IP 62

Agenda Item: ATCM 10, ATCM 14, ATCM 16, CEP 3, CEP 9 Presented by: ASOC Original: English

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IP 62

The Antarctic and Climate Change

Information Paper

Submitted by ASOC to the XXIX ATCM

(CEP Agenda Items 3 and 9, ATCM Agenda Items 10, 14 and 16)

I. Introduction

Globally significant scientific research carried out in the Antarctic provides crucial information about the impacts of human activities on global climate change. Hopefully, concentrated climate change research being undertaken by many Antarctic Treaty countries during the International Polar Year (2007-2009) will quickly further our understanding on the complex interactions of the climate system. However, there is already strong and sufficient scientific evidence to indicate that most of the change in global climate in the past 50 years is attributable to human activities, predominantly due to the burning of fossil fuels and release of greenhouse gases into the atmosphere.

The four-yearly assessments of the UN Intergovernmental Panel on Climate Change (IPCC) as well as numerous scientific studies have identified potentially large changes that could take place globally if the consumption of fossil fuels is allowed to continue to rise. Being the largest areas covered in snow and ice on Earth, the Arctic and the Antarctic are, at the same time, extremely important and remarkably vulnerable to global climate change.

This Information Paper provides an overview of recent research in the Antarctic about various aspects of climate change in order to inform ATCM delegates, the public and decision-makers around the world about these research findings.

Based on the evidence flowing from Antarctic research about climate change, ASOC urges all governments to take immediate steps to reduce the risk of dangerous climate change, which is adversely affecting both Antarctic ecosystems and those of the rest of the planet.

II. Overview

Antarctica comprises two geologically distinct regions, East and , separated by the and joined together by the all-encompassing . The is Earth's largest reservoir of fresh water. The presence of the high ice sheet and the polar location make Antarctica a powerful heat sink that strongly affects the climate of the whole Earth. The white surfaces of snow and ice reflect 90% of the sun’s radiation. The annual sea-ice cover around the continent, which seasonally reaches an area greater than that of the continent itself, modulates exchanges of heat, moisture and gases between the atmosphere and ocean. As the sea ice forms each winter, the salt it rejects sinks to the sea floor to form cold dense oxygen-rich Antarctic Bottom Water that flows north under the world’s oceans, driving the “ocean conveyor” and ventilating deep-sea life.

The Antarctic ice sheet contains sufficient ice to raise world-wide sea level by more than 60 meters if melted completely. The greatest short-term threat to the inhabited world comes from the melting of the (WAIS), which rests on a bed far below sea level and has the potential for rapid shrinkage. Its total collapse would raise global sea level by more than 5 m; loss of even a fraction of that ice, which could

3 IP 62 happen within decades, would inundate large portions of the world’s low-lying countries and coastal cities.1 The East Antarctic ice sheet, on the other hand, appears to be thickening, but this is more than offset by losses from West Antarctic.2 The fact that rates of discharge from some Antarctic ice streams have increased markedly in recent decades suggests that the mass balance may also be rapidly changing.

Winter temperatures over the Antarctic continent as well as the have risen by more than 2°C in the past 30 years. The warming in the middle troposphere (the layer of the atmosphere at 5 km above ground) over the Antarctic is the largest regional warming on Earth at this level.3 In western Antarctica, the northerly region of the has experienced rapid warming over the last 50 years and glaciers are shrinking rapidly. In one study on trends in 244 marine glacier fronts on the Antarctic peninsula and associated islands over the past 61 years, 87% were shown to have retreated, and a clear boundary between mean advance and retreat has migrated progressively southward.4 The complete disintegration of Antarctic Peninsula glaciers would raise sea level by about 0.5 meter, and recent research suggests that they are making an as yet unknown contribution to present-day .

"Disintegration of the West Antarctic ice sheet (WAIS) has long served as a benchmark of dangerous climate change. Recent findings with implications for the future of the WAIS may be of importance to policy makers and others grappling with the meaning of Article 2 of the U.N Framework Convention on Climate Change and its injunction to avoid 'dangerous anthropogenic interference with the climate system.' These observations show acceleration of glaciers coupled to abrupt ice-shelf disintegration along the Antarctic Peninsula. The key issue is whether the main body of the ice sheet would behave similarly if its ice shelves were thinned or removed by a warming climate."5

Future enhanced greenhouse warming will affect the mass balance of the ice sheet. Oceanic warming could increase basal melting of the floating ice shelves, whose thinning could result in faster flow of the ice into the ocean, contributing to sea-level rise. Although atmospheric warming and reduction in sea-ice cover almost surely will continue to give rise to increased evaporation over the ocean and increased snowfall on the continent, thereby tending to lower sea level, this will reduce and then go negative as temperatures rise further. A reduction in sea-ice cover would also have significant impacts on ice-dependent species such as penguins and krill, as well as far-reaching consequences on the global ocean circulation.

