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climate change

Climate Projections for Hong Kong


Projected annual number of extreme rainfall days (daily rainfall ≥ 100 mm) in Hong Kong under different greenhouse gas concentration scenarios

Decade RCP2.6
Low
RCP4.5
Medium-low
RCP6.0
Medium-high
RCP8.5
High
Mean Likely range Mean Likely range Mean Likely range Mean Likely range
2011 - 2020 4.2 2.7 - 6.0 4.0 2.2 - 6.1 3.9 2.4 - 6.7 3.7 2.2 - 6.5
2021 - 2030 4.4 2.4 - 6.9 4.1 2.7 - 5.7 3.8 2.4 - 5.6 4.0 2.4 - 6.2
2031 - 2040 4.7 3.4 - 6.2 4.5 2.3 - 7.4 4.5 2.3 - 6.3 4.2 2.6 - 6.0
2041 - 2050 4.5 2.6 - 6.3 4.5 3.2 - 5.8 3.9 2.2 - 5.6 4.8 2.2 - 7.6
2051 - 2060 4.6 2.9 - 6.2 4.5 2.4 - 7.1 4.6 2.3 - 6.4 5.0 3.0 - 6.9
2061 - 2070 4.8 2.3 - 6.8 4.5 2.4 - 6.4 4.7 3.1 - 7.2 5.0 2.6 - 7.0
2071 - 2080 4.8 2.7 - 6.6 4.8 2.9 - 6.7 4.9 2.5 - 7.2 4.9 2.4 - 7.5
2081 - 2090 4.7 3.0 - 6.4 5.1 2.8 - 7.2 4.4 2.5 - 6.1 5.6 2.9 - 9.5
2091 - 2100 4.2 2.3 - 6.0 4.4 2.6 - 6.4 4.9 2.8 - 6.8 5.1 2.9 - 7.4

Notes on the climate projection data

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Projected average rainfall intensity (annual rainfall divided by the number of rain days, unit in mm/day) in Hong Kong under different greenhouse gas concentration scenarios

Decade RCP2.6
Low
RCP4.5
Medium-low
RCP6.0
Medium-high
RCP8.5
High
Mean Likely range Mean Likely range Mean Likely range Mean Likely range
2011 - 2020 24.1 22.0 - 26.4 23.3 19.7 - 27.8 23.3 20.8 - 26.7 22.7 19.5 - 27.1
2021 - 2030 23.7 19.5 - 29.0 24.2 21.1 - 28.4 23.2 20.9 - 25.7 23.5 20.1 - 27.8
2031 - 2040 25.3 22.1 - 29.1 24.7 21.1 - 29.0 24.3 20.9 - 27.2 23.6 21.3 - 26.4
2041 - 2050 24.5 22.0 - 29.6 24.8 21.9 - 27.5 23.4 20.3 - 27.1 25.9 22.1 - 30.1
2051 - 2060 25.0 22.0 - 28.4 25.0 21.5 - 30.5 24.3 19.0 - 30.0 25.4 21.6 - 30.3
2061 - 2070 24.5 19.8 - 27.7 24.4 21.1 - 28.3 24.9 21.1 - 28.0 25.9 20.8 - 32.2
2071 - 2080 25.2 20.7 - 28.2 25.2 22.0 - 28.8 25.0 21.9 - 29.0 26.0 21.1 - 32.0
2081 - 2090 25.3 21.9 - 30.3 25.3 20.5 - 30.1 24.6 21.1 - 27.8 27.6 22.2 - 37.0
2091 - 2100 23.9 20.5 - 27.2 24.0 21.3 - 27.2 25.5 23.2 - 28.6 26.7 22.0 - 31.8

Notes on the climate projection data

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Projected annual maximum daily rainfall (mm) in Hong Kong under different greenhouse gas concentration scenarios

Decade RCP2.6
Low
RCP4.5
Medium-low
RCP6.0
Medium-high
RCP8.5
High
Mean Likely range Mean Likely range Mean Likely range Mean Likely range
2011 - 2020 246 157 - 481 224 140 - 378 219 144 - 343 215 138 - 416
2021 - 2030 230 154 - 436 237 144 - 505 205 132 - 287 221 151 - 359
2031 - 2040 260 172 - 523 250 163 - 450 214 147 - 326 211 152 - 328
2041 - 2050 262 159 - 512 238 155 - 406 200 131 - 318 256 154 - 413
2051 - 2060 251 164 - 459 246 146 - 461 223 137 - 393 243 158 - 414
2061 - 2070 235 140 - 398 243 148 - 458 240 134 - 330 258 165 - 488
2071 - 2080 274 158 - 550 256 165 - 435 235 148 - 355 260 164 - 472
2081 - 2090 264 164 - 559 247 143 - 421 248 157 - 385 298 170 - 624
2091 - 2100 261 160 - 414 228 159 - 397 255 158 - 398 273 158 - 534

