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Climate Projections for Hong Kong

Climate Projections for Hong Kong

Projected changes in the annual temperature (°C) of Hong Kong relative to the average of 1986-2005 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
2021 - 2030 0.8 0.5 - 1.3 0.8 0.5 - 1.2 0.8 0.4 - 1.2 0.9 0.6 - 1.4
2031 - 2040 1.0 0.6 - 1.6 1.1 0.6 - 1.6 0.9 0.6 - 1.2 1.3 0.8 - 1.9
2041 - 2050 1.2 0.7 - 1.9 1.4 0.9 - 1.9 1.2 0.8 - 1.5 1.7 1.1 - 2.4
2051 - 2060 1.3 0.8 - 1.9 1.7 1.0 - 2.4 1.4 0.9 - 2.0 2.2 1.6 - 3.0
2061 - 2070 1.3 0.8 - 1.9 1.9 1.2 - 2.6 1.7 1.1 - 2.3 2.7 2.0 - 3.8
2071 - 2080 1.3 0.7 - 2.0 2.0 1.4 - 2.9 2.1 1.6 - 2.8 3.2 2.2 - 4.3
2081 - 2090 1.3 0.7 - 2.1 2.1 1.3 - 3.1 2.4 1.7 - 3.2 3.7 2.6 - 5.0
2091 - 2100 1.3 0.7 - 2.2 2.2 1.4 - 3.2 2.6 1.8 - 3.6 4.2 3.1 - 5.5

Notes on the climate projection data

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Projected annual number of hot nights (days with a minimum temperature of 28°C or above) in Hong Kong under different greenhouse gas concentration scenarios. The average annual number of hot nights in 1986-2005 was 18.

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
2021 - 2030 37 28 - 49 35 20 - 50 34 23 - 50 39 25 - 56
2031 - 2040 47 33 - 63 45 24 - 68 32 20 - 45 47 31 - 68
2041 - 2050 54 30 - 78 55 34 - 77 45 30 - 70 61 40 - 82
2051 - 2060 55 36 - 82 65 43 - 88 49 34 - 73 81 51 - 109
2061 - 2070 54 37 - 77 73 46 - 98 60 42 - 83 99 70 - 127
2071 - 2080 53 34 - 73 79 48 - 108 77 53 - 102 116 80 - 150
2081 - 2090 52 33 - 78 78 51 - 107 88 64 - 119 133 93 - 165
2091 - 2100 50 36 - 65 78 49 - 106 96 67 - 127 149 112 - 183

Notes on the climate projection data

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Projected annual number of very hot days (days with a maximum temperature of 33°C or above) in Hong Kong under different greenhouse gas concentration scenarios. The average annual number of very hot days in 1986-2005 was 9.

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
2021 - 2030 25 17 - 36 24 13 - 38 23 16 - 36 27 17 - 40
2031 - 2040 30 21 - 41 30 16 - 47 21 14 - 31 31 20 - 46
2041 - 2050 33 19 - 60 35 21 - 52 27 15 - 50 39 23 - 58
2051 - 2060 34 20 - 53 42 27 - 62 28 16 - 47 52 28 - 81
2061 - 2070 34 20 - 55 45 24 - 72 34 19 - 61 64 39 - 101
2071 - 2080 30 17 - 44 48 27 - 75 45 27 - 75 81 46 - 124
2081 - 2090 27 16 - 45 44 25 - 75 53 30 - 91 95 56 - 142
2091 - 2100 24 15 - 40 45 23 - 70 57 32 - 101 112 66 - 159

Notes on the climate projection data

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Projected annual number of cold days (days with a minimum temperature of 12°C or below) in Hong Kong under different greenhouse gas concentration scenarios. The average annual number of cold days in 1986-2005 was 15.

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
2021 - 2030 9 5 - 14 10 6 - 14 10 6 - 15 9 5 - 12
2031 - 2040 8 4 - 12 8 4 - 12 9 5 - 14 8 4 - 14
2041 - 2050 7 4 - 12 7 4 - 11 7 3 - 11 5 2 - 9
2051 - 2060 6 3 - 10 6 2 - 11 7 4 - 11 4 1 - 8
2061 - 2070 6 3 - 10 4 2 - 9 6 2 - 10 3 0 - 8
2071 - 2080 6 3 - 9 4 2 - 7 4 1 - 7 2 0 - 6
2081 - 2090 6 3 - 9 4 1 - 8 3 1 - 7 1 0 - 4
2091 - 2100 6 3 - 10 3 1 - 7 3 1 - 6 1 0 - 4

Notes on the climate projection data

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Projected annual rainfall anomaly (mm) of Hong Kong relative to the average of 1986-2005 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
2021 - 2030 -171 -501 - 198 -150 -448 - 206 -171 -410 - 149 -103 -404 - 317
2031 - 2040 -135 -366 - 85 -93 -385 - 251 -130 -364 - 142 -99 -447 - 193
2041 - 2050 -60 -373 - 291 56 -283 - 334 -155 -517 - 131 -50 -343 - 319
2051 - 2060 6 -264 - 320 -13 -382 - 343 -161 -488 - 212 16 -324 - 339
2061 - 2070 -22 -428 - 213 -23 -268 - 303 -114 -464 - 159 90 -426 - 607
2071 - 2080 -88 -386 - 189 1 -317 - 317 -43 -301 - 205 125 -200 - 532
2081 - 2090 -19 -311 - 362 142 -201 - 539 -18 -322 - 343 158 -268 - 729
2091 - 2100 -145 -381 - 63 -24 -387 - 396 90 -190 - 552 177 -263 - 806

