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| Titel |
Evaluating the climate and air quality impacts of short-lived pollutants |
| VerfasserIn |
A. Stohl, B. Aamaas, M. Amann, L. H. Baker, N. Bellouin, T. K. Berntsen, O. Boucher, R. Cherian, W. Collins, N. Daskalakis, M. Dusinska, S. Eckhardt, J. S. Fuglestvedt, M. Harju, C. Heyes, Ø. Hodnebrog, J. Hao, U. Im, M. Kanakidou, Z. Klimont, K. Kupiainen, K. S. Law, M. T. Lund, R. Maas, C. R. MacIntosh, G. Myhre, S. Myriokefalitakis, D. Olivié, J. Quaas, B. Quennehen, J.-C. Raut, S. T. Rumbold, B. H. Samset, M. Schulz, Ø. Seland, K. P. Shine, R. B. Skeie, S. Wang, K. E. Yttri, T. Zhu |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 18 ; Nr. 15, no. 18 (2015-09-24), S.10529-10566 |
| Datensatznummer |
250120049
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| Publikation (Nr.) |
 copernicus.org/acp-15-10529-2015.pdf |
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| Zusammenfassung |
| This paper presents a summary of the work done within the European Union's
Seventh Framework Programme project ECLIPSE (Evaluating the Climate and Air
Quality Impacts of Short-Lived Pollutants). ECLIPSE had a unique systematic
concept for designing a realistic and effective mitigation scenario for
short-lived climate pollutants (SLCPs; methane, aerosols and ozone, and
their precursor species) and quantifying its climate and air quality
impacts, and this paper presents the results in the context of this
overarching strategy. The first step in ECLIPSE was to create a new emission
inventory based on current legislation (CLE) for the recent past and until
2050. Substantial progress compared to previous work was made by including
previously unaccounted types of sources such as flaring of gas associated
with oil production, and wick lamps. These emission data were used for
present-day reference simulations with four advanced Earth system models
(ESMs) and six chemistry transport models (CTMs). The model simulations were
compared with a variety of ground-based and satellite observational data
sets from Asia, Europe and the Arctic. It was found that the models still
underestimate the measured seasonality of aerosols in the Arctic but to a
lesser extent than in previous studies. Problems likely related to the
emissions were identified for northern Russia and India, in particular. To
estimate the climate impacts of SLCPs, ECLIPSE followed two paths of
research: the first path calculated radiative forcing (RF) values for a
large matrix of SLCP species emissions, for different seasons and regions
independently. Based on these RF calculations, the Global Temperature change Potential metric for a time horizon of 20 years (GTP20) was calculated
for each SLCP emission type. This climate metric was then used in an
integrated assessment model to identify all emission mitigation measures
with a beneficial air quality and short-term (20-year) climate impact. These
measures together defined a SLCP mitigation (MIT) scenario. Compared to CLE,
the MIT scenario would reduce global methane (CH4) and black carbon (BC)
emissions by about 50 and 80 %, respectively. For CH4, measures
on shale gas production, waste management and coal mines were most
important. For non-CH4 SLCPs, elimination of high-emitting vehicles and
wick lamps, as well as reducing emissions from gas flaring, coal and biomass
stoves, agricultural waste, solvents and diesel engines were most important.
These measures lead to large reductions in calculated surface concentrations
of ozone and particulate matter. We estimate that in the EU, the loss of
statistical life expectancy due to air pollution was 7.5 months in 2010,
which will be reduced to 5.2 months by 2030 in the CLE scenario. The MIT
scenario would reduce this value by another 0.9 to 4.3 months.
Substantially larger reductions due to the mitigation are found for China
(1.8 months) and India (11–12 months). The climate metrics cannot fully
quantify the climate response. Therefore, a second research path was taken.
Transient climate ensemble simulations with the four ESMs were run for the CLE
and MIT scenarios, to determine the climate impacts of the mitigation. In
these simulations, the CLE scenario resulted in a surface temperature
increase of 0.70 ± 0.14 K between the years 2006 and 2050. For the
decade 2041–2050, the warming was reduced by 0.22 ± 0.07 K in the MIT
scenario, and this result was in almost exact agreement with the response
calculated based on the emission metrics (reduced warming of 0.22 ± 0.09 K).
The metrics calculations suggest that non-CH4 SLCPs contribute
~ 22 % to this response and CH4 78 %. This could not
be fully confirmed by the transient simulations, which attributed about
90 % of the temperature response to CH4 reductions. Attribution of
the observed temperature response to non-CH4 SLCP emission reductions
and BC specifically is hampered in the transient simulations
by small forcing and co-emitted species of the emission basket chosen.
Nevertheless, an important conclusion is that our mitigation basket as a
whole would lead to clear benefits for both air quality and climate. The
climate response from BC reductions in our study is smaller than reported
previously, possibly because our study is one of the first to use fully
coupled climate models, where unforced variability and sea ice responses
cause relatively strong temperature fluctuations that may counteract (and, thus, mask) the impacts of small emission reductions. The temperature
responses to the mitigation were generally stronger over the continents than
over the oceans, and with a warming reduction of 0.44 K (0.39–0.49) K the largest
over the Arctic. Our calculations suggest particularly beneficial climate
responses in southern Europe, where surface warming was reduced by about
0.3 K and precipitation rates were increased by about 15 (6–21) mm yr−1 (more
than 4 % of total precipitation) from spring to autumn. Thus, the
mitigation could help to alleviate expected future drought and water
shortages in the Mediterranean area. We also report other important results
of the ECLIPSE project. |
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