Appendix 5 Analysis using RAINS and ASAM

Introduction

In this appendix further implications of the various scenarios are presented. These effects have been modelled using RAINS and ASAM, two integrated assessment models, which cover the whole of the UNECE region at a resolution of 150x150 km. Both models are based on the EMEP Lagrangian meteorological modelling of the relationship between emission sources and receptor areas in Europe. All of the results presented here are based on the RAINS model, the official model used in the UNECE Task Force on Integrated Assessment Modelling, except for those concerning human exposure to secondary particulates which is not covered by RAINS. For these calculations the ASAM model is used. The model has been shown to agree well with the RAINS model and is used for sensitivity analysis and supporting work at the UNECE Task Force on Integrated Assessment Modelling.

Implications of scenarios are presented for (a) the UK and (b) the whole of the UNECE region. Effects analysed are (a) human exposure to secondary particulates (b) acidification of ecosystems (c) eutrophication of ecosystems (d) AOT40 and AOT60 and the associated levels of ozone exposure to crops and human health.

Explanation of Scenarios

Table A5.1 shows the emission levels for the UK in the scenarios covered. The IIASA Reference scenario is the one calculated by IIASA for use at the Task Force on Integrated Assessment Modelling. The full set of European emissions under this scenario and H1 and J1 were given in Appendix II.

The underlying scenario is a variant of the IIASA Reference scenario in which European emissions remain at IIASA Reference whilst UK emissions are altered as shown in Table A5.1.

The ‘additional’ scenarios such as UK1 and UK2 are variants of J1, that is, European emissions remain at J1 whilst the UK alters its emissions to those shown in Table A5.1.

Table A5.1 Annual UK emission ceilings for scenarios examined in 2010 (kt)

SCENARIO	SO2	NOx	NH3	VOC
Basic scenarios:
IIASA Reference	980	1186	297	1351
UKREF	784	1187	329	1300
H1	497	1181	264	964
J1	499	1181	264	1101
Additional scenarios:
UK1	600	1181	297	1200
UK1a	550	1150	274	1200
UK2	550	1100	274	1200
UK3	550	1000	274	1200
UK4	550	1150	274	1101
UK5	550	1100	274	1101
UK6	550	1000	274	1101
UK7	550	1181	274	1150
UK8	550	1100	274	1150
UK9	550	1100	274	1351
UK10	550	1186	274	1351
UKS11	525	1181	264	1101
UKS13	700	1100	264	1101

AOT40 and AOT60: Exposure of humans, vegetation and crops to ozone in excess of critical levels

METHODOLOGY

AOT60: Method a

The RAINS web model was used to extract tables detailing AOT60 totals for the U.K. and for the UNECE region as a whole. RAINS provides average AOT60 values for each country in ppm hours. It also provides population exposures in units of million persons.ppm hours. The results are presented in Table A5.2a. Note that RAINS calculates population exposures using a threshold of 0.4 ppm hours(1).

AOT60: Method b

Since the values of AOT60 were rather small, and RAINS only automatically produces results to one decimal place, more accurate information was extracted from the raw data which could be extracted from the model, totals of AOT60 were recalculated (referred to as method b). These values are shown in Table A5.2b, together with the matching population exposures. A threshold of 0.4 ppm hours has been used in this case(2).

AOT40: Method c

RAINS was also used to extract values of AOT40 (method c). These are the average values in excess of 3 ppm hour critical level for vegetation. RAINS also provides tables of vegetation exposure using this threshold (Table A5.2c).

AOT40: Method d

RAINS was also used to provide raw data for AOT40 so that average AOT40 values (without a threshold) could be calculated for the UK and the UNECE (method d, Table A5.2d). Vegetation exposure was not calculated using this method.

Crop exposure to AOT40

Crop areas exposed to an excess of 3 ppm hours AOT40 were calculated using crop areas obtained from IIASA (Tables A5.2e, f).

