Environmental Engineering Reference
In-Depth Information
Fig. 3.
(a) Adjusted radiative forcing (W m
−2
) in 2030 versus 2005 due to changes in
tropospheric CH
4
(blue) and O
3
(red) calculated with the GFDL AM2 radiative transfer model
following Naik et al. (2007), and (b) percentage of model grid-cell days in the GFDL MOZART-
2 model with daily maximum 8-h average (MDA8) O
3
≥ 70 ppb in summer (June-July-August)
over the United States (62.5-127.5°W; 24-52°N) and Europe (10°W-50°E; 35-70°N), under the
baseline emissions scenario (CLE; global emissions of CH
4
, NO
x
, CO, and NMVOC change by
+29%, +19%, −10% and +3%, respectively) and with decreases in anthropogenic CH
4
emissions
by 2030 of 75 (A), 125 (B; cost-effective with available technologies), and 180 (C; requires
development of additional control technologies) Tg year
−1
, and in a simulation with pre-
industrial CH
4
concentrations (700 ppb). Non-CH
4
O
3
precursors follow the CLE scenario for
2030 in all simulations (Adapted from Table 4 and Figure 12 of Fiore et al. 2008)
Levy et al. (2008) find significant climate impacts by the year 2100 in the
GFDL CM2.1 climate model due to decreasing emissions of sulfur dioxide (SO
2
;
to 35% of 2000 levels by year 2100), the precursor of sulfate aerosol, and increasing
emissions of black carbon (scaled to CO emission projections) according to the
A1B “marker” scenario. In the second half of the 21st century, these projected
changes in emissions of short-lived species contribute substantially to the total
predicted surface temperature warming for the full A1B scenario: 0.2°C in the
Southern Hemisphere, 0.4°C globally, and 0.6°C in the Northern Hemisphere.
We consider only the direct radiative effect of aerosols, which has been shown to
add linearly to the radiative effect of greenhouse gases (e.g., Gillett et al., 2004),
with similar climate responses to their forcings (Levy et al., 2008). In
Fig. 4 w
e
present the radiative forcing and surface temperature change in boreal summer
between the 2090s and the 2000s due to the changes in emissions of short-lived
gases and aerosols. Note that the largest temperature changes occur over the
continental United States, Southern Europe and the Mediterranean, which do not
coincide with the regions of strongest emission changes and radiative forcing
(Southern and Eastern Asia).
Fig. 4.
Radiative forcing (W m
−2
; left) and surface temperature change (°C; right) during boreal
summer resulting from changes in short-lived species from the 2000s (2001-2010 average) to the
2090s (2091-2100 average) in the GFDL CM2.1 model following an SRES A1B emission
scenario (Levy et al., 2008) (Adapted from Levy et al. 2008)
