Shedding new light on the radiative impacts of ozone-depleting substances

2020 ◽  
Author(s):  
Gabriel Chiodo ◽  
Lorenzo M. Polvani
Keyword(s):  
Twentieth Century ◽  
Ozone Depletion ◽  
Stratospheric Ozone ◽  
Walker Circulation ◽  
Climate Impacts ◽  
The Arctic ◽  
Temperature Structure ◽  
Stratospheric Ozone Depletion ◽  
Ozone Depleting Substances ◽  
The Walker Circulation

<p>It is well established that ozone-depleting substances (ODS) have been the primary cause of stratospheric ozone depletion. It is also widely accepted that stratospheric ozone depletion has been the primary driver of summertime circulation trends in the Austral Hemisphere in the second half of the twentieth century. However, the climate impacts of ODS that are independent of ozone depletion have received little attention. It has long been known that, while much less abundant than carbon dioxide, ODS have a much higher global warming potential (GWP) ecent studies have indicated that ODS may have played a key-role in the observed weakening trends of the Walker circulation (Polvani and Bellomo, 2019), and in the warming of the Arctic and the associated sea ice loss (Polvani et al., 2020). <span>that the climate efficacy of ODS may be much larger than previously thought, but </span><span>.</span></p><p>Here, we seek to better understand the radiative effect of ODS in the global atmosphere. Instead of confining our attention on a single metric, e.g. globally averaged radiative forcing (RF) or GWP which are typically reported in the IPCC Assessment Reports, we seek to understand how ODS alter the temperature structure of the entire atmosphere. Focusing on the half-century 1950-2000, which saw the largest growth of ODS concentrations in the atmosphere, we start by performing careful computations of the RF of individual ODS, including the effects of rapid temperature adjustments. We then explore how the vertical and latitudinal distribution of ODS (which are not well mixed in the stratosphere) affects their RF, and what temperature responses are associated with those changes. These calculations are repeated individually for each of the other well-mixed GHG, as well as for other composition changes arising from ODS (ozone depletion). It is shown that ODS, in contrast to other GHG, warm the lower stratosphere, implying a different fingerprint from CO2. Furthermore, the RF of ODS exhibits the largest meridional gradient of any other well-mixed GHG. Implications for the climate efficacy of ODS, and more generally for climate sensitivity, will be discussed.</p><p>References</p><p>Polvani, L.M and K. Bellomo: The key role of ozone depleting substances in weakening the Walker circulation in the second half of the 20th century, <em>J. Climate</em>, <strong>32</strong>, 1411-1418 (2019).</p><p>Polvani et al.,: Substantial twentieth-century Arctic warmng caused by ozone depleting substances, <em>Nature Climate Change, </em>in press (2019)</p>

scholarly journals The Key Role of Ozone-Depleting Substances in Weakening the Walker Circulation in the Second Half of the Twentieth Century

2019 ◽  
Vol 32 (5) ◽  
pp. 1411-1418 ◽  
Author(s):  
Lorenzo M. Polvani ◽  
Katinka Bellomo
Keyword(s):  
Twentieth Century ◽  
Pacific Ocean ◽  
Greenhouse Gases ◽  
Radiative Forcing ◽  
Climate Model ◽  
Walker Circulation ◽  
Surface Warming ◽  
Ozone Depleting Substances ◽  
The Antarctic ◽  
The Walker Circulation

It is widely appreciated that ozone-depleting substances (ODS), which have led to the formation of the Antarctic ozone hole, are also powerful greenhouse gases. In this study, we explore the consequence of the surface warming caused by ODS in the second half of the twentieth century over the Indo-Pacific Ocean, using the Whole Atmosphere Chemistry Climate Model (version 4). By contrasting two ensembles of chemistry–climate model integrations (with and without ODS forcing) over the period 1955–2005, we show that the additional greenhouse effect of ODS is crucial to producing a statistically significant weakening of the Walker circulation in our model over that period. When ODS concentrations are held fixed at 1955 levels, the forcing of the other well-mixed greenhouse gases alone leads to a strengthening—rather than weakening—of the Walker circulation because their warming effect is not sufficiently strong. Without increasing ODS, a surface warming delay in the eastern tropical Pacific Ocean leads to an increase in the sea surface temperature gradient between the eastern and western Pacific, with an associated strengthening of the Walker circulation. When increasing ODS are added, the considerably larger total radiative forcing produces a much faster warming in the eastern Pacific, causing the sign of the trend to reverse and the Walker circulation to weaken. Our modeling result suggests that ODS may have been key players in the observed weakening of the Walker circulation over the second half of the twentieth century.

scholarly journals In situ measurements of stratospheric ozone depletion rates in the Arctic winter 1991/1992: A Lagrangian approach

