Signatures of the Antarctic ozone hole in Southern Hemisphere surface climate change

Thompson, David W. J.; Solomon, Susan; Kushner, Paul J.; England, Matthew H.; Grise, Kevin M.; Karoly, David J.

doi:10.1038/ngeo1296

Cited by 860 publications

(963 citation statements)

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“…Our simulations support analyses of satellite-tracked sea-ice motion for the period 1992-2010, which indicate large and statistically significant trends in Antarctic ice drift in most sectors of the Southern Ocean that are linked, in most regions, to local winds 16 with the added complexity that there may be lagged responses 20 . Some of the Antarctic sea-ice trends in the Pacific and Atlantic can be attributed to trends in warming, SAM and ENSO, which could arise through both natural variability and effects due to the Southern Hemisphere ozone hole and increased levels of greenhouse gases 35 . However, the present study provides further evidence that wind forcing influences much of the observed heterogeneity in Antarctic sea-ice.…”

Section: Discussionmentioning

confidence: 99%

Sources of heterogeneous variability and trends in Antarctic sea-ice

et al. 2015

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While the Northern Hemisphere sea-ice has uniformly declined over the past several decades, the observed sea-ice in the Southern Hemisphere has exhibited regions of increase and decrease. Here we use a comprehensive set of ocean-sea-ice simulations (1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007) to elucidate the drivers of the observed heterogeneous sea-ice trends. We show wind variability is an important determinant of the heterogeneous pattern of the variability and trends in Southern Hemisphere sea-ice. Only in the West Pacific region does Southern Annular Mode wind forcing contribute significantly to the trend in sea-ice duration. El Niño Southern Oscillation wind forcing contribution to the sea-ice duration trend is confined to the Atlantic and Pacific. In the Indian Ocean, weather is a significant driver of the sea-ice duration trend. Only in the East Pacific region is wind forcing alone insufficient to give rise to the observed sea-ice decline and must be augmented by warming to reproduce the observations.

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Section: Discussionmentioning

confidence: 99%

Sources of heterogeneous variability and trends in Antarctic sea-ice

et al. 2015

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“…However, the consistency of the inferred age changes with the observed intensification of surface westerly winds, which have occurred primarily because of Antarctic stratospheric ozone depletion (6), suggests that Antarctic ozone depletion is the primary cause.…”

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confidence: 90%

“…Because the ventilation of SAMW and CDW occurs on decadal and longer time scales, a lag between peak ozone forcing and maximum changes in ocean ventilation is expected (9). As stratospheric ozone recovers over the next 40 to 60 years, the recent trend of intensifying summer westerly winds may slow or reverse (6,27,28). However, continued increases in greenhouse gases will likely lead to strengthened westerlies during other seasons.…”

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confidence: 99%

“…Over the past few decades, the southern oceans have warmed at roughly twice the rate of the global mean ocean (1), and around 40% of the anthropogenic carbon in the oceans entered south of 40°S (4). Southern ocean ventilation is driven primarily by the westerly winds (5), which have strengthened and shifted poleward over recent decades, primarily as a consequence of Antarctic stratospheric ozone depletion (6). Modeling studies suggest that this has caused changes in the ocean's overturning circulation (7)(8)(9), and carbon uptake (10,11).…”

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Recent Changes in the Ventilation of the Southern Oceans

Waugh

Primeau

DeVries

et al. 2013

Science

153

166

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Surface westerly winds in the Southern Hemisphere have intensified over the past few decades, primarily in response to the formation of the Antarctic ozone hole, and there is intense debate on the impact of this on the ocean's circulation and uptake and redistribution of atmospheric gases. We used measurements of chlorofluorocarbon-12 (CFC-12) made in the southern oceans in the early 1990s and mid-to late 2000s to examine changes in ocean ventilation. Our analysis of the CFC-12 data reveals a decrease in the age of subtropical subantarctic mode waters and an increase in the age of circumpolar deep waters, suggesting that the formation of the Antarctic ozone hole has caused large-scale coherent changes in the ventilation of the southern oceans.T he transport of surface waters into the interior ("ventilation") of the southern oceans plays an important role in global climate and the cycling of carbon, oxygen, and nutrients in the oceans (1-3). Over the past few decades, the southern oceans have warmed at roughly twice the rate of the global mean ocean (1), and around 40% of the anthropogenic carbon in the oceans entered south of 40°S (4). Southern ocean ventilation is driven primarily by the westerly winds (5), which have strengthened and shifted poleward over recent decades, primarily as a consequence of Antarctic stratospheric ozone depletion (6). Modeling studies suggest that this has caused changes in the ocean's overturning circulation (7-9), and carbon uptake (10, 11). However, the sensitivity of the southern ocean circulation and ventilation to decadal changes in wind stresses is under debate (12)(13)(14).Information on ventilation rates can be obtained from measurements of chlorofluorocarbons (CFCs). These compounds are conserved within the oceans, and their atmospheric concentrations have increased rapidly from when they were first produced in the 1930s until the mid1990s ( fig. S1). Because of this time dependence, CFC measurements can provide constraints on the rates and pathways of ocean transport (15, 16).We used CFC-12 measurements made along several sections in the southern oceans in the early 1990s as part of the World Ocean Circulation Experiment (WOCE) and resampled in mid-to late 2000s as part of the Climate Variability and Predictability (CLIVAR) and CO 2 repeat hydrography program (supplementary materials) to examine changes in the ventilation of the southern oceans over the past two decades.The measurements during WOCE show largest pCFC-12 at the surface, with values decreasing with depth along isopycnals (e.g., Fig. 1A). [We express the measurements as the partial pressure of CFC-12 ( pCFC-12), defined as the seawater concentration divided by the solubility (16). This enables direct comparison with the atmospheric history of CFC-12.] The repeat occupations 14 to 16 years later show large increases in pCFC-12 in the subtropical thermocline (~25°t o 45°S, 200 to 1000 m), which correspond to the waters formed by the transport of surface waters along surfaces of constant density (e.g., Fig. 1B). ...

