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2014 Scientific Assessment Panel Report Assessment for Decision-Makers Scientific Assessment of Ozone Depletion: 2014 World Meteorological Organization United Nations Environment Programme WMO Global Ozone Research and Monitoring Project Report No. 56 This is the effort of 282 scientists from 36 countries with the help of numerous individuals and organizations. Please see the Assessment for Decision-Makers (ADM) for the list of all who contributed to the success of this assessment report. Co-Chairs: Ayit-L Ajavon Paul Newman John Pyle A.R. Ravishankara Scientific Steering Committee: Co-Chairs + David Karoly Malcolm Ko Theodore Shepherd Susan Solomon Coordinating Editor: Christine Ennis November 20, 2014MOP High Level Presentation 20141

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Scientific Assessment Panels new approach in 2014 Assessment Assessment for Decision-Makers Scientific Assessment of Ozone Depletion: 2014 Detailed science assessment done as in the pastbut published only on the web (five scientific chapters). Assessment for Decision-Makers (ADM): Synthesized relevant material into a short document for youthe decision-makers. A very short (3-page) executive summary. November 20, 2014MOP High Level Presentation 20142

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Findings of the 2014 Ozone Layer Assessment The Executive Summary summarizes the key findings. The Assessment for Decision-Makers (ADM) discusses these findings in more detail. The ADM and Executive Summary are derived from the 5 science chapters of the 2014 Assessment (available in January 2015). A few key issues are highlighted here: 1.Changes in ozone-depleting substances (ODSs) and the ozone layer 2.The emerging issue of hydrofluorocarbons and connection to climate change 3.A few options for the Parties to consider MOP High Level Presentation 20143November 20, 2014

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Ozone is now increasing in the upper stratosphere 1979-19972000-2013 During the 1979-1997 period, ODSs were increasing, ozone was declining. During the 2000-2013 period, ODSs were declining, and ozone appears to be increasing Observations (black) 35-60N MOP High Level Presentation 20144November 20, 2014

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Models are able to reproduce both the 1979-97 depletion and the 2000-13 increase 1979-19972000-2013 Observations (black) 35-60N Model trends and uncertainty (grey) MOP High Level Presentation 2014 5 November 20, 2014

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We cannot attribute the increase solely to ODS decline. GHG increases are also responsible. 1979-19972000-2013 Observations (black) 35-60N Model trends and uncertainty (grey) Model with only GHGs Models with only ODSs ADM Fig. 3-2 MOP High Level Presentation 2014 6 November 20, 2014

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Levels of ozone- depleting substances were rapidly rising in the 1979-1987 period Ozone levels were declining, and the ozone hole had opened up over Antarctica Oct. 1985 Montreal Protocol is signed MOP High Level Presentation 20147November 20, 2014 ( ppt )

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Levels of ozone- depleting substances continued to grow till mid-1990s Ozone levels continue to decline. The ozone hole worsened till then Oct. 2000 MOP High Level Presentation 20148November 20, 2014 ( ppt )

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Levels of ozone- depleting substances have been declining since the mid-1990s to the present Ozone levels seem to have improved, but we cannot say that this is statistically significant. Oct. 2013 MOP High Level Presentation 20149November 20, 2014 ( ppt )

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Ozone-depleting substances are projected to continue to decline through the 21 st century- assuming continued compliance with the Protocol MOP High Level Presentation 201410November 20, 2014 ( ppt )

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Models simulate current global ozone levels reasonably well, and indicate the ozone layer should recover to 1980 levels around 2030. Ozone-depleting substances are projected to continue to decline through the 21 st century- assuming continued compliance with the Protocol MOP High Level Presentation 201411November 20, 2014 ( ppt )

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Model uncertainties and differences suggest that recovery to 1980 levels will occur in the 2025- 2040 period. November 20, 2014MOP High Level Presentation 201412 ( ppt )

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Models show differing amounts of ozone changes for different greenhouse gas Scenarios- ozone layer recovery is influenced by climate change. ADM Fig. 6-2 November 20, 2014MOP High Level Presentation 201413 ( ppt )

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Background: The Montreal Protocol has also benefitted climate Warming emissions avoided by Ozone-Layer agreement (Montreal Protocol) Warming emissions reduction targeted by the first phase of the 1997 international Climate agreement (Kyoto Protocol) Most ozone-depleting substances are also potent greenhouse gases. MP avoided their build up and is reducing their abundance; thus, it helped reduce climate forcing. The ozone depleting substances are decreasing due to the MP Climate change influenced (influences) ozone layer Flip-side: Ozone layer change issue has influences on climate change November 20, 2014MOP High Level Presentation 201414

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Background: HFCs came about as substitutes of ODSs Hyd rofluorocarbons (HFCs) do not deplete the ozone layer. They are being used to transition out of using ozone-depleting substances. HFCs are the main replacements for ozone- depleting substances in many applications. The use of HFCs has increased and is increasing rapidly. November 20, 2014MOP High Level Presentation 201415

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HFCs are increasing in the atmosphere e.g., HFC-134a used in mobile air conditioners has increased about 7% a year over the past two years. HFC-23, a byproduct of HCFC-22 production, is also increasing. The current contribution of HFCs to climate change is still small (