Table A5.2a. AOT60 mean values and population exposures in UK and UNECE (method a). DJ1 shows the difference between the scenario selected and J1

UK	AOT60 (mean)	DJ1	%loss in benefit	AOT60pop	DJ1	%loss in benefit
	Ppm hrs	Ppm hrs		Million person ppm hrs
IIASA Reference	1.30	0.40		77	28
UKREF	1.3	0.40		75
J1	0.9	0.00		49	0
H1	0.8	-0.1	-25	45	-4	-14.3
UK7	0.9	0	0	52	3	10.7
UK8	0.9	0	0	53	4	14.3
UK9	1.1	0.2	50	62	13	46.4
UK10	1.1	0.2	50	61	12	42.9
UNECE	AOT60	DJ1	%loss in benefit	AOT60pop	DJ1	%loss in benefit
IIASA Reference	0.8	0.3		570	224
UKREF	0.8	0.3		566
J1	0.5	0		346	0
H1	0.6	0.1	33	385	39	17.4
UK7	0.5	0	0	351	5	2.2
UK8	0.5	0	0	352	6	2.7
UK9	0.5	0	0	369	23	10.3
UK10	0.5	0	0	367	21	9.4

Table A5.2b. AOT60 mean values and population. Exposures in UK and UNECE (method b). DJ1 shows the difference between the scenario selected and J1

UK	AOT60 (mean excess)	DJ1	%loss in benefit	AOT60pop	DJ1	%loss in benefit
	Ppm hrs	Ppm hrs		Million person ppm hrs
IIASA Reference	0.95	0.31		79	26
UKREF	0.93			77
J1	0.64	0.00		53	0
H1	0.60	-0.04	-14.4	49	-4	-8.3
UK7	0.66	0.02	6.5	55	2	7.7
UK8	0.67	0.03	9.7	56	3	11.5
UK9	0.76	0.12	38.7	64	11	42.3
UK10	0.75	0.11	35.5	63	10	38.5
UNECE	AOT60	DJ1	%loss in benefit	AOT60pop	DJ1	%loss in benefit
IIASA Reference	0.47	0.17		604	208
UKREF	0.47			600
J1	0.30	0.00		396	0
H1	0.34	0.04	23.5	429	33	15.9
UK7	0.31	0.01	5.9	400	4	1.9
UK8	0.31	0.01	5.9	401	5	2.4
UK9	0.32	0.02	11.8	417	21	10.0
UK10	0.32	0.02	11.8	416	20	9.6

Table A5.2c. AOT40 mean values in excess of 3 ppm hours, and vegetation exposures in UK and UNECE (method a).

UK	AOT40	DJ1	%loss in benefit	AOT40veg	DJ1	%loss in benefit
	Ppm hrs			Ppm hrs area
IIASA Reference	1.9	0.5		153	42
UKREF	1.8	0.1		148
J1	1.4	0		111	0
H1	1.2	-0.2	-40	96	-15	-35.7
UK7	1.4	0	0	116	5	11.9
UK8	1.5	0.1	20	120	9	21.4
UK9	1.7	0.3	60	140	29	69.0
UK10	1.6	0.2	40	136	25	59.5
UNECE	AOT40	DJ1	%loss in benefit	AOT40veg	DJ1	%loss in benefit
IIASA Reference	2.5	0.6		13100	2858
UKREF	2.4			13068
J1	1.9	0		10242	0
H1	1.9	0	0	10245	3	0.1
UK7	1.9	0	0	10271	29	1.0
UK8	1.9	0	0	10274	32	1.1
UK9	1.9	0	0	10394	152	5.3
UK10	1.9	0	0	10391	149	5.2

Table A5.2d. AOT40 mean values in UK and UNECE (method b).

UK	AOT40	DJ1	%loss in benefit
	Ppm hrs
IIASA Reference	4.90	0.6
UKREF	4.82
J1	4.30	0
H1	4.11	-0.29	-48.3
UK7	4.36	0.06	10.1
UK8	4.39	0.09	15.3
UK9	4.64	0.28	47.5
UK10	4.60	0.24	40.7
UNECE	AOT40	DJ1	%loss in benefit
IIASA Reference	5.39	0.63
UKREF	5.38
J1	4.76	0.00
H1	4.94	0.18	28.6
UK7	4.77	0.01	1.6
UK8	4.77	0.01	1.6
UK9	4.81	0.04	6.3
UK10	4.81	0.04	6.3

Table A5.2e. Arable crop areas exposed to AOT40 in excess of threshold, 1000 km².

	IIASA Reference	J1
UK	63	58
UNECE	1995	1958

Table A5.2f. Permanent crop areas exposed to AOT40 in excess of threshold, 1000 km².