Notes on the climate projection data

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Projected annual maximum 3-day rainfall (mm) in Hong Kong under different greenhouse gas concentration scenarios

Decade RCP2.6
Low
RCP4.5
Medium-low
RCP6.0
Medium-high
RCP8.5
High
Mean Likely range Mean Likely range Mean Likely range Mean Likely range
2011 - 2020 495 337 - 795 435 288 - 672 453 306 - 618 424 303 - 685
2021 - 2030 453 327 - 689 466 310 - 821 418 310 - 595 433 320 - 606
2031 - 2040 514 365 - 786 490 309 - 807 451 319 - 594 419 309 - 632
2041 - 2050 501 345 - 840 473 338 - 729 425 292 - 635 505 324 - 698
2051 - 2060 498 359 - 717 482 307 - 734 460 303 - 772 476 337 - 691
2061 - 2070 465 291 - 639 469 313 - 753 491 302 - 666 510 331 - 865
2071 - 2080 531 335 - 893 500 328 - 846 475 343 - 681 510 334 - 810
2081 - 2090 509 339 - 877 496 307 - 748 508 336 - 683 568 351 - 1059
2091 - 2100 486 295 - 684 454 331 - 657 507 362 - 694 523 316 - 821

Notes on the climate projection data

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Projected annual maximum number of consecutive dry days in Hong Kong under different greenhouse gas concentration scenarios

Decade RCP2.6
Low
RCP4.5
Medium-low
RCP6.0
Medium-high
RCP8.5
High
Mean Likely range Mean Likely range Mean Likely range Mean Likely range
2011 - 2020 53 41 - 63 52 39 - 66 52 42 - 68 51 42 - 63
2021 - 2030 48 38 - 55 49 37 - 66 52 38 - 61 51 40 - 68
2031 - 2040 53 40 - 72 50 39 - 66 52 41 - 68 49 38 - 61
2041 - 2050 51 40 - 65 50 40 - 62 52 46 - 63 52 40 - 67
2051 - 2060 51 38 - 65 49 36 - 60 51 41 - 66 54 44 - 68
2061 - 2070 54 38 - 64 50 39 - 67 52 41 - 66 54 42 - 75
2071 - 2080 48 35 - 62 50 39 - 64 54 43 - 63 57 42 - 76
2081 - 2090 52 40 - 64 50 40 - 64 53 37 - 82 55 41 - 76
2091-2100 54 43 - 71 52 39 - 68 53 43 - 62 59 43 - 81

Notes on the climate projection data

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Projected annual number of rain days (daily rainfall ≥ 1 mm) in Hong Kong under different greenhouse gas concentration scenarios

Decade RCP2.6
Low
RCP4.5
Medium-low
RCP6.0
Medium-high
RCP8.5
High
Mean Likely range Mean Likely range Mean Likely range Mean Likely range
2011 - 2020 101 91 - 111 99 89 - 110 101 92 - 109 100 92 - 109
2021 - 2030 100 94 - 113 101 89 - 119 99 91 - 111 101 91 - 112
2031 - 2040 100 88 - 110 102 92 - 111 100 90 - 109 101 93 - 110
2041 - 2050 104 97 - 117 103 93 - 118 98 86 - 107 100 91 - 110
2051 - 2060 104 94 - 113 103 94 - 116 100 84 - 114 100 91 - 111
2061 - 2070 102 94 - 111 105 95 - 114 100 90 - 111 101 88 - 119
2071 - 2080 104 94 - 113 103 93 - 116 100 85 - 108 98 85 - 116
2081 - 2090 104 92 - 120 106 98 - 119 99 89 - 109 98 86 - 119
2091 - 2100 102 94 - 108 102 91 - 114 102 96 - 109 97 85 - 116

 

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Notes on the climate projection data

  1. It is important to note that climate projection is very different from weather or seasonal forecasts. Climate projection involves assumptions in future greenhouse gas concentration/emission scenarios and aims at describing the plausible change in the future climate from a long-term perspective, rather than depicting the "day-to-day" or "year-to-year" variations in weather.

  2. Although a majority of the model projections suggests in general consistent trends for the changes in the climate of the 21st century, inter-model differences in the projections for the future climate are still rather large. This, to a certain extent, reflects that climate projection is still subject to various uncertainties in the simulation of future climate, which depend very much on such factors as future greenhouse gas emissions, the choice of models, the ability of climate models to simulate physical processes, the downscaling methodology, the stability of the statistical downscaling relationship in the future. The technique is expected to continue to improve over time as scientists know more about various physical processes that impact on the climate.

  3. The Observatory utilizes data of a number of climate models in the IPCC Fifth Assessment Report (AR5) to project the temperature, rainfall and sea level changes in Hong Kong in the 21st century. Urbanization effect has been considered in the temperature projection.

  4. The data are provided to support climate research and impact studies. Proper acknowledgement of the data source should be made.