Notes on the climate projection data

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Projected extremely wet (annual rainfall > 3168 mm) and extremely dry (annual rainfall < 1289 mm) years 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
Extremely wet years 7 1 - 12 9 3 - 17 8 3 - 14 12 5 - 20
Extremely dry years 3 0 - 5 2 0 - 5 3 0 - 7 2 0 - 6

Notes on the climate projection data

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Projected changes in the mean sea level in Hong Kong and its adjacent waters (with the effect of local vertical land displacement incorporated) under different greenhouse gas concentration scenarios (relative to the average of 1986-2005, unit in metre)

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
2021 - 2030 0.16 0.10 - 0.22 0.16 0.11 - 0.21 0.17 0.12 - 0.21 0.16 0.11 - 0.22
2031 - 2040 0.22 0.16 - 0.29 0.22 0.16 - 0.29 0.23 0.16 - 0.28 0.24 0.17 - 0.32
2041 - 2050 0.29 0.21 - 0.38 0.30 0.22 - 0.38 0.30 0.22 - 0.37 0.33 0.24 - 0.42
2051 - 2060 0.36 0.26 - 0.46 0.37 0.27 - 0.48 0.38 0.27 - 0.46 0.43 0.32 - 0.55
2061 - 2070 0.42 0.31 - 0.55 0.46 0.34 - 0.59 0.45 0.33 - 0.56 0.54 0.41 - 0.70
2071 - 2080 0.49 0.36 - 0.63 0.54 0.40 - 0.70 0.54 0.41 - 0.68 0.67 0.50 - 0.86
2081 - 2090 0.54 0.40 - 0.71 0.63 0.47 - 0.81 0.63 0.47 - 0.80 0.81 0.61 - 1.05
2091 - 2100 0.60 0.44 - 0.79 0.71 0.53 - 0.92 0.73 0.54 - 0.93 0.98 0.73 - 1.28

# SROCC has not provided projections under the RCP6.0 scenario. Projections based on AR5 data are shown here.

Notes on the climate projection data

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Projected changes in the mean sea level in Hong Kong and its adjacent waters (without the effect of local vertical land displacement incorporated) under different greenhouse gas concentration scenarios (relative to the average of 1986-2005, unit in metre)

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
2021 - 2030 0.10 0.05 - 0.16 0.10 0.05 - 0.14 0.11 0.06 - 0.15 0.10 0.05 - 0.16
2031 - 2040 0.14 0.08 - 0.21 0.14 0.08 - 0.21 0.15 0.09 - 0.20 0.16 0.09 - 0.23
2041 - 2050 0.19 0.11 - 0.28 0.20 0.12 - 0.28 0.20 0.13 - 0.27 0.22 0.14 - 0.32
2051 - 2060 0.23 0.15 - 0.33 0.25 0.16 - 0.35 0.26 0.16 - 0.34 0.31 0.20 - 0.42
2061 - 2070 0.28 0.18 - 0.40 0.32 0.20 - 0.45 0.31 0.20 - 0.41 0.40 0.27 - 0.55
2071 - 2080 0.32 0.20 - 0.46 0.38 0.25 - 0.53 0.38 0.26 - 0.51 0.51 0.35 - 0.69
2081 - 2090 0.36 0.22 - 0.52 0.45 0.29 - 0.62 0.45 0.30 - 0.61 0.63 0.44 - 0.87
2091 - 2100 0.40 0.24 - 0.58 0.51 0.34 - 0.71 0.53 0.35 - 0.72 0.78 0.53 - 1.08

# SROCC has not provided projections under the RCP6.0 scenario. Projections based on AR5 data are shown here.

Notes on the climate projection data

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Projected annual number of extremely warm-and-humid days (days with a maximum wet-bulb temperature of 28.2°C or above) 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
2021 - 2030 15 9 - 22 14 7 - 25 14 10 - 18 16 9 - 24
2031 - 2040 21 12 - 32 20 8 - 34 13 10 - 18 23 13 - 36
2041 - 2050 24 11 - 42 27 15 - 43 21 11 - 32 36 19 - 59
2051 - 2060 25 12 - 41 35 21 - 56 23 13 - 41 52 24 - 81
2061 - 2070 25 14 - 40 39 19 - 66 30 13 - 52 65 36 - 99
2071 - 2080 22 12 - 35 42 21 - 73 41 23 - 60 79 40 - 129
2081 - 2090 19 9 - 36 36 18 - 63 48 25 - 78 89 48 - 135
2091 - 2100 17 9 - 27 35 16 - 59 47 19 - 82 96 48 - 148

Notes on the climate projection data

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Projected annual maximum number of consecutive extremely warm-and-humid 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
2021 - 2030 6 4 - 8 6 3 - 9 6 4 - 8 6 4 - 9
2031 - 2040 8 5 - 12 8 4 - 15 6 4 - 8 8 5 - 13
2041 - 2050 8 5 - 15 9 6 - 14 8 5 - 12 11 7 - 17
2051 - 2060 8 5 - 14 11 7 - 19 8 5 - 14 16 9 - 29
2061 - 2070 9 5 - 13 12 6 - 22 10 5 - 17 19 10 - 40
2071 - 2080 8 5 - 11 13 7 - 23 13 8 - 22 24 11 - 59
2081 - 2090 7 4 - 11 10 5 - 17 16 8 - 27 26 13 - 58
2091 - 2100 7 4 - 10 11 6 - 24 14 7 - 30 28 12 - 65

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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 AR5 to project the temperature and rainfall changes in Hong Kong in the 21st century. Urbanization effect has been considered in the temperature projection. Sea level rise projections are based on SROCC and AR5 data.

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