antarctic ice shelves could lead to break-up.3DeConto R.M. Pollard D. Contribution of Antarctica to past and future sea-level rise.Nature. 2016; 531: 591-597Crossref PubMed Scopus (522) Google Scholar, 34Kingslake J. Ely J.C. Das I. Bell R.E. Widespread movement of meltwater onto and across Antarctic ice shelves.Nature. 2017; 544: 349-352Crossref PubMed Scopus (35) Google Scholar The extended summer melting event on the Ross Ice Shelf and Marie Byrd Land in 2016 originated from the poleward advection of maritime air into the continent linked to a strong ENSO event in the tropical Pacific Ocean.35Nicolas J.P. Vogelmann A.M. Scott R.C. Wilson A.B. Cadeddu M.P. Bromwich D.H. Verlinde J. Lubin D. Russell L.M. Jenkinson C. et al.January 2016 extensive summer melt in West Antarctica favoured by strong El Niño.Nat. Commun. 2017; 8: 15799Crossref PubMed Scopus (33) Google Scholar Such extreme events may become more frequent as strong ENSOs become more common with consequences for the stability of the Ross and other large ice shelves (Q.2, Q.8, and Q.9). Projected increases in precipitation due to a changing climate may mitigate sea-level rise by partially offsetting ice melt loss.36Medley B. Thomas E.R. Increased snowfall over the Antarctic Ice Sheet mitigated twentieth-century sea-level rise.Nat. Clim. Change. 2019; 9: 34Crossref Scopus (9) Google Scholar Cloud prediction is the largest uncertainty in atmospheric models over land ice, sea ice, and the ocean, with profound impacts on coupling with the underlying surfaces.37Hyder P. Edwards J.M. Allan R.P. Hewitt H.T. Bracegirdle T.J. Gregory J.M. Wood R.A. Meijers A.J.S. Mulcahy J. Field P. et al.Critical Southern Ocean climate model biases traced to atmospheric model cloud errors.Nat. Commun. 2018; 9: 3625Crossre