Intercontinental scaletransport of air pollution

John MurlisDepartment of GeographyUniversity College London

Based on a presentation by Henning RodheStockholm University

Overview

• Pollution acts on a wide range of scales• Impacts vary across scales• Management regimes developed, but gaps remain• Evidence for impacts on different scales:

– Acidification/Eutrophication

– Ozone

– Aerosols/Particulate matter

• Conclusions

Pollution Acts on a Range of Scales

• Local

• Regional

• Intercontinental/Hemispheric

• Global

The Great London Smog

Disaster, 1952

Regional scale pollutantsLifetime days to weeks

Components related to - Acidification (SOx, NOx, NHx)- Eutrophication (NOx, NHx) and- Aerosol formation (SOx, NOx,

NHx, Carbon compounds)Particulate matter

Regional air pollutionWhat are the issues?

• Acidification: soil chemistry, lake ecology (SOx, NOx, NHx)

• Eutrophication: algal blooms, biodiversity (NOx, NHx)

• Excess ozone: health, vegetation, climate (NOx, VOC, CO)

• Aerosols: health, climate (SOx, NOx, NHx, VOC,..)

• Corrosion (SOx, H+, O3, NOx, )• Toxic species (Hg, Pb, Cs-137, PCB …)

Continental and hemispheric scale

pollutants

Life time weeks to months

Tropospheric ozoneand its precursors(NOx, VOC, CO..)

Particulate Matter?

Daniel Jacob, 2002

Huntzinger &Schlager 2004

North America CO over Germany

Model calculations by Derwent et al. 2002

Origins of model ozone at Mace Head, Ireland

Global scale pollutants

Lifetime > years

* Longlived greenhouse gasesand ozone depleting substances: CO2, CH4, N2O, CFCs,..

* Stratospheric aerosols * Mercury

Keating et al., 2004

Evolution of the perceived spatial scale of air pollution problems in the US

Regional/Hemispheric Scale

• Acidification and Eutrophication

• Sulphur and Nitrogen

Soil sensitivity to acid deposition

Kuylenstierna et al. Ambio 2001

Terrestria l E co system S en sitivity to A cid ic D ep o sitio n in So u th A sia

S ource : K uylenstie rna et a l. 200 1

Simplified model of precipitation acidity:

[H+] = [SO42-] + [NO3

-] - [NH4+] -

[Ca2+]

When [H+] > 0: ‘real’ [H+]

When [H+] < 0: [HCO3-]

Number of years to deplete base cations in soil

NE India 150 (40 – 220)

Malaysia 110 (40 – 160)

S China 17 (6 – 35)

Hicks et al. 2004

Sulfur

Continental scale transport of man-made sulfur

Tarrason & Iversen, 1998

European sources North American sources

Magnuz EngardtSMHISwedenPers. com.

Sulfur deposition

MATCH model calculations (RAPIDC)by Magnuz Engardt, SMHI, Sweden

Oxidized sulfur

Estimates of S depositionEmissions only from Andra Pradesh, Kamataka, Goa

Nitrogen

MATCH model calculations (RAPIDC)by Magnuz Engardt, SMHI, Sweden

Oxidized sulfur Oxidized nitrogen

Estimates of S and N depositionEmissions only from Andra Pradesh, Kamataka, Goa

S and N

Future Emissions?

Global SO2 emission scenarios (SRES)Tg S/yr

1990 2010 2030 2050 2070 2090

120

60

180

Nakicenovic et al. 2000

IPCC Special Report on Emissions Scenarios

SO2

2000 2005 2010 2015 2020 2025 2030

Emissions of SO2 from land-based sourcesin the 25 EU countries and from internationalshipping in European sea areas

IPCC Special Report on Emissions Scenarios

NOx

N America

Europe

FSU China

E Asia

S Asia

Conclusions on S and N(Acidification and Eutrophication

Intercontinental transport does occur but how significant is it?

UNECE Task force will assess for N Northern Hemisphere

Ozone

From Wild et al.JGR June 2004

Contributions to ozone over Japanfrom Europe, US,East Asia and Japan

Total

European

N American

E Asian

Local

Estimate of a possible increase in surface ozone2000 to 2100

Prather et al. GRL 2003

Keating et al.2004

Conclusions on ozone

*Potential for large increase of ozone levels in many tropical and subtropical countries (China, India, Africa) as NOx emissions go up

* Ozone and its precursors (CO, VOC, NOx) subject to substantial intercontinental transport

* N H background of ozone may reach standardvalues set for health during this century

Aerosols

                                                                                               

                                                                                     

Pollution haze over NE India and the Bay of Bengal

December 2004

Brown haze over Nepal, UNEP ABC Assessment report 2002

Aerosol optical depth over ChinaAugust 2004

MODIS satellite data

Fig. 5. Simulated (top) and obs                

Extinction of sunlightdue to aerosols in China

Observations - JJA

Model - JJA

Qian et al. Tellus B 2003

N of ITCZS of ITCZ

Total

NSS-sulfate

Ammonium

Potassium

Norman et al. 2003

Aerosol componentsin surface airduring ABC

Calcium

Sea salt

Trans-Pacific transport path of Asian dust to North America in April 1998

Cloud forcing dueto sulfate aerosols

Temperatureresponse

Ekman & Rodhe, 2003

Conclusions on aerosols

Intercontinental scale transport doesoccur (episodically) but how

significant as a driver of control strategy ?

1. Aerosols and health: urban & regional

2. Aerosols and climate: global (interactionswith radiation and with clouds)

3. Tropospheric ozone: regional/hemispheric(agriculture, health)

3. N, S: regional/hemispheric (Acidification/eutrophication)

A subjective expert ”concern list” of air pollution issues at different scales:

Prospects for the future

- Sulfur emissions:up in China, India ..down in Europe, US ..global total up - or down

- NOx: up in many developing countries- NH3:?- Ca: probably down

Conclusions• Transport on a Regional/Hemispheric Scale

established for wide range of air pollutants• Further work needed to establish full significance• At this stage, most concern about tropospheric

ozone• Some concern about pm/aerosol• N and S Significant but regional transport still

dominates• As local and regional pollution comes under

control, longer range transport will be more significant