Four degrees and beyond: the potential for a global ... - Amper

More documents

Recommendations

Info

72 R. A. Betts et al. billions of tons of carbon 13 12 11 10 9 8 7 6 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 year 2010 2012 2014 2016 2018 2020 Figure 3. Comparison of actual fossil-fuel CO2 emissions from 1990 to 2007 with SRES emissions scenarios. Dashed lines show mean emissions from all IAMs for each SRES storyline, and solid lines show the emissions from the SRES marker scenarios as used in the IPCC climate projections (figures 1 and 2). Observed emissions (published October 2008) are from Carbon Dioxide Information and Analysis Center, ‘Latest Published Global Estimates’ and ‘2006–2007 Global and National Estimates by Extrapolation’ (http://cdiac.ornl.gov/trends/emis/meth_reg.html). Filled squares, actual; red line, A1B; orange line, A1FI; grey line, A1T; green line, A2; brown line, B1; blue line, B2; red dashed line, A1B*; orange dashed line, A1FI*; grey dashed line, A1T*; green dashed line, A2*; brown dashed line, B1*; blue dashed line, B2*. Adapted from Leggett & Logan [9]. Cooperation and Development (OECD) countries and Russia fell by 7 per cent owing to the economic situation, but this was almost balanced by an increase in emissions from China and India [7]. Suggestions that actual emissions have been above the upper limit of the IPCC SRES range are erroneous, and appear to be based on comparisons with the averages of different versions of the scenarios from different IAMs ([8]; dashed lines in figure 3) rather than with the individual scenarios that were actually used in climate models. Actual emissions have been within the range of the marker scenarios [3,6,9]. Given the uncertainties in the emissions scenarios themselves, and their aim of capturing long-term trends rather than short-term variations, it is still considered too early to reliably assess whether any particular SRES marker scenario is more plausible than any other [9]. 3. Airborne fraction of CO2 emissions: projections and recent observations In the AR4, it was noted that projections of climate change should consider not only the uncertainties in the response of global temperature to a given change in CO2 concentration (‘climate sensitivity’ 2 ), but also the uncertainties 2 Climate sensitivity is the equilibrium response of global mean temperature to a doubling of atmospheric CO2 concentration (or CO2 equivalent of other greenhouse gases). In climate projections driven by time-dependent scenarios of greenhouse-gas concentrations, in which temperature change lags the change in forcing, a related measure is the temperature change at the time of CO2 doubling (‘transient climate response’). Phil. Trans. R. Soc. A (2011) Downloaded from rsta.royalsocietypublishing.org on November 30, 2010
Review. Global warming reaching 4 ◦ C 73 in translating emissions scenarios into concentrations. The ratio between the rate of rise of atmospheric CO2 concentrations and the rate of emissions is termed the future ‘airborne fraction’. There is now a large body of evidence suggesting that the airborne fraction can be expected to be greater with climate change than without, particularly as land carbon sinks are projected to become weaker as a consequence of climate change [10–13]. The airborne fraction is currently approximately 40 ± 14% [14], and interpretations vary on whether the airborne fraction is already increasing significantly. Le Quéré et al. [6] suggest a trend of increasing airborne fraction of 0.3 ± 0.2% yr −1 between 1959 and 2008, whereas Knorr [16] suggests an insignificant trend of 0.07 ± 0.14% yr −1 since 1850. Uncertainties, particularly in CO2 emissions from land-use change, make a precise determination of any trend difficult. The Coupled Climate–Carbon Cycle Model Intercomparison Project (C4MIP; [12]) used a number of coupled climate–carbon-cycle models to examine uncertainties in the strength of feedbacks between climate change and the carbon cycle. The