MOP High Level Presentation 2014 1

2014 Scientific Assessment Panel Report

Assessment for Decision-Makers

Scientific Assessment of Ozone Depletion: 2014

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 AjavonPaul NewmanJohn PyleA.R. Ravishankara

Scientific Steering Committee:Co-Chairs +David KarolyMalcolm KoTheodore ShepherdSusan Solomon

Coordinating Editor:Christine Ennis

November 20, 2014

MOP High Level Presentation 2014 2

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, 2014

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 layer2. The emerging issue of hydrofluorocarbons and

connection to climate change3. A few options for the Parties to consider

MOP High Level Presentation 2014 3November 20, 2014

Ozone is now increasing in the upper stratosphere

1979-1997 2000-2013During 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) 35-60˚N

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Models are able to reproduce both the 1979-97 depletion and the 2000-13 increase

1979-1997 2000-2013

Observations (black) 35-60˚NModel trends and uncertainty (grey)

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We cannot attribute the increase solely to ODS decline. GHG increases are also responsible.

1979-1997 2000-2013

Observations (black) 35-60˚NModel trends and uncertainty (grey)

Model with only GHGsModels with only ODSsADM Fig. 3-2

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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

Mon

trea

l Pro

toco

l is

sign

ed

MOP High Level Presentation 2014 7November 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. 2000

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(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. 2013

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(ppt

)

Ozone-depleting substances are

projected to continue to decline through the

21st century- assuming continued compliance with the

Protocol

MOP High Level Presentation 2014 10November 20, 2014

(ppt

)

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 21st century- assuming continued compliance with the

Protocol

MOP High Level Presentation 2014 11November 20, 2014

(ppt

)

Model uncertainties and differences

suggest that recovery to 1980 levels will occur in the 2025-

2040 period.

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(ppt

)

Models show differing amounts of ozone

changes for different greenhouse gas

Scenarios- ozone layer recovery is influenced

by climate change.

ADM Fig. 6-2November 20, 2014 MOP High Level Presentation 2014 13

(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, 2014

MOP High Level Presentation 2014 15

Background: HFCs came about as substitutes of ODSs

Hydrofluorocarbons (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, 2014

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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 (<1% of GHGs).

November 20, 2014

HFC-23 HFC-23

Abundances (ppt)

1995 2000 2005 2010 1980 1990 2000 2010

Emissions (kT/yr)

1995 2000 2005 2010 1990 2000 2010

0

20

40

60

50

100

150

10

15

20

25

0

4

8

12

16

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

CO2 future emissions.o Future HFC emissions can significantly hinder the 450 ppm CO2

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 2014 18November 20, 2014

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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, 2014

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, 2014 MOP High Level Presentation 2014 20

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 2014 21November 20, 2014

Thank you for your attention

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Backup slides

November 20, 2014

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

CO2 future emissions (scenarios from SRES).

Future HFC emissions can significantly hinder achieving the 450

ppm stabilization target.MOP High Level Presentation 2014 24November 20, 2014

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Montreal Protocol’s substitution strategy

Tho

usan

ds o

f to

nnes

November 20, 2014

Climate Benefits of Montreal Protocol

Reduction Montreal Protocol of ~11 GtCO2-eq/yr

Role of ozone depletion cooling due to CFCs? Could reduce this by perhaps a third but….

MOP High Level Presentation 2014 26

Many ODSs are potent greenhouse gases - Ramanathan

November 20, 2014

Velders et al., 2007