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: Ayité-Lô 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

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

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

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

Models are able to reproduce both the depletion and the increase Observations (black) 35-60˚N Model trends and uncertainty (grey) MOP High Level Presentation November 20, 2014

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

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

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

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 MOP High Level Presentation 20149November 20, 2014 ( ppt )

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

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

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

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 ( ppt )

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

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

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 (<1% of GHGs). November 20, 2014MOP High Level Presentation HFC-23 Abundances (ppt) Emissions (kT/yr)

Future emissions HFCs could make a large contribution to climate change  Future HFC contribution to climate change (as measured by radiative forcing) can be large. o Radiative forcing by future HFC emissions can be ~25% of that of CO 2 future emissions. o Future HFC emissions can significantly hinder the 450 ppm CO 2 stabilization target. 17 Various HFC Scenarios

There are ways to avoid large climate effects of HFCs  Possible to retain a <1% contribution in 2050 by using low- GWP HFCs (GWP <20) and other alternatives, even for the upper range emissions Scenarios.  Such alternatives appear to be available.  Replacement of current mix of high-GWP HFCs with low- GWP compounds and not-in-kind technologies would essentially avoid these climate effects of HFCs.  TFA from HFO-1234yf, a potential substitute, is considered to be negligible over the the next few decades. Potential longer- term impacts require future evaluations. MOP High Level Presentation November 20, 2014

Possible Options to Advance Ozone Layer Return to 1980 levels  Options to advance the return of the ozone layer to 1980 levels are not as extensive as in the past- Montreal Protocol has done a lot!  The cumulative effects of the elimination of emissions from all banks and production advances the return to 1980 levels by 11 years. November 20, 2014MOP High Level Presentation

We highlighted a few key issues: 1.Changes in ozone-depleting substances and the ozone layer. 2.Increases in hydrofluorocarbons (HFCs) and their consequences. 3.Some information asked for by the parties in the remit for the SAP worth noting: -Differences in estimated emissions of Carbon tetrachloride (CTC): atmospheric observations vs. reported values. -Details of methyl bromide trends. -Role of banks in the future of the ozone layer and impacts on climate. Findings of the 2014 Ozone-Layer Assessment November 20, 2014MOP High Level Presentation

For further details, we refer you to: The Executive Summary - key findings The ADM- more detail Soon-to-be released science chapters Findings of the 2014 Ozone-Layer Assessment MOP High Level Presentation November 20, 2014

Thank you for your attention MOP High Level Presentation November 20, 2014

Backup slides November 20, 2014MOP High Level Presentation

HFCs contribution to climate change by future emissions can be large  Unabated, future HFC contribution radiative forcing can be large.  Radiative forcing by future HFC emissions can be ~25% of that of CO 2 future emissions (scenarios from SRES).  Future HFC emissions can significantly hinder achieving the 450 ppm stabilization target. MOP High Level Presentation November 20, 2014

Montreal Protocol’s substitution strategy Thousands of tonnes November 20, 2014MOP High Level Presentation

Climate Benefits of Montreal Protocol Reduction Montreal Protocol of ~11 GtCO 2 -eq/yr Role of ozone depletion cooling due to CFCs? Could reduce this by perhaps a third but…. MOP High Level Presentation Many ODSs are potent greenhouse gases - Ramanathan November 20, 2014 Velders et al., 2007