C4MIP included some models based on GCMs (including several that were closely aligned to those used for the main projections in the IPCC), and also Earth System Models of Intermediate Complexity (EMIC). The C4MIP models were driven by observed twentieth century emissions and the SRES A2 scenario of future emissions, and simulated the resulting carboncycle processes, including changes in land and ocean carbon sinks and in atmospheric CO2 concentrations. The models were used in two modes: (i) changes in atmospheric CO2 affecting the climate through changes in the greenhouse effect, to allow for climate change to affect the carbon cycle and (ii) ‘switching off’ the greenhouse contribution of additional CO2, to isolate the behaviour of the carbon cycle in the absence of feedbacks from climate change. The different projections of atmospheric CO2 concentration between (i) and (ii), therefore, showed the magnitude of the climate–carbon-cycle feedback. The C4MIP models simulated airborne fractions of 38–56% in the absence of climate-change effects, and importantly, none of the models simulated a significant increase in the airborne fraction from 1960 to 2006, even when climatechange effects were included; indeed many of the models simulate a decrease in the airborne fraction (figure 4). The lack of increase in the airborne fraction over the twentieth century can be explained by the strong dependency on previous emissions [17]. Although the C4MIP models simulate a weaker land carbon sink over the twentieth century when climate-change effects are included, this does not translate into an increase in the airborne fraction at that time because previous emissions are still the dominant factor. In the projections of twenty-first century CO2 rise and climate change under the SRES A2 emissions scenario, all C4MIP models simulated a faster CO2 rise and increasing airborne fraction when climate-change effects were included over the twenty-first century [12]. While there were shown to be large uncertainties in the strength of the climate–carbon-cycle feedback [18] and the consequent impact on the rate of rise in atmospheric CO2 concentrations, there was unanimous agreement between the C4MIP models that this feedback is positive in sign and hence is expected to lead to an acceleration of the rise in CO2 levels (figure 5). Recent simulations with coupled climate–carbon-cycle models now including Phil. Trans. R. Soc. A (2011) Downloaded from rsta.royalsocietypublishing.org on November 30, 2010
Page 1 and 2:
ISSN 1364-503X volume 369 number 19
Page 3 and 4:
Phil. Trans. R. Soc. A (2011) 369,
Page 5 and 6:
Editorial David Garner Phil. Trans.
Page 7 and 8:
Four degrees and beyond: the potent
Page 9 and 10:
Preface 5 commitments might give us
Page 11 and 12:
Downloaded from rsta.royalsocietypu
Page 13 and 14:
8 M. New et al. In the final plenar
Page 15 and 16:
10 M. New et al. supports the messa
Page 17 and 18:
12 M. New et al. Table 1. Impacts a
Page 19 and 20:
14 M. New et al. actors (NNSAs)—r
Page 21 and 22:
16 M. New et al. as permanent crop
Page 23 and 24:
18 M. New et al. 24 Boe, J. L., Hal
Page 25 and 26:
Beyond 'dangerous' climate change:
Page 27 and 28:
Beyond dangerous climate change 21
Page 29 and 30: Beyond dangerous climate change 23
Page 33 and 34: (i) Energy and industrial process e
Page 39 and 40: (a) 50 (b) GtCO 2e yr -1 40 30 20 1
Page 41 and 42: Table 1. Summary of scenario pathwa
Page 51 and 52: Cumulative carbon emissions, emissi
Page 53 and 54: 46 N. H. A. Bowerman et al. althoug
Page 55 and 56: 48 N. H. A. Bowerman et al. a likel
Page 57 and 58: 50 N. H. A. Bowerman et al. (b) Mod
Page 59 and 60: 52 N. H. A. Bowerman et al. In most
Page 61 and 62: 54 N. H. A. Bowerman et al. rates o
Page 63 and 64: 56 N. H. A. Bowerman et al. (a) pea
Page 65 and 66: 58 N. H. A. Bowerman et al. We can
Page 67 and 68: 60 N. H. A. Bowerman et al. (a) rel
Page 69 and 70: 62 N. H. A. Bowerman et al. (a) 0.3
Page 71 and 72: 64 N. H. A. Bowerman et al. 4. Conc