1998 ◽  
Vol 103 (D5) ◽  
pp. 5843-5853 ◽  
Author(s):  
M. Rex ◽  
P. von der Gathen ◽  
N. R. P. Harris ◽  
D. Lucic ◽  
B. M. Knudsen ◽  
...  
Keyword(s):  
Ozone Depletion ◽  
Stratospheric Ozone ◽  
In Situ Measurements ◽  
Lagrangian Approach ◽  
The Arctic ◽  
Stratospheric Ozone Depletion

Stratospheric ozone depletion over the Arctic

Nature ◽  
1991 ◽  
Vol 349 (6307) ◽  
pp. 279-280 ◽  
Author(s):  
Martyn Chipperfield
Keyword(s):  
Ozone Depletion ◽  
Stratospheric Ozone ◽  
The Arctic ◽  
Stratospheric Ozone Depletion

Impacts of Stratospheric Ozone Extremes on Arctic High Cloud

2021 ◽  
Author(s):  
Karen Smith ◽  
Sarah Maleska ◽  
John Virgin
Keyword(s):  
Northern Hemisphere ◽  
Ozone Depletion ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Global Climate Models ◽  
Arctic Climate ◽  
The Arctic ◽  
Stratospheric Ozone Depletion ◽  
High Cloud ◽  
The Impact

<p>Stratospheric ozone depletion in the Antarctic is well known to cause changes in Southern Hemisphere tropospheric climate; however, because of its smaller magnitude in the Arctic, the effects of stratospheric ozone depletion on Northern Hemisphere tropospheric climate are not as obvious or well understood. Recent research using both global climate models and observational data has determined that the impact of ozone depletion on ozone extremes can affect interannual variability in tropospheric circulation in the Northern Hemisphere in spring. To further this work, we use a coupled chemistry–climate model to examine the difference in high cloud between years with anomalously low and high Arctic stratospheric ozone concentrations. We find that low ozone extremes during the late twentieth century, when ozone-depleting substances (ODS) emissions are higher, are related to a decrease in upper tropospheric stability and an increase in high cloud fraction, which may contribute to enhanced Arctic surface warming in spring through a positive longwave cloud radiative effect. A better understanding of how Arctic climate is affected by ODS emissions, ozone depletion, and ozone extremes will lead to improved predictions of Arctic climate and its associated feedbacks with atmospheric fields as ozone levels recover.</p>

scholarly journals Stratospheric Ozone Depletion: The Main Driver of Twentieth-Century Atmospheric Circulation Changes in the Southern Hemisphere

2011 ◽  
Vol 24 (3) ◽  
pp. 795-812 ◽  
Author(s):  
Lorenzo M. Polvani ◽  
Darryn W. Waugh ◽  
Gustavo J. P. Correa ◽  
Seok-Woo Son
Keyword(s):  
Twentieth Century ◽  
Greenhouse Gases ◽  
Atmospheric Circulation ◽  
Southern Hemisphere ◽  
Ozone Depletion ◽  
General Circulation ◽  
Stratospheric Ozone ◽  
Hadley Cell ◽  
Stratospheric Ozone Depletion ◽  
Circulation Changes

Abstract The importance of stratospheric ozone depletion on the atmospheric circulation of the troposphere is studied with an atmospheric general circulation model, the Community Atmospheric Model, version 3 (CAM3), for the second half of the twentieth century. In particular, the relative importance of ozone depletion is contrasted with that of increased greenhouse gases and accompanying sea surface temperature changes. By specifying ozone and greenhouse gas forcings independently, and performing long, time-slice integrations, it is shown that the impacts of ozone depletion are roughly 2–3 times larger than those associated with increased greenhouse gases, for the Southern Hemisphere tropospheric summer circulation. The formation of the ozone hole is shown to affect not only the polar tropopause and the latitudinal position of the midlatitude jet; it extends to the entire hemisphere, resulting in a broadening of the Hadley cell and a poleward extension of the subtropical dry zones. The CAM3 results are compared to and found to be in excellent agreement with those of the multimodel means of the recent Coupled Model Intercomparison Project (CMIP3) and Chemistry–Climate Model Validation (CCMVal2) simulations. This study, therefore, strongly suggests that most Southern Hemisphere tropospheric circulation changes, in austral summer over the second half of the twentieth century, have been caused by polar stratospheric ozone depletion.

scholarly journals Synchronous volcanic eruptions and abrupt climate change ∼17.7 ka plausibly linked by stratospheric ozone depletion

