Linking air quality and climate policies and the aerosol issue

Transcription

1 Linking air quality and climate policies and the aerosol issue Sandro Fuzzi Ins:tute of Atmospheric Sciences and Climate Na:onal Research Council Bologna, Italy ALPINE SUMMER SCHOOL Climate, Aerosols and the Cryosphere Valsavarenche, Valle d'aosta (Italy), June, 2012

2 The atmosphere: our waste disposal The atmosphere is one of the largest waste disposal for our society Most pollutants disappear from the atmosphere within a few days through deposi:on and/or chemical reac:ons The cleaning capacity of the atmosphere for other compounds is much lower and they remain in the air fair longer

3 Common roots of air pollu:on and climate change CO 2 and N 2 O, long- lived compounds, have not been considered as pollutants, since they are not directly toxic for humans or the environment. These compounds affect the radia:on balance of the Earth and thus climate Some of the short- lived compounds, tradi:onally considered air pollutants, may also affect climate Ozone and aerosols are the most important species which exert both effects and are therefore included in both air quality and climate assessments It is thus impossible to unambiguously separate many compounds into dis:nct groups of either air pollutants or climate- influencing compounds

4 Pollu:on/climate links Compound Residence.me Pollu.on effects CO years acidifica:on of oceans climate gas N 2 O 110 years destruc:on stratosph. O 3 climate gas CH 4 7 years precursor troposph. O 3 climate gas O 3 1 month affects health and vegeta:on SO 2 1 week precursor of par:cles, health effects NO X 1 week precursor of par:cles and tropospheric O 3, health effects NH 3 1 week precursor of par:cles, eutrophica:on Climate change proper.es climate gas scaaering aerosol precursor, suppressing warming scaaering aerosol precursor, suppressing warming scaaering aerosol precursor, suppressing warming BC 1 week health effects absorbing aerosol, warming agent

5 Emission reduc:ons EU27 and US (Tg/year) Compound US 1990 US 2006 Trend (%) EU EU Trend (%) SO 2 23,077 14, ,323 8, NO X 25,527 17, ,136 11, NH 3 4,320 4, ,120 4,094-20

6 SO 2 vs. CO 2 emission abatement

7 Two sides of the same coin? Policies measures for the mi:ga:on of air pollu:on and climate change overlap, and an integrated approach is required to assess their inter- linkages Abatement of air pollu:on is associated with considerable costs, but it can also result in major savings from health improvement and ecosystem effects Since major greenhouse gases originate from the same sources as air pollutants, a coordinated abatement strategy is beneficial, also in economic terms

8 Air Quality Policy Design REGULATION Policy TARGET Anthropogenic emissions Atmospheric composi.on/ processes Air quality

9 Air Quality and Climate Policy REGULATION Natural systems/ exchanges Policy TARGET TARGET Climate change Anthropogenic emissions Atmospheric composi.on/ processes Air quality

10 Climate vs. air quality In most countries, the mi:ga:on policies for climate and air quality remain dis:nct and ignore therefore the rela:ons between them Many of the tools required to quan:fy the climate impacts of air pollutants have been developed Less research has been conducted on the impacts of climate change on air quality

11 Public percep:on The adverse effects of air pollu:on are highly visible since they act on a short :me basis On the contrary climate change has a :me scale of several decades The pressure of ci:zens on governments is much higher for air quality than for climate change

12 Policy perspec:ve Public policy priori:es vary in different parts of the world In the developed world climate change is presently a top priority Developing Countries, where air pollu:on threaths to human health are s:ll huge, privilege to invest in limi:ng air pollu:on The two priori:es are not in conflict with each other

13 Atmospheric aerosol

14 Aerosol sources

15 Global aerosol emission (Tg/yr) Component Mass emission best guess (min - max) Primary organic (0-2 µm) Biomass burning 54 (26 70) Fossil fuel 4 (3 9) Biological 35 (15 70) Secondary organic Anthropogenic 3.5 ( ) Biogenic 25 (2.5 79) Black carbon (0-2 µm) Open burning and biofuel 6 (5 7) Fossil fuel 4.5 (3 6) Sulfate Biogenic 57 (28 118) Anthropogenic 122 (69 214) Volcanic 21 (9 48) Nitrate 18 (12 27) Industrial/road dust 100 (40 130) Sea spray Submicron 180 (60 500) Coarse 9940 (3,000 20,000) Mineral dust Submicron 165 Coarse 1488 Total anthropogenic (0-2 µm) 312 ( ) Total biogenic (0-2 µm) 117 ( ) Andreae and Rosenfeld, Earth- Science Reviews (2008)

16 Global aerosol distribu:on Aerosol par:cles have a life:me of days to weeks, their spa:al distribu:on is therefore highly variable Satellite data Modelled

17 Aerosol and human health Fine (i.e. sub- micrometer) par:cles are a major focus of air pollu:on policies due to their effect on human health There are great uncertain:es in the assessment of what par:cles and which proper:es are the cause of these effects Abatement strategies are therefore directed towards all fine par:cles, regardless of the origin Loss in life expectancy attributable to anthropogenic PM2.5 [months]

18 Effects of aerosol on climate hea.ng effect due to black carbon which absorbs solar radia.on and heats the atmosphere cooling effect due to reflec.on of solar radia.on back to space aerosols form clouds which have a cooling effect due to reflec.on of solar radia.on back to space Net effect of aerosol on climate à COOLING