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“…The Southern Annular Mode index generally increased from 1970 to about 2000, and positive values have been related to an increase of greenhouse gas concentrations and depletion of stratospheric ozone (Thompson et al, 2011) There have been associated decreases in sea-ice extent and duration in the Bellingshausen Sea and Antarctic Peninsula regions of the Southern Ocean (Lefebvre et al, 2004;Stammerjohn et al, 2008aStammerjohn et al, , 2008b, and increases in sea-ice cover in the Ross Sea (Lefebvre et al, 2004;Stammerjohn Fig. 7.…”

Section: Atmospheric Conditions and Circulation In The Antarcticmentioning

confidence: 99%

Advection in polar and sub-polar environments: Impacts on high latitude marine ecosystems

Hunt

Drinkwater

Arrigo

et al. 2016

Progress in Oceanography

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a b s t r a c tWe compare and contrast the ecological impacts of atmospheric and oceanic circulation patterns on polar and sub-polar marine ecosystems. Circulation patterns differ strikingly between the north and south. Meridional circulation in the north provides connections between the sub-Arctic and Arctic despite the presence of encircling continental landmasses, whereas annular circulation patterns in the south tend to isolate Antarctic surface waters from those in the north. These differences influence fundamental aspects of the polar ecosystems from the amount, thickness and duration of sea ice, to the types of organisms, and the ecology of zooplankton, fish, seabirds and marine mammals. Meridional flows in both the North Pacific and the North Atlantic oceans transport heat, nutrients, and plankton northward into the Chukchi Sea, the Barents Sea, and the seas off the west coast of Greenland. In the North Atlantic, the advected heat warms the waters of the southern Barents Sea and, with advected nutrients and plankton, supports immense biomasses of fish, seabirds and marine mammals. On the Pacific side of the Arctic, cold waters flowing northward across the northern Bering and Chukchi seas during winter and spring limit the ability of boreal fish species to take advantage of high seasonal production there. Southward flow of cold Arctic waters into sub-Arctic regions of the North Atlantic occurs mainly through Fram Strait with less through the Barents Sea and the Canadian Archipelago. In the Pacific, the transport of Arctic waters and plankton southward through Bering Strait is minimal.In the Southern Ocean, the Antarctic Circumpolar Current and its associated fronts are barriers to the southward dispersal of plankton and pelagic fishes from sub-Antarctic waters, with the consequent evolution of Antarctic zooplankton and fish species largely occurring in isolation from those to the north. The Antarctic Circumpolar Current also disperses biota throughout the Southern Ocean, and as a result, the biota tends to be similar within a given broad latitudinal band. South of the Southern Boundary of the ACC, there is a large-scale divergence that brings nutrient-rich water to the surface. This divergence, along with more localized upwelling regions and deep vertical convection in winter, generates elevated nutrient levels throughout the Antarctic at the end of austral winter. However, such elevated nutrient levels do not support elevated phytoplankton productivity through the entire Southern Ocean, as iron concentrations are rapidly removed to limiting levels by spring blooms in deep waters. However, coastal http://dx

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Signatures of the Antarctic ozone hole in Southern Hemisphere surface climate change

Cited by 860 publications

References 100 publications

Sources of heterogeneous variability and trends in Antarctic sea-ice

Sources of heterogeneous variability and trends in Antarctic sea-ice

Recent Changes in the Ventilation of the Southern Oceans

Advection in polar and sub-polar environments: Impacts on high latitude marine ecosystems

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