2017 ◽  
Vol 114 (38) ◽  
pp. 10035-10040 ◽  
Author(s):  
Joseph R. McConnell ◽  
Andrea Burke ◽  
Nelia W. Dunbar ◽  
Peter Köhler ◽  
Jennie L. Thomas ◽  
...  
Keyword(s):  
Southern Hemisphere ◽  
Ozone Depletion ◽  
Stratospheric Ozone ◽  
Ice Core ◽  
Ice Cores ◽  
Volcanic Eruptions ◽  
Climate Impacts ◽  
Stratospheric Ozone Depletion ◽  
Climate Conditions ◽  
West Antarctic

Glacial-state greenhouse gas concentrations and Southern Hemisphere climate conditions persisted until ∼17.7 ka, when a nearly synchronous acceleration in deglaciation was recorded in paleoclimate proxies in large parts of the Southern Hemisphere, with many changes ascribed to a sudden poleward shift in the Southern Hemisphere westerlies and subsequent climate impacts. We used high-resolution chemical measurements in the West Antarctic Ice Sheet Divide, Byrd, and other ice cores to document a unique, ∼192-y series of halogen-rich volcanic eruptions exactly at the start of accelerated deglaciation, with tephra identifying the nearby Mount Takahe volcano as the source. Extensive fallout from these massive eruptions has been found >2,800 km from Mount Takahe. Sulfur isotope anomalies and marked decreases in ice core bromine consistent with increased surface UV radiation indicate that the eruptions led to stratospheric ozone depletion. Rather than a highly improbable coincidence, circulation and climate changes extending from the Antarctic Peninsula to the subtropics—similar to those associated with modern stratospheric ozone depletion over Antarctica—plausibly link the Mount Takahe eruptions to the onset of accelerated Southern Hemisphere deglaciation ∼17.7 ka.

Impacts of Stratospheric Ozone Extremes on Arctic High Cloud

2020 ◽  
Vol 33 (20) ◽  
pp. 8869-8884
Author(s):  
Sarah Maleska ◽  
Karen L. Smith ◽  
John Virgin
Keyword(s):  
Northern Hemisphere ◽  
Ozone Depletion ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Global Climate Models ◽  
Arctic Climate ◽  
The Arctic ◽  
Stratospheric Ozone Depletion ◽  
High Cloud ◽  
The Impact

AbstractStratospheric ozone depletion in the Antarctic is well known to cause changes in Southern Hemisphere tropospheric climate; however, because of its smaller magnitude in the Arctic, the effects of stratospheric ozone depletion on Northern Hemisphere tropospheric climate are not as obvious or well understood. Recent research using both global climate models and observational data has determined that the impact of ozone depletion on ozone extremes can affect interannual variability in tropospheric circulation in the Northern Hemisphere in spring. To further this work, we use a coupled chemistry–climate model to examine the difference in high cloud between years with anomalously low and high Arctic stratospheric ozone concentrations. We find that low ozone extremes during the late twentieth century, when ozone-depleting substances (ODS) emissions are higher, are related to a decrease in upper tropospheric stability and an increase in high cloud fraction, which may contribute to enhanced Arctic surface warming in spring through a positive longwave cloud radiative effect. A better understanding of how Arctic climate is affected by ODS emissions, ozone depletion, and ozone extremes will lead to improved predictions of Arctic climate and its associated feedbacks with atmospheric fields as ozone levels recover.

Impacts of stratospheric ozone extremes on Arctic high cloud

2020 ◽  
Author(s):  
Karen Smith ◽  
Sarah Maleska ◽  
John Virgin
Keyword(s):  
Northern Hemisphere ◽  
Ozone Depletion ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Global Climate Models ◽  
Arctic Climate ◽  
The Arctic ◽  
Stratospheric Ozone Depletion ◽  
High Cloud ◽  
The Impact

<p>Stratospheric ozone depletion in the Antarctic is well known to cause changes in Southern Hemisphere tropospheric climate; however, due to its smaller magnitude in the Arctic, the effects of stratospheric ozone depletion on Northern Hemisphere tropospheric climate are not as obvious or well understood. Recent research using both global climate models and observational data has determined that the impact of ozone depletion on ozone extremes can affect interannual variability in tropospheric circulation in the Northern Hemisphere in spring. To further this work, we use a coupled chemistry-climate model to examine the difference in high cloud between years with anomalously low and high Arctic stratospheric ozone concentrations. We find that low ozone extremes during the late twentieth century, when ODS emissions are higher, are related to a decrease in upper tropospheric stability and an increase in high cloud fraction, which may have contributed to Arctic surface warming via a positive longwave cloud radiative effect in the past few decades compared to other regions. A better understanding of how Arctic climate is affected by ODS emissions, ozone depletion and ozone extremes will lead to improved predictions of Arctic climate and its associated feedbacks with atmospheric fields as ozone levels recover.</p>

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