19 Levels of aerosols in the atmosphere are decreasing as a consequence of measures to protect human health Mishchenko et al., Science (2007)

20 Effects on climate of aerosol decrease If more stringent air pollu:on abatements were implemented worldwide, the present- day nega:ve total aerosol top- of- the- atmosphere radia:ve forcing would be strongly reduced in the future Climate change thereaker would therefore be controlled to a larger extent by changes in greenhouse gas emissions

21 Climate simula:ons of decreased aerosol emissions According to a recent study, the projected temperature response to increasing greenhouse gas concentra:ons and reduced aerosol emissions leads to a global annual mean equilibrium temperature response of 2.2 K If aerosols were to be abated only in the Industry and Power Plant sector, with the Domes:c and Transport sectors staying with currently enforced regula:ons, the temperature increase es:mated by the same model would be 1.9 K In contrast, a maximum feasible abatement applied only in the domes:c and transport sector would lead to a smaller temperature increase of 1.4 K Makkonen et al., ACP (2012)

22 Feedbacks of air quality policies This highlights the huge poten:al impact of future air pollu:on mi:ga:on strategies on climate and support the need for urgent GHG emission reduc:ons Since aerosols impact strongly surface forcing and thus have a high hydrological sensi:vity, the consequences of plausible precipita:on increases associated with global warming would be even stronger GHG and aerosol forcing is not independent of each other, as they both influence and are influenced by changes in the hydrological cycle

23 A proposed ac:on hap:// A recent study ini:ated by UNEP and WMO has inves:gated emission reduc:on measures for BC and ozone that can lead to an improvement in air quality while also benefi:ng the climate A limited number of measures are necessary to reach co- benefits The report also produces a cost- benefit analysis of the suggested measures with reference to health and crop produc:on Shindell et al., Science, 2012

24 Why BC and O 3? BC results from the incomplete combus:on of fossil fuels, wood and other biomass BC warms the atmosphere by intercep:ng sunlight and absorbing it BC par:cles are a powerful warming agent, second only to CO 2, darken the snow when are deposited and influence cloud forma:on BC is also harmful for human health Tropospheric O 3 is both a greenhouse gas and affects human health O 3 is a secondary compound formed by reac:on of precursors (CH 4, NO X, VOC, CO) Reduc:on in CH 4 and CO emissions substan:ally reduce global warming Reducing VOC and NO X has a small impact on global climate

25 Annual mean trend of O 3 and BC Allen et al., Nature (2012)

26 The ABC Project Pyramid Observatory

27 The Pyramid Observatory Tibet KHUMBU GLACIER Nepal

28 BC at the Pyramid 5000 a.s.l. Bonasoni et al., ACP (2010)

29 Criteria for the Report When considering strategies to avoid climate change and improve air quality there is a need to assess the impacts on both, and try to iden:fy synergies (win- win) and avoid trade- offs (win- lose) O 3 and BC par:cles, have atmospheric life:mes of the order of days to weeks Reducing the emissions of short- lived pollutants will reduce their concentra:ons in a maaer of weeks, with an effect on global temperature established during the following decade Reducing emissions of long- lived greenhouse gases will have an effect only on much longer :me scales

30 Emission control measures Using the GAINS model of IIASA a limited set of 16 measures were selected among 2000 different measures (these 16 measures provide 90% of the climate benefit of the whole 2000 set) All emission reduc:on measures were also beneficial for health by reducing BC and/or O 3 Emission reduc:ons not beneficial for both climate and human health were not considered

31 Different scenarios The set of measures was compared to a reference scenario which incorporates all presently agreed emission policies

32 Effects of the proposed measures on emissions

33

34 Time to act

35 Benefits for climate, health, crops

36 Benefits by Country

37 Effects of climate change on air quality Less research has been conducted on the impacts of climate change on air quality Natural emissions of several pollutant gases by the ecosystems and soils (i.e., ozone and aerosol precursors) exhibit strong dependence on climate (i.e., temperature and hydrology). Climate change will generally increase these natural emissions thus increasing aerosol load Climate change is expected to produce more frequent wildfires with consequently increased emissions of carbon monoxide, VOCs, nitrogen oxides and black carbon. Climate change could therefore erode the benefits of air quality policies

38 - 3) - 3 Changes in ( µg m 8 f0 or K Changes in PPMM ( µg m for ) fm or ay M0ay 8 +f2.5 or +K Nitrate Ammonium Pandis, 2011 unpublished results Sulfate Organic aerosol

39 Aerosol Increase in 2050 due to Climate Change No change in biogenic VOC Emissions T- dependent Biogenic VOC Emissions Pandis, 2011 unpublished results

40 Uncertain effect of climate change on aerosol concentra:on Changes in climate- generated meteorology (e.g., air stagna:on episodes, cross tropopause exchanges, precipita:on regimes, etc.) could affect the atmospheric life:me and concentra:ons of primary and secondary pollutants, exacerba:ng uncertain:es in future air quality The impact of climate change on aerosol concentra:on and removal rate is not well quan:fied. Even the sign in the change for aerosols is uncertain

41 Take- home messages Air pollu:on and climate are oken treated as separate issues, while they are two sides of the same coin Policies measures for the mi:ga:on of air pollu:on and climate change overlap, and integrated assessments are required to assess their inter- linkages Many of the tools required to quan:fy the climate impacts of air pollutants have been developed Less research has been conducted on the impacts of climate change on air quality There is a considerable financial and societal benefit in simultaneously cuqng emissions of air pollutants and greenhouse gases