Transcript climate change – fixed climate - School of GeoSciences

Overlaps of AQ and climate policy –
global modelling perspectives
David Stevenson
Institute of Atmospheric and Environmental Science
School of GeoSciences
The University of Edinburgh
Thanks to:
Ruth Doherty (Univ. Edinburgh)
Dick Derwent (rdscientific)
Mike Sanderson, Colin Johnson, Bill Collins (Met Office)
Frank Dentener, Peter Bergamaschi, Frank Raes (JRC Ispra)
Markus Amann, Janusz Cofala, Reinhard Mechler (IIASA)
NERC and the Environment Agency for funding
Material mainly from 2 current publications:
The impact of air pollutant and methane emission
controls on tropospheric ozone and radiative
forcing: CTM calculations for the period 1990-2030
Dentener et al (2004) Atmos. Chem. Phys. Disc.
(currently open for discussion on the web)
Impacts of climate change and variability on
tropospheric ozone and its precursors
Stevenson et al (2005) Faraday Discussions
(upcoming discussion meeting at Leeds in April)
Rationale
• Regional-global scale AQ legislation has
implications for climate forcing – quantify
these for current and possible future policies
(use 2 very different models to try and reduce
model uncertainty)
• Climate change will influence AQ – use
coupled climate-chemistry model to identify
potentially important interactions
Modelling Approach
•
•
Global chemistry-climate model: STOCHEMHadAM3 (also some results from TM3+others)
Three transient runs: 1990 → 2030, following
different emissions/climate scenarios:
1. Current Legislation (CLE)
Assumes full implementation of all current legislation
2. Maximum Feasible Reductions (MFR)
Assumes full implementation of all available current emission
reduction technology
3. CLE + climate change
For 1 and 2, climate is unforced, and doesn’t change.
For 3, climate is forced by the is92a scenario, and shows a global
surface warming of ~1K between 1990 and 2030.
STOCHEM-HadAM3
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•
•
•
•
•
Global Lagrangian chemistry-climate model
Meteorology: HadAM3 + prescribed SSTs
GCM grid: 3.75° x 2.5° x 19 levels
CTM: 50,000 air parcels, 1 hour timestep
CTM output: 5° x 5° x 9 levels
Detailed tropospheric chemistry
•
Interactive lightning NOx, C5H8 from veg.
•
− CH4-CO-NOx-hydrocarbons (70 species)
− includes S chemistry
•
these respond to changing climate
~3 years/day on 36 processors (SGI Altix)
Global NOx emissions
200.0
SRES A2
160.0
120.0
CLE
80.0
40.0
MFR
0.0
1990
2000
Europe
Asia + Oceania
Africa + Middle East
SRES A2 - World Total
2010
2020
2030
North America
Latin America
Maximum Feasible Reduction (MFR)
SRES B2 - World Total
Figure 1. Projected development of IIASA anthropogenic NOx emissions by SRES world region (Tg NO2 yr-1).
Global CO emissions
1000.0
SRES A2
800.0
600.0
400.0
CLE
200.0
MFR
0.0
1990
2000
Europe
Asia + Oceania
Africa + Middle East
SRES A2 - World Total
2010
2020
2030
North America
Latin America
Maximum Feasible Reduction (MFR)
SRES B2 - World Total
Figure 2 Projected development of IIASA anthropogenic CO emissions by SRES world region (Tg CO yr-1).
Global CH4 emissions
SRES A2
600
500
CLE
400
MFR
300
200
100
0
1990
2000
Europe
Asia + Oceania
Africa + Middle East
SRES A2 - World Total
2010
2020
North America
Latin America
Maximum Feasible Reduction (MFR)
SRES B2 - World Total
Figure 3: Projected development of IIASA anthropogenic CH4 emissions by SRES region
(Tg CH4 yr-1).