III. Recent Scientific Research Results

The most recent scientific results make for alarming reading.

A. Ice Cores

Ice cores from the Antarctic continent have provided one of the key pieces of information in understanding humans’ role in global climate change. Ice cores from and revealed that today’s concentration of greenhouse gases in the atmosphere has not been exceeded during the past 650,000 years6 and likely not during the past 20 million years.20 They also showed that the rate of increase of greenhouse gases in the atmosphere over the past century is unprecedented, at least during the past

1 Bindschadler RA, Bentley CR. 2002. On thin ice? Scientific American, 287(6), 98-105; C. R. Bentley. 2002. Antarctica. In T. Munn, ed., Encyclopedia of Global Environmental Change, Volume 1, The Earth system: physical and chemical dimensions of global environmental change, M. C. MacCracken and J. S. Perry, eds, John Wiley & Sons, 184–189. 2 Davis C. H., Li Y., McConnell J. R., Frey M. M. & Hanna E. 2005. Snowfall-driven growth in East Antarctic ice sheet mitigates recent sea-level rise. Science, 308(5730), 1898-1901. 3 Turner, J., Lachlan-Cope, T.A., Colwell, S., Marshall, G.J., Connolley, M. 2006. Significant Warming of the Antarctic Winter Troposphere. Science 311 (5769), 1914-1917. 4 Cook, A.J. et al. 2005. Retreating Glacier Fronts on the Antarctic Peninsula over the Past Half-Century. Science, 308(5721), 541-544. 5 Oppenheimer, M., and R.B. Alley. 2004. The West Antarctic Ice Sheet and Long Term Climate Policy. Climatic Change, 64(1-2), 1-10. 6 Spahni, R. et al., 2005. Atmospheric methane and nitrous oxide of the Late from Antarctic ice cores. Science. 310(5752):1285-7. 4 IP 62

20,000 years. Using these data, researchers found a close correlation between global temperature and greenhouse gas concentrations in the atmosphere over the past 420,000 years,7 supporting the link between human use of fossil fuels and global climate change that is already evident from isotopic measurements showing a significant fossil fuel imprint on carbon in the earth’s atmosphere.

B. Mass Balance of the Ice Sheet

By using satellite measurements of Earth’s gravity field, researchers from the University of Colorado determined mass variations of the Antarctic ice sheet during 2002-2005, finding that the ice sheet mass decreased significantly, at a rate of 152 ± 80 km3/year of ice. Most of this mass loss came from the West Antarctic Ice Sheet.8 The resultant equivalent rise in global sea level amounts to 0.4 ± 0.2 mm/year, which is 10-30% of the rate of global sea level rise measured over the 20th century.

In the most comprehensive survey ever undertaken of the ice sheets covering both Greenland and Antarctica, NASA scientists confirm that climate warming is changing how much water remains locked in Earth's largest storehouses of ice and snow. "If the trends we're seeing continue and climate warming continues as predicted, the polar ice sheets could change dramatically," said survey lead author Jay Zwally of NASA's Goddard Space Flight Center, Greenbelt, Md. The survey shows that there was a net loss of ice from the combined polar ice sheets between 1992 and 2002 and a corresponding rise in sea level. It documented for the first time extensive thinning of the West Antarctic ice shelves. Net loss of ice from Antarctic was estimated to be about 31 billion tons per year.9

C. West Antarctic Ice Sheet, Melting Glaciers and Disintegrating Ice Shelves

Based on the latest evidence, the WAIS is thought by some in the scientific community to be capable of catastrophic disintegration due to global warming, which could raise sea levels by 5 metres in a few centuries.

British Antarctic Survey (BAS) 2005 reports on the melting of Antarctic Peninsula glaciers indicate that they are melting much faster than previously predicted. Some have concluded that the melting of these glaciers is already likely contributing a non-negligible part to sea level rise.10 In the sector of West Antarctica, accelerating glacier melt is now discharging enough excess ice to raise sea level more than 0.2 mm per year; this is the sector widely believed to be the most vulnerable portion of the WAIS, with the potential for a further rapid acceleration of ice discharge.11

The stability of Antarctic ice shelves in a warming climate has long been discussed, and the recent collapse of a significant part of the Larsen ice shelf off the Antarctic Peninsula has led to a refocus on the implications of ice shelf decay for the stability of Antarctica's grounded ice. Records from six marine sediment cores in the vicinity of the Larsen ice shelf demonstrate that the recent collapse of the Larsen B ice shelf is unprecedented during the Holocene - since the end of the last ice age more than 10,000 years ago. This research implies that the Larsen B ice shelf has been thinning throughout the Holocene, and that the recent prolonged period of warming in the Antarctic Peninsula region, in combination with the long-term thinning, has led to the collapse of the ice shelf.12

