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

More documents

Recommendations

Info

Downloaded from rsta.royalsocietypublishing.org on November 30, 2010 Phil. Trans. R. Soc. A (2011) 369, 85–98 doi:10.1098/rsta.2010.0283 Regional temperature and precipitation changes under high-end (≥4 ◦ C) global warming BY M. G. SANDERSON*, D. L. HEMMING AND R. A. BETTS Met Office Hadley Centre, Fitzroy Road, Exeter EX1 3PB, UK Climate models vary widely in their projections of both global mean temperature rise and regional climate changes, but are there any systematic differences in regional changes associated with different levels of global climate sensitivity? This paper examines model projections of climate change over the twenty-first century from the Intergovernmental Panel on Climate Change Fourth Assessment Report which used the A2 scenario from the IPCC Special Report on Emissions Scenarios, assessing whether different regional responses can be seen in models categorized as ‘high-end’ (those projecting 4◦C or more by the end of the twenty-first century relative to the preindustrial). It also identifies regions where the largest climate changes are projected under high-end warming. The mean spatial patterns of change, normalized against the global rate of warming, are generally similar in high-end and ‘non-high-end’ simulations. The exception is the higher latitudes, where land areas warm relatively faster in boreal summer in high-end models, but sea ice areas show varying differences in boreal winter. Many continental interiors warm approximately twice as fast as the global average, with this being particularly accentuated in boreal summer, and the winter-time Arctic Ocean temperatures rise more than three times faster than the global average. Large temperature increases and precipitation decreases are projected in some of the regions that currently experience water resource pressures, including Mediterranean fringe regions, indicating enhanced pressure on water resources in these areas. Keywords: regional climate change; precipitation; temperature; global climate models 1. Introduction Global emissions of greenhouse gases have continued to rise, with an increasing trend, throughout the twentieth century and the first decade of the twenty-first century. This has occurred against a backdrop of almost two decades of political efforts to limit greenhouse gas emissions since the Rio Earth Summit in 1992. The Copenhagen Accord, agreed in December 2009, has a stated aim of limiting global warming to 2 ◦ C above preindustrial temperatures. This target may be *Author for correspondence (michael.sanderson@metoffice.gov.uk). One contribution of 13 to a Theme Issue ‘Four degrees and beyond: the potential for a global temperature increase of four degrees and its implications’. 85 This journal is © 2011 The Royal Society
86 M. G. Sanderson et al. technically possible to achieve but will probably require substantial cuts in global greenhouse gas emissions in the very near future [1]. However, current national emissions-reduction pledges appear to be insufficient to keep global warming below 2 ◦ C[2]. Under scenarios of emissions in the absence of international climate policy, climate model projections assessed in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report ([3]; henceforth referred to as AR4) indicate a range of global mean warming between 1.1 ◦ C and 6.4 ◦ C for 2090–2099, relative to 1980–1999. Global temperatures rose by about 0.5 ◦ C between the preindustrial period and 1980–1999; hence, current climate projections encompass a range of 1.6–6.9 ◦ C for the end of the twenty-first century, relative to the preindustrial period. Such changes would be expected to exert major impacts and stresses on physical and human systems worldwide [4,5]. However, there are significant differences and uncertainties among the various climate models and their projections, and current knowledge on the potential for and implications of such extreme climate changes over the twenty-first century is limited. One key issue is whether changes in global mean temperature are a useful guide to changes in a particular region. Observational data and models agree that the world is not warming at a uniform rate across the globe, and this geographical variation in the rate of warming is expected to continue. There have been previous analyses of regional climate change from global climate projections and identification of areas most strongly affected. Giorgi & Bi [6] analysed temperature and precipitation changes for 26 land regions using an ensemble of global climate projections that were forced by the Special Report on Emissions Scenarios (SRES) A1B scenario [7]. They found that, in the model simulations, temperatures increased in all regions during the twentyfirst century, and precipitation decreased the most in Central America, southern South America, the Mediterranean and northern Africa, Central Asia, southern Africa and Australia. Precipitation increased over most other land areas, showing that, generally, rainfall decreased over dry areas but increased over wetter areas. Further analyses by Giorgi & Bi [8] identified when precipitation changes outside of the range of model projections and variability occur in various regions. Baettig et al. [9] developed climate change indices to identify regions where large changes in temperature and precipitation might occur. Using results from three global climate models, their results (for precipitation) were in agreement with those of Giorgi & Bi [6], except over the Amazon, southern South America and Central Asia. Some models project a faster rate of global warming than others, but it is not yet clear whether this involves systematic differences at the regional scale. This is an important issue as it could indicate whether a faster rate of warming could be associated with particular regional changes. This paper begins to address this question by analysing atmosphere–ocean global climate model (AOGCM) projections from the AR4. The range of projected global warming of 1.6–6.9 ◦ C was from a wide set of emission scenarios examined with a number of different types of models, including AOGCMs, simple climate models and Earth system models (including both GCMs and simple models incorporating biogeochemical feedbacks). This paper focuses on a subset of these projections, specifically the AR4 AOGCM simulations driven by a single emissions scenario (the SRES A2 scenario; [7]). 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:
Page 31 and 32:
Page 33 and 34:
(i) Energy and industrial process e
Page 35 and 36:
Page 37 and 38:
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 43 and 44: Beyond dangerous climate change 37
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 and 80: Review. Global warming reaching 4
Page 83 and 84: global surface warming (°C) 6 5 4
Page 87 and 88: temperature (relative to 1861-1890
Page 89 and 90: °C above pre-industrial 8 7 6 5 4
Page 93: Regional temperature and precipitat
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?