2030
1990
2000
2030 CLE
2030 MFR
Regional NOx emissions
Figure 4. Regional emissions separated for sources categories in 1990, 2000, 2030-CLE and 2030-MFR for NOx [Tg NO2 yr-1]
Surface O3 (ppbv) 1990s
CLE
+2 to 4 ppbv over
N. Atlantic/Pacific
>+10 ppbv
India
A large fraction is
due to ship NOx
Change in surface O3, CLE 2020s-1990s
BAU
CLE Surface Annual Mean O3 2020s-1990s
TM3 (top) and STOCHEM (bottom)
Figure 13. Decadal averaged ozone volume mixing ratio differences [ppbv] comparing the 2020s and
1990s for (a) TM3 CLE and STOCHEM CLE.
Surface ΔO3
2030CLE–2000
(NB July)
18 Models from
IPCC-ACCENT
intercomparison
Up to -10 ppbv
over continents
Change in surface O3, MFR 2020s-1990s
MRF
BAU
MFR Surface Annual Mean O3 2020s-1990s
TM3 (top) and STOCHEM (bottom)
Figure 13(b) Decadal averaged ozone volume mixing ratio differences [ppbv] comparing the 2020s and
1990s for TM3 MFR and STOCHEM MFR
Surface ΔO3
2030MFR–2000
(NB July)
18 Models from
IPCC-ACCENT
intercomparison
CH4, CH4 & OH trajectories 1990-2030
CLE
CLEcc
Rad. Forcing / W/m2
If the world opts for MFR
over CLE, net reduction in
0.3 forcing of 0.2-0.3 W m-2
radiative
for the period 2000-2030
0.25
Methane controls
are the most
effective for RF
0.2
0.15
CH4
O3
0.1
0.05
0
-0.05
-0.1
CLE CLE MFR MFR MFR- MFRTM3 STOC TM3 STOC CH4
pol
CH4 0.167 0.125 0.004 0.003 -0.039 0.221
O3
0.075 0.041 -0.073 -0.072 0.029 -0.03
Part 1 Summary
• Co-benefits for both AQ and climate from some
emissions controls
• Methane offers the best opportunity (also CO and
NMVOCs)
• NOx controls (alone) benefit AQ, but probably worsen
climate forcing (via OH and CH4) (Similarly for SO2)
• AQ policies influence climate –
this study gives a quantitative assessment
• Use of many models shows results are quite
consistent
ΔO3 from climate change
Warmer
temperatures &
higher humidities
increase O3
destruction
over the oceans
But also a role
from increases
in isoprene
emissions from
vegetation &
changes in
lightning NOx
2020s CLEcc2020s CLE
Zonal mean ΔT (2020s-1990s)
Zonal mean H2O increase 2020s1990s
Zonal mean change in convective
updraught flux 2020s-1990s
C5H8 change 2020s (climate change –
fixed climate)
Lightning NOx change 2020s
(climate change –
fixed climate)
HadCM3
Amazon
drying
More lightning in N mid-lats
Less, but higher, tropical convection
No overall trend in Lightning NOx
emissions
Zonal mean PAN decrease 2020s
(climate change – fixed climate)
Colder LS
Increased
PAN
thermal
decomposition,
due to
increased T
Zonal mean NOx change 2020s
(climate change – fixed climate)
Less
tropical
convection
and
lightning
Increased
N mid-lat
convection
and
lightning
Increased
PAN
decomposition
Zonal mean O3 budget changes 2020s (climate
change – fixed climate)
Zonal mean O3 decrease 2020s (climate
change – fixed climate)
Zonal mean OH change 2020s
(climate change – fixed climate)
Complex
function:
F(H2O,
NOx,
O3,
T,…)
Influence of climate change on O3 –
4 IPCC ACCENT models
Part 2 Summary
• Climate change will introduce feedbacks that
•
modify air quality
These include:
– More O3 destruction from H2O
– More stratospheric input of ozone
– More isoprene emissions from vegetation
– Changes in lightning NOx
– Increases in sulphate from OH and H2O2
– Wetland CH4 emissions (not studied here)
– Changes in stomatal uptake? (``)
• These are quite poorly constrained – different
models show quite a wide range of response:
large uncertainties