7 Petit, J.R., et al. 1999. Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica. Nature 399: 429-436. 8 Isabella Velicogna and John Wahr, Measurements of Time-Variable Gravity Show Mass Loss in Antarctica, Published online March 2 2006; 10.1126/science.1123785 (Science Express Reports) 9 Zwally, H.J., M.B. Giovinetto, J. Li, H.G. Cornejo, M.A. Beckley, A.C. Brenner, J.L. Saba, and D. Yi. 2005. Mass changes of the Greenland and Antarctic ice sheets and shelves and contributions to sea-level rise: 1992-2002. Journal of Glaciology, 51(175), 509-527. 10 Rignot, E. et al. 2005. Recent ice loss from the Fleming and other glaciers, Wordie Bay, West Antarctic Peninsula. Geophysical Research Letters, 32(7), L07502 10.1029/2004GL021947; Cook, A.J. et al. 2005. Retreating Glacier Fronts on the Antarctic Peninsula over the Past Half-Century. Science, 308(5721), 541-544. 11 Thomas, R., et al. 2004. Accelerated Sea-Level Rise from West Antarctica. Science, 306 (5694), 255-258. 12 Domack, E., et al. 2005. Stability of the Larsen B ice shelf on the Antarctic Peninsula during the Holocene epoch. Nature, Vol. 436, 681-685. 5 IP 62

Reduction or loss of a restraining ice shelf will cause speed-up of flow from contiguous ice streams, contributing to sea-level rise. Loss of buttressing for an ice stream similar to , West Antarctica is modeled to contribute at least 1 mm of sea-level rise over a few decades.13 Satellite radar measurements show that ice shelves in Pine Island Bay have thinned by up to 5.5 meters per year over the past decade. The thinning of the ice shelves, apparently from ocean currents on average 0.5°C warmer than freezing, is mirrored by the thinning of their tributaries - Pine Island, Thwaites and Smith glaciers. The imbalance of the glaciers in response to the thinning of the ice shelves shows that Antarctica is more sensitive to changing climates than was previously considered.14 A growing body of observational data suggests that Pine Island Glacier in West Antarctica is changing on decadal or shorter time scales. These changes may have far-reaching consequences for the future of the West Antarctic ice sheet (WAIS) and global sea levels because of the glacier's role as one of the ice sheet's primary drainage portals. The speed at which these changes are propagated upstream implies a tight coupling between the ice-sheet interior and the surrounding ocean.15

Antarctic Peninsula glaciers that fed the former Larsen B ice shelf sped up by factors of two to eight following the collapse of the ice shelf in 2002. In contrast, glaciers further south did not accelerate as they are still buttressed by an ice shelf. The mass loss associated with the flow acceleration exceeds 27 cubic kilometers per year and ice is thinning at rates of tens of meters per year. This abrupt evolution of the glaciers is attributed to the removal of the buttressing ice shelf. The magnitude of the glacier changes illustrates the importance of ice shelves on ice sheet mass balance and contribution to sea level change.16

D. Stability of the East Antarctic ice sheet

The East Antarctic ice sheet has long been regarded as mainly frozen to the base and inherently stable. In fact it has been expected to increase in mass for some decades through increased snowfall from warmer temperatures.17 However geologists have for some time questioned its stability, with the suggestion that significant ice loss as recently as 400,000 years ago contributed 8 m of SLE along with the loss of the West Antarctic and Greenland ice sheets.18 The East Antarctic ice sheet has extensive areas of melting, including over 150 lakes, in areas of thick ice. Recent detailed high resolution satellite imagery has charted the simultaneous rise and compensating fall of two patches of the ice sheet over 200 km apart, reflecting the discharge of one lake to another, and at the same time making us aware of the potential instability of this huge body of ice.19

E. Impacts on Antarctic ecosystems

Alien microbes, fungi, plants and animals have arrived on most of the sub-Antarctic islands and some parts of the Antarctic continent as a result of human activity. Over the past two centuries, they have led to substantial loss of local biodiversity and changes to ecosystem processes. Current climatic trends will further enhance alien invasion, and relatively milder areas with increased human visitation and the most dramatic changes in environmental conditions will be most under threat. South Georgia, with climate warming, glacial retreat and a large and increasing number of visitors, undoubtedly stands out as the most threatened area.20