Page 73 and 74: 66 N. H. A. Bowerman et al. increas
Page 75 and 76: Downloaded from rsta.royalsocietypu
Page 77 and 78: emissions (GtC) Review. Global warm
Page 79: Review. Global warming reaching 4
Page 83 and 84: global surface warming (°C) 6 5 4
Page 85 and 86: Review. Global warming reaching 4
Page 87 and 88: temperature (relative to 1861-1890
Page 89 and 90: °C above pre-industrial 8 7 6 5 4
Page 91 and 92: Review. Global warming reaching 4
Page 93 and 94: Regional temperature and precipitat
Page 95 and 96: 86 M. G. Sanderson et al. technical
Page 97 and 98: 88 M. G. Sanderson et al. Table 1.
Page 99 and 100: 90 M. G. Sanderson et al. (a) 90°
Page 101 and 102: 92 M. G. Sanderson et al. An area o
Page 103 and 104: 94 M. G. Sanderson et al. South Ame
Page 105 and 106: 96 M. G. Sanderson et al. For DJF (
Page 107 and 108: 98 M. G. Sanderson et al. 12 Betts,
Page 109 and 110: Downloaded from rsta.royalsocietypu
Page 111 and 112: Water availability in +2 ◦ C and
Page 113 and 114: (ii) Water stress index Water avail
Page 115 and 116: (b) (c) (d) (a) Water availability
Page 119 and 120: (a) number of models, black line nu
Page 121 and 122: change in run-off (%) change in run
Page 127 and 128: Agriculture and food systems in sub
Page 129 and 130: 118 P. K. Thornton et al. 1. Introd
Page 131 and 132:
120 P. K. Thornton et al. increases
Page 133 and 134:
122 P. K. Thornton et al. Table 1.
Page 135 and 136:
124 P. K. Thornton et al. century.
Page 137 and 138:
126 P. K. Thornton et al. and polit
Page 139 and 140:
128 P. K. Thornton et al. — The r
Page 141 and 142:
130 P. K. Thornton et al. keepers i
Page 143 and 144:
132 P. K. Thornton et al. 3 Frayne,
Page 145 and 146:
134 P. K. Thornton et al. 41 Erikse
Page 147 and 148:
136 P. K. Thornton et al. 83 Challi
Page 149 and 150:
Page 151 and 152:
Humid tropical forests on a warmer
Page 153 and 154:
(a) Humid tropical forests on a war
Page 155 and 156:
Page 157 and 158:
Page 159 and 160:
Page 161 and 162:
0 retraction risk 17 120 80 40 (a)
Page 163 and 164:
Page 165 and 166:
0 retraction risk 17 120 80 40 0
Page 167 and 168:
Page 169 and 170:
Page 171 and 172:
Page 173 and 174:
Sea-level rise and its possible imp
Page 175 and 176:
162 R. J. Nicholls et al. expected.
Page 177 and 178:
164 R. J. Nicholls et al. sea-level
Page 179 and 180:
166 R. J. Nicholls et al. mean temp
Page 181 and 182:
168 R. J. Nicholls et al. interglac
Page 183 and 184:
170 R. J. Nicholls et al. discussed
Page 185 and 186:
172 R. J. Nicholls et al. land loss
Page 187 and 188:
174 R. J. Nicholls et al. global ad
Page 189 and 190:
176 R. J. Nicholls et al. Hence, th
Page 191 and 192:
178 R. J. Nicholls et al. to climat
Page 193 and 194:
180 R. J. Nicholls et al. 43 Pardae
Page 195 and 196:
Climate-induced population displace
Page 197 and 198:
Page 199 and 200:
Page 201 and 202:
Page 203 and 204:
Page 205 and 206:
Page 207 and 208:
Page 209 and 210:
Page 211 and 212:
Page 213 and 214:
198 M. Stafford Smith et al. the di
Page 215 and 216:
200 M. Stafford Smith et al. greate
Page 217 and 218:
202 M. Stafford Smith et al. Table
Page 219 and 220:
204 M. Stafford Smith et al. (c) Go
Page 221 and 222:
206 M. Stafford Smith et al. mean g
Page 223 and 224:
208 M. Stafford Smith et al. These
Page 225 and 226:
210 M. Stafford Smith et al. consid
Page 227 and 228:
212 M. Stafford Smith et al. — De
Page 229 and 230:
214 M. Stafford Smith et al. 12 Lem
Page 231 and 232:
216 M. Stafford Smith et al. 51 Ste
Page 233 and 234:
REVIEW Phil. Trans. R. Soc. A (2011
Page 235 and 236:
Review. Interactions in a 4 ◦ C w
Page 237 and 238:
Page 239 and 240:
spread in mosquitoborne disease may
Page 241 and 242:
[89,94,95] further acidification by
Page 243 and 244:
Page 245 and 246:
Page 247 and 248:
Page 249 and 250:
Page 251 and 252:
Page 253 and 254:
Page 255 and 256:
Page 257 and 258:
Page 259:
Editorial Editorial 3 D. Garner Pre
show all

Four degrees and beyond: the potential for a global ... - Amper

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?