	IIASA Reference	J1
UK	0.52	0.50
UNECE	135.1	135.1

Scenarios explained in terms of VOC and NO_x emissions

The basic scenarios examined are IIASA Reference, UKREF, H1 and J1.

UK10 is J1 with the emissions of the UK at the IIASA Reference values for NO_x and VOC, i.e. designed to investigate the non-participation of the UK in further ozone reduction strategies.

UK7 is UK10 with VOC emission ceiling of 1150 kt/yr applied (approaching J1 at 1100); i.e. designed to investigate the non-participation of the UK in reducing NO_x emissions.

UK8 is UK7 with NO_x reduced from IIASA Reference value of 1181 to 1100 kt/yr

UK9 is UK10 with NO_x reduced from IIASA Reference value of 1181 to 1100 kt/yr

These last two scenarios investigate the possibility of exchanging UK NO_x reductions in place of UK VOC reductions.

RESULTS

AOT60

a. UK values of AOT60

IIASA Reference to J1 produces a benefit in terms of a reduction in UK AOT60 of 32%. This applies whether mean AOT60, or excess AOT60 over the threshold of 0.4 ppm hours, is considered.

Moving from J1 to UK10, by relaxing the commitments of the UK to IIASA Reference, causes 36% of this benefit to be lost; for UK7, in which VOC emissions move closer to J1, only 6% is lost. These losses are a result of the non-abatement of VOC in the UK.

Taking UK10, if NO_x is now reduced below the J1 value to 1100 kt/yr (scenario UK9), whilst VOC remain at IIASA Reference, the loss increases to39%. Taking UK7, if NO_x is again reduced to 1100 kt/yr (scenario UK8) loss increases from 6 to 10%. These increased losses demonstrate the increased ozone resulting from abating NO_x beyond IIASA Reference whilst VOC remain at the IIASA Reference scenario (UK9) or between the IIASA Reference scenario and J1 (UK8).

Thus, if NO_x is reduced below J1, much of the benefit of J1 in reducing ozone in the UK will be lost unless VOC are also reduced. It is not beneficial, in terms of ozone reductions to trade off reductions in VOC, which may be difficult or expensive, with the less expensive reductions in NO_x.

b. UK Population Exposure to AOT60

Population exposures are similarly affected. IIASA Reference to J1 produces a benefit through reducing population exposure in the UK by 36% (method a) or 33% (method b).

If UK emissions remain at IIASA Reference (scenario UK10) 21% of this benefit is lost. If NO_x emissions remain at IIASA Reference whilst VOC emissions approach J1 (scenario UK7), only 2% of this improvement is lost.

Taking UK10, if NO_x is reduced below J1, loss increases to 23%.

Taking UK7, if NO_x is reduced below J1, loss increases to 6%.

Thus the benefits of J1 to the UK in terms of population exposure to ozone are reduced by 21% if UK remains at the IIASA Reference scenario and by 23% if additional reductions in NO_x occur.

c. UNECE values

IIASA Reference to J1 produces a benefit through reducing UNECE AOT60 of 37%, whether mean values or mean excess values over the threshold are considered.

Only the more detailed analysis reveals the losses of up to 12% (of the improvement) observed for the scenarios in which UK VOC is not reduced from the IIASA Reference value of 1351 kt. When VOC is reduced to 1150 kt/yr, losses are still 6%.

Thus, significant losses in benefit also accrue in Europe if UK VOC remains at IIASA Reference.

Correspondingly, population exposures in the UNECE region fall from IIASA Reference to J1 by 39% (method a) or 34% (method b). The more detailed analysis (method b) indicates that leaving UK emissions at IIASA Reference (UK10) results in a 20% loss if this improvement. Reducing VOC closer to J1 (UK7) reduces this loss to 4%. Simultaneous reduction of NO_x below J1 to 1100 kt/yr increases each of these losses by 1%.

Therefore, these investigations reinforce the message that at the J1 scenario it is important to reduce the VOC emissions to 1101 kt/yr if ozone is to be maintained at J1 levels. Decreasing NO_x and increasing VOC emissions causes AOT60 and population exposure to AOT60 to increase both in the UK and in Europe as a whole.