13 Dupont, T.K., and R.B. Alley. 2005. Assessment of the importance of ice-shelf buttressing to ice-sheet flow. Geophysical Research Letters, 32(4), L04503, doi:10.1029/2004GL022024. 14 Shepherd, A., et al. 2004. Warm ocean is eroding West Antarctic Ice Sheet. Geophysical Research Letters, 31(23), L23402, doi:10.1029/2004GL021106. 15 Payne, A.J., et al. 2004. Recent dramatic thinning of largest West Antarctic ice stream triggered by oceans. Geophysical Research Letters, 31(23), L23401, doi:10.1029/2004GL021284. 16 Rignot, et al. 2004. Accelerated ice discharge from the Antarctic Peninsula following the collapse of Larsen B ice shelf. Geophysical Research Letters, 31(18), L18401, doi:10.1029/2004GL020697. 17 Huybrechts P., 1993. Glaciological modelling of the Late Cenozoic East Antarctic ice sheet: stability or dynamism? Geografiska Annaler, 75A, 221-238. 18 Hearty, P. J., P. Kindler, H. Cheng, and R. L. Edwards, A +20 m middle Pleistocene sea-level highstand (Bermuda and the Bahamas) due to partial collapse of Antarctic ice, Geology, 27, 375-378, 1999. 19 Wingham, D. J. Wingham, Siegert, M.J., Shepherd, A. & Muir, A.S. 2006. Rapid discharge connects Antarctic sub- glacial lakes. Nature, 400, 440, 283-6. 20 Frenot, et al. 2005. Biological invasions in the Antarctic: extent, impacts and implications. Biol. Rev. (2005), 80, pp. 45–72. 6 IP 62

A study of Antarctic krill records encompassing data collected between 1926 and 2003 results showed an 80% decrease in krill abundance in the last 30 years. The decline was linked to loss of winter sea ice, under which krill over-winters. Such a massive reduction in krill stocks has great implications for Antarctic marine species for which krill are a major prey species.21

French researchers have analyzed the only long-term record of arrival and egg-laying for all species of seabird that come to breed in continental Antarctica, and conclude that breeding delays are linked to changes in East . Bird species are arriving at their colonies an average of nine days later and laying eggs on average two days later than they did in the 1950s. A 12-20% reduction in the extent of sea ice over the last 50 years has been linked to a decline in numbers of the krill and other marine organisms that are the major food source for seabirds. In addition, the sea ice season has been getting longer since the 1970s. The late break-up of sea ice is known to delay access to seabird colonies and food resources at sea. These two factors reduce the quantity and accessibility of food supplies available in early spring, with birds requiring more time to build up the reserves they need to breed. If seabirds continue to arrive and breed later and later, it looks likely that juveniles will fledge - gain the ability to fly - just before winter, and would face very harsh conditions just after fledging.22

Extreme reductions in Antarctic fur seal pup production at South Georgia have been linked to conditions of persistently high sea surface temperatures during the 1980s and 1990s. Persistently high sea surface temperatures at South Georgia were likely associated with low availability of prey, largely krill, which affected Antarctic fur seal females over time scales longer than their breeding cycle.23

IV. Conclusions

No Antarctic Treaty member state can continue to ignore the realities revealed by the research being carried in Antarctica. They should, as a matter of urgency, use this information to take tangible steps both domestically and through international treaties to address the threats posed by the rapidly growing levels of CO2 and other greenhouse gases globally. It is especially appropriate for Antarctic Treaty member states to take the lead in making use of the unique information resulting from their own scientific programs in the region, to take appropriate actions at national and global levels.

All states must act on the knowledge being obtained in the Antarctic and elsewhere to take the steps needed to avoid dangerous climate change, as articulated by the Intergovernmental Panel on Climate Change. The longer that effective action is delayed, the worse the legacy that this generation will leave. Those Antarctic Treaty states that have so far not joined the global consensus in favor of concerted actions to slow the growth of greenhouse gas emissions need to do so. ASOC urges all governments to take immediate steps to reduce the risk of dangerous climate change, which is adversely affecting both Antarctic ecosystems and those of the rest of the planet.

ASOC also notes that some global activities, such as international air travel, remain completely outside existing international commitments, even though its share of global emissions is rising and burning fossil fuels at high altitudes has enhanced global warming effects.

Although emissions from Antarctica are very low compared to the rest of the world, there will be greatly enhanced media attention on the increased Antarctic activities that will begin during the International Polar Year, 2007-09, including live broadcasts of life at Antarctic stations. Antarctic scientific and logistics programs should, therefore, encourage conservation and energy efficiency, including the installation and utilization of renewable energy at stations and field camps, thereby serving as exemplars to the rest of the world.

21 Atkinson, A., Siegel, V., Pakhomov, E., Rothery, P., 2004. Long-term decline in krill stock and increase in salps within the Southern Ocean. Nature 432: 100-103). 22 Marc Rincon, BBC News, April 4, 2006, reporting on Proceedings of the National Academy of Sciences Journal. 23 Forcada et al., The effects of global climate variability in pup production of Antarctic fur seals. Ecology: 86 (9), 2408–2417. 7 IP 62

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