AOT40

a. UK values of AOT40

IIASA Reference to J1 reduces UK mean AOT40 in excess of 3 ppm hours by 26% (method a) or 24% of mean AOT40 (method b). Use of UK7 results in a loss of 10% of this benefit (method b) and UK10 a loss of 41% of the improvement, showing substantial increases in ozone if VOC are not reduced beyond IIASA Reference. If NO_x is reduced below IIASA Reference, the losses in benefit are larger, as high as 48% for the case where VOC remains at IIASA Reference and NO_x is reduced to 1100 kt/yr.

b. UNECE values of AOT40

IIASA Reference to J1 produces a reduction in UNECE mean AOT40 in excess of 3 ppm hours of 12 %.

Use of UK7 to 8 results in a loss of 1 to 2% of this European improvement, whilst scenarios UK9 to 10 affect this by 7%. Thus, significant losses in benefit also accrue in Europe if UK VOC emissions remain at IIASA Reference.

c. Vegetation exposure to AOT40

Vegetation exposures could only be calculated using method a. IIASA Reference to J1 produces a reduction of 27% in the UK and 21% in the UNECE region. UK7 produces a loss in these improvements of 12% and UK10, of 60%. If NO_x emissions are reduced to 1150 kt/yr whilst VOC remain at IIASA Reference, 69% of the benefit of J1 for vegetation exposure to ozone in the UK is lost. Losses in the UNECE of about 5% accompany this.

d. Crop exposure to AOT40

Of the 67,545 km² of arable crop land in the UK, 66,041 km² fall in EMEP grid cells for which RAINS indicated AOT40 levels in excess of the critical level for crops. Therefore, the maximum area that could be exposed, according to RAINS, is 66,041 km².

There is additional data for a total of 522 km² permanent crops grown in the UK. According to MAFF, permanent crops comprise orchards, hops, and other fruit.

There is a 7.5% reduction in the area of UK arable crops exposed to excess levels of AOT40 upon moving from IIASA Reference to J1. The area concerned decreases from 63,000 to 58,000 km².

The attached map A5.1 shows the location of arable crops in the UK, and the location of those exposed, for the two scenarios, is shown on maps A5.2 and A5.3. The decrease in area exposed lies in Northern Ireland and S Scotland.

Since the area of permanent crops in the UK is rather small, the observed increases in protection levels are also small.

There are also considerable improvements in AOT40 levels in the areas of arable crops that remain exposed. Crop exposure has specifically been calculated to fall from 178 ppm hours 1000 km² (IIASA Reference) to 132 ppm hours 1000 km² (J1) in the UK.

Maps A5.2 and A5.3 show the crop exposure in each EMEP grid cell in the UK for the two scenarios. The biggest reductions in crop exposure are in the areas where most of the crops are to be found. In (17,14) exposure falls from 356 to 266 ppm hours 100 km² in excess of the threshold; whilst in (18,14) it falls from 307 to 247; and in (17,13) from 244 to 184. These three grid cells hold the largest areas of arable crops in the UK.

Conclusions

These investigations produce the message that if the full benefit of a J1 scenario is to be realised in the UK as far as exposures of humans to AOT60 and vegetation to AOT40 is concerned, it is important to reduce the VOC emissions to 1101 kt/yr. This maintains ozone at J1 levels. Decreasing NO_x below J1 and allowing VOC emissions to increase above J1, in at attempt to ‘trade’ VOC reductions for NO_x reductions, causes AOT60 and population exposure to AOT60 to increase both in the UK and in Europe as a whole.

For AOT40 and AOT60 the percentage of the benefit of J1 which is lost as a result of switching to the ‘UK’ suite of scenarios is rather large, both for human exposure and vegetation exposure. Only the UK7 scenario, in which VOC is reduced to 1150 kt/yr whilst NO_x remains at IIASA Reference, shows a relatively small increase in ozone exposures compared to J1.

The J1 scenario has considerable benefits in reducing crop exposure to AOT40 in the UK. Application of alternative UK scenarios would show similar trends as seen for AOT40 vegetation exposure.

ACIDIFICATION

Relevant scenarios

Apart from the basic scenarios, two additional scenarios are examined in which UK sulphur emissions are increased from J1 (499 kt SO₂/yr) to 525 (UKS11) and 700 (UKS13). It is the effect of the increasing S emissions that is being examined here.

Methods and Results

RAINS was used to extract areas protected from acidification in different countries under the various scenarios. Maps of areas protected were also produced in order that effects in individual grid cells could be examined.

1. Changes in area protection in individual grid cells
2. Basic scenarios